[Bug tree-optimization/42145] Incorrect "may be used uninitialized warning" for a very specific test case

[marcel at telka dot sk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42145

--- Comment #11 from Marcel Telka <marcel at telka dot sk> ---
It is reproducible even with -O1:

int f(void);

int
main(void)
{
        int a, b;

        a = f();
        if (a)
                b = f();

        if (a && b)
                return 1;

        return 0;
}


$ gcc -O1 -Wuninitialized -c a.c
a.c: In function 'main':
a.c:12:15: warning: 'b' may be used uninitialized in this function
[-Wmaybe-uninitialized]
         if (a && b)
               ^
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/gcc/4.8/lib/gcc/sparc-sun-solaris2.11/4.8.2/lto-wrapper
Target: sparc-sun-solaris2.11
Configured with:
/ws/builds2/jenkins/src/du/dilos-userland-review/components/gcc48/gcc-4.8.2/configure
--prefix=/usr/gcc/4.8 --mandir=/usr/gcc/4.8/share/man --bindir=/usr/gcc/4.8/bin
--libdir=/usr/gcc/4.8/lib --sbindir=/usr/gcc/4.8/sbin --infodir=/usr/share/info
--without-gnu-as --with-as=/usr/bin/as --build=sparc-sun-solaris2.11
--infodir=/usr/gcc/4.8/share/info --libexecdir=/usr/gcc/4.8/lib
--enable-languages=c,c++,fortran,objc --enable-shared
--enable-targets=sparcv9-sun-solaris2.11 --without-gnu-ld --with-ld=/usr/bin/ld
Thread model: posix
gcc version 4.8.2 (GCC) 
$