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

Addresses some performance regression in the GenericBinaryOpStub on ARM following Crankshaft introduction. 

BUG=none
TEST=none

Patch by Rodolph Perfetta from ARM Ltd.

Review URL: http://codereview.chromium.org/5781010


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6146 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -1222,16 +1222,22 @@ void GenericBinaryOpStub::HandleBinaryOpSlowCases(
   bool generate_code_to_calculate_answer = true;
 
   if (ShouldGenerateFPCode()) {
+    // 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) {
       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;
 
+        case Token::DIV:
+          // DIV has neither SmiSmi fast code nor specialized slow code.
+          // So don't try to patch a DIV Stub.
+          break;
+
         default:
           break;
       }
@@ -1292,7 +1298,8 @@ void GenericBinaryOpStub::HandleBinaryOpSlowCases(
       // 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.

src/arm/code-stubs-arm.h

@@ -77,7 +77,7 @@ class GenericBinaryOpStub : public CodeStub {
         rhs_(rhs),
         constant_rhs_(constant_rhs),
         specialized_on_rhs_(RhsIsOneWeWantToOptimizeFor(op, constant_rhs)),
-        runtime_operands_type_(BinaryOpIC::DEFAULT),
+        runtime_operands_type_(BinaryOpIC::UNINIT_OR_SMI),
         name_(NULL) { }
 
   GenericBinaryOpStub(int key, BinaryOpIC::TypeInfo type_info)
@@ -178,6 +178,10 @@ class GenericBinaryOpStub : public CodeStub {
     return lhs_is_r0 ? r1 : r0;
   }
 
+  bool HasSmiSmiFastPath() {
+    return op_ != Token::DIV;
+  }
+
   bool ShouldGenerateSmiCode() {
     return ((op_ != Token::DIV && op_ != Token::MOD) || specialized_on_rhs_) &&
         runtime_operands_type_ != BinaryOpIC::HEAP_NUMBERS &&

src/arm/full-codegen-arm.cc

@@ -38,6 +38,8 @@
 #include "scopes.h"
 #include "stub-cache.h"
 
+#include "arm/code-stubs-arm.h"
+
 namespace v8 {
 namespace internal {