* tree-ssa-live.c (remove_unused_scope_block_p): Keep variables

[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa-live.c

diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 0673fab..c7366ff 100644 (file)
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -435,6 +435,17 @@ remove_unused_scope_block_p (tree scope)
         will be output to file.  */
       if (TREE_CODE (*t) == FUNCTION_DECL)
        unused = false;
+
+      /* If a decl has a value expr, we need to instantiate it
+        regardless of debug info generation, to avoid codegen
+        differences in memory overlap tests.  update_equiv_regs() may
+        indirectly call validate_equiv_mem() to test whether a
+        SET_DEST overlaps with others, and if the value expr changes
+        by virtual register instantiation, we may get end up with
+        different results.  */
+      else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t))
+       unused = false;
+
       /* Remove everything we don't generate debug info for.  */
       else if (DECL_IGNORED_P (*t))
        {
@@ -552,7 +563,9 @@ mark_all_vars_used (tree *expr_p, void *data)
   walk_tree (expr_p, mark_all_vars_used_1, data, NULL);
 }
 
-/* Dump scope blocks.  */
+
+/* Dump scope blocks starting at SCOPE to FILE.  INDENT is the
+   indentation level and FLAGS is as in print_generic_expr.  */
 
 static void
 dump_scope_block (FILE *file, int indent, tree scope, int flags)
@@ -606,12 +619,26 @@ dump_scope_block (FILE *file, int indent, tree scope, int flags)
   fprintf (file, "\n%*s}\n",indent, "");
 }
 
+
+/* Dump the tree of lexical scopes of current_function_decl to FILE.
+   FLAGS is as in print_generic_expr.  */
+
 void
 dump_scope_blocks (FILE *file, int flags)
 {
   dump_scope_block (file, 0, DECL_INITIAL (current_function_decl), flags);
 }
 
+
+/* Dump the tree of lexical scopes of current_function_decl to stderr.
+   FLAGS is as in print_generic_expr.  */
+
+void
+debug_scope_blocks (int flags)
+{
+  dump_scope_blocks (stderr, flags);
+}
+
 /* Remove local variables that are not referenced in the IL.  */
 
 void
@@ -623,6 +650,12 @@ remove_unused_locals (void)
   var_ann_t ann;
   bitmap global_unused_vars = NULL;
 
+  /* Removing declarations from lexical blocks when not optimizing is
+     not only a waste of time, it actually causes differences in stack
+     layout.  */
+  if (!optimize)
+    return;
+
   mark_scope_block_unused (DECL_INITIAL (current_function_decl));
 
   /* Assume all locals are unused.  */
@@ -685,8 +718,7 @@ remove_unused_locals (void)
 
       if (TREE_CODE (var) != FUNCTION_DECL
          && (!(ann = var_ann (var))
-             || !ann->used)
-         && (optimize || DECL_ARTIFICIAL (var)))
+             || !ann->used))
        {
          if (is_global_var (var))
            {
@@ -745,8 +777,7 @@ remove_unused_locals (void)
        && TREE_CODE (t) != PARM_DECL
        && TREE_CODE (t) != RESULT_DECL
        && !(ann = var_ann (t))->used
-       && !TREE_ADDRESSABLE (t)
-       && (optimize || DECL_ARTIFICIAL (t)))
+       && !TREE_ADDRESSABLE (t))
       remove_referenced_var (t);
   remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
   if (dump_file && (dump_flags & TDF_DETAILS))