[LLVMdev] Optimization passes organization and tradeoffs

[Chris Lattner]

On Wed, 21 May 2008, David Greene wrote:
> On Wednesday 21 May 2008 15:48, Chris Lattner wrote:
>>> What's the difference between GVN and GCSE, if they both perform common
>>> subexpression elimination?
>>
>> GVN does more, and is a better algorithm.  GCSE is basically deprecated
>> and should be removed at some point.
>
> Er...waitaminute.  Maybe there's something I don't fully grok about GVN,
> but in general, value numbering and CSE are different and often complementary.
> Neither is "more powerful" than the other.

I'm talking about the LLVM passes here, not the abstract algorithms.

-Chris

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