[PATCH] D68930: [InstCombine] Shift amount reassociation in shifty sign bit test (PR43595)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

@spatel

In D68930#1715726 <https://reviews.llvm.org/D68930#1715726>, @lebedev.ri wrote:

> In D68930#1715721 <https://reviews.llvm.org/D68930#1715721>, @spatel wrote:
>
> > In D68930#1715680 <https://reviews.llvm.org/D68930#1715680>, @lebedev.ri wrote:
> >
> > >
> >
> >
> > , and I agree it's out-of-scope to beat up on this patch alone, so I won't hold it up. But we should take a step back, do some measurements, and decide how things can be split up.
>
>
> Any thoughts on the approach i suggested:
>
> > All that being said, if it's really this much of a concern to warrant immediate action,
> >  can't we simply expose `"Depth"` in the `llvm::SimplifyAddInst()`
> >  and call it with such a depth that either disallows recursive reasoning,
> >  or severely limits it? Some fastpaths will likely needed to be added then most likely.
> >  That may be the best outcome considering the options..
>
> ?


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