On Sat, Aug 8, 2026 at 4:05 AM Kael Andrew Franco <[email protected]> wrote: > > Bootstrap and tested with > https://gcc.gnu.org/pipermail/gcc-patches/2026-August/726688.html > > > From 21c1ad7db9cce4061d30162e98a8baa8109c48b4 Mon Sep 17 00:00:00 2001 > From: Kael Andrew Alonzo Franco <[email protected]> > Date: Fri, 7 Aug 2026 18:24:36 -0400 > Subject: [PATCH] match: 1 / X -> X == 1 for positive X. [PR125735] > > TYPE_UNSIGNED (type) doesn't cover positive signed types > so use tree_expr_nonnegative_p (). > > Bootstrapped and tested on x86_64-pc-linux-gnu. > > PR tree-optimization/125735 > > gcc/ChangeLog: > > * match.pd: 1 / X -> X == 1 for positive X. [PR125735]
Ok, once my patch gets pushed. > > gcc/testsuite/ChangeLog: > > * gcc.dg/pr125735.c: New test. > > Signed-off-by: Kael Andrew Franco <[email protected]> > --- > gcc/match.pd | 7 ++++--- > gcc/testsuite/gcc.dg/pr125735.c | 11 +++++++++++ > 2 files changed, 15 insertions(+), 3 deletions(-) > create mode 100644 gcc/testsuite/gcc.dg/pr125735.c > > diff --git a/gcc/match.pd b/gcc/match.pd > index a2a48e1b475..8850e993425 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -628,8 +628,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > && TYPE_UNSIGNED (type)) > (trunc_divmod @0 @1)))) > > -/* 1 / X -> X == 1 for unsigned integer X. > - 1 / X -> X >= -1 && X <= 1 ? X : 0 for signed integer X. > +/* 1 / X -> X == 1 for positive integer X. > + 1 / X -> X >= -1 && X <= 1 ? X : 0 for when X could be negative. > But not for 1 / 0 so that we can get proper warnings and errors, > and not for 1-bit integers as they are edge cases better handled > elsewhere. Delay the conversion of the signed division until late > @@ -640,7 +640,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > && TYPE_PRECISION (type) > 1 > && !integer_zerop (@1) > && (!flag_non_call_exceptions || tree_expr_nonzero_p (@1))) > - (if (TYPE_UNSIGNED (type)) > + (if (TYPE_UNSIGNED (type) > + || tree_expr_nonnegative_p (@1)) > (convert (eq:boolean_type_node @1 @0)) > (if (fold_before_rtl_expansion_p ()) > (with { tree utype = unsigned_type_for (type); } > diff --git a/gcc/testsuite/gcc.dg/pr125735.c b/gcc/testsuite/gcc.dg/pr125735.c > new file mode 100644 > index 00000000000..b94d95c0de7 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/pr125735.c > @@ -0,0 +1,11 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > + > +_Bool > +one_div_positive (int b) > +{ > + if (b < 1) return 0; > + return (1 / b); > +} > + > +/* { dg-final { scan-tree-dump "b_\[0-9\]+.D. == 1" "optimized" } } */ > -- > 2.55.0 > >
