[all-commits] [llvm/llvm-project] 1d4309: [ConstraintElim] Don't decompose values wider than...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1d43096e16ff7288c7feac1ae81fd4f745ce10bb
      https://github.com/llvm/llvm-project/commit/1d43096e16ff7288c7feac1ae81fd4f745ce10bb
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2023-10-16 (Mon, 16 Oct 2023)

  Changed paths:
    M llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
    M llvm/test/Transforms/ConstraintElimination/large-constant-ints.ll
    M llvm/test/Transforms/ConstraintElimination/shl.ll

  Log Message:
  -----------
  [ConstraintElim] Don't decompose values wider than 64 bits (#68803)

Our coefficients are 64-bits, so adding/multiplying them can wrap in
64-bits even if there would be no wrapping the full bit width.

The alternative would be to check for overflows during all adds/muls in
decomposition. I assume that we don't particularly care about handling
wide integers here, so I've opted to bail out.

Fixes https://github.com/llvm/llvm-project/issues/68751.