[turbofan] Add backend support for float32.

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index 5fe7bad81d93ea93fd4cded75390f505d534e40e..a3172e5e0ecacf36f79fcae10f98f460a07dcb5a 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -478,6 +478,13 @@ void InstructionSelector::VisitInt64UMod(Node* node) {
 }
 
 
+void InstructionSelector::VisitChangeFloat32ToFloat64(Node* node) {
+  X64OperandGenerator g(this);
+  // TODO(turbofan): X64 SSE conversions should take an operand.
+  Emit(kSSECvtss2sd, g.DefineAsRegister(node), g.UseRegister(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitChangeInt32ToFloat64(Node* node) {
   X64OperandGenerator g(this);
   Emit(kSSEInt32ToFloat64, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
@@ -516,6 +523,13 @@ void InstructionSelector::VisitChangeUint32ToUint64(Node* node) {
 }
 
 
+void InstructionSelector::VisitTruncateFloat64ToFloat32(Node* node) {
+  X64OperandGenerator g(this);
+  // TODO(turbofan): X64 SSE conversions should take an operand.
+  Emit(kSSECvtsd2ss, g.DefineAsRegister(node), g.UseRegister(node->InputAt(0)));
+}
+
+
 void InstructionSelector::VisitTruncateInt64ToInt32(Node* node) {
   X64OperandGenerator g(this);
   Emit(kX64Movl, g.DefineAsRegister(node), g.Use(node->InputAt(0)));