Small improvement in x64 assembler

src/x64/macro-assembler-x64.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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2893 matching lines @@
   jmp(&done, Label::kNear);
   bind(&conv_failure);
   Set(result_reg, 0);
   ucomisd(input_reg, temp_xmm_reg);
   j(below, &done, Label::kNear);
   Set(result_reg, 255);
   bind(&done);
 }
 
 
-static double kUint32Bias =
-    static_cast<double>(static_cast<uint32_t>(0xFFFFFFFF)) + 1;
-
-
 void MacroAssembler::LoadUint32(XMMRegister dst,
                                 Register src,
                                 XMMRegister scratch) {
-  Label done;
-  cmpl(src, Immediate(0));
-  movq(kScratchRegister,
-       reinterpret_cast<int64_t>(&kUint32Bias),
-       RelocInfo::NONE64);
-  movsd(scratch, Operand(kScratchRegister, 0));
-  cvtlsi2sd(dst, src);
-  j(not_sign, &done, Label::kNear);
-  addsd(dst, scratch);
-  bind(&done);
+  if (FLAG_debug_code) {
+    cmpq(src, Immediate(0xffffffff));
+    Assert(below_equal, "input GPR is expected to have upper32 cleared");
+  }
+  cvtqsi2sd(dst, src);

[Yang, 2013/02/06 10:28:59]

The uses of this indicate that the input is indeed uint32, so I think thet
assert is sufficient.

 }
 
 
 void MacroAssembler::LoadInstanceDescriptors(Register map,
                                              Register descriptors) {
   movq(descriptors, FieldOperand(map, Map::kDescriptorsOffset));
 }
 
 
 void MacroAssembler::NumberOfOwnDescriptors(Register dst, Register map) {
@@ skipping 1683 matching lines @@
   CompareRoot(MemOperand(scratch_reg, -AllocationSiteInfo::kSize),
               Heap::kAllocationSiteInfoMapRootIndex);
   j(equal, allocation_info_present);
   bind(&no_info_available);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64