[PATCH] D51317: Handle BumpPtrAllocator::Allocate(0) without undefined behavior
Brent Royal-Gordon via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 5 03:02:42 PDT 2018
> On Sep 4, 2018, at 2:23 AM, Hans Wennborg via Phabricator <reviews at reviews.llvm.org> wrote:
>
> I'd like to see some kind of benchmark to verify this doesn't have negative performance impact.
This is a little rough because it uses time(1), but here's twenty compiles of oggenc.c (1.7 MB) at -O3 on macOS with as much extraneous stuff closed as possible:
Without change:
103.81 real 101.95 user 1.48 sys
With change:
101.31 real 99.55 user 1.46 sys
Additional runs under less controlled conditions (e.g. a web browser open in the background) didn't necessarily show the changed version being faster, but they were always quite close. Test runs the other day with bzip2.c (cited in the original commit) also looked pretty close, but it compiled so fast that I had a tough time getting solid numbers. I had trouble getting gcc.c to compile on macOS.
--
Brent Royal-Gordon
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