[v8-dev] ARM: Optimize WrapReceiver

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 4e1cc2f7a58bce915542263d8f182b8058f34463..c81d3e963900f4f4da120a8c9c6b24f6e0818ad1 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3496,12 +3496,13 @@ void LCodeGen::DoArgumentsLength(LArgumentsLength* instr) {
 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.
@@ -3511,11 +3512,11 @@ void LCodeGen::DoWrapReceiver(LWrapReceiver* instr) {
          FieldMemOperand(scratch, SharedFunctionInfo::kCompilerHintsOffset));
   __ tst(scratch,
          Operand(1 << (SharedFunctionInfo::kStrictModeFunction + kSmiTagSize)));
-  __ b(ne, &receiver_ok);
+  __ b(ne, &result_in_receiver);
 
   // Do not transform the receiver to object for builtins.
   __ tst(scratch, Operand(1 << (SharedFunctionInfo::kNative + kSmiTagSize)));
-  __ b(ne, &receiver_ok);
+  __ b(ne, &result_in_receiver);
 
   // Normal function. Replace undefined or null with global receiver.
   __ LoadRoot(scratch, Heap::kNullValueRootIndex);
@@ -3530,13 +3531,21 @@ void LCodeGen::DoWrapReceiver(LWrapReceiver* instr) {
   DeoptimizeIf(eq, instr->environment());
   __ CompareObjectType(receiver, scratch, scratch, FIRST_SPEC_OBJECT_TYPE);
   DeoptimizeIf(lt, instr->environment());
-  __ jmp(&receiver_ok);
+  __ b(&result_in_receiver);
 
   __ bind(&global_object);
-  __ ldr(receiver, GlobalObjectOperand());
-  __ ldr(receiver,
-         FieldMemOperand(receiver, JSGlobalObject::kGlobalReceiverOffset));
-  __ bind(&receiver_ok);
+  __ ldr(result, GlobalObjectOperand());
+  __ ldr(result,
+         FieldMemOperand(result, JSGlobalObject::kGlobalReceiverOffset));
+  if (result.is(receiver)) {
+    __ bind(&result_in_receiver);
+  } else {
+    Label result_ok;
+    __ b(&result_ok);
+    __ bind(&result_in_receiver);
+    __ mov(result, receiver);
+    __ bind(&result_ok);
+  }
 }