https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96722
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|marxin at gcc dot gnu.org |unassigned at gcc dot
gnu.org
Status|ASSIGNED |NEW
--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
So the problematic transformation happens in einline:
BEFORE:
void foo(S*) (struct S * a)
{
<bb 2> [0.00%] [count: INV]:
if (a_2(D) != 0B)
goto <bb 4>; [0.00%] [count: INV]
else
goto <bb 3>; [0.00%] [count: INV]
<bb 3> [100.00%] [count: INV]:
MEM[(struct &)a_2(D)] ={v} {CLOBBER};
<bb 4> [0.00%] [count: INV]:
return;
}
after:
void foo(S*) (struct S * a)
{
<bb 2> [0.00%] [count: INV]:
if (a_2(D) != 0B)
goto <bb 3>; [0.00%] [count: INV]
else
goto <bb 4>; [0.00%] [count: INV]
<bb 3> [0.00%] [count: INV]:
// predicted unlikely by early return (on trees) predictor.
goto <bb 5>; [0.00%] [count: INV]
<bb 4> [100.00%] [count: INV]:
MEM[(struct &)a_2(D)] ={v} {CLOBBER};
<bb 5> [0.00%] [count: INV]:
return;
}
So as seen, the CFG is more complex as there's an extra GIMPLE_PREDICT.
main then inlines to:
Scope blocks after cleanups:
{ Scope block #0
{ Scope block #7 ../pr96722.C:8 Originating from : extern void S (struct S
*, int);
}
{ Scope block #8 ../pr96722.C:14 Originating from : extern void S (struct S
*, int);
}
}
int main() ()
{
int _5;
<bb 2> [100.00%] [count: INV]:
_5 = 0;
return _5;
}
No longer having address taken: s
Scope blocks after cleanups:
{ Scope block #0
{ Scope block #7 ../pr96722.C:8 Originating from : extern void S (struct S
*, int);
{ Scope block #8 Originating from :#0
}
}
{ Scope block #9 ../pr96722.C:14 Originating from : extern void S (struct S
*, int);
}
}
int main() ()
{
int _5;
<bb 2> [100.00%] [count: INV]:
MEM[(struct &)0B] ={v} {CLOBBER};
_5 = 0;
return _5;
}
So I bet it's hidden in a CFG cleanup where it somehow removes the clobber?
I guess it was latent before my revision..
