A64: Improve constraints for StoreNamedField

Improve register constraints for cases that don't need write barriers, and
remove TODOs.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/189373006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19807 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/a64/lithium-a64.cc

@@ -2236,17 +2236,29 @@ LInstruction* LChunkBuilder::DoStoreKeyedGeneric(HStoreKeyedGeneric* instr) {
 
 
 LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
-  // TODO(jbramley): Optimize register usage in this instruction. For now, it
-  // allocates everything that it might need because it keeps changing in the
-  // merge and keeping it valid is time-consuming.
-
   // TODO(jbramley): It might be beneficial to allow value to be a constant in
   // some cases. x64 makes use of this with FLAG_track_fields, for example.
 
   LOperand* object = UseRegister(instr->object());
-  LOperand* value = UseRegisterAndClobber(instr->value());
-  LOperand* temp0 = TempRegister();
-  LOperand* temp1 = TempRegister();
+  LOperand* value;
+  LOperand* temp0 = NULL;
+  LOperand* temp1 = NULL;
+
+  if (instr->access().IsExternalMemory() ||
+      instr->field_representation().IsDouble()) {
+    value = UseRegister(instr->value());
+  } else if (instr->NeedsWriteBarrier()) {
+    value = UseRegisterAndClobber(instr->value());
+    temp0 = TempRegister();
+    temp1 = TempRegister();
+  } else if (instr->NeedsWriteBarrierForMap()) {
+    value = UseRegister(instr->value());
+    temp0 = TempRegister();
+    temp1 = TempRegister();
+  } else {
+    value = UseRegister(instr->value());
+    temp0 = TempRegister();
+  }
 
   LStoreNamedField* result =
       new(zone()) LStoreNamedField(object, value, temp0, temp1);

src/a64/lithium-codegen-a64.cc

@@ -5172,48 +5172,45 @@ void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
 }
 
 
-// TODO(jbramley): Once the merge is done and we're tracking bleeding_edge, try
-// to tidy up this function.
 void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   Representation representation = instr->representation();
 
   Register object = ToRegister(instr->object());
-  Register temp0 = ToRegister(instr->temp0());
-  Register temp1 = ToRegister(instr->temp1());
   HObjectAccess access = instr->hydrogen()->access();
+  Handle<Map> transition = instr->transition();
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
+    ASSERT(transition.is_null());
+    ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     Register value = ToRegister(instr->value());
     __ Store(value, MemOperand(object, offset), representation);
     return;
+  } else if (representation.IsDouble()) {
+    ASSERT(transition.is_null());
+    ASSERT(access.IsInobject());
+    ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
+    FPRegister value = ToDoubleRegister(instr->value());
+    __ Str(value, FieldMemOperand(object, offset));
+    return;
   }
 
-  Handle<Map> transition = instr->transition();
-  SmiCheck check_needed =
-      instr->hydrogen()->value()->IsHeapObject()
+  Register value = ToRegister(instr->value());
+
+  SmiCheck check_needed = instr->hydrogen()->value()->IsHeapObject()
       ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
 
-  if (representation.IsHeapObject()) {
-    Register value = ToRegister(instr->value());
-    if (!instr->hydrogen()->value()->type().IsHeapObject()) {
+  if (representation.IsHeapObject() &&
+      !instr->hydrogen()->value()->type().IsHeapObject()) {
     DeoptimizeIfSmi(value, instr->environment());
 
     // We know that value is a smi now, so we can omit the check below.
     check_needed = OMIT_SMI_CHECK;
   }
-  } else if (representation.IsDouble()) {
-    ASSERT(transition.is_null());
-    ASSERT(access.IsInobject());
-    ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
-    FPRegister value = ToDoubleRegister(instr->value());
-    __ Str(value, FieldMemOperand(object, offset));
-    return;
-  }
 
   if (!transition.is_null()) {
     // Store the new map value.
-    Register new_map_value = temp0;
+    Register new_map_value = ToRegister(instr->temp0());
     __ Mov(new_map_value, Operand(transition));
     __ Str(new_map_value, FieldMemOperand(object, HeapObject::kMapOffset));
     if (instr->hydrogen()->NeedsWriteBarrierForMap()) {
@@ -5221,7 +5218,7 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
       __ RecordWriteField(object,
                           HeapObject::kMapOffset,
                           new_map_value,
-                          temp1,
+                          ToRegister(instr->temp1()),
                           GetLinkRegisterState(),
                           kSaveFPRegs,
                           OMIT_REMEMBERED_SET,
@@ -5230,11 +5227,11 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   }
 
   // Do the store.
-  Register value = ToRegister(instr->value());
   Register destination;
   if (access.IsInobject()) {
     destination = object;
   } else {
+    Register temp0 = ToRegister(instr->temp0());
     __ Ldr(temp0, FieldMemOperand(object, JSObject::kPropertiesOffset));
     destination = temp0;
   }
@@ -5243,8 +5240,15 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
      instr->hydrogen()->value()->representation().IsInteger32()) {
     ASSERT(instr->hydrogen()->store_mode() == STORE_TO_INITIALIZED_ENTRY);
 #ifdef DEBUG
-    __ Ldr(temp1, FieldMemOperand(destination, offset));
-    __ AssertSmi(temp1);
+    Register temp0 = ToRegister(instr->temp0());
+    __ Ldr(temp0, FieldMemOperand(destination, offset));
+    __ AssertSmi(temp0);
+    // If destination aliased temp0, restore it to the address calculated
+    // earlier.
+    if (destination.Is(temp0)) {
+      ASSERT(!access.IsInobject());
+      __ Ldr(destination, FieldMemOperand(object, JSObject::kPropertiesOffset));
+    }
 #endif
     STATIC_ASSERT(kSmiValueSize == 32 && kSmiShift == 32 && kSmiTag == 0);
     __ Store(value, UntagSmiFieldMemOperand(destination, offset),
@@ -5256,7 +5260,7 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
     __ RecordWriteField(destination,
                         offset,
                         value,                        // Clobbered.
-                        temp1,      // Clobbered.
+                        ToRegister(instr->temp1()),   // Clobbered.
                         GetLinkRegisterState(),
                         kSaveFPRegs,
                         EMIT_REMEMBERED_SET,