Combine %_SubString and %_StringCharAt.

src/ia32/code-stubs-ia32.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 5677 matching lines @@
   if (!result_.is(eax)) {
     __ mov(result_, eax);
   }
   call_helper.AfterCall(masm);
   __ jmp(&exit_);
 
   __ Abort("Unexpected fallthrough from CharFromCode slow case");
 }
 
 
-// -------------------------------------------------------------------------
-// StringCharAtGenerator
-
-void StringCharAtGenerator::GenerateFast(MacroAssembler* masm) {
-  char_code_at_generator_.GenerateFast(masm);
-  char_from_code_generator_.GenerateFast(masm);
-}
-
-
-void StringCharAtGenerator::GenerateSlow(
-    MacroAssembler* masm,
-    const RuntimeCallHelper& call_helper) {
-  char_code_at_generator_.GenerateSlow(masm, call_helper);
-  char_from_code_generator_.GenerateSlow(masm, call_helper);
-}
-
-
 void StringAddStub::Generate(MacroAssembler* masm) {
   Label call_runtime, call_builtin;
   Builtins::JavaScript builtin_id = Builtins::ADD;
 
   // Load the two arguments.
   __ mov(eax, Operand(esp, 2 * kPointerSize));  // First argument.
   __ mov(edx, Operand(esp, 1 * kPointerSize));  // Second argument.
 
   // Make sure that both arguments are strings if not known in advance.
   if (flags_ == NO_STRING_ADD_FLAGS) {
@@ skipping 646 matching lines @@
   // Shorter than original string's length: an actual substring.
   __ j(below, &not_original_string, Label::kNear);
   // Longer than original string's length or negative: unsafe arguments.
   __ j(above, &runtime);
   // Return original string.
   Counters* counters = masm->isolate()->counters();
   __ IncrementCounter(counters->sub_string_native(), 1);
   __ ret(3 * kPointerSize);
   __ bind(&not_original_string);
 
+  Label single_char;
+  __ cmp(ecx, Immediate(Smi::FromInt(1)));
+  __ j(equal, &single_char);
+
   // eax: string
   // ebx: instance type
   // ecx: sub string length (smi)
   // edx: from index (smi)
   // Deal with different string types: update the index if necessary
   // and put the underlying string into edi.
   Label underlying_unpacked, sliced_string, seq_or_external_string;
   // If the string is not indirect, it can only be sequential or external.
   STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
   STATIC_ASSERT(kIsIndirectStringMask != 0);
@@ skipping 150 matching lines @@
   __ IncrementCounter(counters->sub_string_native(), 1);
   __ ret(3 * kPointerSize);
 
   // Drop pushed values on the stack before tail call.
   __ bind(&runtime_drop_two);
   __ Drop(2);
 
   // Just jump to runtime to create the sub string.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kSubString, 3, 1);
+
+  __ bind(&single_char);
+  // eax: string
+  // ebx: instance type
+  // ecx: sub string length (smi)
+  // edx: from index (smi)
+  StringCharAtGenerator generator(
+      eax, edx, ecx, eax, &runtime, &runtime, &runtime, STRING_INDEX_IS_NUMBER);
+  generator.GenerateFast(masm);
+  __ ret(3 * kPointerSize);
+  generator.SkipSlow(masm, &runtime);
 }
 
 
 void StringCompareStub::GenerateFlatAsciiStringEquals(MacroAssembler* masm,
                                                       Register left,
                                                       Register right,
                                                       Register scratch1,
                                                       Register scratch2) {
   Register length = scratch1;
 
@@ skipping 1137 matching lines @@
   // Restore ecx.
   __ pop(ecx);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32