[Bug middle-end/104088] [12/13 Regression] '-O2' (or higher) GCN offloading (only) 'libgomp.oacc-c-c++-common/vprop.c' excess errors: 'warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]'

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104088

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |burnus at gcc dot gnu.org

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> ---
I did have a look at this the other day. If I recall correctly, the issue was
that

  tree destsize = compute_objsize (dest, stmt, ostype, &aref, &ptr_qry);

in strlen_pass::maybe_warn_overflow (in file tree-ssa-strlen.cc) wrongly
returned 0
for a   var[i]._char_memb. Somewhere ('var'?) was a variable which did not use
the 64bit generic memory space but a 32-byte one. My feeling is that the
problem is related to having a non-generic memory space.

(Disclaimer: It was a couple of days back when I had a quick look and I might
misremember. The 'var[i]._char_memb' matches pattern wise but the name was
surely different.)

However, reading now the commit message title, quoted in comment 0 - "Use
enclosing object size if it's smaller than member" -, explains why the 1-byte
character type's length is not used even if it looks fine.