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| author | Alex Coplan <alex.coplan@arm.com> | 2024-08-02 09:56:07 +0100 |
|---|---|---|
| committer | Alex Coplan <alex.coplan@arm.com> | 2024-09-11 11:50:48 +0100 |
| commit | 3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b (patch) | |
| tree | 21a03d791832cad9a9b818df3b103fd4c20446e0 | |
| parent | 9759f6299d9633cabac540e5c893341c708093ac (diff) | |
| download | gcc-3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b.zip gcc-3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b.tar.gz gcc-3fd07d4f04f43816a038daf9b16c6d5bf2e96c9b.tar.bz2 | |
libstdc++: Restore unrolling in std::find using pragma [PR116140]
Together with the preparatory compiler patches, this patch restores
unrolling in std::__find_if, but this time relying on the compiler to do
it by using:
#pragma GCC unroll 4
which should restore the majority of the regression relative to the
hand-unrolled version while still being vectorizable with WIP alignment
peeling enhancements.
On Neoverse V1 with LTO, this reduces the regression in xalancbmk (from
SPEC CPU 2017) from 5.8% to 1.7% (restoring ~71% of the lost
performance).
libstdc++-v3/ChangeLog:
PR libstdc++/116140
* include/bits/stl_algobase.h (std::__find_if): Add #pragma to
request GCC to unroll the loop.
| -rw-r--r-- | libstdc++-v3/include/bits/stl_algobase.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h index 27f6c37..f13662f 100644 --- a/libstdc++-v3/include/bits/stl_algobase.h +++ b/libstdc++-v3/include/bits/stl_algobase.h @@ -2104,6 +2104,7 @@ _GLIBCXX_END_NAMESPACE_ALGO inline _Iterator __find_if(_Iterator __first, _Iterator __last, _Predicate __pred) { +#pragma GCC unroll 4 while (__first != __last && !__pred(__first)) ++__first; return __first; |