On Wed, 29 Jul 2026, Jakub Jelinek wrote: > Hi! > > When working on the last patch, I've noticed that the parity(bswap(x)) > optimization only optimizes the 16/32/64/128-bit bswaps, but not > generic _BitInt bswap, and doesn't optimize any of the bitreverses. > Both all bswap and all bitreverse builtins/ifns preserve values of all the > bits, just permute them, so parity (and popcount too) can be optimized. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK. > 2026-07-29 Jakub Jelinek <[email protected]> > > * match.pd (parity(bswap(x)) is parity(x)): Use BSWAP BITREVERSE > instead of BUILT_IN_BSWAP16 BUILT_IN_BSWAP32 BUILT_IN_BSWAP64 > BUILT_IN_BSWAP128. > > * gcc.dg/bitint-140.c: New test. > > --- gcc/match.pd.jj 2026-07-29 16:13:46.327108421 +0200 > +++ gcc/match.pd 2026-07-29 16:24:13.355136668 +0200 > @@ -10786,8 +10786,7 @@ (define_operator_list SYNC_FETCH_AND_AND > > /* parity(bswap(x)) is parity(x). */ > (for parity (PARITY) > - (for bswap (BUILT_IN_BSWAP16 BUILT_IN_BSWAP32 > - BUILT_IN_BSWAP64 BUILT_IN_BSWAP128) > + (for bswap (BSWAP BITREVERSE) > (simplify > (parity (convert?@0 (bswap:s@1 @2))) > (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) > --- gcc/testsuite/gcc.dg/bitint-140.c.jj 2026-07-29 16:30:57.379000085 > +0200 > +++ gcc/testsuite/gcc.dg/bitint-140.c 2026-07-29 16:30:41.617200472 +0200 > @@ -0,0 +1,17 @@ > +/* { dg-do compile { target bitint575 } } */ > +/* { dg-options "-O2 -fdump-tree-cplxlower1" } */ > +/* { dg-final { scan-tree-dump-not "\.BSWAP \\\(" "cplxlower1" } } */ > +/* { dg-final { scan-tree-dump-not "\.BITREVERSE \\\(" "cplxlower1" } } */ > +/* { dg-final { scan-tree-dump-times "\.PARITY \\\(x_" 2 "cplxlower1" } } */ > + > +int > +foo (unsigned _BitInt(512) x) > +{ > + return __builtin_parityg (__builtin_bswapg (x)); > +} > + > +int > +bar (unsigned _BitInt(575) x) > +{ > + return __builtin_parityg (__builtin_bitreverseg (x)); > +} > > Jakub > > -- Richard Biener <[email protected]> SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg, Germany; GF: Jochen Jaser, Andrew McDonald, Abhinav Puri; (HRB 36809, AG Nuernberg)
