[PATCH] D76973: [LangRef] Clarify the semantics of branch on undef

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune marked an inline comment as done.
aqjune added a comment.

With this semantics, separating `if (cond1 && cond2)` into `if (cond1) { if(cond2) { .. } }` becomes incorrect. If cond1 is undef and cond2 is false, this introduces UB.
There are several places where this happens, such as `test/Transforms/SimplifyCFG/switch_create.ll` and `test/SimpleLoopUnswitch/LIV-loop-condtion.ll`. They can be fixed by introducing `freeze`.


Repository:
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https://reviews.llvm.org/D76973