[PATCH] D75799: [JumpThreading] Don't create PHI nodes with "is.constant" values

Fri Mar 13 02:15:40 PDT 2020

lebedev.ri added a comment.

In D75799#1920869 <https://reviews.llvm.org/D75799#1920869>, @void wrote:

> In D75799#1920392 <https://reviews.llvm.org/D75799#1920392>, @lebedev.ri wrote:
>
> > Can you post standalone example on godbolt that shows this link failure without this patch please?
>
>
> I'm not sure what that will achieve. It would include all of the Linux kernel as part of the linking process, and it's only one file (the one I reduced the testcase from) that has the `__bad_copy_from()` reference still in it. Perhaps I'm missing something?

I personally still don't understand *why* after this transform we fail to DCE. Is this pass ordering issue? Heuristics issue?

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  https://reviews.llvm.org/D75799/new/

https://reviews.llvm.org/D75799