[interpreter] Filter expression positions at source.

src/interpreter/bytecode-array-builder.h

 // Copyright 2015 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_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_
 #define V8_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_
 
 #include "src/ast/ast.h"
 #include "src/interpreter/bytecode-array-writer.h"
 #include "src/interpreter/bytecode-register-allocator.h"
@@ skipping 297 matching lines @@
                     uint32_t operand0);
 
   BytecodeArrayBuilder& OutputJump(Bytecode jump_bytecode,
                                    BytecodeLabel* label);
 
 
   bool OperandIsValid(Bytecode bytecode, OperandScale operand_scale,
                       int operand_index, uint32_t operand_value) const;
   bool RegisterIsValid(Register reg, OperandSize reg_size) const;
 
+  // Test if bytecode needs an expression position to be attached.
+  static bool NeedExpressionPosition(Bytecode bytecode);

[Yang, 2016/06/08 13:04:54]

I wonder whether that should belong in interpreter::Bytecodes. We have a bunch
of static functions like IsCallOrNew, IsBytecodeWithScalableOperands,
IsWithoutExternalSideEffects etc.

By that convention it would also be singular, i.e. NeedsExpressionPosition.

[oth, 2016/06/08 15:04:21]

Yes, it could do. The only quirk with this is that it depends on a v8 flag and
none of the other Bytecodes methods do so it's behaviour is not independent of
options.

I've tweaked to put it in a private namespace so it's no longer exposed. Happy
to put it in Bytecodes or leave as-is if anyone has a stronger opinion on this.

+
   // Attach latest source position to |node|.
   void AttachSourceInfo(BytecodeNode* node);
 
   // Gets a constant pool entry for the |object|.
   size_t GetConstantPoolEntry(Handle<Object> object);
 
   // Not implemented as the illegal bytecode is used inside internally
   // to indicate a bytecode field is not valid or an error has occured
   // during bytecode generation.
   BytecodeArrayBuilder& Illegal();
@@ skipping 31 matching lines @@
   BytecodeSourceInfo latest_source_info_;
 
   DISALLOW_COPY_AND_ASSIGN(BytecodeArrayBuilder);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_