[llvm-commits] [PATCH] Implement new LibCallSimplifier class

[Eric Christopher]

I like the code in general.

On Thu, Oct 4, 2012 at 8:14 AM, Meador Inge <meadori at codesourcery.com> wrote:
> This patch implements the new LibCallSimplifier class as outlined in [1].
> In addition to providing the new base library simplification infrastructure,
> all the fortified library call simplifications were moved over to the new
> infrastructure.  The rest of the library simplification optimizations will
> be moved over with follow up patches.
>

OK.

> NOTE: The original fortified library call simplifier located in the
> SimplifyFortifiedLibCalls class was not removed because it is still
> used by CodeGenPrepare.  This class will eventually go away too.
>

Good. I was wondering about that.

> +    /// replaceCall - Implemented by derived classes to control exactly
> +    /// how the optimized instruction gets replaced.  The new replacement
> +    /// instruction should be returned or 0 if no replacement is possible.
> +    virtual Instruction *replaceCall(CallInst *CI, Value *With) = 0;
> +
> +    /// fold - Take the given call instruction and if possible returns the
> +    /// optimized instruction that has replaced the original call by way
> +    /// of 'replaceCall'.  If no optimization can be found, then 0 is
> +    /// returned.
> +    Instruction *fold(CallInst *CI);
> +  };
>

This interface seems a bit odd. Why not just "optimizeCall" and either
return NULL if it's not changed or just return the original instruction?

-eric