On Thu, 13 Mar 2025, Richard Sandiford wrote: > Updates in v2: > > - Make one of the pointer-arith-11.c scans require LP64, since > the constant is printed differently for ILP32, and would be > printed differently still for 16-bit targets. > > - Avoid use of element_precision in scalar-only folds > > - Use tree_int_cst_sgn instead of wi::to_widest. > > Original message: > > gcc.target/aarch64/sve/pr98119.c has been failing since r15-268. > The test expects pointer alignment to be done with a plain AND, > but that no longer happens. > > It was combine that previously generated the ANDs, but I think it's > fair to argue that it isn't combine's job to handle this case. > The test's gimple output is pretty suboptimal. > > The current gimple is: > > _21 = (unsigned long) vectp_x.4_22; > _20 = _21 >> 1; > _17 = (unsigned int) _20; > _16 = _17 & 15; > _9 = (sizetype) _16; > _18 = (unsigned int) _9; > _32 = _18 w* 2; > _33 = -_32; // -(_21 & 30) > vectp_x.6_10 = x_13(D) + _33; // x_31(D) & ~30 > _41 = 18446744073709551584 - _32; // -32 - (_21 & 30) > vectp_x.9_38 = x_13(D) + _41; // (x_31(D) - 32) & ~30 > _55 = _16 + 1000; > > This series adds two groups of folds that together give: > > _21 = (unsigned long) vectp_x.4_22; > _20 = _21 >> 1; > _17 = (unsigned int) _20; > _16 = _17 & 15; > vectp_x.6_10 = x_13(D) & -31B; > _18 = x_13(D) & -31B; > vectp_x.9_38 = _18 + 18446744073709551584; > _55 = _16 + 1000; > > The duplicate "x_13(D) & -31B"s are unfortunate, but RTL CSE does get > rid of them. > > I asked on IRC whether new folds to fix this kind of regression were > acceptable, but I admit that the patches ended up being bigger than > I'd imagined. I'll fully understand if they seem like too much for > stage 4 after all. > > Bootstrapped & regression-tested on aarch64-linux-gnu. Also tested > in its original form on x86_64-linux-gnu. OK to install?
OK. Thanks, Richard. > Richard > > > Richard Sandiford (2): > match.pd: Fold ((X >> C1) & C2) * (1 << C1) > match.pd: Extend pointer alignment folds > > gcc/match.pd | 55 +++++++++++++ > gcc/testsuite/gcc.dg/fold-mul-and-lshift-1.c | 59 ++++++++++++++ > gcc/testsuite/gcc.dg/fold-mul-and-lshift-2.c | 15 ++++ > gcc/testsuite/gcc.dg/pointer-arith-11.c | 39 ++++++++++ > gcc/testsuite/gcc.dg/pointer-arith-12.c | 82 ++++++++++++++++++++ > 5 files changed, 250 insertions(+) > create mode 100644 gcc/testsuite/gcc.dg/fold-mul-and-lshift-1.c > create mode 100644 gcc/testsuite/gcc.dg/fold-mul-and-lshift-2.c > create mode 100644 gcc/testsuite/gcc.dg/pointer-arith-11.c > create mode 100644 gcc/testsuite/gcc.dg/pointer-arith-12.c > > -- Richard Biener <rguent...@suse.de> SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg, Germany; GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
