| Message ID | CAFULd4bPUK+WyGeKV+fHGAE7EJDwHaJQJX61OGrYMyTnwPGuwg@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Mar 18, 2016 at 4:33 PM, Uros Bizjak <ubizjak@gmail.com> wrote: > On Mon, Mar 7, 2016 at 2:34 PM, Marek Polacek <polacek@redhat.com> wrote: >> On Fri, Mar 04, 2016 at 07:17:46PM +0100, Uros Bizjak wrote: >>> Hello! >>> >>> > This is not a regression but I thought I'd post this anyway. Martin reported >>> > that we generate -Wunused-value warnings on the attached testcase, which >>> > arguable doesn't make sense. Setting TREE_USED suppresses the warning. Since >>> > we already compute 'fetch_op' I used that. (This warning doesn't trigger e.g. >>> > for __atomic_load/store/compare.) >>> > >>> > Bootstrapped/regtested on x86_64-linux, ok for trunk or gcc7? >>> > >>> > 2016-03-04 Marek Polacek <polacek@redhat.com> >>> > >>> > PR c/69407 >>> > * c-common.c (resolve_overloaded_builtin): Set TREE_USED for the fetch >>> > operations. >>> > >>> > * gcc.dg/atomic-op-6.c: New test. >>> >>> You can probably revert my workaround [1] that suppressed these >>> warnings in libsupc++/guard.cc. >> >> Ah, thanks for the heads-up, I'll do that once I get the patch in. > > I have committed the attached revert after bootstrap on > x86_64-linux-gnu {,-m32}. There were no warnings when compiling > guard.cc. > > 2016-03-18 Uros Bizjak <ubizjak@gmail.com> > > Revert: > 2015-07-02 Uros Bizjak <ubizjak@gmail.com> > > * libsupc++/guard.cc (__test_and_acquire): Use __p after __atomic_load > to avoid unused variable warning. > (__set_and_release): Use __p after __atomic_store to avoid unused > variable warning. Whoops, I looked at the wrong part of the build log ... unfortunately, the warning still happens, and I have to revert the revert ... Sorry for the noise, Uros.
Index: libsupc++/guard.cc =================================================================== --- libsupc++/guard.cc (revision 234330) +++ libsupc++/guard.cc (working copy) @@ -117,7 +117,6 @@ __test_and_acquire (__cxxabiv1::__guard *g) unsigned char __c; unsigned char *__p = reinterpret_cast<unsigned char *>(g); __atomic_load (__p, &__c, __ATOMIC_ACQUIRE); - (void) __p; return _GLIBCXX_GUARD_TEST(&__c); } # define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G) @@ -133,7 +132,6 @@ __set_and_release (__cxxabiv1::__guard *g) unsigned char *__p = reinterpret_cast<unsigned char *>(g); unsigned char val = 1; __atomic_store (__p, &val, __ATOMIC_RELEASE); - (void) __p; } # define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G) # endif