[llvm] [GlobalISel] Combine G_ZEXT of undef -> 0 (PR #113764)

[Matt Arsenault via llvm-commits]

Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/113764 at github.com>


https://github.com/arsenm requested changes to this pull request.

replaceInstWithConstant reads as a must-succeed operation. The match function should have the legality information. In an ideal future, the tablegen apply could automatically check the legality 

https://github.com/llvm/llvm-project/pull/113764