[turbofan] Add backend support for float32.

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 4a9893f3b742b1d405bf581b936c159bb684679a..d0ecde49e3a092dbf4cfa242928b99758b4a146f 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -373,6 +373,12 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
                        0, 2);
       break;
     }
+    case kArm64Float32ToFloat64:
+      __ Fcvt(i.OutputDoubleRegister(), i.InputDoubleRegister(0).S());
+      break;
+    case kArm64Float64ToFloat32:
+      __ Fcvt(i.OutputDoubleRegister().S(), i.InputDoubleRegister(0));
+      break;
     case kArm64Float64ToInt32:
       __ Fcvtzs(i.OutputRegister32(), i.InputDoubleRegister(0));
       break;
@@ -415,20 +421,12 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArm64Str:
       __ Str(i.InputRegister(2), i.MemoryOperand());
       break;
-    case kArm64LdrS: {
-      UseScratchRegisterScope scope(masm());
-      FPRegister scratch = scope.AcquireS();
-      __ Ldr(scratch, i.MemoryOperand());
-      __ Fcvt(i.OutputDoubleRegister(), scratch);
+    case kArm64LdrS:
+      __ Ldr(i.OutputDoubleRegister().S(), i.MemoryOperand());
       break;
-    }
-    case kArm64StrS: {
-      UseScratchRegisterScope scope(masm());
-      FPRegister scratch = scope.AcquireS();
-      __ Fcvt(scratch, i.InputDoubleRegister(2));
-      __ Str(scratch, i.MemoryOperand());
+    case kArm64StrS:
+      __ Str(i.InputDoubleRegister(2).S(), i.MemoryOperand());
       break;
-    }
     case kArm64LdrD:
       __ Ldr(i.OutputDoubleRegister(), i.MemoryOperand());
       break;