[LLVMbugs] [Bug 18556] New: clang (both trunk and 3.4) hangs at -Os and above on x86_64-linux-gnu

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18556

            Bug ID: 18556
           Summary: clang (both trunk and 3.4) hangs at -Os and above 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: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The following testcase causes the current clang trunk and clang 3.4 to hang
when compiling at -Os and above in both 32-bit and 64-bit mode on
x86_64-linux-gnu.

This is a regression from clang 3.3. 

$ clang-trunk -v
clang version 3.5 (trunk 199196)
Target: x86_64-unknown-linux-gnu
Thread model: posix
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/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
$ clang-trunk -O1 -c small.c
$ clang-3.3 -Os -c small.c
$ 
$ timeout -s 9 10 clang-trunk -Os -c small.c
Killed
$ timeout -s 9 10 clang-3.4 -Os -c small.c
Killed
$ 


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


int a, b, e, *g = &e; 
unsigned short c, d;

void
fn1 ()
{
  int *e, **f; 
  f = &e;
  *f = 0;
  for (c = 0; c != 1;)
    {
      for (d = 1; d; d++)
    {
      *f = &a;
      if (**f)
        continue;
      *g = 0;
    }
      if (**f)
    continue;
      b = 0;
    }
}

void
fn2 ()
{
  fn1 ();
  fn1 ();
}

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