[llvm-commits] [llvm] r137830 - in /llvm/trunk: include/llvm/MC/ lib/Target/ARM/Disassembler/ lib/Target/MBlaze/Disassembler/ lib/Target/X86/Disassembler/ test/MC/Disassembler/ARM/ tools/llvm-mc/ utils/TableGen/

Jim Grosbach grosbach at apple.com
Tue Aug 30 12:15:24 PDT 2011


ping?

On Aug 26, 2011, at 11:56 AM, Jim Grosbach wrote:

> Sorry for the late comments. I missed this catching these bits the first time around (saw the patch, just missed this aspect).
> 
> On Aug 17, 2011, at 10:44 AM, Owen Anderson wrote:
> 
>> Author: resistor
>> Date: Wed Aug 17 12:44:15 2011
>> New Revision: 137830
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=137830&view=rev
>> Log:
>> Allow the MCDisassembler to return a "soft fail" status code, indicating an instruction that is disassemblable, but invalid.  Only used for ARM UNPREDICTABLE instructions at the moment.
>> Patch by James Molloy.
>> 
>> Modified:
>>   llvm/trunk/include/llvm/MC/MCDisassembler.h
>>   llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
>>   llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.h
>>   llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp
>>   llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.h
>>   llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.cpp
>>   llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.h
>>   llvm/trunk/test/MC/Disassembler/ARM/invalid-LDRB_POST-arm.txt
>>   llvm/trunk/tools/llvm-mc/Disassembler.cpp
>>   llvm/trunk/utils/TableGen/DisassemblerEmitter.cpp
>>   llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.cpp
>>   llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.h
>> 
>> Modified: llvm/trunk/include/llvm/MC/MCDisassembler.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCDisassembler.h?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/MC/MCDisassembler.h (original)
>> +++ llvm/trunk/include/llvm/MC/MCDisassembler.h Wed Aug 17 12:44:15 2011
>> @@ -25,6 +25,34 @@
>> ///   and provides an array of assembly instructions.
>> class MCDisassembler {
>> public:
>> +  /// Ternary decode status. Most backends will just use Fail and
>> +  /// Success, however some have a concept of an instruction with
>> +  /// understandable semantics but which is architecturally
>> +  /// incorrect. An example of this is ARM UNPREDICTABLE instructions
>> +  /// which are disassemblable but cause undefined behaviour.
>> +  ///
>> +  /// Because it makes sense to disassemble these instructions, there
>> +  /// is a "soft fail" failure mode that indicates the MCInst& is
>> +  /// valid but architecturally incorrect.
>> +  ///
>> +  /// The enum numbers are deliberately chosen such that reduction
>> +  /// from Success->SoftFail ->Fail can be done with a simple
>> +  /// bitwise-AND:
>> +  ///
>> +  ///   LEFT & TOP =  | Success       Unpredictable   Fail
>> +  ///   --------------+-----------------------------------
>> +  ///   Success       | Success       Unpredictable   Fail
>> +  ///   Unpredictable | Unpredictable Unpredictable   Fail
>> +  ///   Fail          | Fail          Fail            Fail
>> +  ///
>> +  /// An easy way of encoding this is as 0b11, 0b01, 0b00 for
>> +  /// Success, SoftFail, Fail respectively.
>> +  enum DecodeStatus {
>> +    Fail = 0,
>> +    SoftFail = 1,
>> +    Success = 3
>> +  };
>> +
>>  /// Constructor     - Performs initial setup for the disassembler.
>>  MCDisassembler() : GetOpInfo(0), DisInfo(0), Ctx(0) {}
>> 
>> @@ -41,8 +69,11 @@
>>  /// @param address  - The address, in the memory space of region, of the first
>>  ///                   byte of the instruction.
>>  /// @param vStream  - The stream to print warnings and diagnostic messages on.
>> -  /// @return         - True if the instruction is valid; false otherwise.
>> -  virtual bool          getInstruction(MCInst& instr,
>> +  /// @return         - MCDisassembler::Success if the instruction is valid,
>> +  ///                   MCDisassembler::SoftFail if the instruction was 
>> +  ///                                            disassemblable but invalid,
>> +  ///                   MCDisassembler::Fail if the instruction was invalid.
>> +  virtual DecodeStatus  getInstruction(MCInst& instr,
>>                                       uint64_t& size,
>>                                       const MemoryObject &region,
>>                                       uint64_t address,
>> 
>> Modified: llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp (original)
>> +++ llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp Wed Aug 17 12:44:15 2011
>> @@ -24,188 +24,201 @@
>> #include "llvm/Support/ErrorHandling.h"
>> #include "llvm/Support/raw_ostream.h"
>> 
>> +// Pull DecodeStatus and its enum values into the global namespace.
>> +typedef llvm::MCDisassembler::DecodeStatus DecodeStatus;
>> +#define Success llvm::MCDisassembler::Success
>> +#define Unpredictable llvm::MCDisassembler::SoftFail
>> +#define Fail llvm::MCDisassembler::Fail
>> +
> 
> Please don't do this sort of thing (#defines to get around scoping). Reference the names explicitly, including the scoping operators, instead.
> 
>> +// Helper macro to perform setwise reduction of the current running status
>> +// and another status, and return if the new status is Fail.
>> +#define CHECK(S,X) do {                           \
>> +    S = (DecodeStatus) ((int)S & (X));            \
> 
> It's better to use the enum values directly rather than casting integers like this. The code shouldn't know what the actual values of the enums are.
> 
>> +    if (S == Fail) return Fail;                   \
>> +  } while(0)
>> +
> 
> Having an early exit buried in a macro obfuscates the code. The way the code previously did this is better. Please change this back or refactor differently.
> 
>> // Forward declare these because the autogenerated code will reference them.
>> // Definitions are further down.
>> -static bool DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> -static bool DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder);
>> 
>> -static bool DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> 
>> -static bool DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> 
>> -static bool DecodeMemMultipleWritebackInstruction(llvm::MCInst & Inst,
>> +static DecodeStatus DecodeMemMultipleWritebackInstruction(llvm::MCInst & Inst,
>>                                                  unsigned Insn,
>>                                                  uint64_t Adddress,
>>                                                  const void *Decoder);
>> -static bool DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeCoprocessor(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeCoprocessor(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeMSRMask(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeMSRMask(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD1LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD1LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD2LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD2LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD3LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD3LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVLD4LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD4LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVST1LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST1LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVST2LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST2LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVST3LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST3LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeVST4LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST4LN(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder);
>> 
>> 
>> -static bool DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Val,
>> +static DecodeStatus DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Val,
>>                               uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Insn,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> -static bool DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                                uint64_t Address, const void *Decoder);
>> 
>> #include "ARMGenDisassemblerTables.inc"
>> @@ -230,15 +243,14 @@
>>  return instInfoARM;
>> }
>> 
>> -
>> -bool ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
>> -                                     const MemoryObject &Region,
>> -                                     uint64_t Address,raw_ostream &os) const {
>> +DecodeStatus ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
>> +                                             const MemoryObject &Region,
>> +                                             uint64_t Address,raw_ostream &os) const {
>>  uint8_t bytes[4];
>> 
>>  // We want to read exactly 4 bytes of data.
>>  if (Region.readBytes(Address, 4, (uint8_t*)bytes, NULL) == -1)
>> -    return false;
>> +    return Fail;
>> 
>>  // Encoded as a small-endian 32-bit word in the stream.
>>  uint32_t insn = (bytes[3] << 24) |
>> @@ -247,10 +259,10 @@
>>                  (bytes[0] <<  0);
>> 
>>  // Calling the auto-generated decoder function.
>> -  bool result = decodeARMInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  DecodeStatus result = decodeARMInstruction32(MI, insn, Address, this);
>> +  if (result != Fail) {
>>    Size = 4;
>> -    return true;
>> +    return result;
>>  }
>> 
>>  // Instructions that are shared between ARM and Thumb modes.
>> @@ -258,53 +270,53 @@
>>  // fact that we fail to encode a few instructions properly for Thumb.
>>  MI.clear();
>>  result = decodeCommonInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>> -    return true;
>> +    return result;
>>  }
>> 
>>  // VFP and NEON instructions, similarly, are shared between ARM
>>  // and Thumb modes.
>>  MI.clear();
>>  result = decodeVFPInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeNEONDataInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    // Add a fake predicate operand, because we share these instruction
>>    // definitions with Thumb2 where these instructions are predicable.
>> -    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
>> -    return true;
>> +    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return Fail;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeNEONLoadStoreInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    // Add a fake predicate operand, because we share these instruction
>>    // definitions with Thumb2 where these instructions are predicable.
>> -    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
>> -    return true;
>> +    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return Fail;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeNEONDupInstruction32(MI, insn, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    // Add a fake predicate operand, because we share these instruction
>>    // definitions with Thumb2 where these instructions are predicable.
>> -    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
>> -    return true;
>> +    if (!DecodePredicateOperand(MI, 0xE, Address, this)) return Fail;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>> 
>> -  return false;
>> +  return Fail;
>> }
>> 
>> namespace llvm {
>> @@ -403,22 +415,21 @@
>>  }
>> }
>> 
>> -
>> -bool ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
>> -                                       const MemoryObject &Region,
>> -                                       uint64_t Address,raw_ostream &os) const {
>> +DecodeStatus ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
>> +                                               const MemoryObject &Region,
>> +                                               uint64_t Address,raw_ostream &os) const {
>>  uint8_t bytes[4];
>> 
>>  // We want to read exactly 2 bytes of data.
>>  if (Region.readBytes(Address, 2, (uint8_t*)bytes, NULL) == -1)
>> -    return false;
>> +    return Fail;
>> 
>>  uint16_t insn16 = (bytes[1] << 8) | bytes[0];
>> -  bool result = decodeThumbInstruction16(MI, insn16, Address, this);
>> -  if (result) {
>> +  DecodeStatus result = decodeThumbInstruction16(MI, insn16, Address, this);
>> +  if (result != Fail) {
>>    Size = 2;
>>    AddThumbPredicate(MI);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>> @@ -428,12 +439,12 @@
>>    bool InITBlock = !ITBlock.empty();
>>    AddThumbPredicate(MI);
>>    AddThumb1SBit(MI, InITBlock);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeThumb2Instruction16(MI, insn16, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 2;
>>    AddThumbPredicate(MI);
>> 
>> @@ -456,12 +467,12 @@
>>      ITBlock.push_back(firstcond);
>>    }
>> 
>> -    return true;
>> +    return result;
>>  }
>> 
>>  // We want to read exactly 4 bytes of data.
>>  if (Region.readBytes(Address, 4, (uint8_t*)bytes, NULL) == -1)
>> -    return false;
>> +    return Fail;
>> 
>>  uint32_t insn32 = (bytes[3] <<  8) |
>>                    (bytes[2] <<  0) |
>> @@ -469,44 +480,44 @@
>>                    (bytes[0] << 16);
>>  MI.clear();
>>  result = decodeThumbInstruction32(MI, insn32, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    bool InITBlock = ITBlock.size();
>>    AddThumbPredicate(MI);
>>    AddThumb1SBit(MI, InITBlock);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeThumb2Instruction32(MI, insn32, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    AddThumbPredicate(MI);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeCommonInstruction32(MI, insn32, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    AddThumbPredicate(MI);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeVFPInstruction32(MI, insn32, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    UpdateThumbVFPPredicate(MI);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  MI.clear();
>>  result = decodeNEONDupInstruction32(MI, insn32, Address, this);
>> -  if (result) {
>> +  if (result != Fail) {
>>    Size = 4;
>>    AddThumbPredicate(MI);
>> -    return true;
>> +    return result;
>>  }
>> 
>>  if (fieldFromInstruction32(insn32, 24, 8) == 0xF9) {
>> @@ -515,10 +526,10 @@
>>    NEONLdStInsn &= 0xF0FFFFFF;
>>    NEONLdStInsn |= 0x04000000;
>>    result = decodeNEONLoadStoreInstruction32(MI, NEONLdStInsn, Address, this);
>> -    if (result) {
>> +    if (result != Fail) {
>>      Size = 4;
>>      AddThumbPredicate(MI);
>> -      return true;
>> +      return result;
>>    }
>>  }
>> 
>> @@ -529,14 +540,14 @@
>>    NEONDataInsn |= (NEONDataInsn & 0x10000000) >> 4; // Move bit 28 to bit 24
>>    NEONDataInsn |= 0x12000000; // Set bits 28 and 25
>>    result = decodeNEONDataInstruction32(MI, NEONDataInsn, Address, this);
>> -    if (result) {
>> +    if (result != Fail) {
>>      Size = 4;
>>      AddThumbPredicate(MI);
>> -      return true;
>> +      return result;
>>    }
>>  }
>> 
>> -  return false;
>> +  return Fail;
>> }
>> 
>> 
>> @@ -554,30 +565,30 @@
>>  ARM::R12, ARM::SP, ARM::LR, ARM::PC
>> };
>> 
>> -static bool DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 15)
>> -    return false;
>> +    return Fail;
>> 
>>  unsigned Register = GPRDecoderTable[RegNo];
>>  Inst.addOperand(MCOperand::CreateReg(Register));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                       uint64_t Address, const void *Decoder) {
>> -  if (RegNo == 15) return false;
>> +  if (RegNo == 15) return Fail;
>>  return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
>> }
>> 
>> -static bool DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 7)
>> -    return false;
>> +    return Fail;
>>  return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
>> }
>> 
>> -static bool DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  unsigned Register = 0;
>>  switch (RegNo) {
>> @@ -600,16 +611,16 @@
>>      Register = ARM::R12;
>>      break;
>>    default:
>> -      return false;
>> +      return Fail;
>>    }
>> 
>>  Inst.addOperand(MCOperand::CreateReg(Register));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>> -  if (RegNo == 13 || RegNo == 15) return false;
>> +  if (RegNo == 13 || RegNo == 15) return Fail;
>>  return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
>> }
>> 
>> @@ -624,14 +635,14 @@
>>    ARM::S28, ARM::S29, ARM::S30, ARM::S31
>> };
>> 
>> -static bool DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 31)
>> -    return false;
>> +    return Fail;
>> 
>>  unsigned Register = SPRDecoderTable[RegNo];
>>  Inst.addOperand(MCOperand::CreateReg(Register));
>> -  return true;
>> +  return Success;
>> }
>> 
>> static const unsigned DPRDecoderTable[] = { 
>> @@ -645,27 +656,27 @@
>>    ARM::D28, ARM::D29, ARM::D30, ARM::D31
>> };
>> 
>> -static bool DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 31)
>> -    return false;
>> +    return Fail;
>> 
>>  unsigned Register = DPRDecoderTable[RegNo];
>>  Inst.addOperand(MCOperand::CreateReg(Register));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 7)
>> -    return false;
>> +    return Fail;
>>  return DecodeDPRRegisterClass(Inst, RegNo, Address, Decoder);
>> }
>> 
>> -static bool DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 15)
>> -    return false;
>> +    return Fail;
>>  return DecodeDPRRegisterClass(Inst, RegNo, Address, Decoder);
>> }
>> 
>> @@ -677,65 +688,66 @@
>> };
>> 
>> 
>> -static bool DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>> +static DecodeStatus DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
>>                                   uint64_t Address, const void *Decoder) {
>>  if (RegNo > 31)
>> -    return false;
>> +    return Fail;
>>  RegNo >>= 1;
>> 
>>  unsigned Register = QPRDecoderTable[RegNo];
>>  Inst.addOperand(MCOperand::CreateReg(Register));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>> -  if (Val == 0xF) return false;
>> +  if (Val == 0xF) return Fail;
>>  // AL predicate is not allowed on Thumb1 branches.
>>  if (Inst.getOpcode() == ARM::tBcc && Val == 0xE)
>> -    return false;
>> +    return Fail;
>>  Inst.addOperand(MCOperand::CreateImm(Val));
>>  if (Val == ARMCC::AL) {
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  } else
>>    Inst.addOperand(MCOperand::CreateReg(ARM::CPSR));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  if (Val)
>>    Inst.addOperand(MCOperand::CreateReg(ARM::CPSR));
>>  else
>>    Inst.addOperand(MCOperand::CreateReg(0));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  uint32_t imm = Val & 0xFF;
>>  uint32_t rot = (Val & 0xF00) >> 7;
>>  uint32_t rot_imm = (imm >> rot) | (imm << (32-rot));
>>  Inst.addOperand(MCOperand::CreateImm(rot_imm));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  Val <<= 2;
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(Val)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> 
>>  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
>>  unsigned type = fieldFromInstruction32(Val, 5, 2);
>>  unsigned imm = fieldFromInstruction32(Val, 7, 5);
>> 
>>  // Register-immediate
>> -  if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>> 
>>  ARM_AM::ShiftOpc Shift = ARM_AM::lsl;
>>  switch (type) {
>> @@ -759,19 +771,20 @@
>>  unsigned Op = Shift | (imm << 3);
>>  Inst.addOperand(MCOperand::CreateImm(Op));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> 
>>  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
>>  unsigned type = fieldFromInstruction32(Val, 5, 2);
>>  unsigned Rs = fieldFromInstruction32(Val, 8, 4);
>> 
>>  // Register-register
>> -  if (!DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> -  if (!DecodeGPRnopcRegisterClass(Inst, Rs, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder));
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rs, Address, Decoder));
>> 
>>  ARM_AM::ShiftOpc Shift = ARM_AM::lsl;
>>  switch (type) {
>> @@ -791,49 +804,55 @@
>> 
>>  Inst.addOperand(MCOperand::CreateImm(Shift));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  // Empty register lists are not allowed.
>> -  if (CountPopulation_32(Val) == 0) return false;
>> +  if (CountPopulation_32(Val) == 0) return Fail;
>>  for (unsigned i = 0; i < 16; ++i) {
>>    if (Val & (1 << i)) {
>> -      if (!DecodeGPRRegisterClass(Inst, i, Address, Decoder)) return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, i, Address, Decoder));
>>    }
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Vd = fieldFromInstruction32(Val, 8, 4);
>>  unsigned regs = Val & 0xFF;
>> 
>> -  if (!DecodeSPRRegisterClass(Inst, Vd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeSPRRegisterClass(Inst, Vd, Address, Decoder));
>>  for (unsigned i = 0; i < (regs - 1); ++i) {
>> -    if (!DecodeSPRRegisterClass(Inst, ++Vd, Address, Decoder)) return false;
>> +    CHECK(S, DecodeSPRRegisterClass(Inst, ++Vd, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Vd = fieldFromInstruction32(Val, 8, 4);
>>  unsigned regs = (Val & 0xFF) / 2;
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Vd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Vd, Address, Decoder));
>>  for (unsigned i = 0; i < (regs - 1); ++i) {
>> -    if (!DecodeDPRRegisterClass(Inst, ++Vd, Address, Decoder)) return false;
>> +    CHECK(S, DecodeDPRRegisterClass(Inst, ++Vd, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Val,
>>                                      uint64_t Address, const void *Decoder) {
>>  // This operand encodes a mask of contiguous zeros between a specified MSB
>>  // and LSB.  To decode it, we create the mask of all bits MSB-and-lower,
>> @@ -845,11 +864,13 @@
>>  uint32_t msb_mask = (1 << (msb+1)) - 1;
>>  uint32_t lsb_mask = (1 << lsb) - 1;
>>  Inst.addOperand(MCOperand::CreateImm(~(msb_mask ^ lsb_mask)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>>  unsigned CRd = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned coproc = fieldFromInstruction32(Insn, 8, 4);
>> @@ -875,7 +896,7 @@
>>    case ARM::STCL_POST:
>>    case ARM::STCL_OPTION:
>>      if (coproc == 0xA || coproc == 0xB)
>> -        return false;
>> +        return Fail;
>>      break;
>>    default:
>>      break;
>> @@ -883,7 +904,7 @@
>> 
>>  Inst.addOperand(MCOperand::CreateImm(coproc));
>>  Inst.addOperand(MCOperand::CreateImm(CRd));
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  switch (Inst.getOpcode()) {
>>    case ARM::LDC_OPTION:
>>    case ARM::LDCL_OPTION:
>> @@ -952,17 +973,19 @@
>>    case ARM::STCL_PRE:
>>    case ARM::STCL_POST:
>>    case ARM::STCL_OPTION:
>> -      if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +      CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>> @@ -982,13 +1005,13 @@
>>    case ARM::STRT_POST_IMM:
>>    case ARM::STRBT_POST_REG:
>>    case ARM::STRBT_POST_IMM:
>> -      if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>> 
>>  // On loads, the writeback operand comes after Rt.
>>  switch (Inst.getOpcode()) {
>> @@ -1002,14 +1025,13 @@
>>    case ARM::LDRBT_POST_IMM:
>>    case ARM::LDRT_POST_REG:
>>    case ARM::LDRT_POST_IMM:
>> -      if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -        return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> 
>>  ARM_AM::AddrOpc Op = ARM_AM::add;
>>  if (!fieldFromInstruction32(Insn, 23, 1))
>> @@ -1022,10 +1044,10 @@
>>  else if (!P && writeback)
>>    idx_mode = ARMII::IndexModePost;
>> 
>> -  if (writeback && (Rn == 15 || Rn == Rt)) return false; // UNPREDICTABLE
>> +  if (writeback && (Rn == 15 || Rn == Rt)) S = Unpredictable; // UNPREDICTABLE
>> 
>>  if (reg) {
>> -    if (!DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder));
>>    ARM_AM::ShiftOpc Opc = ARM_AM::lsl;
>>    switch( fieldFromInstruction32(Insn, 5, 2)) {
>>      case 0:
>> @@ -1041,7 +1063,7 @@
>>        Opc = ARM_AM::ror;
>>        break;
>>      default:
>> -        return false;
>> +        return Fail;
>>    }
>>    unsigned amt = fieldFromInstruction32(Insn, 7, 5);
>>    unsigned imm = ARM_AM::getAM2Opc(Op, amt, Opc, idx_mode);
>> @@ -1053,13 +1075,15 @@
>>    Inst.addOperand(MCOperand::CreateImm(tmp));
>>  }
>> 
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 13, 4);
>>  unsigned Rm = fieldFromInstruction32(Val,  0, 4);
>>  unsigned type = fieldFromInstruction32(Val, 5, 2);
>> @@ -1082,8 +1106,8 @@
>>      break;
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  unsigned shift;
>>  if (U)
>>    shift = ARM_AM::getAM2Opc(ARM_AM::add, imm, ShOp);
>> @@ -1091,11 +1115,13 @@
>>    shift = ARM_AM::getAM2Opc(ARM_AM::sub, imm, ShOp);
>>  Inst.addOperand(MCOperand::CreateImm(shift));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>> @@ -1116,7 +1142,7 @@
>>    case ARM::LDRD:
>>    case ARM::LDRD_PRE:
>>    case ARM::LDRD_POST:
>> -      if (Rt & 0x1) return false;
>> +      if (Rt & 0x1) return Fail;
>>      break;
>>  default:
>>    break;
>> @@ -1136,16 +1162,14 @@
>>    case ARM::STRH:
>>    case ARM::STRH_PRE:
>>    case ARM::STRH_POST:
>> -      if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -        return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>    }
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>>  switch (Inst.getOpcode()) {
>>    case ARM::STRD:
>>    case ARM::STRD_PRE:
>> @@ -1153,8 +1177,7 @@
>>    case ARM::LDRD:
>>    case ARM::LDRD_PRE:
>>    case ARM::LDRD_POST:
>> -      if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder))
>> -        return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder));
>>      break;
>>    default:
>>      break;
>> @@ -1177,33 +1200,32 @@
>>    case ARM::LDRSB_POST:
>>    case ARM::LDRHTr:
>>    case ARM::LDRSBTr:
>> -      if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -        return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>    }
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> 
>>  if (type) {
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>    Inst.addOperand(MCOperand::CreateImm(U | (imm << 4) | Rm));
>>  } else {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>    Inst.addOperand(MCOperand::CreateImm(U));
>>  }
>> 
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeRFEInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeRFEInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned mode = fieldFromInstruction32(Insn, 23, 2);
>> 
>> @@ -1223,14 +1245,16 @@
>>  }
>> 
>>  Inst.addOperand(MCOperand::CreateImm(mode));
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeMemMultipleWritebackInstruction(llvm::MCInst &Inst,
>> +static DecodeStatus DecodeMemMultipleWritebackInstruction(llvm::MCInst &Inst,
>>                                  unsigned Insn,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>>  unsigned reglist = fieldFromInstruction32(Insn, 0, 16);
>> @@ -1265,16 +1289,15 @@
>>    return DecodeRFEInstruction(Inst, Insn, Address, Decoder);
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)   ||
>> -      !DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)   || // Tied
>> -      !DecodePredicateOperand(Inst, pred, Address, Decoder) ||
>> -      !DecodeRegListOperand(Inst, reglist, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)); // Tied
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> +  CHECK(S, DecodeRegListOperand(Inst, reglist, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                 uint64_t Address, const void *Decoder) {
>>  unsigned imod = fieldFromInstruction32(Insn, 18, 2);
>>  unsigned M = fieldFromInstruction32(Insn, 17, 1);
>> @@ -1282,30 +1305,32 @@
>>  unsigned mode = fieldFromInstruction32(Insn, 0, 5);
>> 
>>  // imod == '01' --> UNPREDICTABLE
>> -  if (imod == 1) return false;
>> +  if (imod == 1) return Fail;
>> 
>>  if (M && mode && imod && iflags) {
>>    Inst.setOpcode(ARM::CPS3p);
>>    Inst.addOperand(MCOperand::CreateImm(imod));
>>    Inst.addOperand(MCOperand::CreateImm(iflags));
>>    Inst.addOperand(MCOperand::CreateImm(mode));
>> -    return true;
>> +    return Success;
>>  } else if (!mode && !M) {
>>    Inst.setOpcode(ARM::CPS2p);
>>    Inst.addOperand(MCOperand::CreateImm(imod));
>>    Inst.addOperand(MCOperand::CreateImm(iflags));
>> -    return true;
>> +    return Success;
>>  } else if (!imod && !iflags && M) {
>>    Inst.setOpcode(ARM::CPS1p);
>>    Inst.addOperand(MCOperand::CreateImm(mode));
>> -    return true;
>> +    return Success;
>>  }
>> 
>> -  return false;
>> +  return Fail;
>> }
>> 
>> -static bool DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rn = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 8, 4);
>> @@ -1315,57 +1340,60 @@
>>  if (pred == 0xF)
>>    return DecodeCPSInstruction(Inst, Insn, Address, Decoder);
>> 
>> -  if (!DecodeGPRnopcRegisterClass(Inst, Rd, Address, Decoder) ||
>> -      !DecodeGPRnopcRegisterClass(Inst, Rn, Address, Decoder) ||
>> -      !DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder) ||
>> -      !DecodeGPRnopcRegisterClass(Inst, Ra, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder));
>> +  CHECK(S, DecodeGPRnopcRegisterClass(Inst, Ra, Address, Decoder));
>> 
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
>>                           uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned add = fieldFromInstruction32(Val, 12, 1);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 12);
>>  unsigned Rn = fieldFromInstruction32(Val, 13, 4);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> 
>>  if (!add) imm *= -1;
>>  if (imm == 0 && !add) imm = INT32_MIN;
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
