[PATCH] D158960: [ValueTracking] Handle conflicts when computing knownbits of PHI nodes in deadcode; PR65022

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n added inline comments.


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Comment at: llvm/test/Analysis/ValueTracking/knownbits-phi-deadcode.ll:2
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt -O1 -S < %s | FileCheck %s
+; This reduced testcase from pr65022. We are only testing that is doesn't crash.
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nikic wrote:
> Please reduce this to a single pass invocation.
Done, by chance do you know if there is a way to get llvm-reduce to do this for you?

I ended up going through the `-O1` passes manually until I could isolate to a single pass (and get necessary transforms from pre-existing passes) but have to feel there is a better way.

Also tried `--print-after-all` but that often doesn't give complete IR. Just curious if there is some "good" way to do this or is it just figure it out with pass pipeline + ir dumps?


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  https://reviews.llvm.org/D158960/new/

https://reviews.llvm.org/D158960