[turbofan] Add backend support for float32.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 429 matching lines @@
         __ popfq();
       }
       __ j(parity_even, &mod_loop);
       // Move output to stack and clean up.
       __ fstp(1);
       __ fstp_d(Operand(rsp, 0));
       __ movsd(i.OutputDoubleRegister(), Operand(rsp, 0));
       __ addq(rsp, Immediate(kDoubleSize));
       break;
     }
+    case kCvtss2sd:
+      __ cvtss2sd(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
+      break;
+    case kCvtsd2ss:
+      __ cvtsd2ss(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
+      break;
     case kSSEFloat64ToInt32: {
       RegisterOrOperand input = i.InputRegisterOrOperand(0);
       if (input.type == kDoubleRegister) {
         __ cvttsd2si(i.OutputRegister(), input.double_reg);
       } else {
         __ cvttsd2si(i.OutputRegister(), input.operand);
       }
       break;
     }
     case kSSEFloat64ToUint32: {
@@ skipping 94 matching lines @@
         if (HasImmediateInput(instr, index)) {
           __ movq(operand, i.InputImmediate(index));
         } else {
           __ movq(operand, i.InputRegister(index));
         }
       }
       break;
     case kX64Movss:
       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 kX64Movsd:
       if (instr->HasOutput()) {
         __ movsd(i.OutputDoubleRegister(), i.MemoryOperand());
       } else {
         int index = 0;
         Operand operand = i.MemoryOperand(&index);
         __ movsd(operand, i.InputDoubleRegister(index));
       }
@@ skipping 426 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8