struct A
{
int* x[2];
A() { for (int** p=x; p<x+2; ++p) *p = 0; }
};
struct B
{
char c;
A a0, a1, a2, a3, *p;
B() {}
B(const B& b) : c(), a0(b.a0), p(b.p) {}
~B() { delete p; }
};
inline void foo(const B& b) { new B(b); }
void bar()
{
foo(B());
foo(B());
}
After cfg_cleanup after loop header copying we end up with unfolded
&D.2114.a0D.2019.xD.1986[2] > &D.2114.a0D.2019.xD.1986[0]
because in fold_binary where we handle this kind of stuff we have
if (!offset0 || !offset1
|| TREE_TYPE (offset0) == TREE_TYPE (offset1))
{
...
and unfortunately the constants 2 and 0 have distinct types:
(gdb) call debug_tree(offset0)
<integer_cst 0x4026e888 type <integer_type 0x402474ac> constant invariant 8>
(gdb) call debug_tree(offset1)
<integer_cst 0x4018d180 type <integer_type 0x4019f000 unsigned int> constant
invariant 0>
--
Summary: Unfolded comparison after cfg_cleanup
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26198
