[PATCH] D38374: [memcpyopt] Memcpy-memcpy dependence isn't detected across basic blocks
Dan Gohman via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 28 13:53:25 PDT 2017
sunfish added a comment.
In https://reviews.llvm.org/D38374#883738, @dberlin wrote:
> 1. non-local calls in GVN are the cause of pretty much all of it's massive slowdown.
>
> Have you measured the effect this has on larger memory-using testcases?
I've measured compile times on some C++ and Rust testcases, and it doesn't appear to significantly slow down -O2. memcpyopt remains under 1% of the time, according to -time-passes.
> 2. If you are interested, someone already ported it to memoryssa: https://reviews.llvm.org/D26739
That's interesting, though I'm still interested in the focused and incremental patch here.
Repository:
rL LLVM
https://reviews.llvm.org/D38374
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