[PATCH] D156458: GVNSink: add test to show GVN-aware sinking

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/test/Transforms/GVNSink/gvn-awareness.ll:50
+  %beam.addr = alloca i32, align 4
+  %i = alloca i32, align 4
+  store ptr %a, ptr %a.addr, align 8
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artagnon wrote:
> xbolva00 wrote:
> > artagnon wrote:
> > > nikic wrote:
> > > > Please at least run this through SROA. The test is a weird mix of completely unoptimized IR plus a GVN replacement.
> > > When I run it through SROA, `gvn-sink` no longer works.
> > Maybe also add phaseordering test?
> > 
> > If this fails to work after sroa, than this optimization will not work anyway with -O2/-O3
> Sorry, what do you mean by a phaseordering test?
A phase ordering test checks the whole `O3` pipeline. In cases like these where optimization depends on precise pass ordering, a phase ordering test ensures that the correct pass interaction is preserved going forward.


I've committed a phase ordering test for your motivating case in https://github.com/llvm/llvm-project/commit/bbe2887f5e9ca005b0f1b96c858969ee3ba646f4 and submitted D156532 for a possible fix that does not rely on GVNSink.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156458/new/

https://reviews.llvm.org/D156458