Correct handling of adding a string and a smal integer...

src/ia32/codegen-ia32.cc

 // Copyright 2010 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 8546 matching lines @@
     case Token::ADD: {
       // Test for string arguments before calling runtime.
       Label not_strings, not_string1, string1, string1_smi2;
 
       // If this stub has already generated FP-specific code then the arguments
       // are already in edx, eax
       if (!ShouldGenerateFPCode() && !HasArgsInRegisters()) {
         GenerateLoadArguments(masm);
       }
 
-      __ test(edx, Immediate(kSmiTagMask));
+      // Registers containing left and right operands respectively.
+      Register lhs, rhs;
+      if (HasArgsReversed()) {
+        lhs = eax;
+        rhs = edx;
+      } else {
+        lhs = edx;
+        rhs = eax;
+      }
+
+      // Test if first argument is a string.
+      __ test(lhs, Immediate(kSmiTagMask));
       __ j(zero, &not_string1);
-      __ CmpObjectType(edx, FIRST_NONSTRING_TYPE, ecx);
+      __ CmpObjectType(lhs, FIRST_NONSTRING_TYPE, ecx);
       __ j(above_equal, &not_string1);
 
       // First argument is a string, test second.
-      __ test(eax, Immediate(kSmiTagMask));
+      __ test(rhs, Immediate(kSmiTagMask));
       __ j(zero, &string1_smi2);
-      __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, ecx);
+      __ CmpObjectType(rhs, FIRST_NONSTRING_TYPE, ecx);
       __ j(above_equal, &string1);
 
       // First and second argument are strings. Jump to the string add stub.
       StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
       __ TailCallStub(&string_add_stub);
 
       __ bind(&string1_smi2);
       // First argument is a string, second is a smi. Try to lookup the number
       // string for the smi in the number string cache.
       NumberToStringStub::GenerateLookupNumberStringCache(
-          masm, eax, edi, ebx, ecx, true, &string1);
+          masm, rhs, edi, ebx, ecx, true, &string1);
 
-      // Call the string add stub to make the result.
-      __ EnterInternalFrame();
-      __ push(edx);  // Original first argument.
-      __ push(edi);  // Number to string result for second argument.
-      __ CallStub(&string_add_stub);
-      __ LeaveInternalFrame();
-      __ ret(2 * kPointerSize);
+      // Replace second argument on stack and tailcall string add stub to make
+      // the result.
+      __ mov(Operand(esp, 1 * kPointerSize), edi);
+      __ TailCallStub(&string_add_stub);
 
+      // Only first argument is a string.
       __ bind(&string1);
-      __ InvokeBuiltin(
-          HasArgsReversed() ?
-              Builtins::STRING_ADD_RIGHT :
-              Builtins::STRING_ADD_LEFT,
-          JUMP_FUNCTION);
+      __ InvokeBuiltin(Builtins::STRING_ADD_LEFT, JUMP_FUNCTION);
 
       // First argument was not a string, test second.
       __ bind(&not_string1);
-      __ test(eax, Immediate(kSmiTagMask));
+      __ test(rhs, Immediate(kSmiTagMask));
       __ j(zero, &not_strings);
-      __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, ecx);
+      __ CmpObjectType(rhs, FIRST_NONSTRING_TYPE, ecx);
       __ j(above_equal, &not_strings);
 
       // Only second argument is a string.
-      __ InvokeBuiltin(
-          HasArgsReversed() ?
-              Builtins::STRING_ADD_LEFT :
-              Builtins::STRING_ADD_RIGHT,
-          JUMP_FUNCTION);
+      __ InvokeBuiltin(Builtins::STRING_ADD_RIGHT, JUMP_FUNCTION);
 
       __ bind(&not_strings);
       // Neither argument is a string.
       __ InvokeBuiltin(Builtins::ADD, JUMP_FUNCTION);
       break;
     }
     case Token::SUB:
       __ InvokeBuiltin(Builtins::SUB, JUMP_FUNCTION);
       break;
     case Token::MUL:
@@ skipping 3126 matching lines @@
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 #undef __
 
 } }  // namespace v8::internal