https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88433
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |alias
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-12-11
Component|target |rtl-optimization
Depends on| |49330
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think this is a dup of the bug pointing to RTL alias analysis which cannot
properly distinguish between pointers and integers when following to base
terms.
We expand from
<bb 2> [local count: 1073741825]:
ix_5 = (long int) &x;
ix_6 = ix_5 + 4;
ix.1_1 = (int *) ix_6;
p = ix.1_1;
q = &y;
_14 = MEM[(char * {ref-all})&p];
_15 = MEM[(char * {ref-all})&q];
if (_14 == _15)
goto <bb 3>; [33.00%]
else
goto <bb 4>; [67.00%]
<bb 3> [local count: 354334802]:
*ix.1_1 = 11;
y.4_3 = y;
__builtin_printf ("%i", y.4_3); [tail call]
where RTL has plenty opportunity to track down ix.1_1 to &x + 4 which
makes it non-aliasing to y.
Note we are saved for f just beacuse of optimization propagating a
conditional equivalence p_5 == &y.
Dup of PR49330.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49330
[Bug 49330] Integer arithmetic on addresses optimised with pointer arithmetic
rules
