[Bug c/18739] New: warning of uninitialized value gets suppressed without optimization with initialization after continue in loop

[Bug c/18739] New: warning of uninitialized value gets suppressed without optimization with initialization after continue in loop

[maierkom at rcs dot ei dot tum dot de]

when compiling the following code without optimization no warning is given. when
optimization is enabled the following warning is printed:
warning: `i' might be used uninitialized in this function

This occures with gcc >= 3.3.2 (tested on 3.4.2 and 3.3.2) and independent of
host/target/build triplet (testet sparc-sun-solaris2.9 and i686-pc-linux-gnu)
with c and c++ frontend.

int a();

int b();

void f(int j)
{
	int i;
	do {
		if (a())
			continue;
		i = b();
	} while (i);
}

-- 
           Summary: warning of uninitialized value gets suppressed without
                    optimization with initialization after continue in loop
           Product: gcc
           Version: 3.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: maierkom at rcs dot ei dot tum dot de
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: sparc-sun-solaris2.9
  GCC host triplet: sparc-sun-solaris2.9
GCC target triplet: sparc-sun-solaris2.9


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18739

[Bug c/18739] warning of uninitialized value gets suppressed without optimization with initialization after continue in loop

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-30 14:17 -------
No the warning is correct as continue, still checks the loop exit condition.

Oh if you are wondering why we don't warn without optimization, well this is because of flow reasons, it 
would take more time to get the flow analysis up and running to do the optimization but we don't want 
to slow down -O0 compiling.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18739