MIPS: Eliminate map checks of constant values.

Port r15819 (a453a0e)

BUG=

Review URL: https://codereview.chromium.org/19876006
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15831 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -5187,6 +5187,7 @@ void LCodeGen::DoCheckMapCommon(Register map_reg,
 
 
 void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
+  if (instr->hydrogen()->CanOmitMapChecks()) return;
   Register map_reg = scratch0();
   LOperand* input = instr->value();
   ASSERT(input->IsRegister());
@@ -5255,6 +5256,8 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  if (instr->hydrogen()->CanOmitPrototypeChecks()) return;
+
   Register prototype_reg = ToRegister(instr->temp());
   Register map_reg = ToRegister(instr->temp2());
 
@@ -5263,12 +5266,10 @@ void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
 
   ASSERT(prototypes->length() == maps->length());
 
-  if (!instr->hydrogen()->CanOmitPrototypeChecks()) {
-    for (int i = 0; i < prototypes->length(); i++) {
-      __ LoadHeapObject(prototype_reg, prototypes->at(i));
-      __ lw(map_reg, FieldMemOperand(prototype_reg, HeapObject::kMapOffset));
-      DoCheckMapCommon(map_reg, maps->at(i), instr->environment());
-    }
+  for (int i = 0; i < prototypes->length(); i++) {
+    __ LoadHeapObject(prototype_reg, prototypes->at(i));
+    __ lw(map_reg, FieldMemOperand(prototype_reg, HeapObject::kMapOffset));
+    DoCheckMapCommon(map_reg, maps->at(i), instr->environment());
   }
 }
 

src/mips/lithium-mips.cc

@@ -1951,9 +1951,14 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LUnallocated* temp1 = TempRegister();
-  LOperand* temp2 = TempRegister();
+  LUnallocated* temp1 = NULL;
+  LOperand* temp2 = NULL;
+  if (!instr->CanOmitPrototypeChecks()) {
+    temp1 = TempRegister();
+    temp2 = TempRegister();
+  }
   LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
+  if (instr->CanOmitPrototypeChecks()) return result;
   return AssignEnvironment(result);
 }
 
@@ -1965,8 +1970,10 @@ LInstruction* LChunkBuilder::DoCheckFunction(HCheckFunction* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckMaps(HCheckMaps* instr) {
-  LOperand* value = UseRegisterAtStart(instr->value());
+  LOperand* value = NULL;
+  if (!instr->CanOmitMapChecks()) value = UseRegisterAtStart(instr->value());
   LInstruction* result = new(zone()) LCheckMaps(value);
+  if (instr->CanOmitMapChecks()) return result;
   return AssignEnvironment(result);
 }