[llvm-commits] [llvm] r76215 - /llvm/trunk/include/llvm/Value.h

[Daniel Dunbar]

Hi Dan,

On Fri, Jul 17, 2009 at 11:56 AM, Dan Gohman<gohman at apple.com> wrote:
> +  /// clearOptionalData - Clear any optional optimization data from this Value.
> +  /// Transformation passes must call this method whenever changing the IR
> +  /// in a way that would affect the values produced by this Value, unless
> +  /// it takes special care to ensure correctness in some other way.

What does this mean? It isn't clear if the optional data is based on
the structure of the Value, or the semantics of the Value. If I change
the operand of an add, do I have to clear it? If I change the the
operand of an add, do I have to clear the flag for all users of the
add (which would mean I have to do a full walk of the use graph).

 - Daniel

> +  void clearOptionalData() { SubclassOptionalData = 0; }
> +
>   //----------------------------------------------------------------------
>   // Methods for handling the chain of uses of this Value.
>   //
>
>
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