Collect type feedback for power-of-2 right operands in BinaryOps.

src/arm/code-stubs-arm.cc

 // Copyright 2012 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
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 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2011 matching lines @@
   if (allow_heapnumber_results == BinaryOpStub::ALLOW_HEAPNUMBER_RESULTS) {
     BinaryOpStub_GenerateFPOperation(
         masm, BinaryOpIC::UNINITIALIZED, BinaryOpIC::UNINITIALIZED, true,
         use_runtime, gc_required, &not_smis, op, mode);
   }
   __ bind(&not_smis);
 }
 
 
 void BinaryOpStub::GenerateSmiStub(MacroAssembler* masm) {
-  Label not_smis, call_runtime;
+  Label right_arg_changed, call_runtime;
+
+  if (op_ == Token::MOD && has_fixed_right_arg_) {
+    // It is guaranteed that the value will fit into a Smi, because if it
+    // didn't, we wouldn't be here, see BinaryOp_Patch.
+    __ cmp(r0, Operand(Smi::FromInt(fixed_right_arg_value())));
+    __ b(ne, &right_arg_changed);
+  }
 
   if (result_type_ == BinaryOpIC::UNINITIALIZED ||
       result_type_ == BinaryOpIC::SMI) {
     // Only allow smi results.
     BinaryOpStub_GenerateSmiCode(
         masm, &call_runtime, NULL, op_, NO_HEAPNUMBER_RESULTS, mode_);
   } else {
     // Allow heap number result and don't make a transition if a heap number
     // cannot be allocated.
     BinaryOpStub_GenerateSmiCode(
         masm, &call_runtime, &call_runtime, op_, ALLOW_HEAPNUMBER_RESULTS,
         mode_);
   }
 
   // Code falls through if the result is not returned as either a smi or heap
   // number.
+  __ bind(&right_arg_changed);
   GenerateTypeTransition(masm);
 
   __ bind(&call_runtime);
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
     GenerateRegisterArgsPush(masm);
     GenerateCallRuntime(masm);
   }
   __ Ret();
 }
@@ skipping 151 matching lines @@
                                                   mode_);
         __ sub(r0, heap_number_result, Operand(kHeapObjectTag));
         __ vstr(d5, r0, HeapNumber::kValueOffset);
         __ mov(r0, heap_number_result);
         __ Ret();
 
         // A DIV operation expecting an integer result falls through
         // to type transition.
 
       } else {
+        if (has_fixed_right_arg_) {
+          __ Vmov(d8, fixed_right_arg_value(), scratch1);
+          __ VFPCompareAndSetFlags(d1, d8);

[Rodolph Perfetta, 2013/06/03 16:33:17]

Wouldn't it be possible to compare to the already converted int32:

  __ cmp(right, Operand(fixed_right_arg_value());

[Sven Panne, 2013/06/04 07:48:09]

Hmmm, unless I misunderstood things, 'right' doesn't contain the int32 value at
that point, it still contains the right operand, which could be a Smi or a
HeapNumber. On Intel things are different, the conversion macro instructions set
both floating register *and* a normal one. Because this doesn't appear to be the
case here, I did it the other way round (int=>double, then compare the double).

Nevertheless, if you see some way to improve this, I'll be happy to review the
change.

+          __ b(ne, &transition);
+        }
+
         // We preserved r0 and r1 to be able to call runtime.
         // Save the left value on the stack.
         __ Push(r5, r4);
 
         Label pop_and_call_runtime;
 
         // Allocate a heap number to store the result.
         heap_number_result = r5;
         BinaryOpStub_GenerateHeapResultAllocation(masm,
                                                   heap_number_result,
@@ skipping 5103 matching lines @@
      __ Jump(generic_construct_stub, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM