gimple-low.c (expand_var_p): Don't look at TREE_ADDRESSABLE...

        * gimple-low.c (expand_var_p): Don't look at TREE_ADDRESSABLE,
        TREE_THIS_VOLATILE, may_aliases, or optimization level.
        (remove_useless_vars): Dump debugging info.
        (expand_used_vars): Move ...
        * cfgexpand.c (expand_used_vars): ... here.  Make static.
        * tree-flow-inline.h (set_is_used): New.
        (set_default_def): Use get_var_ann.
        * tree-flow.h: Update decls.
        * tree-ssa-live.c (mark_all_vars_used_1, mark_all_vars_used): New.
        (create_ssa_var_map): Use it.
        * tree-ssa.c (set_is_used): Remove.

From-SVN: r85034

7 files changed, 97 insertions, 60 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 784b66d..02ba103 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2004-07-21  Richard Henderson  <rth@redhat.com>
+
+	* gimple-low.c (expand_var_p): Don't look at TREE_ADDRESSABLE,
+	TREE_THIS_VOLATILE, may_aliases, or optimization level.
+	(remove_useless_vars): Dump debugging info.
+	(expand_used_vars): Move ...
+	* cfgexpand.c (expand_used_vars): ... here.  Make static.
+	* tree-flow-inline.h (set_is_used): New.
+	(set_default_def): Use get_var_ann.
+	* tree-flow.h: Update decls.
+	* tree-ssa-live.c (mark_all_vars_used_1, mark_all_vars_used): New.
+	(create_ssa_var_map): Use it.
+	* tree-ssa.c (set_is_used): Remove.
+
 2004-07-22  Ben Elliston  <bje@au.ibm.com>
 
 	* gdbinit.in: Set a breakpoint on internal_error.
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index f4fe860..30004f2 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -37,6 +37,22 @@ Boston, MA 02111-1307, USA.  */
 #include "flags.h"
 
 
+/* Expand variables in the unexpanded_var_list.  */
+
+static void
+expand_used_vars (void)
+{
+  tree cell;
+
+  cfun->unexpanded_var_list = nreverse (cfun->unexpanded_var_list);
+
+  for (cell = cfun->unexpanded_var_list; cell; cell = TREE_CHAIN (cell))
+    expand_var (TREE_VALUE (cell));
+
+  cfun->unexpanded_var_list = NULL_TREE;
+}
+
+
 /* A subroutine of expand_gimple_basic_block.  Expand one COND_EXPR.
    Returns a new basic block if we've terminated the current basic
    block and created a new one.  */
@@ -420,10 +436,7 @@ tree_expand_cfg (void)
   /* Prepare the rtl middle end to start recording block changes.  */
   reset_block_changes ();
 
-  /* Expand the variables recorded during gimple lowering.  This must
-     occur before the call to expand_function_start to ensure that
-     all used variables are expanded before we expand anything on the
-     PENDING_SIZES list.  */
+  /* Expand the variables recorded during gimple lowering.  */
   expand_used_vars ();
 
   /* Set up parameters and prepare for return, for the function.  */
diff --git a/gcc/gimple-low.c b/gcc/gimple-low.c
index f164bd9..828a36f 100644
--- a/gcc/gimple-low.c
+++ b/gcc/gimple-low.c
@@ -475,15 +475,13 @@ expand_var_p (tree var)
   if (TREE_CODE (var) != VAR_DECL)
     return true;
 
-  /* Remove all unused, unaliased temporaries.  Also remove unused, unaliased
-     local variables during highly optimizing compilations.  */
+  /* Leave statics and externals alone.  */
+  if (TREE_STATIC (var) || DECL_EXTERNAL (var))
+    return true;
+
+  /* Remove all unused local variables.  */
   ann = var_ann (var);
-  if (ann
-      && ! ann->may_aliases
-      && ! ann->used
-      && ! TREE_ADDRESSABLE (var)
-      && ! TREE_THIS_VOLATILE (var)
-      && (DECL_ARTIFICIAL (var) || optimize >= 2))
+  if (!ann || !ann->used)
     return false;
 
   return true;
@@ -495,6 +493,13 @@ static void
 remove_useless_vars (void)
 {
   tree var, *cell;
+  FILE *df = NULL;
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      df = dump_file;
+      fputs ("Discarding as unused:\n", df);
+    }
 
   for (cell = &cfun->unexpanded_var_list; *cell; )
     {
@@ -502,27 +507,22 @@ remove_useless_vars (void)
 
       if (!expand_var_p (var))
 	{
+	  if (df)
+	    {
+	      fputs ("  ", df);
+	      print_generic_expr (df, var, dump_flags);
+	      fputc ('\n', df);
+	    }
+
 	  *cell = TREE_CHAIN (*cell);
 	  continue;
 	}
 
       cell = &TREE_CHAIN (*cell);
     }
-}
-
-/* Expand variables in the unexpanded_var_list.  */
-
-void
-expand_used_vars (void)
-{
-  tree cell;
-
-  cfun->unexpanded_var_list = nreverse (cfun->unexpanded_var_list);
-
-  for (cell = cfun->unexpanded_var_list; cell; cell = TREE_CHAIN (cell))
-    expand_var (TREE_VALUE (cell));
 
-  cfun->unexpanded_var_list = NULL_TREE;
+  if (df)
+    fputc ('\n', df);
 }
 
 struct tree_opt_pass pass_remove_useless_vars = 
diff --git a/gcc/tree-flow-inline.h b/gcc/tree-flow-inline.h
index 08dc0ef..d48f205 100644
--- a/gcc/tree-flow-inline.h
+++ b/gcc/tree-flow-inline.h
@@ -421,6 +421,16 @@ phi_arg_from_edge (tree phi, edge e)
   return -1;
 }
 
