X87: Eliminate special keyed load string stub in favor of uniform handlers

port r24661.

original commit message:

  Eliminate special keyed load string stub in favor of uniform handlers.

  KeyedLoadIC installs a special case if the receiver is a string.
  Although there are several maps for strings, in practice we seem to
  be able to treat them individually because a given KeyedLoad site
  only sees 1-2 string types

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/643783005

Patch from Chunyang Dai <chunyang.dai@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24674 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ic/x87/ic-x87.cc

@@ -478,33 +478,6 @@ void KeyedLoadIC::GenerateGeneric(MacroAssembler* masm) {
 }
 
 
-void KeyedLoadIC::GenerateString(MacroAssembler* masm) {
-  // Return address is on the stack.
-  Label miss;
-
-  Register receiver = LoadDescriptor::ReceiverRegister();
-  Register index = LoadDescriptor::NameRegister();
-  Register scratch = ebx;
-  DCHECK(!scratch.is(receiver) && !scratch.is(index));
-  Register result = eax;
-  DCHECK(!result.is(scratch));
-
-  StringCharAtGenerator char_at_generator(receiver, index, scratch, result,
-                                          &miss,  // When not a string.
-                                          &miss,  // When not a number.
-                                          &miss,  // When index out of range.
-                                          STRING_INDEX_IS_ARRAY_INDEX);
-  char_at_generator.GenerateFast(masm);
-  __ ret(0);
-
-  StubRuntimeCallHelper call_helper;
-  char_at_generator.GenerateSlow(masm, call_helper);
-
-  __ bind(&miss);
-  GenerateMiss(masm);
-}
-
-
 void KeyedStoreIC::GenerateSloppyArguments(MacroAssembler* masm) {
   // Return address is on the stack.
   Label slow, notin;

src/x87/code-stubs-x87.cc

@@ -371,6 +371,37 @@ void LoadIndexedInterceptorStub::Generate(MacroAssembler* masm) {
 }
 
 
+void LoadIndexedStringStub::Generate(MacroAssembler* masm) {
+  // Return address is on the stack.
+  Label miss;
+
+  Register receiver = LoadDescriptor::ReceiverRegister();
+  Register index = LoadDescriptor::NameRegister();
+  Register scratch = ebx;
+  DCHECK(!scratch.is(receiver) && !scratch.is(index));
+  Register result = eax;
+  DCHECK(!result.is(scratch));
+
+  // TODO(mvstanton): the generator doesn't need to verify that
+  // receiver is a string map, that is done outside the handler.
+  StringCharAtGenerator char_at_generator(receiver, index, scratch, result,
+                                          &miss,  // When not a string.
+                                          &miss,  // When not a number.
+                                          &miss,  // When index out of range.
+                                          STRING_INDEX_IS_ARRAY_INDEX,
+                                          RECEIVER_IS_STRING);
+  char_at_generator.GenerateFast(masm);
+  __ ret(0);
+
+  StubRuntimeCallHelper call_helper;
+  char_at_generator.GenerateSlow(masm, call_helper);
+
+  __ bind(&miss);
+  PropertyAccessCompiler::TailCallBuiltin(
+      masm, PropertyAccessCompiler::MissBuiltin(Code::KEYED_LOAD_IC));
+}
+
+
 void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
   // The key is in edx and the parameter count is in eax.
   DCHECK(edx.is(ArgumentsAccessReadDescriptor::index()));