[Mips][Disassembler]When disassembler meets load/store from coprocessor 2 instructions for mips r6 it crashes as the access to operands array is out of range. This patch adds dedicated decoder method that properly handles decoding of these instructions.

llvm-svn: 226652

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
index da33f3b913c..98fc1ebba15 100644
--- a/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ b/llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -304,6 +304,10 @@ static DecodeStatus DecodeFMem3(MCInst &Inst, unsigned Insn,
                                uint64_t Address,
                                const void *Decoder);
 
+static DecodeStatus DecodeFMemCop2R6(MCInst &Inst, unsigned Insn,
+                               uint64_t Address,
+                               const void *Decoder);
+
 static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
                                        unsigned Insn,
                                        uint64_t Address,
@@ -1354,6 +1358,23 @@ static DecodeStatus DecodeFMem3(MCInst &Inst,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeFMemCop2R6(MCInst &Inst,
+                                    unsigned Insn,
+                                    uint64_t Address,
+                                    const void *Decoder) {
+  int Offset = SignExtend32<11>(Insn & 0x07ff);
+  unsigned Reg = fieldFromInstruction(Insn, 16, 5);
+  unsigned Base = fieldFromInstruction(Insn, 11, 5);
+
+  Reg = getReg(Decoder, Mips::COP2RegClassID, Reg);
+  Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
+
+  Inst.addOperand(MCOperand::CreateReg(Reg));
+  Inst.addOperand(MCOperand::CreateReg(Base));
+  Inst.addOperand(MCOperand::CreateImm(Offset));
+
+  return MCDisassembler::Success;
+}
 static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
                                        unsigned Insn,
                                        uint64_t Address,
diff --git a/llvm/lib/Target/Mips/Mips32r6InstrInfo.td b/llvm/lib/Target/Mips/Mips32r6InstrInfo.td
index 185d12ec93f..baf746061be 100644
--- a/llvm/lib/Target/Mips/Mips32r6InstrInfo.td
+++ b/llvm/lib/Target/Mips/Mips32r6InstrInfo.td
@@ -561,6 +561,7 @@ class COP2LD_DESC_BASE<string instr_asm, RegisterOperand COPOpnd> {
   string AsmString = !strconcat(instr_asm, "\t$rt, $addr");
   list<dag> Pattern = [];
   bit mayLoad = 1;
+  string DecoderMethod = "DecodeFMemCop2R6";
 }
 
 class LDC2_R6_DESC : COP2LD_DESC_BASE<"ldc2", COP2Opnd>;
@@ -572,6 +573,7 @@ class COP2ST_DESC_BASE<string instr_asm, RegisterOperand COPOpnd> {
   string AsmString = !strconcat(instr_asm, "\t$rt, $addr");
   list<dag> Pattern = [];
   bit mayStore = 1;
+  string DecoderMethod = "DecodeFMemCop2R6";
 }
 
 class SDC2_R6_DESC : COP2ST_DESC_BASE<"sdc2", COP2Opnd>;