On Mon, Oct 21, 2024 at 4:22 PM Akram Ahmad <akram.ah...@arm.com> wrote: > > This patch adds a new case for unsigned scalar saturating subtraction > using a branch with a greater-than-or-equal condition. For example, > > X >= (X - Y) ? (X - Y) : 0 > > is transformed into SAT_SUB (X, Y) when X and Y are unsigned scalars, > which therefore correctly matches more cases of IFN SAT_SUB. > > This passes the aarch64-none-linux-gnu regression tests with no failures.
Can you also add a testcase that exercises this? Otherwise looks good. Thanks, Richard. > gcc/ChangeLog: > > * match.pd: Add new match for SAT_SUB. > --- > gcc/match.pd | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/gcc/match.pd b/gcc/match.pd > index ee53c25cef9..4fc5efa6247 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -3360,6 +3360,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > } > (if (wi::eq_p (sum, wi::uhwi (0, precision))))))) > > +/* Unsigned saturation sub, case 11 (branch with ge): > + SAT_U_SUB = X >= (X - Y) ? (X - Y) : 0. */ > +(match (unsigned_integer_sat_sub @0 @1) > + (cond^ (ge @0 (minus @0 @1)) > + (convert? (minus (convert1? @0) (convert1? @1))) integer_zerop) > + (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type) > + && TYPE_UNSIGNED (TREE_TYPE (@0)) && types_match (@0, @1)))) > + > /* Signed saturation sub, case 1: > T minus = (T)((UT)X - (UT)Y); > SAT_S_SUB = (X ^ Y) & (X ^ minus) < 0 ? (-(T)(X < 0) ^ MAX) : minus; > -- > 2.34.1 >
