X64: Use roundsd for DoMathFloor.

src/x64/assembler-x64.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 2845 matching lines @@
 void Assembler::ucomisd(XMMRegister dst, const Operand& src) {
   EnsureSpace ensure_space(this);
   emit(0x66);
   emit_optional_rex_32(dst, src);
   emit(0x0f);
   emit(0x2e);
   emit_sse_operand(dst, src);
 }
 
 
+void Assembler::roundsd(XMMRegister dst, XMMRegister src,
+                        Assembler::RoundingMode mode) {
+  ASSERT(CpuFeatures::IsEnabled(SSE4_1));
+  EnsureSpace ensure_space(this);
+  emit(0x66);
+  emit_optional_rex_32(dst, src);
+  emit(0x0f);
+  emit(0x3a);
+  emit(0x0b);
+  emit_sse_operand(dst, src);
+  // Mask precision exeption.
+  emit(static_cast<byte>(mode) | 0x8);
+}
+
+
 void Assembler::movmskpd(Register dst, XMMRegister src) {
   EnsureSpace ensure_space(this);
   emit(0x66);
   emit_optional_rex_32(dst, src);
   emit(0x0f);
   emit(0x50);
   emit_sse_operand(dst, src);
 }
 
 
@@ skipping 78 matching lines @@
   // specially coded on x64 means that it is a relative 32 bit address, as used
   // by branch instructions.
   return (1 << rmode_) & kApplyMask;
 }
 
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64