>>                                   uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 9, 4);
>>  unsigned U = fieldFromInstruction32(Val, 8, 1);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 8);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> 
>>  if (U)
>>    Inst.addOperand(MCOperand::CreateImm(ARM_AM::getAM5Opc(ARM_AM::add, imm)));
>>  else
>>    Inst.addOperand(MCOperand::CreateImm(ARM_AM::getAM5Opc(ARM_AM::sub, imm)));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
>>                                   uint64_t Address, const void *Decoder) {
>>  return DecodeGPRRegisterClass(Inst, Val, Address, Decoder);
>> }
>> 
>> -static bool DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                   uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>>  unsigned imm = fieldFromInstruction32(Insn, 0, 24) << 2;
>> 
>> @@ -1373,39 +1401,42 @@
>>    Inst.setOpcode(ARM::BLXi);
>>    imm |= fieldFromInstruction32(Insn, 24, 1) << 1;
>>    Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(imm)));
>> -    return true;
>> +    return S;
>>  }
>> 
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(imm)));
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(64 - Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
>>                                   uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rm = fieldFromInstruction32(Val, 0, 4);
>>  unsigned align = fieldFromInstruction32(Val, 4, 2);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  if (!align)
>>    Inst.addOperand(MCOperand::CreateImm(0));
>>  else
>>    Inst.addOperand(MCOperand::CreateImm(4 << align));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                   uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned wb = fieldFromInstruction32(Insn, 16, 4);
>> @@ -1414,7 +1445,7 @@
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>> 
>>  // First output register
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> 
>>  // Second output register
>>  switch (Inst.getOpcode()) {
>> @@ -1466,7 +1497,7 @@
>>    case ARM::VLD4d8_UPD:
>>    case ARM::VLD4d16_UPD:
>>    case ARM::VLD4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder));
>>      break;
>>    case ARM::VLD2b8:
>>    case ARM::VLD2b16:
>> @@ -1486,7 +1517,7 @@
>>    case ARM::VLD4q8_UPD:
>>    case ARM::VLD4q16_UPD:
>>    case ARM::VLD4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder));
>>    default:
>>      break;
>>  }
>> @@ -1527,7 +1558,7 @@
>>    case ARM::VLD4d8_UPD:
>>    case ARM::VLD4d16_UPD:
>>    case ARM::VLD4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder));
>>      break;
>>    case ARM::VLD3q8:
>>    case ARM::VLD3q16:
>> @@ -1541,7 +1572,7 @@
>>    case ARM::VLD4q8_UPD:
>>    case ARM::VLD4q16_UPD:
>>    case ARM::VLD4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder));
>>      break;
>>    default:
>>      break;
>> @@ -1569,7 +1600,7 @@
>>    case ARM::VLD4d8_UPD:
>>    case ARM::VLD4d16_UPD:
>>    case ARM::VLD4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder));
>>      break;
>>    case ARM::VLD4q8:
>>    case ARM::VLD4q16:
>> @@ -1577,7 +1608,7 @@
>>    case ARM::VLD4q8_UPD:
>>    case ARM::VLD4q16_UPD:
>>    case ARM::VLD4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder));
>>      break;
>>    default:
>>      break;
>> @@ -1622,28 +1653,29 @@
>>    case ARM::VLD4q8_UPD:
>>    case ARM::VLD4q16_UPD:
>>    case ARM::VLD4q32_UPD:
>> -      if (!DecodeGPRRegisterClass(Inst, wb, Address, Decoder)) return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, wb, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>>  // AddrMode6 Base (register+alignment)
>> -  if (!DecodeAddrMode6Operand(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeAddrMode6Operand(Inst, Rn, Address, Decoder));
>> 
>>  // AddrMode6 Offset (register)
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned wb = fieldFromInstruction32(Insn, 16, 4);
>> @@ -1690,25 +1722,24 @@
>>    case ARM::VST4q8_UPD:
>>    case ARM::VST4q16_UPD:
>>    case ARM::VST4q32_UPD:
>> -      if (!DecodeGPRRegisterClass(Inst, wb, Address, Decoder))
>> -        return false;
>> +      CHECK(S, DecodeGPRRegisterClass(Inst, wb, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>>  // AddrMode6 Base (register+alignment)
>> -  if (!DecodeAddrMode6Operand(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeAddrMode6Operand(Inst, Rn, Address, Decoder));
>> 
>>  // AddrMode6 Offset (register)
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>>  // First input register
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> 
>>  // Second input register
>>  switch (Inst.getOpcode()) {
>> @@ -1760,7 +1791,7 @@
>>    case ARM::VST4d8_UPD:
>>    case ARM::VST4d16_UPD:
>>    case ARM::VST4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder));
>>      break;
>>    case ARM::VST2b8:
>>    case ARM::VST2b16:
>> @@ -1780,7 +1811,7 @@
>>    case ARM::VST4q8_UPD:
>>    case ARM::VST4q16_UPD:
>>    case ARM::VST4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder));
>>      break;
>>    default:
>>      break;
>> @@ -1822,7 +1853,7 @@
>>    case ARM::VST4d8_UPD:
>>    case ARM::VST4d16_UPD:
>>    case ARM::VST4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder));
>>      break;
>>    case ARM::VST3q8:
>>    case ARM::VST3q16:
>> @@ -1836,7 +1867,7 @@
>>    case ARM::VST4q8_UPD:
>>    case ARM::VST4q16_UPD:
>>    case ARM::VST4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder));
>>      break;
>>    default:
>>      break;
>> @@ -1864,7 +1895,7 @@
>>    case ARM::VST4d8_UPD:
>>    case ARM::VST4d16_UPD:
>>    case ARM::VST4d32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder));
>>      break;
>>    case ARM::VST4q8:
>>    case ARM::VST4q16:
>> @@ -1872,17 +1903,19 @@
>>    case ARM::VST4q8_UPD:
>>    case ARM::VST4q16_UPD:
>>    case ARM::VST4q32_UPD:
>> -      if (!DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                    uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>> @@ -1893,28 +1926,30 @@
>> 
>>  align *= (1 << size);
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  if (regs == 2) {
>> -    if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
>> +    CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder));
>>  }
>>  if (Rm == 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>> 
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                    uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>> @@ -1924,54 +1959,57 @@
>>  unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
>>  align *= 2*size;
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder));
>>  if (Rm == 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>> 
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                    uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)          ||
>> -      !DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder) ||
>> -      !DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder));
>>  if (Rm == 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(0));
>> 
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                    uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>> @@ -1993,29 +2031,30 @@
>>    }
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)            ||
>> -      !DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder)   ||
>> -      !DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder) ||
>> -      !DecodeDPRRegisterClass(Inst, (Rd+3*inc)%32, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, (Rd+3*inc)%32, Address, Decoder));
>>  if (Rm == 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>> 
>>  if (Rm == 0xD)
>>    Inst.addOperand(MCOperand::CreateReg(0));
>>  else if (Rm != 0xF) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                        uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned imm = fieldFromInstruction32(Insn, 0, 4);
>> @@ -2026,9 +2065,9 @@
>>  unsigned Q = fieldFromInstruction32(Insn, 6, 1);
>> 
>>  if (Q) {
>> -    if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +    CHECK(S, DecodeQPRRegisterClass(Inst, Rd, Address, Decoder));
>>  } else {
>> -    if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +    CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  }
>> 
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> @@ -2038,62 +2077,66 @@
>>    case ARM::VORRiv2i32:
>>    case ARM::VBICiv4i16:
>>    case ARM::VBICiv2i32:
>> -      if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +      CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>      break;
>>    case ARM::VORRiv8i16:
>>    case ARM::VORRiv4i32:
>>    case ARM::VBICiv8i16:
>>    case ARM::VBICiv4i32:
>> -      if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +      CHECK(S, DecodeQPRRegisterClass(Inst, Rd, Address, Decoder));
>>      break;
>>    default:
>>      break;
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                        uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  Rm |= fieldFromInstruction32(Insn, 5, 1) << 4;
>>  unsigned size = fieldFromInstruction32(Insn, 18, 2);
>> 
>> -  if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +  CHECK(S, DecodeQPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rm, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(8 << size));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(8 - Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(16 - Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(32 - Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
