X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Ftree-ssa-live.c;h=80ab42558cc10fac58a5401d2a91be463f5955bd;hb=6956abd25f4834e2c451819a57af52874dd0aace;hp=4216b22585109252f681c93d1f0e6c53f5c54c27;hpb=dd045aeeddc65c15840ac25e90f729e2805dfc17;p=pf3gnuchains%2Fgcc-fork.git

diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 4216b225851..80ab42558cc 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -1,5 +1,5 @@
 /* Liveness for SSA trees.
-   Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010
+   Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
    Contributed by Andrew MacLeod <amacleod@redhat.com>
 
@@ -374,7 +374,8 @@ mark_all_vars_used_1 (tree *tp, int *walk_subtrees, void *data)
      eliminated as unused.  */
   if (TREE_CODE (t) == VAR_DECL)
     {
-      if (data != NULL && bitmap_clear_bit ((bitmap) data, DECL_UID (t)))
+      if (data != NULL && bitmap_clear_bit ((bitmap) data, DECL_UID (t))
+	  && DECL_CONTEXT (t) == current_function_decl)
 	mark_all_vars_used (&DECL_INITIAL (t), data);
       set_is_used (t);
     }
@@ -450,11 +451,8 @@ remove_unused_scope_block_p (tree scope)
       else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t))
 	unused = false;
 
-      /* Remove everything we don't generate debug info for.
-	 Don't remove larger vars though, because BLOCK_VARS are
-	 used also during expansion to determine which variables
-	 might share stack space.  */
-      else if (DECL_IGNORED_P (*t) && is_gimple_reg (*t))
+      /* Remove everything we don't generate debug info for.  */
+      else if (DECL_IGNORED_P (*t))
 	{
 	  *t = DECL_CHAIN (*t);
 	  next = t;
@@ -688,6 +686,7 @@ remove_unused_locals (void)
   referenced_var_iterator rvi;
   bitmap global_unused_vars = NULL;
   unsigned srcidx, dstidx, num;
+  bool have_local_clobbers = false;
 
   /* Removing declarations from lexical blocks when not optimizing is
      not only a waste of time, it actually causes differences in stack
@@ -720,6 +719,12 @@ remove_unused_locals (void)
 	  if (is_gimple_debug (stmt))
 	    continue;
 
+	  if (gimple_clobber_p (stmt))
+	    {
+	      have_local_clobbers = true;
+	      continue;
+	    }
+
 	  if (b)
 	    TREE_USED (b) = true;
 
@@ -753,6 +758,41 @@ remove_unused_locals (void)
 	  TREE_USED (e->goto_block) = true;
     }
 
+  /* We do a two-pass approach about the out-of-scope clobbers.  We want
+     to remove them if they are the only references to a local variable,
+     but we want to retain them when there's any other.  So the first pass
+     ignores them, and the second pass (if there were any) tries to remove
+     them.  */
+  if (have_local_clobbers)
+    FOR_EACH_BB (bb)
+      {
+	gimple_stmt_iterator gsi;
+
+	for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
+	  {
+	    gimple stmt = gsi_stmt (gsi);
+	    tree b = gimple_block (stmt);
+
+	    if (gimple_clobber_p (stmt))
+	      {
+		tree lhs = gimple_assign_lhs (stmt);
+		lhs = get_base_address (lhs);
+		if (TREE_CODE (lhs) == SSA_NAME)
+		  lhs = SSA_NAME_VAR (lhs);
+		if (DECL_P (lhs) && (!var_ann (lhs) || !is_used_p (lhs)))
+		  {
+		    unlink_stmt_vdef (stmt);
+		    gsi_remove (&gsi, true);
+		    release_defs (stmt);
+		    continue;
+		  }
+		if (b)
+		  TREE_USED (b) = true;
+	      }
+	    gsi_next (&gsi);
+	  }
+      }
+
   cfun->has_local_explicit_reg_vars = false;
 
   /* Remove unmarked local vars from local_decls.  */
@@ -794,7 +834,8 @@ remove_unused_locals (void)
 	if (TREE_CODE (var) == VAR_DECL
 	    && is_global_var (var)
 	    && var_ann (var) != NULL
-	    && is_used_p (var))
+	    && is_used_p (var)
+	    && DECL_CONTEXT (var) == current_function_decl)
 	  mark_all_vars_used (&DECL_INITIAL (var), global_unused_vars);
 
       num = VEC_length (tree, cfun->local_decls);
@@ -820,8 +861,7 @@ remove_unused_locals (void)
     if (!is_global_var (t)
 	&& TREE_CODE (t) != PARM_DECL
 	&& TREE_CODE (t) != RESULT_DECL
-	&& !is_used_p (t)
-	&& !var_ann (t)->is_heapvar)
+	&& !is_used_p (t))
       remove_referenced_var (t);
   remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
   if (dump_file && (dump_flags & TDF_DETAILS))