[LLVMbugs] [Bug 19111] New: wrong code by LTO on x86_64-linux-gnu (both 32-bit and 64-bit modes)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=19111

            Bug ID: 19111
           Summary: wrong code by LTO on x86_64-linux-gnu (both 32-bit and
                    64-bit modes)
           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: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The current clang trunk miscompiles the following code when using LTO on
x86_64-linux-gnu in both 32-bit and 64-bit modes. 

$ clang-trunk -v
clang version 3.5.0 (trunk 203564)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
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/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
$ 
$ clang-trunk -O0 foo.c main.c 
$ a.out
$ 
$ clang-trunk -flto -O0 -c foo.c
$ clang-trunk -flto -O1 -c main.c
$ clang-trunk -flto -O1 foo.o main.o
$ a.out
a.out: main.c:12: int main(): Assertion `b == 0' failed.
Aborted (core dumped)
$ 
$ cat foo.c
extern int c, **d;

static int
bar (int p)
{
  return 0;
}

int *
foo (void)
{
  int ***e = &d;
  for (; c < 1; c++)
    bar (*e == 0);
  return 0;
}
$ cat main.c
#include <assert.h>

extern int *foo (void); 

int a, *b = &a, c, **d = &b; 

int
main ()
{
  *b = 0;
  *d = 0;
  assert (b == 0);
  foo ();
  return 0;
}

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