------- Comment #8 from davidxl at gcc dot gnu dot org 2010-04-21 00:27 -------
(In reply to comment #2)
> Note this is not fully a regression but really a progression.
> What is happening now is only partial optimizations is happen before the
> warning to happen.
>
> >I was unable to reduce the test case further without making the warning
> >disappear. In particular, removing the increment of v1->count makes the
> >warning
> >disappear.
> This is because we would then jump thread he jump.
>
> Again this is because we are emitting the warning too soon, I might be able
> to come up with a testcase
> which shows that this is not really a regression but a progression in that we
> have warned in 3.4 and
> 4.0:
> struct {int count;} *v1;
> int c;
> int k;
>
> extern void baz(int);
> void foo(void)
> {
> int i;
> int r;
> if (k == 4)
> {
> i = 1;
> r = 1;
> }
> else
> r = 0;
>
> if (!r)
> {
> if (!c)
> return;
> v1->count++;
> }
> if (!c)
> {
> baz(i);
> }
> }
>
> There is no different from the case above and the functions you gave below.
>
> There has been some talking about moving where we warn about uninitialized
> variables but I feel that
> you can get around this in your code.
To reproduce the problem -- -fno-tree-vrp -fno-tree-dominator-opts
-fno-tree-ccp are needed. This
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20968