+/* Mark VAR as used, so that it'll be preserved during rtl expansion.  */
+
+static inline void
+set_is_used (tree var)
+{
+  var_ann_t ann = get_var_ann (var);
+  ann->used = 1;
+}
+
+
 /*  -----------------------------------------------------------------------  */
 
 /* Return true if T is an executable statement.  */
@@ -453,9 +463,7 @@ is_label_stmt (tree t)
 static inline void
 set_default_def (tree var, tree def)
 {
-  var_ann_t ann = var_ann (var);
-  if (ann == NULL)
-    ann = create_var_ann (var);
+  var_ann_t ann = get_var_ann (var);
   ann->default_def = def;
 }
 
diff --git a/gcc/tree-flow.h b/gcc/tree-flow.h
index 2f32734..bd8bd4a 100644
--- a/gcc/tree-flow.h
+++ b/gcc/tree-flow.h
@@ -535,7 +535,6 @@ extern tree make_rename_temp (tree, const char *);
 /* In gimple-low.c  */
 struct lower_data;
 extern void lower_stmt_body (tree, struct lower_data *);
-extern void expand_used_vars (void);
 extern void record_vars (tree);
 extern bool block_may_fallthru (tree block);
 
@@ -565,7 +564,6 @@ extern void dump_tree_ssa_stats (FILE *);
 extern void debug_tree_ssa_stats (void);
 extern void ssa_remove_edge (edge);
 extern edge ssa_redirect_edge (edge, basic_block);
-extern void set_is_used (tree);
 extern bool tree_ssa_useless_type_conversion (tree);
 extern bool tree_ssa_useless_type_conversion_1 (tree, tree);
 extern void verify_ssa (void);
@@ -647,6 +645,7 @@ bool for_each_index (tree *, bool (*) (tree, tree *, void *), void *);
 static inline int phi_arg_from_edge (tree, edge);
 static inline bool is_call_clobbered (tree);
 static inline void mark_call_clobbered (tree);
+static inline void set_is_used (tree);
 
 /* In tree-eh.c  */
 extern void make_eh_edges (tree);
diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 6daf655..6d006fa 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -285,6 +285,34 @@ change_partition_var (var_map map, tree var, int part)
 }
 
 
+/* Helper function for mark_all_vars_used, called via walk_tree.  */
+
+static tree
+mark_all_vars_used_1 (tree *tp, int *walk_subtrees,
+		      void *data ATTRIBUTE_UNUSED)
+{
+  tree t = *tp;
+
+  /* Only need to mark VAR_DECLS; parameters and return results are not
+     eliminated as unused.  */
+  if (TREE_CODE (t) == VAR_DECL)
+    set_is_used (t);
+
+  if (DECL_P (t) || TYPE_P (t))
+    *walk_subtrees = 0;
+
+  return NULL;
+}
+
+/* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be 
+   eliminated during the tree->rtl conversion process.  */
+
+static inline void
+mark_all_vars_used (tree *expr_p)
+{
+  walk_tree (expr_p, mark_all_vars_used_1, NULL, NULL);
+}
+
 /* This function looks through the program and uses FLAGS to determine what 
    SSA versioned variables are given entries in a new partition table.  This
    new partition map is returned.  */
@@ -338,6 +366,8 @@ create_ssa_var_map (int flags)
 	      arg = PHI_ARG_DEF (phi, i);
 	      if (TREE_CODE (arg) == SSA_NAME)
 		register_ssa_partition (map, arg, true);
+
+	      mark_all_vars_used (&PHI_ARG_DEF_TREE (phi, i));
 	    }
 	}
 
@@ -377,8 +407,6 @@ create_ssa_var_map (int flags)
 	  for (x = 0; x < NUM_VUSES (vuses); x++)
 	    {
 	      tree var = VUSE_OP (vuses, x);
-	      set_is_used (var);
-
 #if defined ENABLE_CHECKING
 	      SET_BIT (used_in_virtual_ops, var_ann (SSA_NAME_VAR (var))->uid);
 #endif
@@ -388,8 +416,6 @@ create_ssa_var_map (int flags)
 	  for (x = 0; x < NUM_V_MAY_DEFS (v_may_defs); x++)
 	    {
 	      tree var = V_MAY_DEF_OP (v_may_defs, x);
-	      set_is_used (var);
-
 #if defined ENABLE_CHECKING
 	      SET_BIT (used_in_virtual_ops, var_ann (SSA_NAME_VAR (var))->uid);
 #endif
@@ -399,11 +425,12 @@ create_ssa_var_map (int flags)
 	  for (x = 0; x < NUM_V_MUST_DEFS (v_must_defs); x++)
 	    {
 	      tree var = V_MUST_DEF_OP (v_must_defs, x);
-	      set_is_used (var);
 #if defined ENABLE_CHECKING
 	      SET_BIT (used_in_virtual_ops, var_ann (SSA_NAME_VAR (var))->uid);
 #endif
 	    }	    
+
+	  mark_all_vars_used (bsi_stmt_ptr (bsi));
 	}
     }
 
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index ad1c174..35db41c 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -463,30 +463,6 @@ verify_ssa (void)
 }
 
 
-/* Set the USED bit in the annotation for T.  */
-
-void
-set_is_used (tree t)
-{
-  while (1)
-    {
-      if (SSA_VAR_P (t))
-	break;
-
-      if (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR)
-	t = TREE_OPERAND (t, 0);
-      else
-	while (handled_component_p (t))
-	  t = TREE_OPERAND (t, 0);
-    }
-
-  if (TREE_CODE (t) == SSA_NAME)
-    t = SSA_NAME_VAR (t);
-
-  var_ann (t)->used = 1;
-}
-
-
 /* Initialize global DFA and SSA structures.  */
 
 void