[all-commits] [llvm/llvm-project] b01c3d: [LAA] Add test case for #82665.

[Florian Hahn via All-commits]

  Branch: refs/heads/release/18.x
  Home:   https://github.com/llvm/llvm-project
  Commit: b01c3dcf2eb5bdadd0df30e9ff5160f2da17293f
      https://github.com/llvm/llvm-project/commit/b01c3dcf2eb5bdadd0df30e9ff5160f2da17293f
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-03-13 (Wed, 13 Mar 2024)

  Changed paths:
    A llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll

  Log Message:
  -----------
  [LAA] Add test case for #82665.

Test case for https://github.com/llvm/llvm-project/issues/82665.

(cherry picked from commit 4cfd4a7896b5fd50274ec8573c259d7ad41741de)


  Commit: c7eb919d2cbef765e058c977b3ab0801b6a89b66
      https://github.com/llvm/llvm-project/commit/c7eb919d2cbef765e058c977b3ab0801b6a89b66
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-03-13 (Wed, 13 Mar 2024)

  Changed paths:
    M llvm/lib/Analysis/ValueTracking.cpp
    M llvm/test/Analysis/LoopAccessAnalysis/underlying-object-loop-varying-phi.ll

  Log Message:
  -----------
  [ValueTracking] Treat phi as underlying obj when not decomposing further (#84339)

At the moment, getUnderlyingObjects simply continues for phis that do
not refer to the same underlying object in loops, without adding them to
the list of underlying objects, effectively ignoring those phis.

Instead of ignoring those phis, add them to the list of underlying
objects. This fixes a miscompile where LoopAccessAnalysis fails to
identify a memory dependence, because no underlying objects can be found
for a set of memory accesses.

Fixes https://github.com/llvm/llvm-project/issues/82665.

PR: https://github.com/llvm/llvm-project/pull/84339
(cherry picked from commit b274b23665dec30f3ae4fb83ccca8b77e6d3ada3)


Compare: https://github.com/llvm/llvm-project/compare/159969b3880b...c7eb919d2cbe

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