[PATCH] D84609: [MemDepAnalysis] Cut-off threshold reshuffling

Alina Sbirlea via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Jul 28 10:40:34 PDT 2020


asbirlea added a comment.

Some general comments:

- The MemDepAnalysis has been known to be problematic for compile-time, so reducing the 100k implicit threshold seems reasonable.
- It's natural the compiler tracker will be happy, but can we consider runtime implications due to potential missed optimizations?
- Could we evaluate which optimizations are missed, in which passes using MemDepAnalysis along with their run-time impact? (in particular for the benchmarks where we see the large compile-time benefits)

AFAIK, the main passes using MemDepAnalysis are DSE, MemCpyOpt and GVN and there is active work in porting these to MemorySSA. The same analysis of compile-time vs run-time benefits is needed for that switch, so having data from reducing thresholds here will be very valuable for the short term (current patch) on deciding how much to reduce it to, and for the long-term switch to MemorySSA.


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https://reviews.llvm.org/D84609



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