Hi all, The constraint Dm is intended to match vectors of minus 1, but actually checks for CONST1_RTX. This doesn't have a bad effect in practice as its only use in the aarch64_wrffr pattern for the setffr instruction which is a VNx16BI operation and -1 and 1 are the same there. That pattern can only be currently generated through intrinsics anyway that create it with a CONSTM1_RTX constant.
Fix the constraint definition so that it doesn't become a footgun if its
used in some other pattern.
Bootstrapped and tested on aarch64-none-linux-gnu.
I’m pushing it to trunk.
Thanks,
Kyrill
Signed-off-by: Kyrylo Tkachov <ktkac...@nvidia.com>
gcc/ChangeLog:
* config/aarch64/constraints.md (Dm): Match CONSTM1_RTX rather
CONST1_RTX.
0001-aarch64-Check-CONSTM1_RTX-in-definition-of-Dm-constr.patch
Description: 0001-aarch64-Check-CONSTM1_RTX-in-definition-of-Dm-constr.patch
