https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104106
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Summary|Fail to remove some useless |Fail to remove stores to
|loop |VLA inside loops
Last reconfirmed| |2022-01-18
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
If we change the VLA to a normal array, GCC is able to optimize f and g.
h is almost done:
<bb 2> [local count: 118111600]:
if (n_8(D) > 0)
goto <bb 3>; [89.00%]
else
goto <bb 4>; [11.00%]
<bb 3> [local count: 105119324]:
_18 = (unsigned int) n_8(D);
_6 = (sizetype) _18;
__builtin_memcpy (&tmp_a, a_11(D), _6);
<bb 4> [local count: 118111600]:
_4 = tmp_a[0];
GCC could do a PRE for the load of tmp_a[0] to a_11[0] and unspecified.
This is true even with the VLA.
As for i, that requires loop fision which GCC does not implement yet (there is
another bug about that even).
