[llvm-bugs] [Bug 27580] New: wrong code at -O2 and above in 32-bit mode on x86_64-linux-gnu

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=27580

            Bug ID: 27580
           Summary: wrong code at -O2 and above in 32-bit mode on
                    x86_64-linux-gnu
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: chengniansun at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

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




$: clang-trunk -v
clang version 3.9.0 (trunk 268002)
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/5.3.0
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/5.3.0
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 -m32 -O2 -w small.c ; timeout -s 9 10 ./a.out
Killed
$: clang-trunk -m32 -O1 -w small.c ; timeout -s 9 10 ./a.out
$: 
$: cat small.c
int a;
long long b = 3;
short c, d;
char e, f;
char fn1(char p1, char p2) { return p1 * p2; }

char fn2(int p1, int p2) { return p1 ? p1 : p1 >> p2; }

void fn3() {
  f = fn1(b, b);
  short g;
  unsigned long long h = b;
  int j, k = fn2(f - ((d = (g = h > 1) <= 7 != h & c) < 40), 2), l = fn2(k, 7),
         i = 0;
  for (; i < 2; i++)
    j = g && g - a ? g : g + a;
  e = l & j;
  if (e)
    for (;;)
      ;
}

int main() {
  fn3();
  return 0;
}
$:

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