[PATCH] D64946: [AMDGPU] Fix trivial PHI into SI_END_CF.

Mon Jul 22 01:57:46 PDT 2019

rampitec added a comment.

In D64946#1595185 <https://reviews.llvm.org/D64946#1595185>, @nhaehnle wrote:

> In D64946#1593675 <https://reviews.llvm.org/D64946#1593675>, @rampitec wrote:
>
> > In D64946#1593334 <https://reviews.llvm.org/D64946#1593334>, @nhaehnle wrote:
> >
> > > How about the following simpler logic:
> > >
> > > - if the PHI is used by any basic-block prologue instruction (except other PHIs), then insert the COPY at the top of the basic block
> > > - otherwise, insert the COPY after the basic-block prologue
> >
> >
> > In this case COPY in the prologue also shall be marked as prologue instruction somehow.
>
>
> You're right, my idea doesn't work.

Unless we find a way to mark it as a prologue. An easiest (but not clean) way is to mark copy as impdef exec.

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