[wasm] Track in the interpreter if a NaN could have been produced.

src/wasm/wasm-interpreter.h

 // Copyright 2016 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_WASM_INTERPRETER_H_
 #define V8_WASM_INTERPRETER_H_
 
 #include "src/wasm/wasm-opcodes.h"
 #include "src/zone/zone-containers.h"
 
@@ skipping 107 matching lines @@
     virtual void Pause() = 0;
     virtual void Reset() = 0;
     virtual ~Thread() {}
 
     // Stack inspection and modification.
     virtual pc_t GetBreakpointPc() = 0;
     virtual int GetFrameCount() = 0;
     virtual const WasmFrame* GetFrame(int index) = 0;
     virtual WasmFrame* GetMutableFrame(int index) = 0;
     virtual WasmVal GetReturnValue(int index = 0) = 0;
+    virtual bool MayProducedNaN() = 0;

[titzer, 2016/10/20 10:53:24]

Call this possibly nondeterministic? And add a comment to explain what it's for,
how it may be set, etc.

[ahaas, 2016/10/20 13:43:23]

Done.

 
     // Thread-specific breakpoints.
     bool SetBreakpoint(const WasmFunction* function, int pc, bool enabled);
     bool GetBreakpoint(const WasmFunction* function, int pc);
   };
 
   WasmInterpreter(WasmInstance* instance, AccountingAllocator* allocator);
   ~WasmInterpreter();
 
   //==========================================================================
@@ skipping 52 matching lines @@
  private:
   Zone zone_;
   WasmInterpreterInternals* internals_;
 };
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_INTERPRETER_H_