https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115277
Bug ID: 115277
Summary: ICF needs to match loop bound estimates
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: hubicka at gcc dot gnu.org
Target Milestone: ---
jan@localhost:/tmp> cat tt.c
int array[1000];
void
test (int a)
{
if (__builtin_expect (a > 3, 1))
return;
for (int i = 0; i < a; i++)
array[i]=i;
}
void
test2 (int a)
{
if (__builtin_expect (a > 10, 1))
return;
for (int i = 0; i < a; i++)
array[i]=i;
}
int
main()
{
test(1);
test(2);
test(3);
test2(10);
if (array[9] != 9)
__builtin_abort ();
return 0;
}
jan@localhost:/tmp> gcc -O2 tt.c ; ./a.out
jan@localhost:/tmp> gcc -O3 tt.c ; ./a.out
Aborted (core dumped)
The problem here is that we do not match value ranges and thus we can end up
with different estimates on number of iterations.
