Cleanup StringAddFlags.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 490091e9da0046ab4eebafa916e06b8926de1751..548cbaace74bc90287efc2acfc56ac10994d1254 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -1353,8 +1353,8 @@ void BinaryOpStub::GenerateBothStringStub(MacroAssembler* masm) {
   __ CmpObjectType(right, FIRST_NONSTRING_TYPE, ecx);
   __ j(above_equal, &call_runtime, Label::kNear);
 
-  StringAddStub string_add_stub((StringAddFlags)
-                                (ERECT_FRAME | NO_STRING_CHECK_IN_STUB));
+  StringAddStub string_add_stub(
+      (StringAddFlags)(STRING_ADD_CHECK_NONE | STRING_ADD_ERECT_FRAME));
   GenerateRegisterArgsPush(masm);
   __ TailCallStub(&string_add_stub);
 
@@ -1999,8 +1999,8 @@ void BinaryOpStub::GenerateAddStrings(MacroAssembler* masm) {
   __ CmpObjectType(left, FIRST_NONSTRING_TYPE, ecx);
   __ j(above_equal, &left_not_string, Label::kNear);
 
-  StringAddStub string_add_left_stub((StringAddFlags)
-      (ERECT_FRAME | NO_STRING_CHECK_LEFT_IN_STUB));
+  StringAddStub string_add_left_stub(
+      (StringAddFlags)(STRING_ADD_CHECK_RIGHT | STRING_ADD_ERECT_FRAME));
   GenerateRegisterArgsPush(masm);
   __ TailCallStub(&string_add_left_stub);
 
@@ -2010,8 +2010,8 @@ void BinaryOpStub::GenerateAddStrings(MacroAssembler* masm) {
   __ CmpObjectType(right, FIRST_NONSTRING_TYPE, ecx);
   __ j(above_equal, &call_runtime, Label::kNear);
 
-  StringAddStub string_add_right_stub((StringAddFlags)
-      (ERECT_FRAME | NO_STRING_CHECK_RIGHT_IN_STUB));
+  StringAddStub string_add_right_stub(
+      (StringAddFlags)(STRING_ADD_CHECK_LEFT | STRING_ADD_ERECT_FRAME));
   GenerateRegisterArgsPush(masm);
   __ TailCallStub(&string_add_right_stub);
 
@@ -5376,7 +5376,11 @@ void StringAddStub::Generate(MacroAssembler* masm) {
   __ 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) != 0) {
+  // Otherwise, at least one of the arguments is definitely a string,
+  // and we convert the one that is not known to be a string.
+  if ((flags_ & STRING_ADD_CHECK_BOTH) == STRING_ADD_CHECK_BOTH) {
+    ASSERT((flags_ & STRING_ADD_CHECK_LEFT) == STRING_ADD_CHECK_LEFT);
+    ASSERT((flags_ & STRING_ADD_CHECK_RIGHT) == STRING_ADD_CHECK_RIGHT);
     __ JumpIfSmi(eax, &call_runtime);
     __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, ebx);
     __ j(above_equal, &call_runtime);
@@ -5385,20 +5389,16 @@ void StringAddStub::Generate(MacroAssembler* masm) {
     __ JumpIfSmi(edx, &call_runtime);
     __ CmpObjectType(edx, FIRST_NONSTRING_TYPE, ebx);
     __ j(above_equal, &call_runtime);
-  } else {
-    // Here at least one of the arguments is definitely a string.
-    // We convert the one that is not known to be a string.
-    if ((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) == 0) {
-      ASSERT((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) != 0);
-      GenerateConvertArgument(masm, 2 * kPointerSize, eax, ebx, ecx, edi,
-                              &call_builtin);
-      builtin_id = Builtins::STRING_ADD_RIGHT;
-    } else if ((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) == 0) {
-      ASSERT((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) != 0);
-      GenerateConvertArgument(masm, 1 * kPointerSize, edx, ebx, ecx, edi,
-                              &call_builtin);
-      builtin_id = Builtins::STRING_ADD_LEFT;
-    }
+  } else if ((flags_ & STRING_ADD_CHECK_LEFT) == STRING_ADD_CHECK_LEFT) {
+    ASSERT((flags_ & STRING_ADD_CHECK_RIGHT) == 0);
+    GenerateConvertArgument(masm, 2 * kPointerSize, eax, ebx, ecx, edi,
+                            &call_builtin);
+    builtin_id = Builtins::STRING_ADD_RIGHT;
+  } else if ((flags_ & STRING_ADD_CHECK_RIGHT) == STRING_ADD_CHECK_RIGHT) {
+    ASSERT((flags_ & STRING_ADD_CHECK_LEFT) == 0);
+    GenerateConvertArgument(masm, 1 * kPointerSize, edx, ebx, ecx, edi,
+                            &call_builtin);
+    builtin_id = Builtins::STRING_ADD_LEFT;
   }
 
   // Both arguments are strings.
@@ -5684,7 +5684,7 @@ void StringAddStub::Generate(MacroAssembler* masm) {
   __ Drop(2);
   // Just jump to runtime to add the two strings.
   __ bind(&call_runtime);
-  if ((flags_ & ERECT_FRAME) != 0) {
+  if ((flags_ & STRING_ADD_ERECT_FRAME) != 0) {
     GenerateRegisterArgsPop(masm, ecx);
     // Build a frame
     {
@@ -5699,7 +5699,7 @@ void StringAddStub::Generate(MacroAssembler* masm) {
 
   if (call_builtin.is_linked()) {
     __ bind(&call_builtin);
-    if ((flags_ & ERECT_FRAME) != 0) {
+    if ((flags_ & STRING_ADD_ERECT_FRAME) != 0) {
       GenerateRegisterArgsPop(masm, ecx);
       // Build a frame
       {