On 12/7/22 06:54, Richard Biener via Gcc-patches wrote:
The following avoids CSE of &ps->wp to &ps->wp.hwnd confusing
-Wstringopt-overflow by making sure to produce addresses to the
biggest container from vectorization. For this I introduce
strip_zero_offset_components which turns &ps->wp.hwnd into
&(*ps) and use that to base the vector data references on.
That will also work for addresses with variable components,
alternatively emitting pointer arithmetic via calling
get_inner_reference and gimplifying that would be possible
but likely more intrusive.
This is by no means a complete fix for all of those issues
(avoiding ADDR_EXPRs in favor of pointer arithmetic might be).
Other passes will have similar issues.
In theory that might now cause false negatives.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
Any opinion?
Thanks,
Richard.
PR tree-optimization/106904
* tree.h (strip_zero_offset_components): Declare.
* tree.cc (strip_zero_offset_components): Define.
* tree-vect-data-refs.cc (vect_create_addr_base_for_vector_ref):
Strip zero offset components before building the address.
* gcc.dg/Wstringop-overflow-pr106904.c: New testcase.
So you're just canonicalizing to the widest container for a zero offset
access. While it may not fix everything, that seems like a good thing
in general when we can do so. I wouldn't be surprised if other passes
could do the same thing to fix some of the missed CSE opportunities.
jeff
