[llvm-commits] [llvm] r54248 - in /llvm/trunk: include/llvm/Target/TargetOptions.h lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp lib/Target/PowerPC/PPCISelLowering.cpp lib/Target/PowerPC/PPCTargetMachine.cpp lib/Target/TargetMachine.cpp

[Chris Lattner]

On Jul 31, 2008, at 11:13 AM, Dale Johannesen wrote:

> Author: johannes
> Date: Thu Jul 31 13:13:12 2008
> New Revision: 54248
>
> URL: http://llvm.org/viewvc/llvm-project?rev=54248&view=rev
> Log:
> Add a flag to disable jump table generation (all
> switches use the binary search algorithm) for
> environments that don't support it.  PPC64 JIT
> is such an environment; turn the flag on for that.

Thanks Dale, one tweak:

> +++ llvm/trunk/include/llvm/Target/TargetOptions.h Thu Jul 31  
> 13:13:12 2008
> @@ -97,6 +97,10 @@
>   /// VerboseAsm - When this flag is set, the asm printer prints  
> additional
>   /// comments to asm directives.
>   extern bool VerboseAsm;
> +
> +  /// DisableJumpTables - This flag indicates jump tables should  
> not be
> +  /// generated.
> +  extern bool DisableJumpTables;

TargetOptions is for things that clients of the code generator set  
when they want to affect the behavior of codegen.

In this case, jump tables are never valid in ppc64 JIT mode.  Why not  
just have the PPC backend mark BR_JT and BRIND as illegal when in 64- 
bit jit mode?  That way no target-indep code changes.

-Chris


> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Thu Jul  
> 31 13:13:12 2008
> @@ -1916,8 +1916,9 @@
> }
>
> static inline bool areJTsAllowed(const TargetLowering &TLI) {
> -  return (TLI.isOperationLegal(ISD::BR_JT, MVT::Other) ||
> -          TLI.isOperationLegal(ISD::BRIND, MVT::Other));
> +  return !DisableJumpTables &&
> +          (TLI.isOperationLegal(ISD::BR_JT, MVT::Other) ||
> +           TLI.isOperationLegal(ISD::BRIND, MVT::Other));
> }
>
> /// handleJTSwitchCase - Emit jumptable for current switch case range
>
> Modified: llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp?rev=54248&r1=54247&r2=54248&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp (original)
> +++ llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp Thu Jul 31  
> 13:13:12 2008
> @@ -43,7 +43,7 @@
>   : TargetLowering(TM), PPCSubTarget(*TM.getSubtargetImpl()) {
>
>   setPow2DivIsCheap();
> -
> +
>   // Use _setjmp/_longjmp instead of setjmp/longjmp.
>   setUseUnderscoreSetJmp(true);
>   setUseUnderscoreLongJmp(true);
>
> Modified: llvm/trunk/lib/Target/PowerPC/PPCTargetMachine.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCTargetMachine.cpp?rev=54248&r1=54247&r2=54248&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Target/PowerPC/PPCTargetMachine.cpp (original)
> +++ llvm/trunk/lib/Target/PowerPC/PPCTargetMachine.cpp Thu Jul 31  
> 13:13:12 2008
> @@ -17,6 +17,7 @@
> #include "llvm/Module.h"
> #include "llvm/PassManager.h"
> #include "llvm/Target/TargetMachineRegistry.h"
> +#include "llvm/Target/TargetOptions.h"
> using namespace llvm;
>
> // Register the targets
> @@ -144,6 +145,9 @@
>     // instructions to materialize arbitrary global variable +  
> function +
>     // constant pool addresses.
>     setRelocationModel(Reloc::PIC_);
> +    // Temporary workaround for the inability of PPC64 JIT to  
> handle jump
> +    // tables.
> +    DisableJumpTables = true;
>   } else {
>     setRelocationModel(Reloc::Static);
>   }
>
> Modified: llvm/trunk/lib/Target/TargetMachine.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/TargetMachine.cpp?rev=54248&r1=54247&r2=54248&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/Target/TargetMachine.cpp (original)
> +++ llvm/trunk/lib/Target/TargetMachine.cpp Thu Jul 31 13:13:12 2008
> @@ -39,6 +39,7 @@
>   unsigned StackAlignment;
>   bool RealignStack;
>   bool VerboseAsm;
> +  bool DisableJumpTables;
> }
>
> static cl::opt<bool, true> PrintCode("print-machineinstrs",
> @@ -156,6 +157,11 @@
>            cl::location(VerboseAsm),
>            cl::init(false));
>
> +static cl::opt<bool, true>
> +DisableSwitchTables(cl::Hidden, "disable-jump-tables",
> +           cl::desc("Do not generate jump tables."),
> +           cl::location(DisableJumpTables),
> +           cl::init(false));
>
> //---------------------------------------------------------------------------
> // TargetMachine Class
>
>
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