[all-commits] [llvm/llvm-project] 24553d: [GlobalISel] Combine `undef / X -> 0` and `undef %...

[Jessica Paquette via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 24553df57dcc7bb2567697d8697b37ffbbac0bac
      https://github.com/llvm/llvm-project/commit/24553df57dcc7bb2567697d8697b37ffbbac0bac
  Author: Jessica Paquette <jpaquette at apple.com>
  Date:   2022-10-01 (Sat, 01 Oct 2022)

  Changed paths:
    M llvm/include/llvm/Target/GlobalISel/Combine.td
    A llvm/test/CodeGen/AArch64/GlobalISel/combine-binop-undef-left-to-zero.mir
    R llvm/test/CodeGen/AArch64/GlobalISel/combine-shl.mir

  Log Message:
  -----------
  [GlobalISel] Combine `undef / X -> 0` and `undef % X -> 0`

This fixes the `urem_undef_lhs` case in the following:

https://gcc.godbolt.org/z/Wo9x7o679

Also see https://github.com/llvm/llvm-project/issues/57256 for more related
bugs.

This is equivalent to the undef bits in `simplifyDivRem` in the DAGCombiner.

Differential Revision: https://reviews.llvm.org/D135020