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Patch to remove excess NOP stripping


Where an integer constant expression is expected in the C front end,
there is no need to strip NOPs as such an expression will already have
been parsed and folded to an INTEGER_CST (as indeed will many
expressions which are not integer constant expressions): you won't get
INTEGER_CSTs encapsulated in NOP_EXPRs in such circumstances; the same 
applied also to code shared with C++ (attribute handlers).  This
patch removes various such unnecessary NOP stripping.  Bootstrapped
with no regressions on x86_64-unknown-linux-gnu.  Applied to mainline.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
    jsm@polyomino.org.uk (personal mail)
    joseph@codesourcery.com (CodeSourcery mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)

2005-03-20  Joseph S. Myers  <joseph@codesourcery.com>

	* c-common.c (handle_aligned_attribute, check_function_sentinel,
	get_nonnull_operand, handle_sentinel_attribute,
	check_function_arguments_recurse): Do not strip NOPS from
	INTEGER_CSTs.
	* c-decl.c (check_bitfield_type_and_width, build_enumerator):
	Likewise.
	* c-format.c (get_constant): Likewise.
	* c-parser.c (c_parser_postfix_expression): Likewise.
	* c-typeck.c (set_init_index): Likewise.
	(convert_arguments): Don't check for NOP_EXPR containing integer
	constant.

diff -rupN GCC.orig/gcc/c-common.c GCC/gcc/c-common.c
--- GCC.orig/gcc/c-common.c	2005-03-18 20:45:08.000000000 +0000
+++ GCC/gcc/c-common.c	2005-03-20 02:33:59.000000000 +0000
@@ -4481,12 +4481,6 @@ handle_aligned_attribute (tree *node, tr
   else if (TYPE_P (*node))
     type = node, is_type = 1;
 
-  /* Strip any NOPs of any kind.  */
-  while (TREE_CODE (align_expr) == NOP_EXPR
-	 || TREE_CODE (align_expr) == CONVERT_EXPR
-	 || TREE_CODE (align_expr) == NON_LVALUE_EXPR)
-    align_expr = TREE_OPERAND (align_expr, 0);
-
   if (TREE_CODE (align_expr) != INTEGER_CST)
     {
       error ("requested alignment is not a constant");
@@ -5119,7 +5113,6 @@ check_function_sentinel (tree attrs, tre
 	  if (TREE_VALUE (attr))
 	    {
 	      tree p = TREE_VALUE (TREE_VALUE (attr));
-	      STRIP_NOPS (p);
 	      pos = TREE_INT_CST_LOW (p);
 	    }
 
@@ -5199,13 +5192,7 @@ check_nonnull_arg (void * ARG_UNUSED (ct
 static bool
 get_nonnull_operand (tree arg_num_expr, unsigned HOST_WIDE_INT *valp)
 {
-  /* Strip any conversions from the arg number and verify they
-     are constants.  */
-  while (TREE_CODE (arg_num_expr) == NOP_EXPR
-	 || TREE_CODE (arg_num_expr) == CONVERT_EXPR
-	 || TREE_CODE (arg_num_expr) == NON_LVALUE_EXPR)
-    arg_num_expr = TREE_OPERAND (arg_num_expr, 0);
-
+  /* Verify the arg number is a constant.  */
   if (TREE_CODE (arg_num_expr) != INTEGER_CST
       || TREE_INT_CST_HIGH (arg_num_expr) != 0)
     return false;
@@ -5324,7 +5311,6 @@ handle_sentinel_attribute (tree *node, t
     {
       tree position = TREE_VALUE (args);
 
-      STRIP_NOPS (position);
       if (TREE_CODE (position) != INTEGER_CST)
         {
 	  warning ("requested position is not an integer constant");
@@ -5402,10 +5388,6 @@ check_function_arguments_recurse (void (
 	    /* Extract the argument number, which was previously checked
 	       to be valid.  */
 	    format_num_expr = TREE_VALUE (TREE_VALUE (attrs));
-	    while (TREE_CODE (format_num_expr) == NOP_EXPR
-		   || TREE_CODE (format_num_expr) == CONVERT_EXPR
-		   || TREE_CODE (format_num_expr) == NON_LVALUE_EXPR)
-	      format_num_expr = TREE_OPERAND (format_num_expr, 0);
 
 	    gcc_assert (TREE_CODE (format_num_expr) == INTEGER_CST
 			&& !TREE_INT_CST_HIGH (format_num_expr));
diff -rupN GCC.orig/gcc/c-decl.c GCC/gcc/c-decl.c
--- GCC.orig/gcc/c-decl.c	2005-03-20 01:48:47.000000000 +0000
+++ GCC/gcc/c-decl.c	2005-03-20 02:30:52.000000000 +0000
@@ -3637,9 +3637,6 @@ check_bitfield_type_and_width (tree *typ
   unsigned HOST_WIDE_INT w;
   const char *name = orig_name ? orig_name: _("<anonymous>");
 
