[all-commits] [llvm/llvm-project] 24fbe6: [BasicAA] Extend two-variable MinAbsVarIndex heuri...

[Antonio Frighetto via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 24fbe6a64a112c3ab90dab54e08969f2e2640436
      https://github.com/llvm/llvm-project/commit/24fbe6a64a112c3ab90dab54e08969f2e2640436
  Author: Antonio Frighetto <me at antoniofrighetto.com>
  Date:   2026-09-22 (Tue, 22 Sep 2026)

  Changed paths:
    M llvm/include/llvm/Analysis/BasicAliasAnalysis.h
    M llvm/lib/Analysis/BasicAliasAnalysis.cpp
    A llvm/test/Analysis/BasicAA/gep-minabs-different-scale.ll

  Log Message:
  -----------
  [BasicAA] Extend two-variable MinAbsVarIndex heuristic to different scales (#218639)

When performing offset-based reasoning via the min abs heuristic, the
existing two-variables case requires equal absolute scaling factors.
This may be generalized to different scales by factoring the offset as
`GCD*(C0*V0 - C1*V1)`, and relying on cached KnownBits to prove that the
cofactor products differ.

Proof: https://alive2.llvm.org/ce/z/RC4LwD.

Co-authored-by: Alex MacLean <amaclean at nvidia.com>



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