Summary:
Every single benchmark i can run, on large and small cfgs, fully
connected, etc, across 3 different platforms (x86, arm., and PPC) says
that the current pred iterator cache is a losing proposition.
I can't find a case where it's faster than just walking preds, and in some cases, it's 5-10% slower.
This is due to copying the preds.
It also degrades into copying the entire cfg.
The one operation that is occasionally faster is the cached size.
This makes that operation faster by not relying on having the copies available.
I'm not even sure that is faster enough to be worth it. I, again, have
trouble finding cases where this takes long enough in a pass to be
worth caching compared to a million other things they could cache or
improve.
My suggestion:
We next remove the get() interface.
We do stronger benchmarking of size().
We probably end up killing this entire cache.
/
Reviewers: chandlerc
Subscribers: aemerson, llvm-commits, trentxintong
Differential Revision: https://reviews.llvm.org/D30873
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297733 91177308-0d34-0410-b5e6-96231b3b80d8
Add header guards to files that were missing guards. Remove #endif comments
as they don't seem common in LLVM (we can easily add them back if we decide
they're useful)
Changes made by clang-tidy with minor tweaks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215558 91177308-0d34-0410-b5e6-96231b3b80d8
