Fix some erroneous uses of instr->Mask(0).

Change-Id: I7b12ee533713677bdac3f5801a95b86517c81529

4 files changed, 29 insertions, 16 deletions

diff --git a/src/aarch64/constants-aarch64.h b/src/aarch64/constants-aarch64.h
index 6b8454fc..02422ef2 100644
--- a/src/aarch64/constants-aarch64.h
+++ b/src/aarch64/constants-aarch64.h
@@ -414,6 +414,8 @@ enum DataCacheOp {
 enum GenericInstrField {
   SixtyFourBits        = 0x80000000,
   ThirtyTwoBits        = 0x00000000,
+
+  FPTypeMask           = 0x00C00000,
   FP16                 = 0x00C00000,
   FP32                 = 0x00000000,
   FP64                 = 0x00400000
diff --git a/src/aarch64/decoder-aarch64.cc b/src/aarch64/decoder-aarch64.cc
index 1a981864..77900441 100644
--- a/src/aarch64/decoder-aarch64.cc
+++ b/src/aarch64/decoder-aarch64.cc
@@ -895,7 +895,8 @@ void Decoder::DecodeNEONScalarDataProcessing(const Instruction* instr) {
 
 #define DEFINE_VISITOR_CALLERS(A)                               \
   void Decoder::Visit##A(const Instruction* instr) {            \
-    VIXL_ASSERT(instr->Mask(A##FMask) == A##Fixed);             \
+    VIXL_ASSERT(((A##FMask == 0) && (A##Fixed == 0)) ||         \
+                (instr->Mask(A##FMask) == A##Fixed));           \
     std::list<DecoderVisitor*>::iterator it;                    \
     for (it = visitors_.begin(); it != visitors_.end(); it++) { \
       (*it)->Visit##A(instr);                                   \
diff --git a/src/aarch64/instructions-aarch64.h b/src/aarch64/instructions-aarch64.h
index 66ddf624..39c21a11 100644
--- a/src/aarch64/instructions-aarch64.h
+++ b/src/aarch64/instructions-aarch64.h
@@ -194,7 +194,10 @@ class Instruction {
     return ExtractSignedBits(msb, lsb);
   }
 
-  Instr Mask(uint32_t mask) const { return GetInstructionBits() & mask; }
+  Instr Mask(uint32_t mask) const {
+    VIXL_ASSERT(mask != 0);
+    return GetInstructionBits() & mask;
+  }
 
 #define DEFINE_GETTER(Name, HighBit, LowBit, Func)                  \
   int32_t Get##Name() const { return this->Func(HighBit, LowBit); } \
diff --git a/src/aarch64/simulator-aarch64.cc b/src/aarch64/simulator-aarch64.cc
index f1a57d97..787ee2ec 100644
--- a/src/aarch64/simulator-aarch64.cc
+++ b/src/aarch64/simulator-aarch64.cc
@@ -2829,13 +2829,18 @@ void Simulator::VisitFPDataProcessing1Source(const Instruction* instr) {
 
   FPRounding fpcr_rounding = static_cast<FPRounding>(ReadFpcr().GetRMode());
   VectorFormat vform;
-  if (instr->Mask(FP64) == FP64) {
-    vform = kFormatD;
-  } else if (instr->Mask(FP32) == FP32) {
-    vform = kFormatS;
-  } else {
-    VIXL_ASSERT(instr->Mask(FP16) == FP16);
-    vform = kFormatH;
+  switch (instr->Mask(FPTypeMask)) {
+    default:
+      VIXL_UNREACHABLE_OR_FALLTHROUGH();
+    case FP64:
+      vform = kFormatD;
+      break;
+    case FP32:
+      vform = kFormatS;
+      break;
+    case FP16:
+      vform = kFormatH;
+      break;
   }
   SimVRegister& rd = ReadVRegister(instr->GetRd());
   SimVRegister& rn = ReadVRegister(instr->GetRn());
@@ -2934,13 +2939,15 @@ void Simulator::VisitFPDataProcessing2Source(const Instruction* instr) {
   AssertSupportedFPCR();
 
   VectorFormat vform;
-  if (instr->Mask(FP64) == FP64) {
-    vform = kFormatD;
-  } else if (instr->Mask(FP32) == FP32) {
-    vform = kFormatS;
-  } else {
-    VIXL_ASSERT(instr->Mask(FP16) == FP16);
-    vform = kFormatH;
+  switch (instr->Mask(FPTypeMask)) {
+    default:
+      VIXL_UNREACHABLE_OR_FALLTHROUGH();
+    case FP64:
+      vform = kFormatD;
+      break;
+    case FP32:
+      vform = kFormatS;
+      break;
   }
   SimVRegister& rd = ReadVRegister(instr->GetRd());
   SimVRegister& rn = ReadVRegister(instr->GetRn());