https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97821
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Priority|P3 |P2
CC| |matz at gcc dot gnu.org
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm. It takes quite some time for us to elide the dead stores to bd, ar and at
(and only ar and at are vectorized). I guess we run into some alias-walk
limits of DCE and vectorizing the stores fixes that. Unfortunately those
limits are hard-coded:
if (/* Constant but quadratic for small functions. */
total_chain > 128 * 128
/* Linear in the number of may-defs. */
&& total_chain > 32 * longest_chain
/* Linear in the number of uses. */
&& total_chain > nr_walks * 32)
{
this points to the known issue of stack var coalescing with CLOBBERs and
indeed -fstack-reuse=none fixes the testcase, without actually spotting
the bad coalescing.
So related to that duplicate bug we have about this issue.
