https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101384
--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:e0e82856d535f56c916382f892ed2435dde54d4d commit r12-2416-ge0e82856d535f56c916382f892ed2435dde54d4d Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jul 20 17:26:10 2021 +0200 rs6000: Fix up easy_vector_constant_msb handling [PR101384] The following gcc.dg/pr101384.c testcase is miscompiled on powerpc64le-linux. easy_altivec_constant has code to try construct vector constants with different element sizes, perhaps different from CONST_VECTOR's mode. But as written, that works fine for vspltis[bhw] cases, but not for the vspltisw x,-1; vsl[bhw] x,x,x case, because that creates always a V16QImode, V8HImode or V4SImode constant containing broadcasted constant with just the MSB set. The vspltis_constant function etc. expects the vspltis[bhw] instructions where the small [-16..15] or even [-32..30] constant is sign-extended to the remaining step bytes, but that is not the case for the 0x80...00 constants, with step > 1 we can't handle e.g. { 0x80, 0xff, 0xff, 0xff, 0x80, 0xff, 0xff, 0xff, 0x80, 0xff, 0xff, 0xff, 0x80, 0xff, 0xff, 0xff } vectors but do want to handle e.g. { 0, 0, 0, 0x80, 0, 0, 0, 0x80, 0, 0, 0, 0x80, 0, 0, 0, 0x80 } and similarly with copies > 1 we do want to handle e.g. { 0x80808080, 0x80808080, 0x80808080, 0x80808080 }. 2021-07-20 Jakub Jelinek <ja...@redhat.com> PR target/101384 * config/rs6000/rs6000-protos.h (easy_altivec_constant): Change return type from bool to int. * config/rs6000/rs6000.c (vspltis_constant): Fix up handling the EASY_VECTOR_MSB case if either step or copies is not 1. (vspltis_shifted): Fix comment typo. (easy_altivec_constant): Change return type from bool to int, instead of returning true return byte size of the element mode that should be used to synthetize the constant. * config/rs6000/predicates.md (easy_vector_constant_msb): Require that vspltis_shifted is 0, handle the case where easy_altivec_constant assumes using different vector mode from CONST_VECTOR's mode. * config/rs6000/altivec.md (easy_vector_constant_msb splitter): Use easy_altivec_constant to determine mode in which -1 >> -1 should be performed, use rs6000_expand_vector_init instead of gen_vec_initv4sisi. * gcc.dg/pr101384.c: New test. * gcc.target/powerpc/pr101384-1.c: New test. * gcc.target/powerpc/pr101384-2.c: New test.
