[llvm-commits] [llvm] r166982 - in /llvm/trunk: lib/Target/ARM/ARMInstrThumb2.td lib/Target/ARM/Disassembler/ARMDisassembler.cpp test/MC/ARM/thumb2-b.w-encodingT4.s test/MC/Disassembler/ARM/thumb2.txt

[Kevin Enderby]

Author: enderby
Date: Mon Oct 29 18:27:20 2012
New Revision: 166982

URL: http://llvm.org/viewvc/llvm-project?rev=166982&view=rev
Log:
Fix ARM's b.w instruction for thumb 2 and the encoding T4.  The branch target
is 24 bits not 20 and the decoding needed to correctly handle converting the
J1 and J2 bits to their I1 and I2 values to reconstruct the displacement. 

Added:
    llvm/trunk/test/MC/ARM/thumb2-b.w-encodingT4.s
Modified:
    llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td
    llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
    llvm/trunk/test/MC/Disassembler/ARM/thumb2.txt

Modified: llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td?rev=166982&r1=166981&r2=166982&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td (original)
+++ llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td Mon Oct 29 18:27:20 2012
@@ -3245,11 +3245,11 @@
   let Inst{15-14} = 0b10;
   let Inst{12} = 1;
 
-  bits<20> target;
+  bits<24> target;
   let Inst{26} = target{19};
   let Inst{11} = target{18};
   let Inst{13} = target{17};
-  let Inst{21-16} = target{16-11};
+  let Inst{25-16} = target{20-11};
   let Inst{10-0} = target{10-0};
   let DecoderMethod = "DecodeT2BInstruction";
 }

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=166982&r1=166981&r2=166982&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp (original)
+++ llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp Mon Oct 29 18:27:20 2012
@@ -2095,16 +2095,28 @@
 static DecodeStatus
 DecodeT2BInstruction(MCInst &Inst, unsigned Insn,
                      uint64_t Address, const void *Decoder) {
-  DecodeStatus S = MCDisassembler::Success;
-  unsigned imm = (fieldFromInstruction(Insn, 0, 11) << 0) |
-                 (fieldFromInstruction(Insn, 11, 1) << 18) |
-                 (fieldFromInstruction(Insn, 13, 1) << 17) |
-                 (fieldFromInstruction(Insn, 16, 6) << 11) |
-                 (fieldFromInstruction(Insn, 26, 1) << 19);
-  if (!tryAddingSymbolicOperand(Address, Address + SignExtend32<20>(imm<<1) + 4,
+  DecodeStatus Status = MCDisassembler::Success;
+
+  // Note the J1 and J2 values are from the encoded instruction.  So here
+  // change them to I1 and I2 values via as documented:
+  // I1 = NOT(J1 EOR S);
+  // I2 = NOT(J2 EOR S);
+  // and build the imm32 with one trailing zero as documented:
+  // imm32 = SignExtend(S:I1:I2:imm10:imm11:'0', 32);
+  unsigned S = fieldFromInstruction(Insn, 26, 1);
+  unsigned J1 = fieldFromInstruction(Insn, 13, 1);
+  unsigned J2 = fieldFromInstruction(Insn, 11, 1);
+  unsigned I1 = !(J1 ^ S);
+  unsigned I2 = !(J2 ^ S);
+  unsigned imm10 = fieldFromInstruction(Insn, 16, 10);
+  unsigned imm11 = fieldFromInstruction(Insn, 0, 11);
+  unsigned tmp = (S << 23) | (I1 << 22) | (I2 << 21) | (imm10 << 11) | imm11;
+  int imm32 = SignExtend32<24>(tmp << 1);
+  if (!tryAddingSymbolicOperand(Address, Address + imm32 + 4,
                                 true, 4, Inst, Decoder))
-    Inst.addOperand(MCOperand::CreateImm(SignExtend32<20>(imm << 1)));
-  return S;
+    Inst.addOperand(MCOperand::CreateImm(imm32));
+
+  return Status;
 }
 
 static DecodeStatus

Added: llvm/trunk/test/MC/ARM/thumb2-b.w-encodingT4.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb2-b.w-encodingT4.s?rev=166982&view=auto
==============================================================================
--- llvm/trunk/test/MC/ARM/thumb2-b.w-encodingT4.s (added)
+++ llvm/trunk/test/MC/ARM/thumb2-b.w-encodingT4.s Mon Oct 29 18:27:20 2012
@@ -0,0 +1,12 @@
+@ RUN: llvm-mc -triple=thumbv7-apple-darwin -mcpu=cortex-a8 -show-encoding < %s | FileCheck %s
+  .syntax unified
+  .globl _func
+.thumb_func _foo
+.space 0x37c6
+_foo:
+ at ------------------------------------------------------------------------------
+@ B (thumb2 b.w encoding T4) rdar://12585795
+ at ------------------------------------------------------------------------------
+        b.w   0x3680c
+
+@ CHECK: b.w	#223244                    @ encoding: [0x6d,0xf0,0x0c,0xb0]

Modified: llvm/trunk/test/MC/Disassembler/ARM/thumb2.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Disassembler/ARM/thumb2.txt?rev=166982&r1=166981&r2=166982&view=diff
==============================================================================
--- llvm/trunk/test/MC/Disassembler/ARM/thumb2.txt (original)
+++ llvm/trunk/test/MC/Disassembler/ARM/thumb2.txt Mon Oct 29 18:27:20 2012
@@ -169,6 +169,9 @@
 
 0x13 0xf5 0xce 0xa9
 
+# CHECK: b.w   #208962
+
+0x33 0xf0 0x21 0xb8 # rdar://12585795
 
 #------------------------------------------------------------------------------
 # BFC