> On Fri, Nov 13, 2020 at 12:07 AM Richard Biener <rguent...@suse.de> wrote:
> >
> > On Tue, 10 Nov 2020, Jan Hubicka wrote:
> >
> > > Hi,
> > > here is updaed patch.
> > >
> > > Honza
> > >
> > > Bootstrapped/regtested x86_64-linux, OK (after the fnspec fixes)?
> >
> > OK.
> >
> > Thanks,
> > Richard.
> >
>
> This caused:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97836
I have pushed the following fix as obvious. The problem is caused by
fact that I made ipa-modref to set EAF_UNUSED flag for parameters that
are used as scalars but not used to read memory since that suits the
use of the flag in tree-ssa-alias and mostly tree-ssa-structalias with
exception of the rule of escaping to return value.
At monday I will disuss with Richard if we want to adjust EAF_UNUSED or
invernt EAF_NOREAD, but this should prevent wrong code issues.
Honza
2020-11-15 Jan Hubicka <hubi...@ucw.cz>
PR ipa/97836
* ipa-modref.c (analyze_ssa_name_flags): Make return to clear
EAF_UNUSED flag.
gcc/testsuite/ChangeLog:
2020-11-15 Jan Hubicka <hubi...@ucw.cz>
* gcc.c-torture/execute/pr97836.c: New test.
diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index 5273c200f00..4a43c50aa66 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -1224,10 +1224,12 @@ analyze_ssa_name_flags (tree name, vec<unsigned char>
&known_flags, int depth)
print_gimple_stmt (dump_file, use_stmt, 0);
}
- /* Gimple return may load the return value. */
+ /* Gimple return may load the return value.
+ Returning name counts as an use by tree-ssa-structalias.c */
if (greturn *ret = dyn_cast <greturn *> (use_stmt))
{
- if (memory_access_to (gimple_return_retval (ret), name))
+ if (memory_access_to (gimple_return_retval (ret), name)
+ || name == gimple_return_retval (ret))
flags &= ~EAF_UNUSED;
}
/* Account for LHS store, arg loads and flags from callee function. */
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr97836.c
b/gcc/testsuite/gcc.c-torture/execute/pr97836.c
new file mode 100644
index 00000000000..4585e1fc69d
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr97836.c
@@ -0,0 +1,17 @@
+int a;
+
+int b(int c) { return 0; }
+
+static int *d(int *e) {
+ if (a) {
+ a = a && b(*e);
+ }
+ return e;
+}
+
+int main() {
+ int f;
+ if (d(&f) != &f)
+ __builtin_abort();
+ return 0;
+}
