[PATCH] D24164: Remove debug info when hoisting instruction from then/else branch.

Andrea Di Biagio via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 2 02:32:14 PDT 2016

andreadb added a comment.

In https://reviews.llvm.org/D24164#532594, @dblaikie wrote:

> I would worry that this might produce a worse experience for a sanitizer user, for example - but I'm not sure. (the sanitizer user won't have any trail back to why the store in this example is happening - granted, the way the code currently works, they may be told the store is happening in the wrong branch, which isn't great either)

I don't know about the sanitizer user experience. However, based on my experience with sample pgo, this kind of changes tend to improve the quality of the sample profile from autofdo.

we have identified a couple of similar issues where the debug location of a tail-merged instruction is incorrectly set. We already have plans to send a couple of small patches to fix these issues (those would need https://reviews.llvm.org/D24180); in our sample-pgo experiments, this kind of small fixes for hoisted/tail merged instructions tend to have a very positive impact on the quality of the sample profile.


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