http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52409
Bug #: 52409
Summary: ((~a)|(~b)) is not simplified at the tree level
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: pins...@gcc.gnu.org
Take:
int f(int a, int b)
{
a = ~a;
b = ~b;
return a|b;
}
int g(int a, int b)
{
return ~(a&b);
}
--- CUT ---
Currently the tree level does not try to combine them, fold does it though.
I saw this with bools in GCC itself. In the bool case, we can fold it further
to just (a&b) == 0.
Likewise for (~a)&(~b) into ~(a|b).
