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[Bug libfortran/79956] [7 Regression] many new -Wmaybe-uninitialized warnings with bootstrap-O3
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 08 Mar 2017 12:50:50 +0000
- Subject: [Bug libfortran/79956] [7 Regression] many new -Wmaybe-uninitialized warnings with bootstrap-O3
- Auto-submitted: auto-generated
- References: <bug-79956-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79956
--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 8 Mar 2017, trippels at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79956
>
> --- Comment #3 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
> Testcase that only warns with -O3
It also warns with -O1 and -Os (but not -O2). At -O2 the function is
optimized to just
fn1 ()
{
int n;
int d[1];
<bb 2> [0.01%]:
c = 1;
<bb 3> [100.00%]:
goto <bb 3>; [100.00%]
}
at -O3 we have peeled one iteration and are left with
fn1 ()
{
int n;
int d[1];
int b.1_1;
int _2;
<bb 2> [0.01%]:
n_4 = a;
c = 1;
_2 = d[0];
b.1_1 = b;
goto <bb 4>; [100.00%]
... (similar to above)
Note the testcase doesnt' capture the specific case of a bogus
warning as it is in parity_l8.