https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107443
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |10.5
Last reconfirmed| |2022-10-27
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Known to fail| |8.1.0
Summary|Switch conversion removing |[10/11/12/13 Regression]
|code |Removing switch with
| |__builtin_unreachable
| |causes missed optimizations
Known to work| |7.1.0
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Testcase which shows this is a regression and switch conversion just exposed
it:
void dead (unsigned n);
void foo (unsigned n);
void func (unsigned n)
{
switch(n) {
case 0:
__builtin_unreachable();
case 1:
__builtin_unreachable();
case 2:
__builtin_unreachable();
case 3:
__builtin_unreachable();
case 4:
__builtin_unreachable();
case 5:
__builtin_unreachable();
case 6:
__builtin_unreachable();
case 7:
__builtin_unreachable();
default:
;
}
foo (n);
if (n < 8)
dead (n);
}
after building the CFG we get with the above testcase:
Removing basic block 10
Removing basic block 9
Removing basic block 8
Removing basic block 7
Removing basic block 6
Removing basic block 5
Removing basic block 4
Removing basic block 3
Merging blocks 2 and 11