>>                               uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(64 - Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                               uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>> @@ -2103,21 +2146,21 @@
>>  unsigned op = fieldFromInstruction32(Insn, 6, 1);
>>  unsigned length = fieldFromInstruction32(Insn, 8, 2) + 1;
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  if (op) {
>> -    if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false; // Writeback
>> +    CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)); // Writeback
>>  }
>> 
>>  for (unsigned i = 0; i < length; ++i) {
>> -    if (!DecodeDPRRegisterClass(Inst, (Rn+i)%32, Address, Decoder)) return false;
>> +    CHECK(S, DecodeDPRRegisterClass(Inst, (Rn+i)%32, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rm, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
>>                            uint64_t Address, const void *Decoder) {
>>  // The immediate needs to be a fully instantiated float.  However, the
>>  // auto-generated decoder is only able to fill in some of the bits
>> @@ -2139,102 +2182,110 @@
>>  fp_conv.integer |= (~b & 0x1) << 30;
>> 
>>  Inst.addOperand(MCOperand::CreateFPImm(fp_conv.fp));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
>>                                     uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned dst = fieldFromInstruction16(Insn, 8, 3);
>>  unsigned imm = fieldFromInstruction16(Insn, 0, 8);
>> 
>> -  if (!DecodetGPRRegisterClass(Inst, dst, Address, Decoder)) return false;
>> +  CHECK(S, DecodetGPRRegisterClass(Inst, dst, Address, Decoder));
>> 
>>  if (Inst.getOpcode() == ARM::tADR)
>>    Inst.addOperand(MCOperand::CreateReg(ARM::PC));
>>  else if (Inst.getOpcode() == ARM::tADDrSPi)
>>    Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>>  else
>> -    return false;
>> +    return Fail;
>> 
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<12>(Val << 1)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<21>(Val)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<7>(Val << 1)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 0, 3);
>>  unsigned Rm = fieldFromInstruction32(Val, 3, 3);
>> 
>> -  if (!DecodetGPRRegisterClass(Inst, Rn, Address, Decoder) ||
>> -      !DecodetGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodetGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodetGPRRegisterClass(Inst, Rm, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 0, 3);
>>  unsigned imm = fieldFromInstruction32(Val, 3, 5);
>> 
>> -  if (!DecodetGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodetGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(Val << 2));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>>  Inst.addOperand(MCOperand::CreateImm(Val << 2));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 6, 4);
>>  unsigned Rm = fieldFromInstruction32(Val, 2, 4);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 2);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
>> -      !DecoderGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecoderGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Insn,
>>                              uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  if (Inst.getOpcode() != ARM::t2PLDs) {
>>    unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>> -    if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>>  }
>> 
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>> @@ -2257,57 +2308,60 @@
>>        Inst.addOperand(MCOperand::CreateReg(ARM::PC));
>>        break;
>>      default:
>> -        return false;
>> +        return Fail;
>>    }
>> 
>>    int imm = fieldFromInstruction32(Insn, 0, 12);
>>    if (!fieldFromInstruction32(Insn, 23, 1)) imm *= -1;
>>    Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -    return true;
>> +    return S;
>>  }
>> 
>>  unsigned addrmode = fieldFromInstruction32(Insn, 4, 2);
>>  addrmode |= fieldFromInstruction32(Insn, 0, 4) << 2;
>>  addrmode |= fieldFromInstruction32(Insn, 16, 4) << 6;
>> -  DecodeT2AddrModeSOReg(Inst, addrmode, Address, Decoder);
>> +  CHECK(S, DecodeT2AddrModeSOReg(Inst, addrmode, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
>>                           uint64_t Address, const void *Decoder) {
>>  int imm = Val & 0xFF;
>>  if (!(Val & 0x100)) imm *= -1;
>>  Inst.addOperand(MCOperand::CreateImm(imm << 2));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
>>                                   uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 9, 4);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 9);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
>> -      !DecodeT2Imm8S4(Inst, imm, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeT2Imm8S4(Inst, imm, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
>>                         uint64_t Address, const void *Decoder) {
>>  int imm = Val & 0xFF;
>>  if (!(Val & 0x100)) imm *= -1;
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> 
>> -static bool DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 9, 4);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 9);
>> 
>> @@ -2324,27 +2378,28 @@
>>      break;
>>  }
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
>> -      !DecodeT2Imm8(Inst, imm, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeT2Imm8(Inst, imm, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
>>                                  uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Val, 13, 4);
>>  unsigned imm = fieldFromInstruction32(Val, 0, 12);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Insn,
>>                                uint64_t Address, const void *Decoder) {
>>  unsigned imm = fieldFromInstruction16(Insn, 0, 7);
>> 
>> @@ -2352,30 +2407,32 @@
>>  Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>>  Inst.addOperand(MCOperand::CreateImm(imm));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
>>                                uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  if (Inst.getOpcode() == ARM::tADDrSP) {
>>    unsigned Rdm = fieldFromInstruction16(Insn, 0, 3);
>>    Rdm |= fieldFromInstruction16(Insn, 7, 1) << 3;
>> 
>> -    if (!DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder));
>>    Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>> -    if (!DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder));
>>  } else if (Inst.getOpcode() == ARM::tADDspr) {
>>    unsigned Rm = fieldFromInstruction16(Insn, 3, 4);
>> 
>>    Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>>    Inst.addOperand(MCOperand::CreateReg(ARM::SP));
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
>> +static DecodeStatus DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
>>                           uint64_t Address, const void *Decoder) {
>>  unsigned imod = fieldFromInstruction16(Insn, 4, 1) | 0x2;
>>  unsigned flags = fieldFromInstruction16(Insn, 0, 3);
>> @@ -2383,52 +2440,55 @@
>>  Inst.addOperand(MCOperand::CreateImm(imod));
>>  Inst.addOperand(MCOperand::CreateImm(flags));
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
>>                             uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned add = fieldFromInstruction32(Insn, 4, 1);
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) ;
>>  Inst.addOperand(MCOperand::CreateImm(add));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Val,
>>                                 uint64_t Address, const void *Decoder) {
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeCoprocessor(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeCoprocessor(llvm::MCInst &Inst, unsigned Val,
>>                              uint64_t Address, const void *Decoder) {
>>  if (Val == 0xA || Val == 0xB)
>> -    return false;
>> +    return Fail;
>> 
>>  Inst.addOperand(MCOperand::CreateImm(Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
>>                             uint64_t Address, const void *Decoder) {
>>  if (Val == 0)
>>    Inst.addOperand(MCOperand::CreateImm(32));
>>  else
>>    Inst.addOperand(MCOperand::CreateImm(Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Insn,
>>                                       uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned pred = fieldFromInstruction32(Insn, 22, 4);
>>  if (pred == 0xE || pred == 0xF) {
>>    unsigned opc = fieldFromInstruction32(Insn, 4, 2);
>>    switch (opc) {
>>      default:
>> -        return false;
>> +        return Fail;
>>      case 0:
>>        Inst.setOpcode(ARM::t2DSB);
>>        break;
>> @@ -2437,7 +2497,7 @@
>>        break;
>>      case 2:
>>        Inst.setOpcode(ARM::t2ISB);
>> -        return true;
>> +        return Success;
>>    }
>> 
>>    unsigned imm = fieldFromInstruction32(Insn, 0, 4);
>> @@ -2450,17 +2510,16 @@
>>  brtarget |= fieldFromInstruction32(Insn, 16, 6) << 12;
>>  brtarget |= fieldFromInstruction32(Insn, 26, 1) << 20;
>> 
>> -  if (!DecodeT2BROperand(Inst, brtarget, Address, Decoder) ||
>> -      !DecodePredicateOperand(Inst, pred, Address, Decoder))
>> -    return false;
>> +  CHECK(S, DecodeT2BROperand(Inst, brtarget, Address, Decoder));
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> // Decode a shifted immediate operand.  These basically consist
>> // of an 8-bit value, and a 4-bit directive that specifies either
>> // a splat operation or a rotation.
