https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115459
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Maciej W. Rozycki <ma...@gcc.gnu.org>: https://gcc.gnu.org/g:e0dae4da4c45e3959b0624551f80283c45a60446 commit r15-6440-ge0dae4da4c45e3959b0624551f80283c45a60446 Author: Maciej W. Rozycki <ma...@orcam.me.uk> Date: Wed Dec 25 22:23:40 2024 +0000 Alpha: Also use tree information to get base block alignment We hardly ever emit code using machine instructions for aligned memory accesses for block move and clear operation and the reason for this appears to be that suboptimal alignment is often passed by the caller and then we only try to find a better alignment by checking pseudo register pointer alignment information, and from observation it's most often only set for stack frame references. This code originates from before Tree SSA days and we can do better nowadays, by looking up the original tree node associated with a MEM RTL, so implement this approach, factoring out repeating code from `alpha_expand_block_move' and `alpha_expand_block_clear' to a new function. In some cases howewer tree information is not available while pointer alignment is, such as with the case concerned with PR target/115459, where we have: (gdb) pr orig_src (mem:BLK (plus:DI (reg/f:DI 65 virtual-stack-vars [ lock.206_2 ]) (const_int 8368 [0x20b0])) [8 S18 A8]) (gdb) pr orig_dst (mem/j/c:BLK (plus:DI (reg/f:DI 65 virtual-stack-vars [ lock.206_2 ]) (const_int 8208 [0x2010])) [8 MEM[(struct gnat__debug_pools__print_info_stdout__internal__L_18__B1182b__S1183b___PAD *)_339].F[1 ...]{lb: 1 sz: 1}+0 S18 A128]) (gdb) showing no tree information and the alignment of 8 only for `orig_src', while indeed REGNO_POINTER_ALIGN returns 128 for pseudo 65. So retain the old approach and return the largest alignment determined and its associated offset. Add test cases accordingly and remove XFAILs from memclr-a2-o1-c9-ptr.c now that it does get aligned code produced now. gcc/ * config/alpha/alpha.cc (alpha_get_mem_rtx_alignment_and_offset): New function. (alpha_expand_block_move, alpha_expand_block_clear): Use it for alignment retrieval. gcc/testsuite/ * gcc.target/alpha/memclr-a2-o1-c9-ptr.c: Remove XFAILs. * gcc.target/alpha/memcpy-di-aligned.c: New file. * gcc.target/alpha/memcpy-di-unaligned.c: New file. * gcc.target/alpha/memcpy-di-unaligned-dst.c: New file. * gcc.target/alpha/memcpy-di-unaligned-src.c: New file.
