[turbofan] Add backend support for float32.

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 200dcb66053fcd7de01c51274ffc44108c3a136b..f78adddea1bb9bbaa989a9bea613f377a92029c2 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -285,6 +285,12 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ add(esp, Immediate(kDoubleSize));
       break;
     }
+    case kCvtss2sd:
+      __ cvtss2sd(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
+      break;
+    case kCvtsd2ss:
+      __ cvtsd2ss(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
+      break;
     case kSSEFloat64ToInt32:
       __ cvttsd2si(i.OutputRegister(), i.InputOperand(0));
       break;
@@ -360,12 +366,10 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kIA32Movss:
       if (instr->HasOutput()) {
         __ movss(i.OutputDoubleRegister(), i.MemoryOperand());
-        __ cvtss2sd(i.OutputDoubleRegister(), i.OutputDoubleRegister());
       } else {
         int index = 0;
         Operand operand = i.MemoryOperand(&index);
-        __ cvtsd2ss(xmm0, i.InputDoubleRegister(index));
-        __ movss(operand, xmm0);
+        __ movss(operand, i.InputDoubleRegister(index));
       }
       break;
     case kIA32Push: