[PATCH] D80665: [MachineLICM] Assert that locations from debug insts are not lost

Thu May 28 11:33:22 PDT 2020

davide added a comment.

In D80665#2060894 <https://reviews.llvm.org/D80665#2060894>, @davide wrote:

> In D80665#2060766 <https://reviews.llvm.org/D80665#2060766>, @jmorse wrote:
>
> > LGTM -- I'd suggest that the assertion messages could become something like "Shouldn't be hoisting debug instructions" or similar. IMO, as well as the matter of dropping DebugLocs, debug instructions should (almost?) never appears as a candidate to be moved around like another instruction.
>
>
> While I agree with you in theory, the classical counterexample for this claim is merging successors in predecessors, or all the CFG'ish transformations that SimplifyCFG is very good at doing. In that case you just move full blocks around and the likelihood of moving DebugInfo around is very high.

LICM and MachineLICM really don't quite suffer from this problem, as you already pointed out.

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