MIPS: Optimize WrapReceiver

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3355 matching lines @@
   __ SmiUntag(result);
 
   // Argument length is in result register.
   __ bind(&done);
 }
 
 
 void LCodeGen::DoWrapReceiver(LWrapReceiver* instr) {
   Register receiver = ToRegister(instr->receiver());
   Register function = ToRegister(instr->function());
+  Register result = ToRegister(instr->result());
   Register scratch = scratch0();
 
   // If the receiver is null or undefined, we have to pass the global
   // object as a receiver to normal functions. Values have to be
   // passed unchanged to builtins and strict-mode functions.
-  Label global_object, receiver_ok;
+  Label global_object, result_in_receiver;
 
   // Do not transform the receiver to object for strict mode
   // functions.
   __ lw(scratch,
          FieldMemOperand(function, JSFunction::kSharedFunctionInfoOffset));
   __ lw(scratch,
          FieldMemOperand(scratch, SharedFunctionInfo::kCompilerHintsOffset));
 
   // Do not transform the receiver to object for builtins.
   int32_t strict_mode_function_mask =
                   1 <<  (SharedFunctionInfo::kStrictModeFunction + kSmiTagSize);
   int32_t native_mask = 1 << (SharedFunctionInfo::kNative + kSmiTagSize);
   __ And(scratch, scratch, Operand(strict_mode_function_mask | native_mask));
-  __ Branch(&receiver_ok, ne, scratch, Operand(zero_reg));
+  __ Branch(&result_in_receiver, ne, scratch, Operand(zero_reg));
 
   // Normal function. Replace undefined or null with global receiver.
   __ LoadRoot(scratch, Heap::kNullValueRootIndex);
   __ Branch(&global_object, eq, receiver, Operand(scratch));
   __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
   __ Branch(&global_object, eq, receiver, Operand(scratch));
 
   // Deoptimize if the receiver is not a JS object.
   __ SmiTst(receiver, scratch);
   DeoptimizeIf(eq, instr->environment(), scratch, Operand(zero_reg));
 
   __ GetObjectType(receiver, scratch, scratch);
   DeoptimizeIf(lt, instr->environment(),
                scratch, Operand(FIRST_SPEC_OBJECT_TYPE));
-  __ Branch(&receiver_ok);
+  __ Branch(&result_in_receiver);
 
   __ bind(&global_object);
-  __ lw(receiver, GlobalObjectOperand());
-  __ lw(receiver,
-         FieldMemOperand(receiver, JSGlobalObject::kGlobalReceiverOffset));
-  __ bind(&receiver_ok);
+  __ lw(result, GlobalObjectOperand());
+  __ lw(result,
+         FieldMemOperand(result, JSGlobalObject::kGlobalReceiverOffset));
+  if (result.is(receiver)) {
+    __ bind(&result_in_receiver);
+  } else {
+    Label result_ok;
+    __ Branch(&result_ok);
+    __ bind(&result_in_receiver);
+    __ mov(result, receiver);
+    __ bind(&result_ok);
+  }
 }
 
 
 void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
   Register receiver = ToRegister(instr->receiver());
   Register function = ToRegister(instr->function());
   Register length = ToRegister(instr->length());
   Register elements = ToRegister(instr->elements());
   Register scratch = scratch0();
   ASSERT(receiver.is(a0));  // Used for parameter count.
@@ skipping 2442 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal