http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47418
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.01.25 11:24:58
Ever Confirmed|0 |1
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-25
11:24:58 UTC ---
VRP sees
<bb 2>:
D.2725_3 = u.sa_data[15];
D.2726_4 = (int) D.2725_3;
D.2728_6 = u.sa_data[14];
D.2729_7 = (int) D.2728_6;
...
D.2769_47 = u.sa_data[0];
D.2770_48 = (int) D.2769_47;
test_func (0, D.2770_48, D.2768_46, D.2765_43, D.2762_40, D.2759_37,
D.2756_34, D.2753_31, D.2750_28, D.2747_25, D.2744_22, D.2741_19, D.2738_16,
D.2735_13, D.2732_10, D.2729_7, D.2726_4);
return 0;
because of our fancy way of re-building non-addressed components.
With 4.6 the warning is gone and we instead have (thanks to MEM-REF):
<bb 2>:
D.2695_3 = MEM[(char *)&u + 15B];
D.2696_4 = (int) D.2695_3;
D.2698_6 = MEM[(char *)&u + 14B];
D.2699_7 = (int) D.2698_6;
...
D.2740_48 = (int) D.2739_47;
test_func (0, D.2740_48, D.2738_46, D.2735_43, D.2732_40, D.2729_37,
D.2726_34, D.2723_31, D.2720_28, D.2717_25, D.2714_22, D.2711_19, D.2708_16,
D.2705_13, D.2702_10, D.2699_7, D.2696_4);
return 0;
thus, no more array access and still non-address-taken u. 4.4 also warns
about
small-test.c: In function 'main':
small-test.c:18: warning: array subscript is above array bounds
small-test.c:18: warning: array subscript is above array bounds
small-test.c:18: warning: array subscript is above array bounds
small-test.c:18: warning: 'u' is used uninitialized in this function
4.3 doesn't warn at all.
Confirmed. I'd close it as fixed in 4.6 and add a testcase (no time for
that right now).
