[PATCH] D109749: Experimental Partial Mem2Reg

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

I have seen cases where this would be beneficial,
some of those are just due to lack of inlining, but not all.

I strongly believe this should be part of SROA,
it should analyze the alloca's ignoring captures,
and if it is otherwise promoteable, it should:

1. duplicate the original alloca (only for simplicity, this is fine since we know the old alloca goes away)
2. before each capture, load contents of the old alloca, and store it into new alloca
3. after each capture, load contents of the new alloca, and store it into old alloca
4. change captures to refer to the new alloca
5. run AggLoadStoreRewriter on the new alloca - so that all the uses of old alloca we've just introduced are analyzeable by SROA
6. proceed with normal handling of the old alloca - mem2reg will now succeed


Repository:
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  https://reviews.llvm.org/D109749/new/

https://reviews.llvm.org/D109749