https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91682
Bug ID: 91682
Summary: IPA-cp can not propagate value for by-ref argument in
form of *arg = param op constant
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: fxue at os dot amperecomputing.com
CC: marxin at gcc dot gnu.org
Target Milestone: ---
Current IPA only supports CP on by-ref argument assigned with constant. But if
value of the argument is computed via an unary/binary operation on caller's
parameter, it fails to do that. For example.
struct S
{
int a, b;
};
void callee2 (struct S *s)
{
// use s->a;
// use s->b;
}
void callee1 (int a, int *p)
{
struct S s;
s.a = a;
s.b = *p + 1;
callee2 (&s);
}
void caller ()
{
int a = 1;
int b = 2;
callee1 (a, &b);
}
In callee1(), we could know that value of s.a equals 1 and s.b is 3, it is
possible to propagate these value to callee2().
