Addresses some performance regression in the GenericBinaryOpStub on ARM followin...

src/arm/code-stubs-arm.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 1211 matching lines @@
   // After this point we have the left hand side in r1 and the right hand side
   // in r0.
   if (lhs.is(r0)) {
     __ Swap(r0, r1, ip);
   }
 
   // The type transition also calculates the answer.
   bool generate_code_to_calculate_answer = true;
 
   if (ShouldGenerateFPCode()) {
-    if (runtime_operands_type_ == BinaryOpIC::DEFAULT) {
+    // DIV has neither SmiSmi fast code nor specialized slow code.
+    // So don't try to patch a DIV Stub.
+    if ((runtime_operands_type_ == BinaryOpIC::DEFAULT) &&
+        (op_ != Token::DIV)) {
       switch (op_) {
         case Token::ADD:
         case Token::SUB:
         case Token::MUL:
-        case Token::DIV:
           GenerateTypeTransition(masm);  // Tail call.
           generate_code_to_calculate_answer = false;
           break;
 

[Søren Thygesen Gjesse, 2010/12/17 10:28:38]

Wouldn't it be more readable to have an empty case for the DIV with the DIV
specific comment there?

         default:
           break;
       }
     }
 
     if (generate_code_to_calculate_answer) {
       Label r0_is_smi, r1_is_smi, finished_loading_r0, finished_loading_r1;
       if (mode_ == NO_OVERWRITE) {
         // In the case where there is no chance of an overwritable float we may
         // as well do the allocation immediately while r0 and r1 are untouched.
@@ skipping 40 matching lines @@
         __ mov(r7, Operand(r0));
         ConvertToDoubleStub stub3(r3, r2, r7, r4);
         __ push(lr);
         __ Call(stub3.GetCode(), RelocInfo::CODE_TARGET);
         __ pop(lr);
       }
 
       // HEAP_NUMBERS stub is slower than GENERIC on a pair of smis.
       // r0 is known to be a smi. If r1 is also a smi then switch to GENERIC.
       Label r1_is_not_smi;
-      if (runtime_operands_type_ == BinaryOpIC::HEAP_NUMBERS) {
+      if ((runtime_operands_type_ == BinaryOpIC::HEAP_NUMBERS) &&
+          HasSmiSmiFastPath()) {
         __ tst(r1, Operand(kSmiTagMask));
         __ b(ne, &r1_is_not_smi);
         GenerateTypeTransition(masm);  // Tail call.
       }
 
       __ bind(&finished_loading_r0);
 
       // Move r1 to a double in r0-r1.
       __ tst(r1, Operand(kSmiTagMask));
       __ b(eq, &r1_is_smi);  // It's a Smi so don't check it's a heap number.
@@ skipping 3646 matching lines @@
   __ pop(r1);
   __ Jump(r2);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM