[LLVMbugs] [Bug 9346] New: likely memory unsafety error in generated code

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9346

           Summary: likely memory unsafety error in generated code
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: regehr at cs.utah.edu
                CC: llvmbugs at cs.uiuc.edu, chenyang at cs.utah.edu


Notice that (due to ASLR or whatever) two runs of the same executable give
different answers.  The correct answer is "0".

[regehr at gamow ~]$ clang -v
clang version 2.9 (trunk 126682)
Target: x86_64-unknown-linux-gnu
Thread model: posix
[regehr at gamow ~]$ clang -O2 foo.c -o foo
[regehr at gamow ~]$ ./foo
g_1 = 107756488
[regehr at gamow ~]$ ./foo
g_1 = 1634447976
[regehr at gamow ~]$ cat foo.c
long long g_4 = 0;
static int g_1 = 0;

int printf(const char *format, ...);

static int foo(int i1, int i2)
{
   return (i1 % i2);
}

int main (int argc, char* argv[])
{
   foo(1, 1);
   g_1 = foo((g_4 | -2), -1);
   printf("g_1 = %d\n", g_1);
   return 0;
}

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