[llvm-bugs] [Bug 25951] New: wrong code on x86_64-linux-gnu at -O1 and above in 32-bit mode

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=25951

            Bug ID: 25951
           Summary: wrong code on x86_64-linux-gnu at -O1 and above in
                    32-bit mode
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: chengniansun at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

The following code is miscompiled by clang-trunk at -O1 and above in 32-bit
mode (not 64-bit mode) on x86_64-linux-gnu.


$: clang-trunk  -v
clang version 3.8.0 (trunk 256450)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.2.1
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/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
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/4.8.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.6.3
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.7.4
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$: 
$: clang-trunk small.c -m32 -O3 ; ./a.out
127
$: clang-trunk small.c -m32 -O2 ; ./a.out
127
$: clang-trunk small.c -m32 -Os ; ./a.out
127
$: clang-trunk small.c -m32 -O1 ; ./a.out
1
$: clang-trunk small.c -m32 -O0 ; ./a.out
1
$: clang-trunk small.c -m64 -O3 ; ./a.out
1
$: cat small.c
int printf(const char*, ...);
char a, b, d;
int c;
int main() {
  int e = b++;
  c++;
  d = a++ == e;
  if (c)
    printf("%d\n", (int)b);
  return 0;
}

-- 
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/20151227/8bea9429/attachment-0001.html>