[Bug tree-optimization/49161] New: [4.5/4.6/4.7 Regression] Fix VRP on switch stmts

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49161

           Summary: [4.5/4.6/4.7 Regression] Fix VRP on switch stmts
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: ja...@gcc.gnu.org
        ReportedBy: ja...@gcc.gnu.org


The following testcase is miscompiled at -O2 on x86_64/i686, starting with:
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=155937

extern void abort (void);

int c;

__attribute__((noinline, noclone)) void
bar (int x)
{
  if (x != c++)
    abort ();
}

__attribute__((noinline, noclone)) void
foo (int x)
{
  switch (x)
    {
    case 3: goto l1;
    case 4: goto l2;
    case 6: goto l3;
    default: return;
    }
l1:
  goto l4;
l2:
  goto l4;
l3:
  bar (-1);
l4:
  bar (0);
  if (x != 4)
    bar (1);
  if (x != 3)
    bar (-1);
  bar (2);
}

int
main ()
{
  foo (3);
  if (c != 3)
    abort ();
  return 0;
}