[PATCH] D75505: [InstCombine] Enhance cast-of-load->load-of-bitcast fold to handle multiple identical casts

Tue Mar 3 13:47:10 PST 2020

lebedev.ri marked an inline comment as done.
lebedev.ri added a comment.

In D75505#1903908 <https://reviews.llvm.org/D75505#1903908>, @spatel wrote:

> In D75505#1903785 <https://reviews.llvm.org/D75505#1903785>, @lebedev.ri wrote:
>
> > Hm, why SimplifyCFG?
> >  I'm aware that we (still) don't have specialized hoisting/sinking pass..
>
>
> Time to change that? :)

In principle - hell yeah :)

But i'm not sure i have clear understanding how that would look,
so for now i'd settle for either just not touching the pattern,
or doing this conservative instcombine-level change.

> I was just grepping around in SimplifyCFG and saw that it has hoisting transforms gated by instruction costs, so I thought maybe there's a way to squeeze this into the existing code, but I know that's a stretch too.

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