-  /* Necessary?  */
-  STRIP_NOPS (*width);
-
   /* Detect and ignore out of range field width and process valid
      field widths.  */
   if (!INTEGRAL_TYPE_P (TREE_TYPE (*width))
@@ -5624,10 +5621,6 @@ build_enumerator (tree name, tree value)
 
   /* Validate and default VALUE.  */
 
-  /* Remove no-op casts from the value.  */
-  if (value)
-    STRIP_TYPE_NOPS (value);
-
   if (value != 0)
     {
       /* Don't issue more errors for error_mark_node (i.e. an
diff -rupN GCC.orig/gcc/c-format.c GCC/gcc/c-format.c
--- GCC.orig/gcc/c-format.c	2005-03-18 20:45:08.000000000 +0000
+++ GCC/gcc/c-format.c	2005-03-20 02:35:07.000000000 +0000
@@ -147,17 +147,12 @@ check_format_string (tree argument, unsi
   return true;
 }
 
-/* Strip any conversions from the expression, verify it is a constant,
-   and store its value. If validated_p is true, abort on errors.
+/* Verify EXPR is a constant, and store its value.
+   If validated_p is true, abort on errors.
    Returns true on success, false otherwise.  */
 static bool
 get_constant (tree expr, unsigned HOST_WIDE_INT *value, int validated_p)
 {
-  while (TREE_CODE (expr) == NOP_EXPR
-	 || TREE_CODE (expr) == CONVERT_EXPR
-	 || TREE_CODE (expr) == NON_LVALUE_EXPR)
-    expr = TREE_OPERAND (expr, 0);
-
   if (TREE_CODE (expr) != INTEGER_CST || TREE_INT_CST_HIGH (expr) != 0)
     {
       gcc_assert (!validated_p);
diff -rupN GCC.orig/gcc/c-parser.c GCC/gcc/c-parser.c
--- GCC.orig/gcc/c-parser.c	2005-03-13 01:07:03.000000000 +0000
+++ GCC/gcc/c-parser.c	2005-03-20 02:35:30.000000000 +0000
@@ -5019,7 +5019,6 @@ c_parser_postfix_expression (c_parser *p
 	    tree c;
 
 	    c = fold (e1.value);
-	    STRIP_NOPS (c);
 	    if (TREE_CODE (c) != INTEGER_CST)
 	      error ("first argument to %<__builtin_choose_expr%> not"
 		     " a constant");
diff -rupN GCC.orig/gcc/c-typeck.c GCC/gcc/c-typeck.c
--- GCC.orig/gcc/c-typeck.c	2005-03-18 20:45:08.000000000 +0000
+++ GCC/gcc/c-typeck.c	2005-03-20 02:40:28.000000000 +0000
@@ -2234,11 +2234,6 @@ convert_arguments (tree typelist, tree v
 			/* Change in signedness doesn't matter
 			   if a constant value is unaffected.  */
 			;
-		      /* Likewise for a constant in a NOP_EXPR.  */
-		      else if (TREE_CODE (val) == NOP_EXPR
-			       && TREE_CODE (TREE_OPERAND (val, 0)) == INTEGER_CST
-			       && int_fits_type_p (TREE_OPERAND (val, 0), type))
-			;
 		      /* If the value is extended from a narrower
 			 unsigned type, it doesn't matter whether we
 			 pass it as signed or unsigned; the value
@@ -5205,21 +5200,6 @@ set_init_index (tree first, tree last)
       return;
     }
 
-  while ((TREE_CODE (first) == NOP_EXPR
-	  || TREE_CODE (first) == CONVERT_EXPR
-	  || TREE_CODE (first) == NON_LVALUE_EXPR)
-	 && (TYPE_MODE (TREE_TYPE (first))
-	     == TYPE_MODE (TREE_TYPE (TREE_OPERAND (first, 0)))))
-    first = TREE_OPERAND (first, 0);
-
-  if (last)
-    while ((TREE_CODE (last) == NOP_EXPR
-	    || TREE_CODE (last) == CONVERT_EXPR
-	    || TREE_CODE (last) == NON_LVALUE_EXPR)
-	   && (TYPE_MODE (TREE_TYPE (last))
-	       == TYPE_MODE (TREE_TYPE (TREE_OPERAND (last, 0)))))
-      last = TREE_OPERAND (last, 0);
-
   if (TREE_CODE (first) != INTEGER_CST)
     error_init ("nonconstant array index in initializer");
   else if (last != 0 && TREE_CODE (last) != INTEGER_CST)


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