[llvm-bugs] [Bug 27993] New: wrong code at -O2 and -O3 in 32-bit mode on x86_64-linux-gnu

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=27993

            Bug ID: 27993
           Summary: wrong code at -O2 and -O3 in 32-bit mode on
                    x86_64-linux-gnu
           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 the 32-bit mode (but not in the 64-bit
mode).  

This is a regression from 3.8.x.


$ clang-trunk -v
clang version 3.9.0 (trunk 271236)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
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/5.3.0
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-3.8 -m32 -O2 small.c; ./a.out
$ clang-trunk -m64 -O2 small.c; ./a.out
$
$ clang-trunk -m32 -O2 small.c
$ ./a.out
00
$


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


int a = 1, c, d, e, f, g;
char h;

char
fn1 (char p1, int p2)
{ 
  return p1 > 1 || p1 > p2 ? p1 : p1 << p2;
}

static int
fn2 (long long p1, char p2)
{ 
  if (p1 < p2)
    fn2 (f, f);
  c = h;
  return h;
}

int
fn3 ()
{ 
  int i = fn1 (a, 3);
  g = fn2 (a, a);
  c = h;
  return i;
}

int
main ()
{ 
  if (fn3 () < 8)
    __builtin_printf ("%d%d\n", d, e);
  return 0;
}

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