Fix issues with the ARM bl and blx thumb instructions and the J1 and J2 bits
for the assembler and disassembler. Which were not being set/read correctly
for offsets greater than 22 bits in some cases.
Changes to lib/Target/ARM/ARMAsmBackend.cpp from Gideon Myles!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156118 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 28ea0d2..80b2b23 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -3339,10 +3339,25 @@
static DecodeStatus DecodeThumbBLXOffset(MCInst &Inst, unsigned Val,
uint64_t Address, const void *Decoder) {
+ // Val is passed in as S:J1:J2:imm10H:imm10L:’0’
+ // Note only one trailing zero not two. Also the J1 and J2 values are from
+ // the encoded instruction. So here change to I1 and I2 values via:
+ // I1 = NOT(J1 EOR S);
+ // I2 = NOT(J2 EOR S);
+ // and build the imm32 with two trailing zeros as documented:
+ // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:’00’, 32);
+ unsigned S = (Val >> 23) & 1;
+ unsigned J1 = (Val >> 22) & 1;
+ unsigned J2 = (Val >> 21) & 1;
+ unsigned I1 = !(J1 ^ S);
+ unsigned I2 = !(J2 ^ S);
+ unsigned tmp = (Val & ~0x600000) | (I1 << 22) | (I2 << 21);
+ int imm32 = SignExtend32<25>(tmp << 1);
+
if (!tryAddingSymbolicOperand(Address,
- (Address & ~2u) + SignExtend32<22>(Val << 1) + 4,
+ (Address & ~2u) + imm32 + 4,
true, 4, Inst, Decoder))
- Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
+ Inst.addOperand(MCOperand::CreateImm(imm32));
return MCDisassembler::Success;
}
@@ -3456,9 +3471,24 @@
static DecodeStatus DecodeThumbBLTargetOperand(MCInst &Inst, unsigned Val,
uint64_t Address, const void *Decoder){
- if (!tryAddingSymbolicOperand(Address, Address + SignExtend32<22>(Val<<1) + 4,
+ // Val is passed in as S:J1:J2:imm10:imm11
+ // Note no trailing zero after imm11. Also the J1 and J2 values are from
+ // the encoded instruction. So here change to I1 and I2 values via:
+ // 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 = (Val >> 23) & 1;
+ unsigned J1 = (Val >> 22) & 1;
+ unsigned J2 = (Val >> 21) & 1;
+ unsigned I1 = !(J1 ^ S);
+ unsigned I2 = !(J2 ^ S);
+ unsigned tmp = (Val & ~0x600000) | (I1 << 22) | (I2 << 21);
+ int imm32 = SignExtend32<25>(tmp << 1);
+
+ if (!tryAddingSymbolicOperand(Address, Address + imm32 + 4,
true, 4, Inst, Decoder))
- Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
+ Inst.addOperand(MCOperand::CreateImm(imm32));
return MCDisassembler::Success;
}