> From: David Malcolm <dmalc...@redhat.com>
> Date: Tue, 28 Feb 2023 14:12:47 -0500
> On Tue, 2023-02-28 at 19:47 +0100, Hans-Peter Nilsson wrote:
> > Ok to commit?
> > -- >8 --
> > Investigating analyzer tesstsuite errors for cris-elf. The same are
> > seen for pru-elf according to posts to gcc-testresults@.
> >
> > For glibc, errno is #defined as:
> > extern int *__errno_location (void) __THROW __attribute_const__;
> > # define errno (*__errno_location ())
> > while for newlib in its default configuration, it's:
> > #define errno (*__errno())
> > extern int *__errno (void);
>
> We're already handling ___errno (three underscores) for Solaris as of
> 7c9717fcb5cf94ce1e7ef5c903058adf9980ff28; does it fix the issue if you
> add __errno (two underscores) to analyzer/kf.cc's
> register_known_functions in an analogous way to that commit? (i.e.
> wiring it up to kf_errno_location, "teaching" the analyzer that that
> function returns a pointer to the "errno region")
But...there's already "support" for two underscores since
the commit you quote, so I guess not. I strongly believe
"the critical difference is that __attribute__
((__const__))" because I indeed proved it by adding it to
the newlib definition.
I doubt these tests actually *pass* for OS X, because that
one looks identical to the newlib definition as quoted in
that commit (compare to the newlib one I pasted in the quote
above).
It looks like that definition was added for good measure
along with the Solaris definition (that has the
attribute-const) but never tested. Sorry, I don't have an
OS X to test it myself and according to a popular search
engine(...) nobody has posted gcc-testresults@ for anything
"apple" since gcc-4.7 era. :(
brgds, H-P
>
> Dave
>
> >
> > The critical difference is that __attribute__ ((__const__)),
> > where glibc says that the caller will see the same value on
> > all calls (from the same context; read: same thread). I'm
> > not sure the absence of __attribute__ ((__const__)) for the
> > newlib definition is deliberate, but I guess it can.
> > Either way, without the "const" attribute, it can't be known
> > that the same location will be returned the next time, so
> > analyzer-tests that depend the value being known it should
> > see UNKNOWN rather than TRUE, that's why the deliberate
> > check for UNKNOWN rather than xfailing the test.
> >
> > For isatty-1.c, it's the same problem, but here it'd be
> > unweildy with the extra dg-lines, so better just skip it for
> > newlib targets.
> >
> > testsuite:
> > * gcc.dg/analyzer/call-summaries-errno.c: Expect UNKNOWN
> > for newlib after having set errno.
> > * gcc.dg/analyzer/errno-1.c: Ditto.
> > * gcc.dg/analyzer/isatty-1.c: Skip for newlib targets.
> > ---
> > gcc/testsuite/gcc.dg/analyzer/call-summaries-errno.c | 3 ++-
> > gcc/testsuite/gcc.dg/analyzer/errno-1.c | 3 ++-
> > gcc/testsuite/gcc.dg/analyzer/isatty-1.c | 2 +-
> > 3 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/gcc/testsuite/gcc.dg/analyzer/call-summaries-errno.c
> > b/gcc/testsuite/gcc.dg/analyzer/call-summaries-errno.c
> > index e4333b30bb77..cf4d9f7141e4 100644
> > --- a/gcc/testsuite/gcc.dg/analyzer/call-summaries-errno.c
> > +++ b/gcc/testsuite/gcc.dg/analyzer/call-summaries-errno.c
> > @@ -13,5 +13,6 @@ void test_sets_errno (int y)
> > sets_errno (y);
> > sets_errno (y);
> >
> > - __analyzer_eval (errno == y); /* { dg-warning "TRUE" } */
> > + __analyzer_eval (errno == y); /* { dg-warning "TRUE" "errno is at
> > a constant location" { target { ! newlib } } } */
> > + /* { dg-warning "UNKNOWN" "errno is not known to be at a constant
> > location" { target { newlib } } .-1 } */
> > }
> > diff --git a/gcc/testsuite/gcc.dg/analyzer/errno-1.c
> > b/gcc/testsuite/gcc.dg/analyzer/errno-1.c
> > index 6b9d28c10799..af0cc3d52a36 100644
> > --- a/gcc/testsuite/gcc.dg/analyzer/errno-1.c
> > +++ b/gcc/testsuite/gcc.dg/analyzer/errno-1.c
> > @@ -17,7 +17,8 @@ void test_storing_to_errno (int val)
> > {
> > __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
> > errno = val;
> > - __analyzer_eval (errno == val); /* { dg-warning "TRUE" } */
> > + __analyzer_eval (errno == val); /* { dg-warning "TRUE" "errno is
> > at a constant location" { target { ! newlib } } } */
> > + /* { dg-warning "UNKNOWN" "errno is not known to be at a constant
> > location" { target { newlib } } .-1 } */
> > external_fn ();
> > __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
> > }
> > diff --git a/gcc/testsuite/gcc.dg/analyzer/isatty-1.c
> > b/gcc/testsuite/gcc.dg/analyzer/isatty-1.c
> > index 389d2cdf3f18..450a7d71990d 100644
> > --- a/gcc/testsuite/gcc.dg/analyzer/isatty-1.c
> > +++ b/gcc/testsuite/gcc.dg/analyzer/isatty-1.c
> > @@ -1,4 +1,4 @@
> > -/* { dg-skip-if "" { powerpc*-*-aix* } } */
> > +/* { dg-skip-if "" { powerpc*-*-aix* || newlib } } */
> >
> > #include <errno.h>
> > #include "analyzer-decls.h"
>
