MIPS: Clean up handling of global cell stores in the optimizing compiler.

Port r10280 (5f6aec5).

Original commit message:

Tell the register allocator the value is not overwritten.  Never use
temporary registers on ia32, avoid them on x64 and ARM.  Restore the
original copyright date on assembler.cc.

BUG=
TEST=

Review URL: http://codereview.chromium.org/9004017
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10281 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -2141,26 +2141,26 @@ void LCodeGen::DoLoadGlobalGeneric(LLoadGlobalGeneric* instr) {
 
 
 void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
-  Register value = ToRegister(instr->InputAt(0));
-  Register scratch = scratch0();
-  Register scratch2 = ToRegister(instr->TempAt(0));
+  Register value = ToRegister(instr->value());
+  Register cell = scratch0();
 
   // Load the cell.
-  __ li(scratch, Operand(Handle<Object>(instr->hydrogen()->cell())));
+  __ li(cell, Operand(instr->hydrogen()->cell()));
 
   // If the cell we are storing to contains the hole it could have
   // been deleted from the property dictionary. In that case, we need
   // to update the property details in the property dictionary to mark
   // it as no longer deleted.
   if (instr->hydrogen()->RequiresHoleCheck()) {
-    __ lw(scratch2,
-          FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
+    // We use a temp to check the payload.
+    Register payload = ToRegister(instr->TempAt(0));
+    __ lw(payload, FieldMemOperand(cell, JSGlobalPropertyCell::kValueOffset));
     __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
-    DeoptimizeIf(eq, instr->environment(), scratch2, Operand(at));
+    DeoptimizeIf(eq, instr->environment(), payload, Operand(at));
   }
 
   // Store the value.
-  __ sw(value, FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
+  __ sw(value, FieldMemOperand(cell, JSGlobalPropertyCell::kValueOffset));
   // Cells are always rescanned, so no write barrier here.
 }
 

src/mips/lithium-mips.cc

@@ -1782,11 +1782,12 @@ LInstruction* LChunkBuilder::DoLoadGlobalGeneric(HLoadGlobalGeneric* instr) {
 
 
 LInstruction* LChunkBuilder::DoStoreGlobalCell(HStoreGlobalCell* instr) {
-  LOperand* temp = TempRegister();
-  LOperand* value = UseTempRegister(instr->value());
-  LInstruction* result = new LStoreGlobalCell(value, temp);
-  if (instr->RequiresHoleCheck()) result = AssignEnvironment(result);
-  return result;
+  LOperand* value = UseRegister(instr->value());
+  // Use a temp to check the value in the cell in the case where we perform
+  // a hole check.
+  return instr->RequiresHoleCheck()
+      ? AssignEnvironment(new LStoreGlobalCell(value, TempRegister()))
+      : new LStoreGlobalCell(value, NULL);
 }
 
 

src/mips/lithium-mips.h

@@ -1242,6 +1242,8 @@ class LStoreGlobalCell: public LTemplateInstruction<0, 1, 1> {
 
   DECLARE_CONCRETE_INSTRUCTION(StoreGlobalCell, "store-global-cell")
   DECLARE_HYDROGEN_ACCESSOR(StoreGlobalCell)
+
+  LOperand* value() { return inputs_[0]; }
 };