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. I'll also test on x86_64-linux-gnu. OK to install if that passes? Richard Richard Sandiford (2): match.pd: Fold ((X >> C1) & C2) * (1 << C1) match.pd: Extend pointer alignment folds gcc/match.pd | 56 +++++++++++++ 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, 251 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 -- 2.25.1
