[turbofan] Introduce new operators Float32SubPreserveNan and Float64SubPreserveNan for wasm.

src/compiler/machine-operator.h

 // 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.
 
 #ifndef V8_COMPILER_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
 #include "src/base/flags.h"
 #include "src/machine-type.h"
 
@@ skipping 227 matching lines @@
   // integer and vice versa.
   const Operator* BitcastFloat32ToInt32();
   const Operator* BitcastFloat64ToInt64();
   const Operator* BitcastInt32ToFloat32();
   const Operator* BitcastInt64ToFloat64();
 
   // Floating point operators always operate with IEEE 754 round-to-nearest
   // (single-precision).
   const Operator* Float32Add();
   const Operator* Float32Sub();
+  const Operator* Float32SubPreserveNan();
   const Operator* Float32Mul();
   const Operator* Float32Div();
   const Operator* Float32Sqrt();
 
   // Floating point operators always operate with IEEE 754 round-to-nearest
   // (double-precision).
   const Operator* Float64Add();
   const Operator* Float64Sub();
+  const Operator* Float64SubPreserveNan();
   const Operator* Float64Mul();
   const Operator* Float64Div();
   const Operator* Float64Mod();
   const Operator* Float64Sqrt();
 
   // Floating point comparisons complying to IEEE 754 (single-precision).
   const Operator* Float32Equal();
   const Operator* Float32LessThan();
   const Operator* Float32LessThanOrEqual();
 
@@ skipping 284 matching lines @@
 };
 
 
 DEFINE_OPERATORS_FOR_FLAGS(MachineOperatorBuilder::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_OPERATOR_H_