* tree-cfg.c (tree_duplicate_bb): Mark duplicated definitions.

	* tree-flow.h (rewrite_ssa_into_ssa): Declaration changed.
	* tree-into-ssa.c (rewrite_ssa_into_ssa): Use new interface to
	manipulate the duplicated ssa names.
	* tree-ssanames.c (ssa_names_to_rewrite): New variable.
	(marked_for_rewrite_p, any_marked_for_rewrite_p, mark_for_rewrite,
	unmark_all_for_rewrite, marked_ssa_names, release_ssa_name_force):
	New functions.
	(release_ssa_name): Do not release ssa names that may have multiple
	definitions.
	* tree.h (release_ssa_name_force, mark_for_rewrite,
	unmark_all_for_rewrite, marked_for_rewrite_p, any_marked_for_rewrite_p,
	marked_ssa_names): Declare.
	* tree-ssa-loop-ch.c (mark_defs_for_rewrite): Remove.
	(duplicate_blocks): Remove call to mark_defs_for_rewrite.
	Update call to rewrite_ssa_into_ssa.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@85572 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 134 insertions, 71 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0461d107dff..e62fdf50fc6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,23 @@
+2004-08-04  Zdenek Dvorak  <rakdver@atrey.karlin.mff.cuni.cz>
+	    Jeff Law  <law@redhat.com>
+
+	* tree-cfg.c (tree_duplicate_bb): Mark duplicated definitions.
+	* tree-flow.h (rewrite_ssa_into_ssa): Declaration changed.
+	* tree-into-ssa.c (rewrite_ssa_into_ssa): Use new interface to
+	manipulate the duplicated ssa names.
+	* tree-ssanames.c (ssa_names_to_rewrite): New variable.
+	(marked_for_rewrite_p, any_marked_for_rewrite_p, mark_for_rewrite,
+	unmark_all_for_rewrite, marked_ssa_names, release_ssa_name_force):
+	New functions.
+	(release_ssa_name): Do not release ssa names that may have multiple
+	definitions.
+	* tree.h (release_ssa_name_force, mark_for_rewrite,
+	unmark_all_for_rewrite, marked_for_rewrite_p, any_marked_for_rewrite_p,
+	marked_ssa_names): Declare.
+	* tree-ssa-loop-ch.c (mark_defs_for_rewrite): Remove.
+	(duplicate_blocks): Remove call to mark_defs_for_rewrite.
+	Update call to rewrite_ssa_into_ssa.
+
 2004-08-04  Mark Mitchell  <mark@codesourcery.com>
 
 	* defaults.h (TARGET_DECLSPEC): New macro.
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index c9d2424cf4c..576531610eb 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -4297,8 +4297,19 @@ tree_duplicate_bb (basic_block bb)
 {
   basic_block new_bb;
   block_stmt_iterator bsi, bsi_tgt;
+  tree phi;
+  def_optype defs;
+  v_may_def_optype v_may_defs;
+  v_must_def_optype v_must_defs;
+  unsigned j;
 
   new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
+
+  for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
+    {
+      mark_for_rewrite (PHI_RESULT (phi));
+    }
+
   bsi_tgt = bsi_start (new_bb);
   for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
     {
@@ -4308,6 +4319,21 @@ tree_duplicate_bb (basic_block bb)
       if (TREE_CODE (stmt) == LABEL_EXPR)
 	continue;
 
+      /* Record the definitions.  */
+      get_stmt_operands (stmt);
+
+      defs = STMT_DEF_OPS (stmt);
+      for (j = 0; j < NUM_DEFS (defs); j++)
+	mark_for_rewrite (DEF_OP (defs, j));
+
+      v_may_defs = STMT_V_MAY_DEF_OPS (stmt);
+      for (j = 0; j < NUM_V_MAY_DEFS (v_may_defs); j++)
+	mark_for_rewrite (V_MAY_DEF_RESULT (v_may_defs, j));
+
+      v_must_defs = STMT_V_MUST_DEF_OPS (stmt);
+      for (j = 0; j < NUM_V_MUST_DEFS (v_must_defs); j++)
+	mark_for_rewrite (V_MUST_DEF_OP (v_must_defs, j));
+
       copy = unshare_expr (stmt);
 
       /* Copy also the virtual operands.  */
diff --git a/gcc/tree-flow.h b/gcc/tree-flow.h
index 600d46256c2..0a979ef02ce 100644
--- a/gcc/tree-flow.h
+++ b/gcc/tree-flow.h
@@ -581,7 +581,7 @@ extern void kill_redundant_phi_nodes (void);
 
 /* In tree-into-ssa.c  */
 extern void rewrite_into_ssa (bool);
-extern void rewrite_ssa_into_ssa (bitmap);
+extern void rewrite_ssa_into_ssa (void);
 
 void compute_global_livein (bitmap, bitmap);
 tree duplicate_ssa_name (tree, tree);
diff --git a/gcc/tree-into-ssa.c b/gcc/tree-into-ssa.c
index 4d5992e2d56..edeeab5f1bf 100644
--- a/gcc/tree-into-ssa.c
+++ b/gcc/tree-into-ssa.c
@@ -1740,11 +1740,11 @@ rewrite_into_ssa (bool all)
   timevar_pop (TV_TREE_SSA_OTHER);
 }
 
