[turbofan] Add TruncateFloat32ToUint32 operator to Turbofan.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index b52146b4d24a2c08d970a56951df08947d123ff4..1ad21d19944a8b3fee0bb070b06d6995fe1f1ea7 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -742,6 +742,18 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kSSEFloat32ToInt32:
       __ cvttss2si(i.OutputRegister(), i.InputOperand(0));
       break;
+    case kSSEFloat32ToUint32: {
+      Label success;
+      __ cvttss2si(i.OutputRegister(), i.InputOperand(0));
+      __ test(i.OutputRegister(), i.OutputRegister());
+      __ j(positive, &success);
+      __ Move(kScratchDoubleReg, -2147483648.0f);

[ahaas, 2016/01/29 10:45:08]

You could use static_cast<float>(INT32_MIN) here, that would be easier to
understand.

+      __ addss(kScratchDoubleReg, i.InputOperand(0));
+      __ cvttss2si(i.OutputRegister(), kScratchDoubleReg);
+      __ or_(i.OutputRegister(), Immediate(0x80000000));
+      __ bind(&success);
+      break;
+    }
     case kSSEFloat64ToInt32:
       __ cvttsd2si(i.OutputRegister(), i.InputOperand(0));
       break;