>> -static bool DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
>>                          uint64_t Address, const void *Decoder) {
>>  unsigned ctrl = fieldFromInstruction32(Val, 10, 2);
>>  if (ctrl == 0) {
>> @@ -2488,26 +2547,26 @@
>>    Inst.addOperand(MCOperand::CreateImm(imm));
>>  }
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                                        uint64_t Address, const void *Decoder){
>>  Inst.addOperand(MCOperand::CreateImm(Val << 1));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
>>                                       uint64_t Address, const void *Decoder){
>>  Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Val,
>>                                   uint64_t Address, const void *Decoder) {
>>  switch (Val) {
>>  default:
>> -    return false;
>> +    return Fail;
>>  case 0xF: // SY
>>  case 0xE: // ST
>>  case 0xB: // ISH
>> @@ -2520,55 +2579,61 @@
>>  }
>> 
>>  Inst.addOperand(MCOperand::CreateImm(Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeMSRMask(llvm::MCInst &Inst, unsigned Val,
>> +static DecodeStatus DecodeMSRMask(llvm::MCInst &Inst, unsigned Val,
>>                          uint64_t Address, const void *Decoder) {
>> -  if (!Val) return false;
>> +  if (!Val) return Fail;
>>  Inst.addOperand(MCOperand::CreateImm(Val));
>> -  return true;
>> +  return Success;
>> }
>> 
>> -static bool DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
>>                                          uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>> 
>> -  if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return false;
>> +  if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return Fail;
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
>>                                          uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned Rt = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>> 
>> -  if (!DecoderGPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecoderGPRRegisterClass(Inst, Rd, Address, Decoder));
>> 
>> -  if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return false;
>> -  if (Rd == Rn || Rd == Rt || Rd == Rt+1) return false;
>> +  if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return Fail;
>> +  if (Rd == Rn || Rd == Rt || Rd == Rt+1) return Fail;
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
>>                            uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned imm = fieldFromInstruction32(Insn, 0, 12);
>> @@ -2576,18 +2641,20 @@
>>  imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>> 
>> -  if (Rn == 0xF || Rn == Rt) return false; // UNPREDICTABLE
>> +  if (Rn == 0xF || Rn == Rt) return Unpredictable; // UNPREDICTABLE
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> -  if (!DecodeAddrModeImm12Operand(Inst, imm, Address, Decoder)) return false;
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>> +  CHECK(S, DecodeAddrModeImm12Operand(Inst, imm, Address, Decoder));
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
>>                            uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
>>  unsigned imm = fieldFromInstruction32(Insn, 0, 12);
>> @@ -2595,18 +2662,20 @@
>>  imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
>>  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
>> 
>> -  if (Rn == 0xF || Rn == Rt) return false; // UNPREDICTABLE
>> +  if (Rn == 0xF || Rn == Rt) return Unpredictable; // UNPREDICTABLE
>> 
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> -  if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
>> -  if (!DecodeSORegMemOperand(Inst, imm, Address, Decoder)) return false;
>> -  if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
>> +  CHECK(S, DecodeSORegMemOperand(Inst, imm, Address, Decoder));
>> +  CHECK(S, DecodePredicateOperand(Inst, pred, Address, Decoder));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVLD1LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD1LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2617,47 +2686,47 @@
>>  unsigned index = 0;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      break;
>>    case 1:
>>      if (fieldFromInstruction32(Insn, 5, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 6, 2);
>>      if (fieldFromInstruction32(Insn, 4, 1))
>>        align = 2;
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 6, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 4, 2) != 0)
>>        align = 4;
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVST1LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST1LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2668,47 +2737,47 @@
>>  unsigned index = 0;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      break;
>>    case 1:
>>      if (fieldFromInstruction32(Insn, 5, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 6, 2);
>>      if (fieldFromInstruction32(Insn, 4, 1))
>>        align = 2;
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 6, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 4, 2) != 0)
>>        align = 4;
>>  }
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeVLD2LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD2LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2720,7 +2789,7 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> @@ -2735,7 +2804,7 @@
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 5, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 4, 1) != 0)
>>        align = 8;
>> @@ -2744,28 +2813,28 @@
>>      break;
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVST2LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST2LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2777,7 +2846,7 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> @@ -2792,7 +2861,7 @@
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 5, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 4, 1) != 0)
>>        align = 8;
>> @@ -2802,26 +2871,26 @@
>>  }
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeVLD3LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD3LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2833,53 +2902,53 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      break;
>>    case 1:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 6, 2);
>>      if (fieldFromInstruction32(Insn, 5, 1))
>>        inc = 2;
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 4, 2))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 6, 1))
>>        inc = 2;
>>      break;
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVST3LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST3LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2891,22 +2960,22 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 5, 3);
>>      break;
>>    case 1:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 6, 2);
>>      if (fieldFromInstruction32(Insn, 5, 1))
>>        inc = 2;
>>      break;
>>    case 2:
>>      if (fieldFromInstruction32(Insn, 4, 2))
>> -        return false; // UNDEFINED
>> +        return Fail; // UNDEFINED
>>      index = fieldFromInstruction32(Insn, 7, 1);
>>      if (fieldFromInstruction32(Insn, 6, 1))
>>        inc = 2;
>> @@ -2914,27 +2983,27 @@
>>  }
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> -static bool DecodeVLD4LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVLD4LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -2946,7 +3015,7 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>>        align = 4;
>> @@ -2968,33 +3037,33 @@
>>      break;
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder));
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> -static bool DecodeVST4LN(llvm::MCInst &Inst, unsigned Insn,
>> +static DecodeStatus DecodeVST4LN(llvm::MCInst &Inst, unsigned Insn,
>>                         uint64_t Address, const void *Decoder) {
>> +  DecodeStatus S = Success;
>> +
>>  unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
>>  unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
>>  unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
>> @@ -3006,7 +3075,7 @@
>>  unsigned inc = 1;
>>  switch (size) {
>>    default:
>> -      return false;
>> +      return Fail;
>>    case 0:
>>      if (fieldFromInstruction32(Insn, 4, 1))
>>        align = 4;
>> @@ -3029,22 +3098,20 @@
>>  }
>> 
>>  if (Rm != 0xF) { // Writeback
>> -    if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  }
>> -  if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
>> +  CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(align));
>>  if (Rm != 0xF && Rm != 0xD) {
>> -    if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
>> -      return false;
>> +    CHECK(S, DecodeGPRRegisterClass(Inst, Rm, Address, Decoder));
>>  }
>> 
>> -  if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder)) return false;
>> -  if (!DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder)) return false;
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+2*inc, Address, Decoder));
>> +  CHECK(S, DecodeDPRRegisterClass(Inst, Rd+3*inc, Address, Decoder));
>>  Inst.addOperand(MCOperand::CreateImm(index));
>> 
>> -  return true;
>> +  return S;
>> }
>> 
>> 
>> Modified: llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.h?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.h (original)
>> +++ llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.h Wed Aug 17 12:44:15 2011
>> @@ -40,11 +40,11 @@
>>  }
>> 
>>  /// getInstruction - See MCDisassembler.
>> -  bool getInstruction(MCInst &instr,
>> -                      uint64_t &size,
>> -                      const MemoryObject &region,
>> -                      uint64_t address,
>> -                      raw_ostream &vStream) const;
>> +  DecodeStatus getInstruction(MCInst &instr,
>> +                              uint64_t &size,
>> +                              const MemoryObject &region,
>> +                              uint64_t address,
>> +                              raw_ostream &vStream) const;
>> 
>>  /// getEDInfo - See MCDisassembler.
>>  EDInstInfo *getEDInfo() const;
>> @@ -64,11 +64,11 @@
>>  }
>> 
>>  /// getInstruction - See MCDisassembler.
>> -  bool getInstruction(MCInst &instr,
>> -                      uint64_t &size,
>> -                      const MemoryObject &region,
>> -                      uint64_t address,
>> -                      raw_ostream &vStream) const;
>> +  DecodeStatus getInstruction(MCInst &instr,
>> +                              uint64_t &size,
>> +                              const MemoryObject &region,
>> +                              uint64_t address,
>> +                              raw_ostream &vStream) const;
>> 
>>  /// getEDInfo - See MCDisassembler.
>>  EDInstInfo *getEDInfo() const;
>> 
>> Modified: llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp (original)
>> +++ llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.cpp Wed Aug 17 12:44:15 2011
>> @@ -493,7 +493,7 @@
>> // Public interface for the disassembler
>> //
>> 
>> -bool MBlazeDisassembler::getInstruction(MCInst &instr,
>> +MCDisassembler::DecodeStatus MBlazeDisassembler::getInstruction(MCInst &instr,
>>                                        uint64_t &size,
>>                                        const MemoryObject &region,
>>                                        uint64_t address,
>> @@ -508,7 +508,7 @@
>> 
>>  // We want to read exactly 4 bytes of data.
>>  if (region.readBytes(address, 4, (uint8_t*)bytes, &read) == -1 || read < 4)
>> -    return false;
>> +    return Fail;
>> 
>>  // Encoded as a big-endian 32-bit word in the stream.
>>  insn = (bytes[0]<<24) | (bytes[1]<<16) | (bytes[2]<< 8) | (bytes[3]<<0);
>> @@ -517,7 +517,7 @@
>>  // that it is a valid instruction.
