https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100106
--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alexandre Oliva <aol...@gcc.gnu.org>: https://gcc.gnu.org/g:d6b756447cd58bcca20e6892790582308b869817 commit r14-1187-gd6b756447cd58bcca20e6892790582308b869817 Author: Alexandre Oliva <ol...@adacore.com> Date: Wed May 24 03:07:56 2023 -0300 [PR100106] Reject unaligned subregs when strict alignment is required The testcase for pr100106, compiled with optimization for 32-bit powerpc -mcpu=604 with -mstrict-align expands the initialization of a union from a float _Complex value into a load from an SCmode constant pool entry, aligned to 4 bytes, into a DImode pseudo, requiring 8-byte alignment. The patch that introduced the testcase modified simplify_subreg to avoid changing the MEM to outermode, but simplify_gen_subreg still creates a SUBREG or a MEM that would require stricter alignment than MEM's, and lra_constraints appears to get confused by that, repeatedly creating unsatisfiable reloads for the SUBREG until it exceeds the insn count. Avoiding the unaligned SUBREG, expand splits the DImode dest into SUBREGs and loads each SImode word of the constant pool with the proper alignment. for gcc/ChangeLog PR target/100106 * emit-rtl.cc (validate_subreg): Reject a SUBREG of a MEM that requires stricter alignment than MEM's. for gcc/testsuite/ChangeLog PR target/100106 * gcc.target/powerpc/pr100106-sa.c: New.