-/* The ssa names in NAMES_TO_RENAME may have more than one definition;
+/* The marked ssa names may have more than one definition;
    add phi nodes and rewrite them to fix this.  */
 
 void
-rewrite_ssa_into_ssa (bitmap names_to_rename)
+rewrite_ssa_into_ssa (void)
 {
   bitmap *dfs;
   basic_block bb;
@@ -1753,9 +1753,11 @@ rewrite_ssa_into_ssa (bitmap names_to_rename)
   unsigned i;
   sbitmap snames_to_rename;
   tree name;
+  bitmap to_rename;
   
-  if (bitmap_first_set_bit (names_to_rename) < 0)
+  if (!any_marked_for_rewrite_p ())
     return;
+  to_rename = marked_ssa_names ();
 
   timevar_push (TV_TREE_SSA_OTHER);
 
@@ -1800,7 +1802,7 @@ rewrite_ssa_into_ssa (bitmap names_to_rename)
 
   snames_to_rename = sbitmap_alloc (num_ssa_names);
   sbitmap_zero (snames_to_rename);
-  EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i,
+  EXECUTE_IF_SET_IN_BITMAP (to_rename, 0, i,
 			    SET_BIT (snames_to_rename, i));
 
   mark_def_sites_global_data.kills = sbitmap_alloc (num_ssa_names);
@@ -1826,7 +1828,7 @@ rewrite_ssa_into_ssa (bitmap names_to_rename)
     set_current_def (ssa_name (i), NULL_TREE);
 
   /* Insert PHI nodes at dominance frontiers of definition blocks.  */
-  insert_phi_nodes (dfs, names_to_rename);
+  insert_phi_nodes (dfs, to_rename);
 
   /* Rewrite all the basic blocks in the program.  */
   timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
@@ -1855,8 +1857,9 @@ rewrite_ssa_into_ssa (bitmap names_to_rename)
   /* Finalize the dominator walker.  */
   fini_walk_dominator_tree (&walk_data);
 
-  EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i,
-      release_ssa_name (ssa_name (i)));
+  unmark_all_for_rewrite ();
+
+  EXECUTE_IF_SET_IN_BITMAP (to_rename, 0, i, release_ssa_name (ssa_name (i)));
 
   sbitmap_free (snames_to_rename);
 
@@ -1886,6 +1889,7 @@ rewrite_ssa_into_ssa (bitmap names_to_rename)
       SSA_NAME_AUX (name) = NULL;
     }
 
+  BITMAP_XFREE (to_rename);
   timevar_pop (TV_TREE_SSA_OTHER);
 }
 
diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index ddb2438bae7..f10ec75e1cc 100644
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -99,54 +99,6 @@ should_duplicate_loop_header_p (basic_block header, struct loop *loop,
   return true;
 }
 
-/* Marks variables defined in basic block BB for rewriting.  */
-
-static void
-mark_defs_for_rewrite (basic_block bb)
-{
-  tree stmt, var;
-  block_stmt_iterator bsi;
-  stmt_ann_t ann;
-  def_optype defs;
-  v_may_def_optype v_may_defs;
-  v_must_def_optype v_must_defs;
-  unsigned i;
-
-  for (stmt = phi_nodes (bb); stmt; stmt = TREE_CHAIN (stmt))
-    {
-      var = PHI_RESULT (stmt);
-      bitmap_set_bit (vars_to_rename, SSA_NAME_VERSION (var));
-    }
-
-  for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
-    {
-      stmt = bsi_stmt (bsi);
-      get_stmt_operands (stmt);
-      ann = stmt_ann (stmt);
-
-      defs = DEF_OPS (ann);
-      for (i = 0; i < NUM_DEFS (defs); i++)
-	{
-	  var = DEF_OP (defs, i);
-	  bitmap_set_bit (vars_to_rename, SSA_NAME_VERSION (var));
-	}
-
-      v_may_defs = V_MAY_DEF_OPS (ann);
-      for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
-	{
-	  var = V_MAY_DEF_RESULT (v_may_defs, i);
-	  bitmap_set_bit (vars_to_rename, SSA_NAME_VERSION (var));
-	}
-
-      v_must_defs = V_MUST_DEF_OPS (ann);
-      for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
-	{
-	  var = V_MUST_DEF_OP (v_must_defs, i);
-	  bitmap_set_bit (vars_to_rename, SSA_NAME_VERSION (var));
-	}
-    }
-}
-
 /* Duplicates destinations of edges in BBS_TO_DUPLICATE.  */
 
 static void
@@ -166,18 +118,6 @@ duplicate_blocks (varray_type bbs_to_duplicate)
       preheader_edge = VARRAY_GENERIC_PTR_NOGC (bbs_to_duplicate, i);
       header = preheader_edge->dest;
 