>>  unsigned opcode = getOPCODE(insn);
>>  if (opcode == UNSUPPORTED)
>> -    return false;
>> +    return Fail;
>> 
>>  instr.setOpcode(opcode);
>> 
>> @@ -529,11 +529,11 @@
>>  uint64_t tsFlags = MBlazeInsts[opcode].TSFlags;
>>  switch ((tsFlags & MBlazeII::FormMask)) {
>>  default: 
>> -    return false;
>> +    return Fail;
>> 
>>  case MBlazeII::FRRRR:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED || RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RB));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>> @@ -541,7 +541,7 @@
>> 
>>  case MBlazeII::FRRR:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED || RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    instr.addOperand(MCOperand::CreateReg(RB));
>> @@ -550,23 +550,23 @@
>>  case MBlazeII::FRI:
>>    switch (opcode) {
>>    default: 
>> -      return false;
>> +      return Fail;
>>    case MBlaze::MFS:
>>      if (RD == UNSUPPORTED)
>> -        return false;
>> +        return Fail;
>>      instr.addOperand(MCOperand::CreateReg(RD));
>>      instr.addOperand(MCOperand::CreateImm(insn&0x3FFF));
>>      break;
>>    case MBlaze::MTS:
>>      if (RA == UNSUPPORTED)
>> -        return false;
>> +        return Fail;
>>      instr.addOperand(MCOperand::CreateImm(insn&0x3FFF));
>>      instr.addOperand(MCOperand::CreateReg(RA));
>>      break;
>>    case MBlaze::MSRSET:
>>    case MBlaze::MSRCLR:
>>      if (RD == UNSUPPORTED)
>> -        return false;
>> +        return Fail;
>>      instr.addOperand(MCOperand::CreateReg(RD));
>>      instr.addOperand(MCOperand::CreateImm(insn&0x7FFF));
>>      break;
>> @@ -575,7 +575,7 @@
>> 
>>  case MBlazeII::FRRI:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    switch (opcode) {
>> @@ -592,35 +592,35 @@
>> 
>>  case MBlazeII::FCRR:
>>    if (RA == UNSUPPORTED || RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    instr.addOperand(MCOperand::CreateReg(RB));
>>    break;
>> 
>>  case MBlazeII::FCRI:
>>    if (RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    instr.addOperand(MCOperand::CreateImm(getIMM(insn)));
>>    break;
>> 
>>  case MBlazeII::FRCR:
>>    if (RD == UNSUPPORTED || RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RB));
>>    break;
>> 
>>  case MBlazeII::FRCI:
>>    if (RD == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateImm(getIMM(insn)));
>>    break;
>> 
>>  case MBlazeII::FCCR:
>>    if (RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RB));
>>    break;
>> 
>> @@ -630,7 +630,7 @@
>> 
>>  case MBlazeII::FRRCI:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    instr.addOperand(MCOperand::CreateImm(getSHT(insn)));
>> @@ -638,35 +638,35 @@
>> 
>>  case MBlazeII::FRRC:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    break;
>> 
>>  case MBlazeII::FRCX:
>>    if (RD == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateImm(getFSL(insn)));
>>    break;
>> 
>>  case MBlazeII::FRCS:
>>    if (RD == UNSUPPORTED || RS == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateReg(RS));
>>    break;
>> 
>>  case MBlazeII::FCRCS:
>>    if (RS == UNSUPPORTED || RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RS));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    break;
>> 
>>  case MBlazeII::FCRCX:
>>    if (RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RA));
>>    instr.addOperand(MCOperand::CreateImm(getFSL(insn)));
>>    break;
>> @@ -677,13 +677,13 @@
>> 
>>  case MBlazeII::FCR:
>>    if (RB == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RB));
>>    break;
>> 
>>  case MBlazeII::FRIR:
>>    if (RD == UNSUPPORTED || RA == UNSUPPORTED)
>> -      return false;
>> +      return Fail;
>>    instr.addOperand(MCOperand::CreateReg(RD));
>>    instr.addOperand(MCOperand::CreateImm(getIMM(insn)));
>>    instr.addOperand(MCOperand::CreateReg(RA));
>> @@ -693,7 +693,7 @@
>>  // We always consume 4 bytes of data on success
>>  size = 4;
>> 
>> -  return true;
>> +  return Success;
>> }
>> 
>> static MCDisassembler *createMBlazeDisassembler(const Target &T) {
>> 
>> Modified: llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.h?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.h (original)
>> +++ llvm/trunk/lib/Target/MBlaze/Disassembler/MBlazeDisassembler.h Wed Aug 17 12:44:15 2011
>> @@ -40,7 +40,7 @@
>>  }
>> 
>>  /// getInstruction - See MCDisassembler.
>> -  bool getInstruction(MCInst &instr,
>> +  MCDisassembler::DecodeStatus getInstruction(MCInst &instr,
>>                      uint64_t &size,
>>                      const MemoryObject &region,
>>                      uint64_t address,
>> 
>> Modified: llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.cpp Wed Aug 17 12:44:15 2011
>> @@ -106,11 +106,12 @@
>> // Public interface for the disassembler
>> //
>> 
>> -bool X86GenericDisassembler::getInstruction(MCInst &instr,
>> -                                            uint64_t &size,
>> -                                            const MemoryObject &region,
>> -                                            uint64_t address,
>> -                                            raw_ostream &vStream) const {
>> +MCDisassembler::DecodeStatus
>> +X86GenericDisassembler::getInstruction(MCInst &instr,
>> +                                       uint64_t &size,
>> +                                       const MemoryObject &region,
>> +                                       uint64_t address,
>> +                                       raw_ostream &vStream) const {
>>  InternalInstruction internalInstr;
>> 
>>  int ret = decodeInstruction(&internalInstr,
>> @@ -123,11 +124,11 @@
>> 
>>  if (ret) {
>>    size = internalInstr.readerCursor - address;
>> -    return false;
>> +    return Fail;
>>  }
>>  else {
>>    size = internalInstr.length;
>> -    return !translateInstruction(instr, internalInstr);
>> +    return (!translateInstruction(instr, internalInstr)) ? Success : Fail;
>>  }
>> }
>> 
>> 
>> Modified: llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.h?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.h (original)
>> +++ llvm/trunk/lib/Target/X86/Disassembler/X86Disassembler.h Wed Aug 17 12:44:15 2011
>> @@ -112,11 +112,11 @@
>>  ~X86GenericDisassembler();
>> 
>>  /// getInstruction - See MCDisassembler.
>> -  bool getInstruction(MCInst &instr,
>> -                      uint64_t &size,
>> -                      const MemoryObject &region,
>> -                      uint64_t address,
>> -                      raw_ostream &vStream) const;
>> +  DecodeStatus getInstruction(MCInst &instr,
>> +                              uint64_t &size,
>> +                              const MemoryObject &region,
>> +                              uint64_t address,
>> +                              raw_ostream &vStream) const;
>> 
>>  /// getEDInfo - See MCDisassembler.
>>  EDInstInfo *getEDInfo() const;
>> 
>> Modified: llvm/trunk/test/MC/Disassembler/ARM/invalid-LDRB_POST-arm.txt
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Disassembler/ARM/invalid-LDRB_POST-arm.txt?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/MC/Disassembler/ARM/invalid-LDRB_POST-arm.txt (original)
>> +++ llvm/trunk/test/MC/Disassembler/ARM/invalid-LDRB_POST-arm.txt Wed Aug 17 12:44:15 2011
>> @@ -1,4 +1,4 @@
>> -# RUN: llvm-mc --disassemble %s -triple=arm-apple-darwin9 |& grep {invalid instruction encoding}
>> +# RUN: llvm-mc --disassemble %s -triple=arm-apple-darwin9 |& grep {potentially undefined instruction encoding}
>> 
>> # Opcode=140 Name=LDRB_POST Format=ARM_FORMAT_LDFRM(6)
>> #  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
>> 
>> Modified: llvm/trunk/tools/llvm-mc/Disassembler.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mc/Disassembler.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/tools/llvm-mc/Disassembler.cpp (original)
>> +++ llvm/trunk/tools/llvm-mc/Disassembler.cpp Wed Aug 17 12:44:15 2011
>> @@ -65,15 +65,26 @@
>>  for (Index = 0; Index < Bytes.size(); Index += Size) {
>>    MCInst Inst;
>> 
>> -    if (DisAsm.getInstruction(Inst, Size, memoryObject, Index,
>> -                               /*REMOVE*/ nulls())) {
>> -      Printer.printInst(&Inst, Out);
>> -      Out << "\n";
>> -    } else {
>> +    MCDisassembler::DecodeStatus S;
>> +    S = DisAsm.getInstruction(Inst, Size, memoryObject, Index,
>> +                              /*REMOVE*/ nulls());
>> +    switch (S) {
> 
> 
> Changing this to a switch statement is good. The C bindings in MCDisasembler.cpp and EDDisassembler.cpp need to be changed, too, though. They're still doing "!Disasm->getInstruction()" type constructs.
> 
> 
>> +    case MCDisassembler::Fail:
>>      SM.PrintMessage(SMLoc::getFromPointer(Bytes[Index].second),
>>                      "invalid instruction encoding", "warning");
>>      if (Size == 0)
>>        Size = 1; // skip illegible bytes
>> +      break;
>> +
>> +    case MCDisassembler::SoftFail:
>> +      SM.PrintMessage(SMLoc::getFromPointer(Bytes[Index].second),
>> +                      "potentially undefined instruction encoding", "warning");
>> +      // Fall through
>> +
>> +    case MCDisassembler::Success:
>> +      Printer.printInst(&Inst, Out);
>> +      Out << "\n";
>> +      break;
>>    }
>>  }
>> 
>> 
>> Modified: llvm/trunk/utils/TableGen/DisassemblerEmitter.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/DisassemblerEmitter.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/utils/TableGen/DisassemblerEmitter.cpp (original)
>> +++ llvm/trunk/utils/TableGen/DisassemblerEmitter.cpp Wed Aug 17 12:44:15 2011
>> @@ -128,5 +128,15 @@
>>    return;
>>  }
>> 
>> +  // ARM and Thumb have a CHECK() macro to deal with DecodeStatuses.
