On Tue, May 28, 2024 at 1:24 AM Andrew MacLeod <amacl...@redhat.com> wrote:
>
> The strlen pass currently has a local ranger instance, but when it
> invokes SCEV or any other shared component, SCEV will not be able to
> access to this ranger as it uses get_range_query(). They will be stuck
> with global ranges.
>
> Enable/disable ranger should be used instead of a local version which
> allows other components to use the current range_query.
>
> Bootstraps on 86_64-pc-linux-gnu, but there is one regression. The
> regression is from gcc.dg/Wstringop-overflow-10.c. the function in
> question:
>
> void
> baz (char *a)
> {
> char b[16] = "abcdefg";
> __builtin_strncpy (a, b, __builtin_strnlen (b, 7)); /* { dg-bogus
> "specified bound depends on the length of the source argument" } */
> }
>
> when compiled with -O2 -Wstringop-overflow -Wstringop-truncation
>
> it now spits out:
>
> b2.c: In function ‘baz’:
> b2.c:24:3: warning: ‘__builtin_strncpy’ output 2 truncated before
> terminating nul copying <unknown> bytes from a string of the same length
> [-Wstringop-truncation]
> 24 | __builtin_strncpy (a, b, __builtin_strnlen (b, 7)); /* {
> dg-bogus "specified bound depends on the length of the source argument" } */
>
> It seems like maybe something got smarter by setting the current range
> query and this is a legitimate warning for this line of code? There
> will indeed not be a NULL copied as there are 7 characters in the string...
>
> Is this a testcase issue where this warning should have been issued
> before, or am I misunderstanding the warning?
I think the warning makes sense in this case. But I'm not sure why the
dg-bogus is there, that looks like a valid complaint as well?!
I think the patch is OK.
Richard.
> Andrew
>
> PS im afraid of adjusting the status quo in this pass... :-P Not
> allowing sSCEV to access the current ranger is causing me other issues
> with the fix for 115221. This *should* have been a harmless change
> sigh. :-( The whole mechanism should just use the current range-query
> instad of passing a ranger pointer aorund. But that a much bigger
> issue. one thing at a time.
>
>
>
