[all-commits] [llvm/llvm-project] 940f89: [InstCombine] Do not modify GEP in place

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 940f89255e4a3982d94dad57837e8e658092af78
      https://github.com/llvm/llvm-project/commit/940f89255e4a3982d94dad57837e8e658092af78
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2024-09-13 (Fri, 13 Sep 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
    M llvm/test/Transforms/InstCombine/getelementptr.ll

  Log Message:
  -----------
  [InstCombine] Do not modify GEP in place

This was modifying the GEP in place, with code to adjust the
inbounds flag. This was correct at the time, but now fails to
account for other GEP flags like nuw, leading to miscompilations.

Remove the special case, and always create a new GEP instruction.
Logic for preserving nuw in the cases where it is valid will be
added in a followup patch.



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