[Interpreter] Collect type feedback for subtract operation and pass it to turbofan.

src/ic/ic-state.h

 // Copyright 2012 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_IC_STATE_H_
 #define V8_IC_STATE_H_
 
 #include "src/macro-assembler.h"
 
 namespace v8 {
@@ skipping 235 matching lines @@
 
   // For convenience, a statically declared encoding of strict mode extra
   // IC state.
   static const ExtraICState kStrictModeState = STRICT
                                                << LanguageModeState::kShift;
 
  private:
   const ExtraICState state_;
 };
 
+// TODO(mythria): Move this to a different header that is accessible from
+// code-stub and bytecode-graph-builder.

[Benedikt Meurer, 2016/08/08 04:56:14]

I'd rather use a very simple enum to encode the lattice, i.e. similar to what
hydrogen-types.h did. Something along the lines of:

class BinaryOperationFeedback {
 public:
  enum {
    kNone = 0x00,
    kSignedSmall = 0x01,
    kNumber = 0x3,
    kAny = 0x7
  };
};

Or some enum class even.

That way it's easier to just use the enum names in the code and you still
preserve the simple ORing for combining. 

[mythria, 2016/08/08 07:17:36]

Thanks for the detailed comment Benedikt. Done.

+class BinaryOpTypeFeedback {
+ public:
+  class SmiType : public BitField8<int, 0, 1> {};
+  class NumberType : public BitField8<int, SmiType::kNext, 1> {};
+  class AnyType : public BitField8<int, NumberType::kNext, 1> {};
+};

[mythria, 2016/08/08 04:33:56]

I am not sure where is the right place to add this. This is not exactly
ic-state, so this is not the right place I think.

[Benedikt Meurer, 2016/08/08 04:56:13]

Please move it to globals.h for now.

[mythria, 2016/08/08 07:17:36]

Done.

+
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_IC_STATE_H_