On Tue, Jan 28, 2025 at 04:26:11PM +0100, Richard Biener wrote:
> The following fixes a not properly aligned stack temporary created
> during RTL expansion of a MEM_REF that we handle as a BIT_FIELD_REF
> whose base was allocated to a register but which was originally
> aligned to allow a larger load not trapping. While probably UB
> in C the vectorizer creates aligned accesses that might overread
> a (static) allocation because it is then known not to trap.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> This came originally up in the context of PR117424 and would
> re-surface when the tree_could_trap_p fix would take into
> account alignment as well.
>
> OK?
>
> Thanks,
> Richard.
>
> PR middle-end/118684
> * expr.cc (expand_expr_real_1): When expanding a reference
> based on a register and we end up needing a MEM make sure
> that's aligned as the original reference required.
>
> * gcc.dg/pr118684.c: New testcase.
LGTM.
Jakub
