[PATCH] D73342: Fix EarlyCSE to intersect aliasing metadata.

[Hal Finkel via Phabricator via llvm-commits]

hfinkel added a comment.

In D73342#1839006 <https://reviews.llvm.org/D73342#1839006>, @nikic wrote:

> In D73342#1838974 <https://reviews.llvm.org/D73342#1838974>, @jeroen.dobbelaere wrote:
>
> > Hal Finkel provided following example on the mailing list:
> >
> >   int * restrict r = a;
> >   ...
> >   int x = noaliasing ? *r : *a;
> >   
> >
> > This shows that the intersection of '*r' and '*a' must be taken.
>
>
> So, I guess that the reasoning here is that noalias loads are speculatable and noalias violation is thus poison (not immediate UB), so we can't make inferences from one load to the other. Does that capture it?


Yes. They don't need to be speculatable, but they certainly could be.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D73342/new/

https://reviews.llvm.org/D73342