On 10/13/22 06:06, Eric Botcazou via Gcc-patches wrote:
Hi,
if you compile the attached testcase with -O2 -fno-inline -Wall, you get:
In function 'process_array3':
cc1: warning: 'process_array4' accessing 4 bytes in a region of size 3 [-
Wstringop-overflow=]
cc1: note: referencing argument 1 of type 'char[4]'
t.c:6:6: note: in a call to function 'process_array4'
6 | void process_array4 (char a[4], int n)
| ^~~~~~~~~~~~~~
cc1: warning: 'process_array4' accessing 4 bytes in a region of size 3 [-
Wstringop-overflow=]
cc1: note: referencing argument 1 of type 'char[4]'
t.c:6:6: note: in a call to function 'process_array4'
That's because the ICF IPA pass has identified the two functions and turned
process_array3 into a wrapper of process_array4. This looks sensible to me
given that the only difference between them is an "access" attribute on their
type describing the access size of the parameter and the "access" attribute
does not affect type identity (struct attribute_spec.affects_type_identity).
Hence the proposed fix, tested on x86-64/Linux, OK for the mainline?
2022-10-13 Eric Botcazou <ebotca...@adacore.com>
* gimple-ssa-warn-access.cc (pass_waccess::check_call): Return
early for calls made from thunks.
2022-10-13 Eric Botcazou <ebotca...@adacore.com>
* gcc.dg/Wstringop-overflow-89.c: New test.
Not a fan as it could potentially hide a real issue, but I don't really
have a better solution. I pondered suggesting "access" affect type
identity, but the cases where that's really important are probably
better handled by the "fn spec" attribute, leaving "access" strictly
impacting diagnostics.
OK
jeff
