[PATCH] D85533: [InstCombine] Optimize select(freeze(icmp eq/ne x, y), x, y)

[Nikita Popov via Phabricator via llvm-commits]

nikic accepted this revision.
nikic added a comment.
This revision is now accepted and ready to land.

LGTM



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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:2540
+  // The freeze should be only used by this select. Otherwise, remaining uses of
+  // the freeze can observe a contradictory value.
+  //   c = freeze(x == y)   ; Let's assume that y = poison & x = 42; c is 0 or 1
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I agree the one-use check is necessary, but weirdly alive doesn't seem to require it: https://alive2.llvm.org/ce/z/hzwzM_


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