[llvm-bugs] [Bug 24535] New: wrong code at -O3 on x86_64-linux-gnu in 32-bit mode

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24535

            Bug ID: 24535
           Summary: wrong code at -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 -O3 in 32-bit mode (but not in 64-bit mode).

This is a regression from 3.6.x. 

$ clang-trunk -v
clang version 3.8.0 (trunk 245675)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
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/4.9.2
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 -O2 small.c; ./a.out
-1
$ clang-trunk -m64 -O3 small.c; ./a.out
-1
$ clang-3.6 -m32 -O3 small.c; ./a.out
-1
$ 
$ clang-trunk -m32 -O3 small.c
$ ./a.out
127
$ 


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


int printf (const char *, ...);

int a, b, d, e, f, g;
char c;

void
fn1 (int p)
{
  for (b = 1; b; b = a)
    g = c ? c : p ? 0 : a;
}

int
main ()
{
  c--;
  fn1 (0);
  d--;
  a = e && f;
  d && (e = 0);
  printf ("%d\n", c);
  return 0;
}

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