[PATCH] D38374: [memcpyopt] Memcpy-memcpy dependence isn't detected across basic blocks

[Dan Gohman via Phabricator via llvm-commits]

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