[PATCH] D27174: [LiveRangeEdit] Handle instructions with no defs correctly.
Geoff Berry via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 28 12:23:46 PST 2016
gberry added a comment.
I ran into this issue when making some other changes, and I'm not sure how to test it in isolation. There are a handful of lit tests that hit this case. For example, if the test added above were instead made an assert(isDef()) inside the body of the if, it would fire. But I don't think there is a case that triggers any testable change in output because of the other conditions checked along with isOrigDef.
For some context, the change I was working on that led to this was adding support for re-materializing COPY XZR on AArch64. When this is done, eliminateDeadDef can be called on a KILL XZR instruction, which leads to an assert in VRM->getOriginal(Dest) on line 277 since XZR isn't a vreg.
I could combine this fix with my change to enable COPY XZR re-materialization if that makes more sense.
https://reviews.llvm.org/D27174
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