Hi Duncan, It's possibly expected. It depends on what operation it's performing. I expected a bit of a performance drop in some cases but I have a plan to fix those. Do you have a link to LNT?
On Wed, Jul 13, 2016 at 6:41 PM, Duncan P. N. Exon Smith < dexonsm...@apple.com> wrote: > Hmm. I implied there were other regressions, but I just finished scanning > them. Shootout-C++/hash2 is the only major one. The others were small, > and only at -O0. > > > On 2016-Jul-13, at 17:38, Duncan P. N. Exon Smith via cfe-commits < > cfe-commits@lists.llvm.org> wrote: > > > > We saw mixed results from this on LNT, including some major > regressions. For example, on x86_64, > SingleSource/Benchmarks/Shootout-C++/hash2 regressed 18.5% at -O3 and over > 20% at -Os. > > > > Is this expected? > > ^ Still interested in an answer, though ;). > > > > >> On 2016-Jul-11, at 15:02, Eric Fiselier via cfe-commits < > cfe-commits@lists.llvm.org> wrote: > >> > >> Author: ericwf > >> Date: Mon Jul 11 17:02:02 2016 > >> New Revision: 275114 > >> > >> URL: http://llvm.org/viewvc/llvm-project?rev=275114&view=rev > >> Log: > >> Don't compute modulus of hash if it is smaller than the bucket count. > >> > >> This cleans up a previous optimization attempt in hash, and results in > >> additional performance improvements over that previous attempt. > Additionally > >> this new optimization does not hinder the power of 2 bucket count > optimization. > >> > >> Modified: > >> libcxx/trunk/include/__hash_table > >> > >> Modified: libcxx/trunk/include/__hash_table > >> URL: > http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__hash_table?rev=275114&r1=275113&r2=275114&view=diff > >> > ============================================================================== > >> --- libcxx/trunk/include/__hash_table (original) > >> +++ libcxx/trunk/include/__hash_table Mon Jul 11 17:02:02 2016 > >> @@ -90,7 +90,8 @@ inline _LIBCPP_INLINE_VISIBILITY > >> size_t > >> __constrain_hash(size_t __h, size_t __bc) > >> { > >> - return !(__bc & (__bc - 1)) ? __h & (__bc - 1) : __h % __bc; > >> + return !(__bc & (__bc - 1)) ? __h & (__bc - 1) : > >> + (__h < __bc ? __h : __h % __bc); > >> } > >> > >> inline _LIBCPP_INLINE_VISIBILITY > >> @@ -2201,8 +2202,7 @@ __hash_table<_Tp, _Hash, _Equal, _Alloc> > >> if (__nd != nullptr) > >> { > >> for (__nd = __nd->__next_; __nd != nullptr && > >> - (__hash == __nd->__hash_ > >> - || __constrain_hash(__nd->__hash_, __bc) == > __chash); > >> + __constrain_hash(__nd->__hash_, __bc) == __chash; > >> __nd = > __nd->__next_) > >> { > >> if ((__nd->__hash_ == __hash) && > key_eq()(__nd->__value_, __k)) > >> @@ -2231,8 +2231,7 @@ __hash_table<_Tp, _Hash, _Equal, _Alloc> > >> if (__nd != nullptr) > >> { > >> for (__nd = __nd->__next_; __nd != nullptr && > >> - (__hash == __nd->__hash_ > >> - || __constrain_hash(__nd->__hash_, __bc) == > __chash); > >> + __constrain_hash(__nd->__hash_, __bc) == __chash; > >> __nd = > __nd->__next_) > >> { > >> if ((__nd->__hash_ == __hash) && > key_eq()(__nd->__value_, __k)) > >> > >> > >> _______________________________________________ > >> cfe-commits mailing list > >> cfe-commits@lists.llvm.org > >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > > > > _______________________________________________ > > cfe-commits mailing list > > cfe-commits@lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > >
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