From ac79cd5ab9b4c4c32725845ef3a2c91e29e67f7e Mon Sep 17 00:00:00 2001
From: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Date: Tue, 27 Nov 2001 14:31:29 +0000
Subject: Makefile.in (c-lang.o): Depends on langhooks-def.h.

	* Makefile.in (c-lang.o): Depends on langhooks-def.h.
	(expr.o, varasm.o): Depends on langhooks.h.
	* c-common.c (c_safe_from_p): Always declare.
	(c_expand_expr): Refine when declared.
	* c-lang.c (c-common.h): Now include.
	(LANG_HOOKS_SAFE_FROM_P): Define new hook.
	(c_init): Don't set lang_safe_from_expr.
	* expr.c (langhooks.h): Now include.
	(lang_safe_from_p): No longer define.
	(safe_from_p): Use lang hook.
	(expand_expr): Set IGNORE if VOID_TYPE result of VIEW_CONVERT_EXPR too.
	(expand_expr, case VIEW_CONVERT_EXPR): Pass ro_modifier down.
	* expr.h (lang_expand_constant, lang_safe_from_p): Delete.
	* langhooks-def.h (lhd_return_tree, lhd_safe_from_p): New decls.
	(LANG_HOOKS_EXPAND_CONSTANT, LANG_HOOKS_SAFE_FROM_P): New hooks.
	* langhooks.c (lhd_return_tree, lhd_safe_from_p): New functions.
	* langhooks.h (struct lang_hooks): New fields expand_constant
	and safe_from_p.
	* output.h (output_constant): Size arg is HOST_WIDE_INT.
	* stmt.c (expand_decl_init): No longer need to expand constant
	for CONST_DECL.
	* stor-layout.c (put_pending_size): Don't check for SAVE_EXPR.
	* toplev.c (lang_expand_constant): Delete var.
	* tree.c (save_expr): Don't put another SAVE_EXPR around simple
	operations on SAVE_EXPR.
	* varasm.c (langhooks.h): Now include.
	(compare_constant_1): Use lang_hooks, not lang_expand_constant.
	(record_constant_1, output_addressed_constants): Likewise.
	(initializer_constant_valid_p, output_constant): Likewise.
	(output_constant_def): Process no-defer of string constant.
	(output_addressed_constants, case ADDR_EXPR): Use handled_component_p.
	(output_constant): Strip more conversions.
	Track our size and pad for the rest.
	(array_size_for_constructor): Remove code for non-byte STRING_CST.
	(output_constructor): SIZE now HOST_WIDE_INT.
	* cp/Make-lang.in (cp-lang.o): Depends on c-common.h.
	* cp/cp-lang.c (c-common.h): Include.
	(LANG_HOOKS_EXPAND_CONSTANT, LANG_HOOKS_SAFE_FROM_P): New hooks.
	* cp/decl.c (cxx_init_decl_processing): Don't set lang_safe_from_p.
	* cp/expr.c (init_cplus_expand): Don't set lang_expand_constant.

From-SVN: r47376
---
 gcc/tree.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

(limited to 'gcc/tree.c')

diff --git a/gcc/tree.c b/gcc/tree.c
index 1b6dc79..b86a339 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1549,20 +1549,33 @@ save_expr (expr)
      tree expr;
 {
   tree t = fold (expr);
+  tree inner;
 
   /* We don't care about whether this can be used as an lvalue in this
      context.  */
   while (TREE_CODE (t) == NON_LVALUE_EXPR)
     t = TREE_OPERAND (t, 0);
 
+
+  /* If we have simple operations applied to a SAVE_EXPR or to a SAVE_EXPR and
+     a constant, it will be more efficient to not make another SAVE_EXPR since
+     it will allow better simplification and GCSE will be able to merge the
+     computations if they actualy occur.  */
+  for (inner = t;
+       (TREE_CODE_CLASS (TREE_CODE (inner)) == '1'
+	|| (TREE_CODE_CLASS (TREE_CODE (inner)) == '2'
+	    && TREE_CONSTANT (TREE_OPERAND (inner, 1))));
+       inner = TREE_OPERAND (inner, 0))
+    ;
+
   /* If the tree evaluates to a constant, then we don't want to hide that
      fact (i.e. this allows further folding, and direct checks for constants).
      However, a read-only object that has side effects cannot be bypassed.
      Since it is no problem to reevaluate literals, we just return the
      literal node.  */
-
-  if (TREE_CONSTANT (t) || (TREE_READONLY (t) && ! TREE_SIDE_EFFECTS (t))
-      || TREE_CODE (t) == SAVE_EXPR || TREE_CODE (t) == ERROR_MARK)
+  if (TREE_CONSTANT (inner)
+      || (TREE_READONLY (inner) && ! TREE_SIDE_EFFECTS (inner))
+      || TREE_CODE (inner) == SAVE_EXPR || TREE_CODE (inner) == ERROR_MARK)
     return t;
 
   /* If T contains a PLACEHOLDER_EXPR, we must evaluate it each time, since
-- 
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