-      /* It is sufficient to rewrite the definitions, since the uses of
-	 the operands defined outside of the duplicated basic block are
-	 still valid (every basic block that dominates the original block
-	 also dominates the duplicate).  */
-      mark_defs_for_rewrite (header);
-    }
-
-  for (i = 0; i < VARRAY_ACTIVE_SIZE (bbs_to_duplicate); i++)
-    {
-      preheader_edge = VARRAY_GENERIC_PTR_NOGC (bbs_to_duplicate, i);
-      header = preheader_edge->dest;
-
       if (!header->aux)
 	abort ();
       header->aux = NULL;
@@ -210,8 +150,7 @@ duplicate_blocks (varray_type bbs_to_duplicate)
 
   calculate_dominance_info (CDI_DOMINATORS);
 
-  rewrite_ssa_into_ssa (vars_to_rename);
-  bitmap_clear (vars_to_rename);
+  rewrite_ssa_into_ssa ();
 }
 
 /* Checks whether LOOP is a do-while style loop.  */
diff --git a/gcc/tree-ssanames.c b/gcc/tree-ssanames.c
index 4e8985a4b21..94c14538b16 100644
--- a/gcc/tree-ssanames.c
+++ b/gcc/tree-ssanames.c
@@ -60,7 +60,10 @@ Boston, MA 02111-1307, USA.  */
    
 /* Array of all SSA_NAMEs used in the function.  */
 varray_type ssa_names;
-                                                                                
+
+/* Bitmap of ssa names marked for rewriting.  */
+bitmap ssa_names_to_rewrite;
+
 /* Free list of SSA_NAMEs.  This list is wiped at the end of each function
    after we leave SSA form.  */
 static GTY (()) tree free_ssanames;
@@ -74,6 +77,64 @@ unsigned int ssa_name_nodes_reused;
 unsigned int ssa_name_nodes_created;
 #endif
 
+/* Returns true if ssa name VAR is marked for rewrite.  */
+
+bool
+marked_for_rewrite_p (tree var)
+{
+  if (ssa_names_to_rewrite
+      && bitmap_bit_p (ssa_names_to_rewrite, SSA_NAME_VERSION (var)))
+    return true;
+
+  return false;
+}
+
+/* Returns true if any ssa name is marked for rewrite.  */
+
+bool
+any_marked_for_rewrite_p (void)
+{
+  if (!ssa_names_to_rewrite)
+    return false;
+
+  return bitmap_first_set_bit (ssa_names_to_rewrite) != -1;
+}
+
+/* Mark ssa name VAR for rewriting.  */
+
+void
+mark_for_rewrite (tree var)
+{
+  if (!ssa_names_to_rewrite)
+    ssa_names_to_rewrite = BITMAP_XMALLOC ();
+
+  bitmap_set_bit (ssa_names_to_rewrite, SSA_NAME_VERSION (var));
+}
+
+/* Unmark all ssa names marked for rewrite.  */
+
+void
+unmark_all_for_rewrite (void)
+{
+  if (!ssa_names_to_rewrite)
+    return;
+
+  bitmap_clear (ssa_names_to_rewrite);
+}
+
+/* Return the bitmap of ssa names to rewrite.  Copy the bitmap,
+   so that the optimizers cannot access internals directly  */
+
+bitmap
+marked_ssa_names (void)
+{
+  bitmap ret = BITMAP_XMALLOC ();
+  if (ssa_names_to_rewrite)
+    bitmap_copy (ret, ssa_names_to_rewrite);
+
+  return ret;
+}
+
 /* Initialize management of SSA_NAMEs.  */
 
 void
@@ -182,6 +243,12 @@ release_ssa_name (tree var)
   if (var == var_ann (SSA_NAME_VAR (var))->default_def)
     return;
 
+  /* If the ssa name is marked for rewriting, it may have multiple definitions,
+     but we may happen to remove just one of them.  So do not remove the
+     ssa name now.  */
+  if (marked_for_rewrite_p (var))
+    return;
+
   /* release_ssa_name can be called multiple times on a single SSA_NAME.
      However, it should only end up on our free list one time.   We
      keep a status bit in the SSA_NAME node itself to indicate it has
diff --git a/gcc/tree.h b/gcc/tree.h
index 92e9a55d802..64fde745415 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2658,6 +2658,13 @@ extern void replace_ssa_name_symbol (tree, tree);
 extern void ssanames_print_statistics (void);
 #endif
 
+extern void mark_for_rewrite (tree);
+extern void unmark_all_for_rewrite (void);
+extern bool marked_for_rewrite_p (tree);
+extern bool any_marked_for_rewrite_p (void);
+extern struct bitmap_head_def *marked_ssa_names (void);
+
+
 /* Return the (unique) IDENTIFIER_NODE node for a given name.
    The name is supplied as a char *.  */