https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111677
--- Comment #26 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alex Coplan <acop...@gcc.gnu.org>: https://gcc.gnu.org/g:0529ba8168c89f24314e8750237d77bb132bea9c commit r14-8657-g0529ba8168c89f24314e8750237d77bb132bea9c Author: Alex Coplan <alex.cop...@arm.com> Date: Tue Jan 30 10:22:48 2024 +0000 aarch64: Avoid out-of-range shrink-wrapped saves [PR111677] The PR shows us ICEing due to an unrecognizable TFmode save emitted by aarch64_process_components. The problem is that for T{I,F,D}mode we conservatively require mems to be in range for x-register ldp/stp. That is because (at least for TImode) it can be allocated to both GPRs and FPRs, and in the GPR case that is an x-reg ldp/stp, and the FPR case is a q-register load/store. As Richard pointed out in the PR, aarch64_get_separate_components already checks that the offsets are suitable for a single load, so we just need to choose a mode in aarch64_reg_save_mode that gives the full q-register range. In this patch, we choose V16QImode as an alternative 16-byte "bag-of-bits" mode that doesn't have the artificial range restrictions imposed on T{I,F,D}mode. For T{F,D}mode in GCC 15 I think we could consider relaxing the restriction imposed in aarch64_classify_address, as typically T{F,D}mode should be allocated to FPRs. But such a change seems too invasive to consider for GCC 14 at this stage (let alone backports). Fortunately the new flexible load/store pair patterns in GCC 14 allow this mode change to work without further changes. The backports are more involved as we need to adjust the load/store pair handling to cater for V16QImode in a few places. Note that for the testcase we are relying on the torture options to add -funroll-loops at -O3 which is necessary to trigger the ICE on trunk (but not on the 13 branch). gcc/ChangeLog: PR target/111677 * config/aarch64/aarch64.cc (aarch64_reg_save_mode): Use V16QImode for the full 16-byte FPR saves in the vector PCS case. gcc/testsuite/ChangeLog: PR target/111677 * gcc.target/aarch64/torture/pr111677.c: New test.
