Support load function prototype in hydrogen/lithium.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index d64f528e71c9a6d92221b2741df9c5cf4f82f7dd..5af85dd83ca70670bf28fb28ed7f524c255978b9 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -1837,6 +1837,50 @@ void LCodeGen::DoLoadNamedGeneric(LLoadNamedGeneric* instr) {
 }
 
 
+void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
+  Register function = ToRegister(instr->function());
+  Register temp = ToRegister(instr->temporary());
+  Register result = ToRegister(instr->result());
+
+  // Check that the function really is a function.
+  __ CmpObjectType(function, JS_FUNCTION_TYPE, result);
+  DeoptimizeIf(not_equal, instr->environment());
+
+  // Check whether the function has an instance prototype.
+  NearLabel non_instance;
+  __ test_b(FieldOperand(result, Map::kBitFieldOffset),
+            1 << Map::kHasNonInstancePrototype);
+  __ j(not_zero, &non_instance);
+
+  // Get the prototype or initial map from the function.
+  __ mov(result,
+         FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
+
+  // If the prototype or initial map is the hole, don't return it and
+  // simply miss the cache instead. This will allow us to allocate a

[fschneider, 2010/12/21 17:57:52]

This comment is not 100% up-to-date, since we deoptimize here and handle this
case in non-optimized code.

[Vitaly Repeshko, 2010/12/22 15:43:41]

Updated.

+  // prototype object on-demand in the runtime system.
+  __ cmp(Operand(result), Immediate(Factory::the_hole_value()));
+  DeoptimizeIf(equal, instr->environment());
+
+  // If the function does not have an initial map, we're done.
+  NearLabel done;
+  __ CmpObjectType(result, MAP_TYPE, temp);
+  __ j(not_equal, &done);
+
+  // Get the prototype from the initial map.
+  __ mov(result, FieldOperand(result, Map::kPrototypeOffset));
+  __ jmp(&done);
+
+  // Non-instance prototype: Fetch prototype from constructor field
+  // in the function's map.
+  __ bind(&non_instance);
+  __ mov(result, FieldOperand(result, Map::kConstructorOffset));
+
+  // All done.
+  __ bind(&done);
+}
+
+
 void LCodeGen::DoLoadElements(LLoadElements* instr) {
   ASSERT(instr->result()->Equals(instr->input()));
   Register reg = ToRegister(instr->input());