[patch] for -O2 -finline-functions tramp3d breakage

[Zdenek Dvorak]

Hello,

in remove_dead_stmt, we forget to mark cfg altered if there are two
edges coming out of the basic block and one of them leads to the
postdominator.

Bootstrapped & regtested on i686.

Zdenek

	* tree-cfgcleanup.c (cleanup_tree_cfg): Verify dominance info
	if it claims to be available.
	* tree-ssa-dce.c (remove_dead_stmt): Mark cfg as altered when
	edge is redirected.
	(perform_tree_ssa_dce): Always free postdominators.

Index: tree-cfgcleanup.c
===================================================================
*** tree-cfgcleanup.c	(revision 124214)
--- tree-cfgcleanup.c	(working copy)
*************** cleanup_tree_cfg (void)
*** 615,621 ****
        calculate_dominance_info (CDI_DOMINATORS);
      }
    else
!     changed = false;
  
    changed |= cleanup_tree_cfg_1 ();
  
--- 615,626 ----
        calculate_dominance_info (CDI_DOMINATORS);
      }
    else
!     {
! #ifdef ENABLE_CHECKING
!       verify_dominators (CDI_DOMINATORS);
! #endif
!       changed = false;
!     }
  
    changed |= cleanup_tree_cfg_1 ();
  
Index: tree-ssa-dce.c
===================================================================
*** tree-ssa-dce.c	(revision 124214)
--- tree-ssa-dce.c	(working copy)
*************** remove_dead_stmt (block_stmt_iterator *i
*** 607,613 ****
  	 3. If the post dominator has PHI nodes we may be able to compute
  	    the right PHI args for them.
  
- 
  	 In each of these cases we must remove the control statement
  	 as it may reference SSA_NAMEs which are going to be removed and
  	 we remove all but one outgoing edge from the block.  */
--- 607,612 ----
*************** remove_dead_stmt (block_stmt_iterator *i
*** 620,625 ****
--- 619,629 ----
  	  /* Redirect the first edge out of BB to reach POST_DOM_BB.  */
  	  redirect_edge_and_branch (EDGE_SUCC (bb, 0), post_dom_bb);
  	  PENDING_STMT (EDGE_SUCC (bb, 0)) = NULL;
+ 
+ 	  /* It is not sufficient to set cfg_altered below during edge
+ 	     removal, in case BB has two successors and one of them
+ 	     is POST_DOM_BB.  */
+ 	  cfg_altered = true;
  	}
        EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
        EDGE_SUCC (bb, 0)->count = bb->count;
*************** eliminate_unnecessary_stmts (void)
*** 718,723 ****
--- 722,728 ----
  	    }
  	}
      }
+ 
    return something_changed;
  }
  
*************** perform_tree_ssa_dce (bool aggressive)
*** 837,844 ****
    something_changed |= eliminate_unnecessary_stmts ();
    something_changed |= cfg_altered;
  
!   if (aggressive && something_changed)
!     free_dominance_info (CDI_POST_DOMINATORS);
  
    /* If we removed paths in the CFG, then we need to update
       dominators as well.  I haven't investigated the possibility
--- 842,849 ----
    something_changed |= eliminate_unnecessary_stmts ();
    something_changed |= cfg_altered;
  
!   /* We do not update postdominators, so free them unconditionally.  */
!   free_dominance_info (CDI_POST_DOMINATORS);
  
    /* If we removed paths in the CFG, then we need to update
       dominators as well.  I haven't investigated the possibility