Stub Cache: speed up load callback accessor by allocating data handle on stack.

src/ia32/stub-cache-ia32.cc

Index: src/ia32/stub-cache-ia32.cc
diff --git a/src/ia32/stub-cache-ia32.cc b/src/ia32/stub-cache-ia32.cc
index e47ad1c072ff22603fee86e2e03fee7ea73295c9..fed2ef5cf4a9834f2eb904f27c463939088ef932 100644
--- a/src/ia32/stub-cache-ia32.cc
+++ b/src/ia32/stub-cache-ia32.cc
@@ -447,15 +447,17 @@ void StubCompiler::GenerateLoadCallback(JSObject* object,
   // Push the arguments on the JS stack of the caller.
   __ pop(scratch2);  // remove return address
   __ push(receiver);  // receiver
-  __ push(Immediate(Handle<AccessorInfo>(callback)));  // callback data
-  __ push(name_reg);  // name
   __ push(reg);  // holder
+  __ mov(reg, Immediate(Handle<AccessorInfo>(callback)));  // callback data

[antonm, 2009/07/23 21:12:58]

why not __ push(Immediate....)?

[Vitaly Repeshko, 2009/07/24 13:45:38]

I need this data in a register anyway (to support the push below). Current
approach saves us a relocation entry.

+  __ push(reg);
+  __ push(FieldOperand(reg, AccessorInfo::kDataOffset));

[antonm, 2009/07/23 21:12:58]

ditto (shortcutting if data is not in new space)

[Vitaly Repeshko, 2009/07/24 13:45:38]

I tried it and my measurements didn't show any difference in performance. So I'd
prefer to keep this simple.

+  __ push(name_reg);  // name
   __ push(scratch2);  // restore return address
 
   // Do tail-call to the runtime system.
   ExternalReference load_callback_property =
       ExternalReference(IC_Utility(IC::kLoadCallbackProperty));
-  __ TailCallRuntime(load_callback_property, 4);
+  __ TailCallRuntime(load_callback_property, 5);
 }