[PATCH] D135020: [GlobalISel] Combine `undef / X -> 0` and `undef % X -> 0`

[Jessica Paquette via Phabricator via llvm-commits]

paquette created this revision.
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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.


https://reviews.llvm.org/D135020

Files:
  llvm/include/llvm/Target/GlobalISel/Combine.td
  llvm/test/CodeGen/AArch64/GlobalISel/combine-binop-undef-left-to-zero.mir
  llvm/test/CodeGen/AArch64/GlobalISel/combine-shl.mir

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