[PATCH] Fix PR60903

[Richard Biener <rguenther at suse dot de>]

LIM fails to properly mark new blocks/edges it creates as
belonging to irreducible regions.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk
and 4.9 branch.

Richard.

2014-04-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/60903
	* tree-ssa-loop-im.c (analyze_memory_references): Remove
	commented code block.
	(execute_sm_if_changed): Properly apply IRREDUCIBLE_LOOP
	loop flags to newly created BBs and edges.

	* gcc.dg/torture/pr60903.c: New testcase.

Index: gcc/tree-ssa-loop-im.c
===================================================================
*** gcc/tree-ssa-loop-im.c	(revision 209677)
--- gcc/tree-ssa-loop-im.c	(working copy)
*************** analyze_memory_references (void)
*** 1544,1558 ****
    struct loop *loop, *outer;
    unsigned i, n;
  
- #if 0
-   /* Initialize bb_loop_postorder with a mapping from loop->num to
-      its postorder index.  */
-   i = 0;
-   bb_loop_postorder = XNEWVEC (unsigned, number_of_loops (cfun));
-   FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
-     bb_loop_postorder[loop->num] = i++;
- #endif
- 
    /* Collect all basic-blocks in loops and sort them after their
       loops postorder.  */
    i = 0;
--- 1547,1552 ----
*************** execute_sm_if_changed (edge ex, tree mem
*** 1807,1812 ****
--- 1803,1809 ----
    gimple_stmt_iterator gsi;
    gimple stmt;
    struct prev_flag_edges *prev_edges = (struct prev_flag_edges *) ex->aux;
+   bool irr = ex->flags & EDGE_IRREDUCIBLE_LOOP;
  
    /* ?? Insert store after previous store if applicable.  See note
       below.  */
*************** execute_sm_if_changed (edge ex, tree mem
*** 1821,1828 ****
    old_dest = ex->dest;
    new_bb = split_edge (ex);
    then_bb = create_empty_bb (new_bb);
!   if (current_loops && new_bb->loop_father)
!     add_bb_to_loop (then_bb, new_bb->loop_father);
  
    gsi = gsi_start_bb (new_bb);
    stmt = gimple_build_cond (NE_EXPR, flag, boolean_false_node,
--- 1818,1826 ----
    old_dest = ex->dest;
    new_bb = split_edge (ex);
    then_bb = create_empty_bb (new_bb);
!   if (irr)
!     then_bb->flags = BB_IRREDUCIBLE_LOOP;
!   add_bb_to_loop (then_bb, new_bb->loop_father);
  
    gsi = gsi_start_bb (new_bb);
    stmt = gimple_build_cond (NE_EXPR, flag, boolean_false_node,
*************** execute_sm_if_changed (edge ex, tree mem
*** 1834,1842 ****
    stmt = gimple_build_assign (unshare_expr (mem), tmp_var);
    gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);
  
!   make_edge (new_bb, then_bb, EDGE_TRUE_VALUE);
!   make_edge (new_bb, old_dest, EDGE_FALSE_VALUE);
!   then_old_edge = make_edge (then_bb, old_dest, EDGE_FALLTHRU);
  
    set_immediate_dominator (CDI_DOMINATORS, then_bb, new_bb);
  
--- 1832,1843 ----
    stmt = gimple_build_assign (unshare_expr (mem), tmp_var);
    gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);
  
!   make_edge (new_bb, then_bb,
! 	     EDGE_TRUE_VALUE | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));
!   make_edge (new_bb, old_dest,
! 	     EDGE_FALSE_VALUE | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));
!   then_old_edge = make_edge (then_bb, old_dest,
! 			     EDGE_FALLTHRU | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));
  
    set_immediate_dominator (CDI_DOMINATORS, then_bb, new_bb);
  
Index: gcc/testsuite/gcc.dg/torture/pr60903.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr60903.c	(revision 0)
--- gcc/testsuite/gcc.dg/torture/pr60903.c	(working copy)
***************
*** 0 ****
--- 1,22 ----
+ /* { dg-do compile } */
+ 
+ extern int a, b, k, q;
+ 
+ void
+ foo ()
+ {
+   if (a)
+     {
+       while (q)
+ 	{
+ 	lbl:
+ 	  if (a)
+ 	    {
+ 	      a = 0;
+ 	      goto lbl;
+ 	    }
+ 	}
+       b = k;
+     }
+   goto lbl;
+ }