[LLVMbugs] [Bug 18023] New: possible array wrong code bug

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18023

            Bug ID: 18023
           Summary: possible array wrong code bug
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: regehr at cs.utah.edu
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Although there are a number of wrong-code bugs open right now, this testcase
doesn't look like them, so hopefully not a dup.

$ /home/regehr/z/compiler-install/llvm-r195376-install/bin/clang -O1 small.c ;
./a.out 
1
$ /home/regehr/z/compiler-install/llvm-r195376-install/bin/clang -O2 small.c ;
./a.out 
0
$ gcc -O2 small.c ; ./a.out 
1
$ cat small.c 
int printf(const char *, ...);
int a[3];
volatile int b;
int c;
int main() {
  c = 0;
  for (; c <= 2; c++) {
    a[1] = 1;
    a[c] = 0;
    b;
  }
  printf("%d\n", a[1]);
  return 0;
}
$ /home/regehr/z/compiler-install/llvm-r195376-install/bin/clang -v
clang version 3.5 (trunk 195376)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20131122/9f2c529e/attachment.html>