http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49498
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.06.22 17:27:37
CC| |law at redhat dot com
Ever Confirmed|0 |1
--- Comment #2 from Jeffrey A. Law <law at redhat dot com> 2011-06-22 17:27:37
UTC ---
It looks like the uninit code is being confused by elimination of a test in one
path.
int foo (int n, int l, int m, int r)
{
int v;
if (n < 10 || m > 100 || r < 20 || l)
v = r;
if (m) g++;
else bar();
if ( n < 10 || m > 100 || r < 20 )
blah(v); /* { dg-bogus "uninitialized" "bogus warning" } */
return 0;
}
We end up copying the n < 10 test from the 3rd conditional into the m == 0 path
of the second conditional and threading the false path from the copied
conditional to the r < 20 test (ie, we bypass the m > 100 test as it always
false on that path where m == 0.
This appears to confuse the predicate analysis in tree-ssa-uninit.c. I'm still
trying to wrap my head around its implementation to see if there's a reasonable
way to solve this.
