Message ID | 20240125195712.410550-1-quic_apinski@quicinc.com |
---|---|
State | New |
Headers | show |
Series | aarch64: Fix undefinedness while testing the J constraint [PR100204] | expand |
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_apinski@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 >
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)"))) ;; 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
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. 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_apinski@quicinc.com> --- gcc/config/aarch64/constraints.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)