[llvm-bugs] [Bug 28479] New: wrong code at -O2 and -O3 on x86_64-linux-gnu in the 64-bit mode

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=28479

            Bug ID: 28479
           Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu in the
                    64-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 clang trunk at -O2 and -O3 on
x86_64-linux-gnu in 64-bit mode, but not in 32-bit mode.

This is a regression from 3.8.x.  


$ clang-trunk -v
clang version 3.9.0 (trunk 274832)
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/4.9.3
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.3.0
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/4.8.5
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
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.1.1
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 -m64 -Os small.c; ./a.out
$ clang-3.8 -m64 -O2 small.c; ./a.out
$
$ clang-trunk -m64 -O2 small.c
$ ./a.out
Aborted (core dumped)
$


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


int a, b, d = 1, f, j;
short c;
char e;

void fn1 (int p)
{ 
  short h;
  int i = p != 0;
  if (d)
    { 
      e = h = i;
      f = c = a;
      if (b)
        { 
          if (-p)
            c = 70 && p;
        }
      else
        for (;;)
          ;
      d = p;
    }
}

int main ()
{ 
  for (; j < 1; j++)
    b = 1;
  fn1 (d != 2);

  if (c != 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/20160709/bcbc92c0/attachment.html>