ARM: Add optimization for constant RHS in DoMulI (try 2)

src/arm/code-stubs-arm.cc

 // Copyright 2011 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 3427 matching lines @@
           __ b(ne, &return_heap_number);
           __ bind(&not_zero);
 
           // Tag the result and return.
           __ SmiTag(r0, scratch1);
           __ Ret();
         } else {
           // DIV just falls through to allocating a heap number.
         }
 
+        __ bind(&return_heap_number);
+        // Return a heap number, or fall through to type transition or runtime
+        // call if we can't.
         if (result_type_ >= (op_ == Token::DIV) ? TRBinaryOpIC::HEAP_NUMBER
                                                 : TRBinaryOpIC::INT32) {
-          __ bind(&return_heap_number);
           // We are using vfp registers so r5 is available.
           heap_number_result = r5;
           GenerateHeapResultAllocation(masm,
                                        heap_number_result,
                                        heap_number_map,
                                        scratch1,
                                        scratch2,
                                        &call_runtime);
           __ sub(r0, heap_number_result, Operand(kHeapObjectTag));
           __ vstr(d5, r0, HeapNumber::kValueOffset);
@@ skipping 142 matching lines @@
         __ TailCallStub(&stub);
       }
 
       break;
     }
 
     default:
       UNREACHABLE();
   }
 
-  if (transition.is_linked()) {
+  // We never expect DIV to yield an integer result, so we always generate
+  // type transition code for DIV operations expecting an integer result: the
+  // code will fall through to this type transition.
+  if (transition.is_linked() ||
+      ((op_ == Token::DIV) && (result_type_ <= TRBinaryOpIC::INT32))) {
     __ bind(&transition);
     GenerateTypeTransition(masm);
   }
 
   __ bind(&call_runtime);
   GenerateCallRuntime(masm);
 }
 
 
 void TypeRecordingBinaryOpStub::GenerateOddballStub(MacroAssembler* masm) {
@@ skipping 3284 matching lines @@
   __ str(pc, MemOperand(sp, 0));
   __ Jump(target);  // Call the C++ function.
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM