Bitfield mask instructions are unpredictable if the encoded LSB is higher than the encoded MSB.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139972 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 4e9c3e5..d76fb93 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -1004,12 +1004,15 @@
unsigned msb = fieldFromInstruction32(Val, 5, 5);
unsigned lsb = fieldFromInstruction32(Val, 0, 5);
+ DecodeStatus S = MCDisassembler::Success;
+ if (lsb > msb) Check(S, MCDisassembler::SoftFail);
+
uint32_t msb_mask = 0xFFFFFFFF;
if (msb != 31) msb_mask = (1U << (msb+1)) - 1;
uint32_t lsb_mask = (1U << lsb) - 1;
Inst.addOperand(MCOperand::CreateImm(~(msb_mask ^ lsb_mask)));
- return MCDisassembler::Success;
+ return S;
}
static DecodeStatus DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
