[PATCH] D149404: [ValueTracking][InstCombine] Add a new API to allow to ignore poison generating flags or metadatas when implying poison

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:2938
+    SmallVector<Instruction *> DropFlags;
+    if (impliesPoisonIgnoreFlagsOrMetadatas(FalseVal, CondVal, DropFlags)) {
+      for (Instruction *I : DropFlags)
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nikic wrote:
> goldstein.w.n wrote:
> > Will you ever not loop through instruction and do `dropPoisonGenerating...`? Maybe it should done by `impliesPoisonIgnore...` and if its not always with a `bool` to control it.
> If it's part of a larger transform, one may only want to drop the flags after additional conditions have been checked as well. Analysis utils generally aren't allowed to modify instructions.
then maybe an API in instcombine, or at least a static helper/lambda in the file.


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  https://reviews.llvm.org/D149404/new/

https://reviews.llvm.org/D149404