[PATCH] D72299: [DSE] Improve mayThrowBetween for 2 instructions in the same BB.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp:1706
+  // between them.
+  DenseMap<BasicBlock *, DenseMap<Instruction *, unsigned>> ThrowingBlocks;
 
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fhahn wrote:
> efriedma wrote:
> > This map seems sort of expensive, but maybe not a big deal relative to other stuff we have here already.
> Yep, we probably should populate it lazily.  And I think at least for C/C++ programs, it should not really be needed at all. There's no difference in the MultiSource/SPEC2000/SPEC2006 binaries with and without this patch, now that I updated D72146 to skip throwing instructions modeled in MemorySSA.
That's not surprising.  It's theoretically possible to have a function that's readnone and not nothrow, but it doesn't happen in practice for C/C++ code.


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  https://reviews.llvm.org/D72299/new/

https://reviews.llvm.org/D72299