[Bug tree-optimization/17951] New: Dominance info is incorrect for entry and exit blocks

["dberlin at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The dominance info is incorrect for entry and exit blocks.

According to dominated_by_p, nothing dominates the exit block (which is wrong),
and nothing post-dominates the entry block (which is also wrong).

A simple example:
(gdb) p dominated_by_p (CDI_POST_DOMINATORS, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR)
$4 = 0 '\0'
(gdb) p dominated_by_p (CDI_DOMINATORS, EXIT_BLOCK_PTR, ENTRY_BLOCK_PTR)
$5 = 0 '\0'

Both of these should return true.
Zdenek said he thought he knew why this was.

-- 
           Summary: Dominance info is incorrect for entry and exit blocks
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dberlin at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17951