http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48466
Summary: [4.4/4.5/4.6 Regression] Wrong variable locations at
-O0 on i686
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ja...@gcc.gnu.org
CC: tro...@gcc.gnu.org, h...@gcc.gnu.org
struct S { int a; int *b; };
struct T { struct S a; struct S b; };
struct U { const char *u; };
int n[10];
volatile int v;
struct U
foo (const char *s)
{
struct U r;
r.u = s;
return r;
}
void
bar (struct T *s, int a, int b)
{
s->a.a = a;
s->a.b = &s->a.a;
s->b.a = b;
s->b.b = &s->b.a;
}
int
main ()
{
struct T t;
struct U x = foo ("this is x");
struct S y, z;
y.b = n;
y.a = 0;
bar (&t, 1, 2);
v++;
z = y;
return 0;
}
compiled with -g -O0 -dA, when you debug this in the debugger, &t is different
from the address passed to bar and after the bar call t contains garbage.
Most likely this started with
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=138438
The t variable has DECL_RTL (mem (plus (frame) (const_int -16)), (frame) is
eliminated to bp - 4, but crtl->stack_realign_tried is true (eventhough
fde->stack_realign is false) and thus it is encoded as sp - 20 instead of bp -
20. fde->drap_reg is -1.
http://gcc.gnu.org/ml/gcc-patches/2008-07/msg02391.html
