for  gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	* tree-ssa-loop-ivopts.c (get_phi_with_result): Remove.
	(remove_statement): Likewise.
	(rewrite_use_nonlinear_expr): Adjust.
	(remove_unused_ivs): Collect SSA NAMEs to remove and call...
	* tree-ssa.c (release_defs_bitset): ... this.  New.
	* tree-flow.h (release_defs_bitset): Declare.

Index: gcc/tree-ssa-loop-ivopts.c
===================================================================
--- gcc/tree-ssa-loop-ivopts.c.orig	2009-09-07 19:00:52.000000000 -0300
+++ gcc/tree-ssa-loop-ivopts.c	2009-09-07 19:15:39.000000000 -0300
@@ -5038,42 +5038,6 @@ create_new_ivs (struct ivopts_data *data
     }
 }
 
-/* Returns the phi-node in BB with result RESULT.  */
-
-static gimple
-get_phi_with_result (basic_block bb, tree result)
-{
-  gimple_stmt_iterator i = gsi_start_phis (bb);
-
-  for (; !gsi_end_p (i); gsi_next (&i))
-    if (gimple_phi_result (gsi_stmt (i)) == result)
-      return gsi_stmt (i);
-
-  gcc_unreachable ();
-  return NULL;
-}
-
-
-/* Removes statement STMT (real or a phi node).  If INCLUDING_DEFINED_NAME
-   is true, remove also the ssa name defined by the statement.  */
-
-static void
-remove_statement (gimple stmt, bool including_defined_name)
-{
-  if (gimple_code (stmt) == GIMPLE_PHI)
-    {
-      gimple bb_phi = get_phi_with_result (gimple_bb (stmt), 
-					 gimple_phi_result (stmt));
-      gimple_stmt_iterator bsi = gsi_for_stmt (bb_phi);
-      remove_phi_node (&bsi, including_defined_name);
-    }
-  else
-    {
-      gimple_stmt_iterator bsi = gsi_for_stmt (stmt);
-      gsi_remove (&bsi, true);
-      release_defs (stmt); 
-    }
-}
 
 /* Rewrites USE (definition of iv used in a nonlinear expression)
    using candidate CAND.  */
@@ -5176,7 +5140,9 @@ rewrite_use_nonlinear_expr (struct ivopt
     {
       ass = gimple_build_assign (tgt, op);
       gsi_insert_before (&bsi, ass, GSI_SAME_STMT);
-      remove_statement (use->stmt, false);
+
+      bsi = gsi_for_stmt (use->stmt);
+      remove_phi_node (&bsi, false);
     }
   else
     {
@@ -5414,7 +5380,11 @@ remove_unused_ivs (struct ivopts_data *d
 {
   unsigned j;
   bitmap_iterator bi;
+  bitmap toremove = BITMAP_ALLOC (NULL);
 
+  /* Figure out an order in which to release SSA DEFs so that we don't
+     release something that we'd have to propagate into a debug stmt
+     afterwards.  */
   EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, bi)
     {
       struct version_info *info;
@@ -5425,25 +5395,12 @@ remove_unused_ivs (struct ivopts_data *d
 	  && !info->inv_id
 	  && !info->iv->have_use_for
 	  && !info->preserve_biv)
-	{
-	  if (MAY_HAVE_DEBUG_STMTS)
-	    {
-	      gimple stmt;
-	      imm_use_iterator iter;
-
-	      FOR_EACH_IMM_USE_STMT (stmt, iter, info->iv->ssa_name)
-		{
-		  if (!gimple_debug_bind_p (stmt))
-		    continue;
-
-		  /* ??? We can probably do better than this.  */
-		  gimple_debug_bind_reset_value (stmt);
-		  update_stmt (stmt);
-		}
-	    }
-	  remove_statement (SSA_NAME_DEF_STMT (info->iv->ssa_name), true);
-	}
+	bitmap_set_bit (toremove, SSA_NAME_VERSION (info->iv->ssa_name));
     }
+
+  release_defs_bitset (toremove);
+
+  BITMAP_FREE (toremove);
 }
 
 /* Frees data allocated by the optimization of a single loop.  */
Index: gcc/tree-flow.h
===================================================================
--- gcc/tree-flow.h.orig	2009-07-12 08:19:36.000000000 -0300
+++ gcc/tree-flow.h	2009-09-07 19:15:39.000000000 -0300
@@ -586,9 +586,10 @@ typedef struct 
        (VAR) = next_referenced_var (&(ITER))) 
 
 void propagate_defs_into_debug_stmts (gimple, basic_block,
-				  const gimple_stmt_iterator *);
+				      const gimple_stmt_iterator *);
 void propagate_var_def_into_debug_stmts (tree, basic_block,
-					  const gimple_stmt_iterator *);
+					 const gimple_stmt_iterator *);
+void release_defs_bitset (bitmap toremove);
 
 typedef struct
 {
Index: gcc/tree-ssa.c
===================================================================
--- gcc/tree-ssa.c.orig	2009-09-01 16:16:04.000000000 -0300
+++ gcc/tree-ssa.c	2009-09-07 19:15:39.000000000 -0300
@@ -440,6 +440,74 @@ propagate_defs_into_debug_stmts (gimple 
     }
 }
 
+/* Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing
+   dominated stmts before their dominators, so that release_ssa_defs
+   stands a chance of propagating DEFs into debug bind stmts.  */
+
+void
+release_defs_bitset (bitmap toremove)
+{
+  unsigned j;
+  bitmap_iterator bi;
+
+  /* Performing a topological sort is probably overkill, this will
+     most likely run in slightly superlinear time, rather than the
+     pathological quadratic worst case.  */
+  while (!bitmap_empty_p (toremove))
+    EXECUTE_IF_SET_IN_BITMAP (toremove, 0, j, bi)
+      {
+	bool remove_now = true;
+	tree var = ssa_name (j);
+	gimple stmt;
+	imm_use_iterator uit;
+
+	FOR_EACH_IMM_USE_STMT (stmt, uit, var)
+	  {
+	    ssa_op_iter dit;
+	    def_operand_p def_p;
+
+	    /* We can't propagate PHI nodes into debug stmts.  */
+	    if (gimple_code (stmt) == GIMPLE_PHI
+		|| is_gimple_debug (stmt))
+	      continue;
+
+	    /* If we find another definition to remove that uses
+	       the one we're looking at, defer the removal of this
+	       one, so that it can be propagated into debug stmts
+	       after the other is.  */
+	    FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, dit, SSA_OP_DEF)
+	      {
+		tree odef = DEF_FROM_PTR (def_p);
+
+		if (bitmap_bit_p (toremove, SSA_NAME_VERSION (odef)))
+		  {
+		    remove_now = false;
+		    break;
+		  }
+	      }
+
+	    if (!remove_now)
+	      BREAK_FROM_IMM_USE_STMT (uit);
+	  }
+
+	if (remove_now)
+	  {
+	    gimple def = SSA_NAME_DEF_STMT (var);
+	    gimple_stmt_iterator gsi = gsi_for_stmt (def);
+
+	    if (gimple_code (def) == GIMPLE_PHI)
+	      remove_phi_node (&gsi, true);
+	    else
+	      {
+		gsi_remove (&gsi, true);
+		release_defs (def);
+	      }
+
+	    bitmap_clear_bit (toremove, j);
+	  }
+      }
+}
+
 /* Return true if SSA_NAME is malformed and mark it visited.
 
    IS_VIRTUAL is true if this SSA_NAME was found inside a virtual