------- Comment #6 from mikpe at it dot uu dot se 2010-07-08 12:18 -------
With this short test case:
struct s {
double for_alignment;
struct { int x, y, z; } a[16];
};
void f(struct s *s)
{
unsigned int i;
for (i = 0; i < 16; ++i) {
s->a[i].x = 0;
s->a[i].y = 0;
s->a[i].z = 0;
}
}
revision 161840 changes the generated code as follows:
--- pr44843.s-r161839 2010-07-08 14:00:06.000000000 +0200
+++ pr44843.s-r161840 2010-07-08 14:00:26.000000000 +0200
@@ -6,10 +6,9 @@
.proc 020
f:
mov 16, %g1
.LL2:
- st %g0, [%o0+8]
- st %g0, [%o0+12]
+ stx %g0, [%o0+8]
st %g0, [%o0+16]
addcc %g1, -1, %g1
bne,pt %icc, .LL2
add %o0, 12, %o0
which will fail at runtime due to misalignment in the 2nd loop iteration.
Removing the double which is there to align the struct and the start of the
array eliminates the bug.
--
mikpe at it dot uu dot se changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mikpe at it dot uu dot se
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44843