>> +  if (Target.getName() == "ARM" ||
>> +      Target.getName() == "Thumb") {
>> +    FixedLenDecoderEmitter(Records,
>> +                           "CHECK(S, ", ");",
>> +                           "S", "Fail",
>> +                           "DecodeStatus S = Success;\n(void)S;").run(OS);
>> +    return;
>> +  }
>> +
>>  FixedLenDecoderEmitter(Records).run(OS);
>> }
>> 
>> Modified: llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.cpp?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.cpp (original)
>> +++ llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.cpp Wed Aug 17 12:44:15 2011
>> @@ -238,19 +238,24 @@
>>  // Width of instructions
>>  unsigned BitWidth;
>> 
>> +  // Parent emitter
>> +  const FixedLenDecoderEmitter *Emitter;
>> +
>> public:
>>  FilterChooser(const FilterChooser &FC) :
>>    AllInstructions(FC.AllInstructions), Opcodes(FC.Opcodes),
>>      Operands(FC.Operands), Filters(FC.Filters),
>>      FilterBitValues(FC.FilterBitValues), Parent(FC.Parent),
>> -      BestIndex(FC.BestIndex), BitWidth(FC.BitWidth) { }
>> +    BestIndex(FC.BestIndex), BitWidth(FC.BitWidth),
>> +    Emitter(FC.Emitter) { }
>> 
>>  FilterChooser(const std::vector<const CodeGenInstruction*> &Insts,
>>                const std::vector<unsigned> &IDs,
>>    std::map<unsigned, std::vector<OperandInfo> > &Ops,
>> -                unsigned BW) :
>> +                unsigned BW,
>> +                const FixedLenDecoderEmitter *E) :
>>      AllInstructions(Insts), Opcodes(IDs), Operands(Ops), Filters(),
>> -      Parent(NULL), BestIndex(-1), BitWidth(BW) {
>> +      Parent(NULL), BestIndex(-1), BitWidth(BW), Emitter(E) {
>>    for (unsigned i = 0; i < BitWidth; ++i)
>>      FilterBitValues.push_back(BIT_UNFILTERED);
>> 
>> @@ -264,7 +269,8 @@
>>                FilterChooser &parent) :
>>      AllInstructions(Insts), Opcodes(IDs), Operands(Ops),
>>      Filters(), FilterBitValues(ParentFilterBitValues),
>> -      Parent(&parent), BestIndex(-1), BitWidth(parent.BitWidth) {
>> +      Parent(&parent), BestIndex(-1), BitWidth(parent.BitWidth),
>> +      Emitter(parent.Emitter) {
>>    doFilter();
>>  }
>> 
>> @@ -563,17 +569,17 @@
>> void FilterChooser::emitTop(raw_ostream &o, unsigned Indentation,
>>                            std::string Namespace) {
>>  o.indent(Indentation) <<
>> -    "static bool decode" << Namespace << "Instruction" << BitWidth
>> +    "static MCDisassembler::DecodeStatus decode" << Namespace << "Instruction" << BitWidth
>>    << "(MCInst &MI, uint" << BitWidth << "_t insn, uint64_t Address, "
>>    << "const void *Decoder) {\n";
>> -  o.indent(Indentation) << "  unsigned tmp = 0;\n  (void)tmp;\n";
>> +  o.indent(Indentation) << "  unsigned tmp = 0;\n  (void)tmp;\n" << Emitter->Locals << "\n";
>> 
>>  ++Indentation; ++Indentation;
>>  // Emits code to decode the instructions.
>>  emit(o, Indentation);
>> 
>>  o << '\n';
>> -  o.indent(Indentation) << "return false;\n";
>> +  o.indent(Indentation) << "return " << Emitter->ReturnFail << ";\n";
>>  --Indentation; --Indentation;
>> 
>>  o.indent(Indentation) << "}\n";
>> @@ -744,8 +750,8 @@
>>  }
>> 
>>  if (Decoder != "")
>> -    o.indent(Indentation) << "  if (!" << Decoder
>> -                          << "(MI, tmp, Address, Decoder)) return false;\n";
>> +    o.indent(Indentation) << "  " << Emitter->GuardPrefix << Decoder
>> +                          << "(MI, tmp, Address, Decoder)" << Emitter->GuardPostfix << "\n";
>>  else
>>    o.indent(Indentation) << "  MI.addOperand(MCOperand::CreateImm(tmp));\n";
>> 
>> @@ -776,15 +782,15 @@
>>         I = InsnOperands.begin(), E = InsnOperands.end(); I != E; ++I) {
>>      // If a custom instruction decoder was specified, use that.
>>      if (I->numFields() == 0 && I->Decoder.size()) {
>> -        o.indent(Indentation) << "  if (!" << I->Decoder
>> -                              << "(MI, insn, Address, Decoder)) return false;\n";
>> +        o.indent(Indentation) << "  " << Emitter->GuardPrefix << I->Decoder
>> +                              << "(MI, insn, Address, Decoder)" << Emitter->GuardPostfix << "\n";
>>        break;
>>      }
>> 
>>      emitBinaryParser(o, Indentation, *I);
>>    }
>> 
>> -    o.indent(Indentation) << "  return true; // " << nameWithID(Opc)
>> +    o.indent(Indentation) << "  return " << Emitter->ReturnOK << "; // " << nameWithID(Opc)
>>                          << '\n';
>>    o.indent(Indentation) << "}\n";
>>    return true;
>> @@ -821,14 +827,14 @@
>>       I = InsnOperands.begin(), E = InsnOperands.end(); I != E; ++I) {
>>    // If a custom instruction decoder was specified, use that.
>>    if (I->numFields() == 0 && I->Decoder.size()) {
>> -      o.indent(Indentation) << "  if (!" << I->Decoder
>> -                            << "(MI, insn, Address, Decoder)) return false;\n";
>> +      o.indent(Indentation) << "  " << Emitter->GuardPrefix << I->Decoder
>> +                            << "(MI, insn, Address, Decoder)" << Emitter->GuardPostfix << "\n";
>>      break;
>>    }
>> 
>>    emitBinaryParser(o, Indentation, *I);
>>  }
>> -  o.indent(Indentation) << "  return true; // " << nameWithID(Opc)
>> +  o.indent(Indentation) << "  return " << Emitter->ReturnOK << "; // " << nameWithID(Opc)
>>                        << '\n';
>>  o.indent(Indentation) << "}\n";
>> 
>> @@ -1426,7 +1432,7 @@
>> 
>>    // Emit the decoder for this namespace+width combination.
>>    FilterChooser FC(NumberedInstructions, I->second, Operands,
>> -                     8*I->first.second);
>> +                     8*I->first.second, this);
>>    FC.emitTop(o, 0, I->first.first);
>>  }
>> 
>> 
>> Modified: llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.h?rev=137830&r1=137829&r2=137830&view=diff
>> ==============================================================================
>> --- llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.h (original)
>> +++ llvm/trunk/utils/TableGen/FixedLenDecoderEmitter.h Wed Aug 17 12:44:15 2011
>> @@ -49,9 +49,16 @@
>> 
>> class FixedLenDecoderEmitter : public TableGenBackend {
>> public:
>> -  FixedLenDecoderEmitter(RecordKeeper &R) :
>> +  FixedLenDecoderEmitter(RecordKeeper &R,
>> +                         std::string GPrefix  = "if (",
>> +                         std::string GPostfix = " == MCDisassembler::Fail) return MCDisassembler::Fail;",
>> +                         std::string ROK      = "MCDisassembler::Success",
>> +                         std::string RFail    = "MCDisassembler::Fail",
>> +                         std::string L        = "") :
>>    Records(R), Target(R),
>> -    NumberedInstructions(Target.getInstructionsByEnumValue()) {}
>> +    NumberedInstructions(Target.getInstructionsByEnumValue()),
>> +    GuardPrefix(GPrefix), GuardPostfix(GPostfix),
>> +    ReturnOK(ROK), ReturnFail(RFail), Locals(L) {}
>> 
>>  // run - Output the code emitter
>>  void run(raw_ostream &o);
>> @@ -62,7 +69,10 @@
>>  std::vector<const CodeGenInstruction*> NumberedInstructions;
>>  std::vector<unsigned> Opcodes;
>>  std::map<unsigned, std::vector<OperandInfo> > Operands;
>> -
>> +public:
>> +  std::string GuardPrefix, GuardPostfix;
>> +  std::string ReturnOK, ReturnFail;
>> +  std::string Locals;
>> };
>> 
>> } // end llvm namespace
>> 
>> 
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 




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