[llvm-bugs] [Bug 24991] New: wrong code at -O2 and -O3 on x86_64-linux-gnu (in 32-bit mode)

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24991

            Bug ID: 24991
           Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu (in
                    32-bit mode)
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

The following code is miscompiled by the current clang trunk on
x86_64-linux-gnu at -O2 and -O3 in 32-bit mode (but not in 64-bit mode).

This is a regression from 3.7.x. 


$ clang-trunk -v
clang version 3.8.0 (trunk 248820)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/tools/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.2
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.1.0
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/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.1.0
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 -m32 -Os small.c; ./a.out
$ clang-trunk -m64 -O2 small.c; ./a.out
$ clang-3.7.0 -m32 -O2 small.c; ./a.out
$ 
$ clang-trunk -m32 -O2 small.c
$ ./a.out
Aborted
$ 


-----------------------------------------


int a[1], b, d, e, f, h, i, j;
volatile int c = 1;
char g;

void
fn1 (int p1)
{
  b = a[p1];
}

void
fn2 ()
{
  for (h = 15; h < 22; h += 5)
    if (c)
      {
    d--;
    f--;
    g--;
    if (d)
      {
        j = f < 0 || (f >= 0) > f;
        i = e ^= 1;
      }
    e = 0;
      }
    else
      g = 0;
}

int
main ()
{
  a[0] = 1;
  fn2 ();
  fn1 (g & 1);

  if (b != 1) 
    __builtin_abort (); 

  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/20150929/66931ed3/attachment-0001.html>