On 25/01/2024 11:57, Andrew Pinski wrote: > The J constraint can invoke undefined behavior due to it taking the > negative of the ival if ival was HWI_MIN. The fix is simple as casting > to `unsigned HOST_WIDE_INT` before doing the negative of it. This > does that.
Thanks for doing this. > > Committed as obvious after build/test for aarch64-linux-gnu. > > gcc/ChangeLog: > > PR target/100204 > * config/aarch64/constraints.md (J): Cast to `unsigned HOST_WIDE_INT` > before taking the negative of it. > > Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com> > --- > gcc/config/aarch64/constraints.md | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/gcc/config/aarch64/constraints.md > b/gcc/config/aarch64/constraints.md > index 8566befd727..a2569cea510 100644 > --- a/gcc/config/aarch64/constraints.md > +++ b/gcc/config/aarch64/constraints.md > @@ -118,7 +118,7 @@ (define_constraint "Uat" > (define_constraint "J" > "A constant that can be used with a SUB operation (once negated)." > (and (match_code "const_int") > - (match_test "aarch64_uimm12_shift (-ival)"))) > + (match_test "aarch64_uimm12_shift (- (unsigned HOST_WIDE_INT) ival)"))) Sorry for the nitpick, but: I don't think we want a space after the unary - here (at least according to https://gcc.gnu.org/codingconventions.html). Alex > > ;; We can't use the mode of a CONST_INT to determine the context in > ;; which it is being used, so we must have a separate constraint for > -- > 2.39.3 >
