Fix treatment of ARM unallocated hint instructions.

The reference manual defines only 5 permitted values for the immediate field of the "hint" instruction:
1. nop (imm == 0)
2. yield (imm == 1)
3. wfe (imm == 2)
4. wfi (imm == 3)
5. sev (imm == 4)

Therefore, restrict the permitted values for the "hint" instruction to 0 through 4.

Patch by Mihail Popa <Mihail.Popa@arm.com>

llvm-svn: 179707

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 2e009e55e3b..9c81eceb40f 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -308,6 +308,8 @@ static DecodeStatus DecodeVCVTD(MCInst &Inst, unsigned Insn,
                                 uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeVCVTQ(MCInst &Inst, unsigned Insn,
                                 uint64_t Address, const void *Decoder);
+static DecodeStatus DecodeImm0_4(MCInst &Inst, unsigned Insn, uint64_t Address,
+                                 const void *Decoder);
 
 
 static DecodeStatus DecodeThumbAddSpecialReg(MCInst &Inst, uint16_t Insn,
@@ -4496,6 +4498,15 @@ static DecodeStatus DecodeVCVTQ(MCInst &Inst, unsigned Insn,
   return S;
 }
 
+static DecodeStatus DecodeImm0_4(MCInst &Inst, unsigned Insn, uint64_t Address,
+                                 const void *Decoder)
+{
+  unsigned Imm = fieldFromInstruction(Insn, 0, 3);
+  if (Imm > 4) return MCDisassembler::Fail;
+  Inst.addOperand(MCOperand::CreateImm(Imm));
+  return MCDisassembler::Success;
+}
+
 static DecodeStatus DecodeLDR(MCInst &Inst, unsigned Val,
                                 uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;