[turbofan] Add RoundUint32ToFloat32 operator to Turbofan.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 569 matching lines @@
   call(ces.GetCode(), RelocInfo::DEBUGGER_STATEMENT);
 }
 
 
 void MacroAssembler::Cvtsi2sd(XMMRegister dst, const Operand& src) {
   xorps(dst, dst);
   cvtsi2sd(dst, src);
 }
 
 
+void MacroAssembler::Cvtui2ss(XMMRegister dst, Register src, Register tmp) {
+  Label msb_set_src;
+  Label jmp_return;
+  test(src, src);
+  j(sign, &msb_set_src, Label::kNear);
+  cvtsi2ss(dst, src);
+  jmp(&jmp_return, Label::kNear);
+  bind(&msb_set_src);
+  mov(tmp, src);
+  shr(src, 1);
+  // Recover the least significant bit to avoid rounding errors.
+  and_(tmp, Immediate(1));
+  or_(src, tmp);
+  cvtsi2ss(dst, src);
+  addss(dst, dst);
+  bind(&jmp_return);
+}
+
+
 bool MacroAssembler::IsUnsafeImmediate(const Immediate& x) {
   static const int kMaxImmediateBits = 17;
   if (!RelocInfo::IsNone(x.rmode_)) return false;
   return !is_intn(x.x_, kMaxImmediateBits);
 }
 
 
 void MacroAssembler::SafeMove(Register dst, const Immediate& x) {
   if (IsUnsafeImmediate(x) && jit_cookie() != 0) {
     Move(dst, Immediate(x.x_ ^ jit_cookie()));
@@ skipping 2504 matching lines @@
   mov(eax, dividend);
   shr(eax, 31);
   add(edx, eax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32