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Improve handling of failure and unpredictable cases for CPS, STR, and SMLA instructions. 

Fixes a large class of disassembler crashes found by randomized testing.

llvm-svn: 137995
This commit is contained in:
Owen Anderson 2011-08-18 22:11:02 +00:00
parent d7cbd4c518
commit 67d6f11974
2 changed files with 20 additions and 13 deletions
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31
llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
View File

@ -1317,27 +1317,34 @@ static DecodeStatus DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
unsigned iflags = fieldFromInstruction32(Insn, 6, 3);
unsigned mode = fieldFromInstruction32(Insn, 0, 5);
// imod == '01' --> UNPREDICTABLE
if (imod == 1) return Fail;
DecodeStatus S = Success;
if (M && mode && imod && iflags) {
// imod == '01' --> UNPREDICTABLE
// NOTE: Even though this is technically UNPREDICTABLE, we choose to
// return failure here. The '01' imod value is unprintable, so there's
// nothing useful we could do even if we returned UNPREDICTABLE.
if (imod == 1) CHECK(S, Fail);
if (imod && M) {
Inst.setOpcode(ARM::CPS3p);
Inst.addOperand(MCOperand::CreateImm(imod));
Inst.addOperand(MCOperand::CreateImm(iflags));
Inst.addOperand(MCOperand::CreateImm(mode));
return Success;
} else if (!mode && !M) {
} else if (imod && !M) {
Inst.setOpcode(ARM::CPS2p);
Inst.addOperand(MCOperand::CreateImm(imod));
Inst.addOperand(MCOperand::CreateImm(iflags));
return Success;
} else if (!imod && !iflags && M) {
if (mode) CHECK(S, Unpredictable);
} else if (!imod && M) {
Inst.setOpcode(ARM::CPS1p);
Inst.addOperand(MCOperand::CreateImm(mode));
return Success;
}
if (iflags) CHECK(S, Unpredictable);
} else
// imod == '00' && M == '0' --> UNPREDICTABLE
CHECK(S, Unpredictable);
return Fail;
return S;
}
static DecodeStatus DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
@ -2649,7 +2656,7 @@ static DecodeStatus DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
unsigned pred = fieldFromInstruction32(Insn, 28, 4);
if (Rn == 0xF || Rn == Rt) return Unpredictable; // UNPREDICTABLE
if (Rn == 0xF || Rn == Rt) CHECK(S, Unpredictable);
CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));
@ -2670,7 +2677,7 @@ static DecodeStatus DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
unsigned pred = fieldFromInstruction32(Insn, 28, 4);
if (Rn == 0xF || Rn == Rt) return Unpredictable; // UNPREDICTABLE
if (Rn == 0xF || Rn == Rt) CHECK(S, Unpredictable);
CHECK(S, DecodeGPRRegisterClass(Inst, Rn, Address, Decoder));
CHECK(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder));

2
llvm/test/MC/Disassembler/ARM/invalid-CPS3p-arm.txt
View File

@ -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}
# invalid (imod, M, iflags) combination
0x93 0x1c 0x02 0xf1