[all-commits] [llvm/llvm-project] 52b59b: [DropUnnecessaryAssumes] Make the ephemeral value ...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 52b59b5bc07ae3a05b7643119dc6b34099108bda
      https://github.com/llvm/llvm-project/commit/52b59b5bc07ae3a05b7643119dc6b34099108bda
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2025-09-29 (Mon, 29 Sep 2025)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DropUnnecessaryAssumes.cpp
    M llvm/test/Transforms/DropUnnecessaryAssumes/basic.ll

  Log Message:
  -----------
  [DropUnnecessaryAssumes] Make the ephemeral value check more precise (#160700)

The initial implementation used a very crude check where a value was
considered ephemeral if it has only one use. This is insufficient if
there are multiple assumes acting on the same value, or in more complex
cases like cyclic phis.

Generalize this to a more typical ephemeral value check, i.e. make sure
that all transitive users are in assumes, while stopping at
side-effecting instructions.



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