[Bug c/24635] New: Wrong statement reordering

[worm at arrakis dot es]

/*
 * Summary:
 *      Wrong statement reordering
 * Description:
 *      If you run this program, it will produce an output of 1.
 *      The reason is that the assignment V1=0 which should be
 *      executed before the call to cl_throw() is moved after
 *      this call, and hence when cl_throw() invokes longjmp()
 *      the variable is not assigned a value.
 * Operating system:
 *      Ubuntu 5.10
 * Machine:
 *      Pentium 4
 * Compiler: (gcc -v)
 *      Using built-in specs.
 *      Target: i486-linux-gnu
 *      Configured with: ../src/configure -v
--enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr
--with-gxx-include-dir=/usr/include/c++/4.0.2 --enable-shared
--with-system-zlib --libexecdir=/usr/lib --enable-nls
--without-included-gettext --enable-threads=posix --program-suffix=-4.0
--enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu
--enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk
--enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre
--enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu
 *      Thread model: posix
 *      gcc version 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu9)
 */

typedef int __jmp_buf[6];

typedef struct
  {
    unsigned long int __val[(1024 / (8 * sizeof (unsigned long int)))];
  } __sigset_t;

typedef struct __jmp_buf_tag
  {




    __jmp_buf __jmpbuf;
    int __mask_was_saved;
    __sigset_t __saved_mask;
  } jmp_buf[1];


extern int setjmp (jmp_buf __env) __attribute__ ((__nothrow__));

extern void longjmp (struct __jmp_buf_tag __env[1], int __val)
     __attribute__ ((__nothrow__)) __attribute__ ((__noreturn__));

extern int printf (__const char *__restrict __format, ...);

static jmp_buf foo;

extern void cl_throw();

void cl_throw()
{
 longjmp(foo, 1);
}


int L1foo(int V0)
{
 volatile int V1 = V0;
 if (setjmp (foo)) {
 goto L9;
 }
 V1= 0;
 cl_throw();
L9:;
 return V1;
}

int main ()
{
 printf("%d\n", L1foo(1));
 return 0;
}


-- 
           Summary: Wrong statement reordering
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: worm at arrakis dot es
  GCC host triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24635