[PATCH] D56151: [DebugInfo] PR40010: Avoid register coalesing altering DBG_VALUE valuations

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope added a comment.

FYI: I've downloaded this patch and have been running some tests (on a C code base). Lots of DBG_VALUE:s that now becomes undef. Some of them were totally wrong before (so this patch is good). But in some situations it looks like a regression. Need some more time to analyse those to find out if there is something wrong with mergingChangesDbgValue (that can be easily fixed), or to understand better why we get those regressions.

The defensive approach would of course be to land this, since it obviously fixes some "hard" faults while getting "optimized out" isn't a fault (even if it might be considered a regression). So I just want to understand that it isn't some obvious fault with the liveness checks that makes this just randomly  turning DBG_VALUE:s into undef before I approve this.


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