Hi Jeff, please find attached the patch (incl. test cases) for the unaligned read BUG that I found while investigating on PR#57748: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57748
one test case is this one:
pr57748-3.c:
/* PR middle-end/57748 */
/* { dg-do run } */
/* wrong code in expand_expr_real_1. */
#include <stdlib.h>
extern void abort (void);
typedef long long V
__attribute__ ((vector_size (2 * sizeof (long long)), may_alias));
typedef struct S { V a; V b[0]; } P __attribute__((aligned (1)));
struct __attribute__((packed)) T { char c; P s; };
void __attribute__((noinline, noclone))
check (P *p)
{
if (p->b[0][0] != 3 || p->b[0][1] != 4)
abort ();
}
void __attribute__((noinline, noclone))
foo (struct T *t)
{
V a = { 3, 4 };
t->s.b[0] = a;
}
int
main ()
{
struct T *t = (struct T *) calloc (128, 1);
foo (t);
check (&t->s);
free (t);
return 0;
}
and the other one is
pr57748-4.c:
/* PR middle-end/57748 */
/* { dg-do run } */
/* wrong code in expand_expr_real_1. */
#include <stdlib.h>
extern void abort (void);
typedef long long V
__attribute__ ((vector_size (2 * sizeof (long long)), may_alias));
typedef struct S { V b[1]; } P __attribute__((aligned (1)));
struct __attribute__((packed)) T { char c; P s; };
void __attribute__((noinline, noclone))
check (P *p)
{
if (p->b[1][0] != 3 || p->b[1][1] != 4)
abort ();
}
void __attribute__((noinline, noclone))
foo (struct T *t)
{
V a = { 3, 4 };
t->s.b[1] = a;
}
int
main ()
{
struct T *t = (struct T *) calloc (128, 1);
foo (t);
check (&t->s);
free (t);
return 0;
}
The patch does add a boolean "expand_reference" parameter to expand_expr_real
and
expand_expr_real_1. I pass true when I intend to use the returned memory context
as an array reference, instead of a value. At places where mis-aligned values
are extracted,
I do not return a register with the extracted mis-aligned value if
expand_reference is true.
When I have a VIEW_CONVERT_EXPR I pay attention to pass down the outer
"expand_reference"
to the inner expand_expr_real call. Expand_reference, is pretty much similar to
the
expand_modifier "EXPAND_MEMORY".
Boot-strapped and regression-tested on X86_64-pc-linux-gnu (many times).
Ok for trunk?
Thanks
Bernd. 2013-11-07 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR middle-end/57748
* expr.h (expand_expr_real, expand_expr_real_1): Add new parameter
expand_reference.
(expand_expr, expand_normal): Adjust.
* expr.c (expand_expr_real, expand_expr_real_1): Add new parameter
expand_reference. Use expand_reference to expand inner references.
(store_expr): Adjust.
* cfgexpand.c (expand_call_stmt): Adjust.
testsuite:
2013-11-07 Bernd Edlinger <bernd.edlin...@hotmail.de>
PR middle-end/57748
* gcc.dg/torture/pr57748-3.c: New test.
* gcc.dg/torture/pr57748-4.c: New test.
patch-pr57748-2.diff
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