[Thumb2] Improve disassembly of memory hints

Currently, the ARM disassembler will disassemble the Thumb2 memory hint
instructions (PLD, PLDW and PLI), even for targets which do not have
these instructions. This patch adds the required checks to the
disassmebler.

llvm-svn: 220472

1 files changed, 57 insertions, 7 deletions

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 04b856866e1..b85b7eba794 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -3269,6 +3269,11 @@ static DecodeStatus DecodeT2LoadShift(MCInst &Inst, unsigned Insn,
   unsigned Rt = fieldFromInstruction(Insn, 12, 4);
   unsigned Rn = fieldFromInstruction(Insn, 16, 4);
 
+  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
+                                                          .getFeatureBits();
+  bool hasMP = featureBits & ARM::FeatureMP;
+  bool hasV7Ops = featureBits & ARM::HasV7Ops;
+
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
     case ARM::t2LDRBs:
@@ -3304,11 +3309,10 @@ static DecodeStatus DecodeT2LoadShift(MCInst &Inst, unsigned Insn,
     case ARM::t2LDRSHs:
       return MCDisassembler::Fail;
     case ARM::t2LDRHs:
-      // FIXME: this instruction is only available with MP extensions,
-      // this should be checked first but we don't have access to the
-      // feature bits here.
       Inst.setOpcode(ARM::t2PLDWs);
       break;
+    case ARM::t2LDRSBs:
+      Inst.setOpcode(ARM::t2PLIs);
     default:
       break;
     }
@@ -3316,8 +3320,14 @@ static DecodeStatus DecodeT2LoadShift(MCInst &Inst, unsigned Insn,
 
   switch (Inst.getOpcode()) {
     case ARM::t2PLDs:
-    case ARM::t2PLDWs:
+      break;
     case ARM::t2PLIs:
+      if (!hasV7Ops)
+        return MCDisassembler::Fail;
+      break;
+    case ARM::t2PLDWs:
+      if (!hasV7Ops || !hasMP)
+        return MCDisassembler::Fail;
       break;
     default:
       if (!Check(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)))
@@ -3343,6 +3353,12 @@ static DecodeStatus DecodeT2LoadImm8(MCInst &Inst, unsigned Insn,
   unsigned imm = fieldFromInstruction(Insn, 0, 8);
   imm |= (U << 8);
   imm |= (Rn << 9);
+  unsigned add = fieldFromInstruction(Insn, 9, 1);
+
+  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
+                                                          .getFeatureBits();
+  bool hasMP = featureBits & ARM::FeatureMP;
+  bool hasV7Ops = featureBits & ARM::HasV7Ops;
 
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
@@ -3377,6 +3393,13 @@ static DecodeStatus DecodeT2LoadImm8(MCInst &Inst, unsigned Insn,
     switch (Inst.getOpcode()) {
     case ARM::t2LDRSHi8:
       return MCDisassembler::Fail;
+    case ARM::t2LDRHi8:
+      if (!add)
+        Inst.setOpcode(ARM::t2PLDWi8);
+      break;
+    case ARM::t2LDRSBi8:
+      Inst.setOpcode(ARM::t2PLIi8);
+      break;
     default:
       break;
     }
@@ -3384,9 +3407,15 @@ static DecodeStatus DecodeT2LoadImm8(MCInst &Inst, unsigned Insn,
 
   switch (Inst.getOpcode()) {
   case ARM::t2PLDi8:
+    break;
   case ARM::t2PLIi8:
-  case ARM::t2PLDWi8:
+    if (!hasV7Ops)
+      return MCDisassembler::Fail;
     break;
+  case ARM::t2PLDWi8:
+      if (!hasV7Ops || !hasMP)
+        return MCDisassembler::Fail;
+      break;
   default:
     if (!Check(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)))
       return MCDisassembler::Fail;
@@ -3406,6 +3435,11 @@ static DecodeStatus DecodeT2LoadImm12(MCInst &Inst, unsigned Insn,
   unsigned imm = fieldFromInstruction(Insn, 0, 12);
   imm |= (Rn << 13);
 
+  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
+                                                          .getFeatureBits();
+  bool hasMP = (featureBits & ARM::FeatureMP);
+  bool hasV7Ops = (featureBits & ARM::HasV7Ops);
+
   if (Rn == 15) {
     switch (Inst.getOpcode()) {
     case ARM::t2LDRi12:
@@ -3440,7 +3474,10 @@ static DecodeStatus DecodeT2LoadImm12(MCInst &Inst, unsigned Insn,
     case ARM::t2LDRSHi12:
       return MCDisassembler::Fail;
     case ARM::t2LDRHi12:
-      Inst.setOpcode(ARM::t2PLDi12);
+      Inst.setOpcode(ARM::t2PLDWi12);
+      break;
+    case ARM::t2LDRSBi12:
+      Inst.setOpcode(ARM::t2PLIi12);
       break;
     default:
       break;
@@ -3449,9 +3486,15 @@ static DecodeStatus DecodeT2LoadImm12(MCInst &Inst, unsigned Insn,
 
   switch (Inst.getOpcode()) {
   case ARM::t2PLDi12:
-  case ARM::t2PLDWi12:
+    break;
   case ARM::t2PLIi12:
+    if (!hasV7Ops)
+      return MCDisassembler::Fail;
     break;
+  case ARM::t2PLDWi12:
+      if (!hasV7Ops || !hasMP)
+        return MCDisassembler::Fail;
+      break;
   default:
     if (!Check(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)))
       return MCDisassembler::Fail;
@@ -3509,6 +3552,10 @@ static DecodeStatus DecodeT2LoadLabel(MCInst &Inst, unsigned Insn,
   unsigned U = fieldFromInstruction(Insn, 23, 1);
   int imm = fieldFromInstruction(Insn, 0, 12);
 
+  uint64_t featureBits = ((const MCDisassembler*)Decoder)->getSubtargetInfo()
+                                                          .getFeatureBits();
+  bool hasV7Ops = (featureBits & ARM::HasV7Ops);
+
   if (Rt == 15) {
     switch (Inst.getOpcode()) {
       case ARM::t2LDRBpci:
@@ -3527,7 +3574,10 @@ static DecodeStatus DecodeT2LoadLabel(MCInst &Inst, unsigned Insn,
 
   switch(Inst.getOpcode()) {
   case ARM::t2PLDpci:
+    break;
   case ARM::t2PLIpci:
+    if (!hasV7Ops)
+      return MCDisassembler::Fail;
     break;
   default:
     if (!Check(S, DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)))