[PATCH] Fix stack_protect_classify_type

[Jakub Jelinek]

Hi!

stack_protect_classify_type considers char arrays whose max value of the
array domain is smaller than --param ssp-buffer-size.
But this doesn't correspond with -Wstack-protector, where the warning
says:
      if (has_short_buffer && !cfun->stack_protect_guard)
        warning (0, "not protecting function: no buffer at least %d bytes long",
                 (int) PARAM_VALUE (PARAM_SSP_BUFFER_SIZE));
The following patch changes stack_protect_classify_type to use
TYPE_SIZE_UNIT instead, which is array size in bytes.  As host_integerp
is used with second argument 1, I have also used unsigned HOST_WIDE_INT
instead of HOST_WIDE_INT.
With this patch, char buf[8] with the default ssp-buffer-size param (8)
will already use the stack canary, while with --param ssp-buffer-size=9
it will not.

Ok to commit?

2005-07-09  Jakub Jelinek  <jakub@redhat.com>

	* cfgexpand.c (stack_protect_classify_type): Use TYPE_SIZE_UNIT (type)
	instead of TYPE_MAX_VALUE (TYPE_DOMAIN (type)) to get array size in
	bytes.

--- gcc/cfgexpand.c.jj	2005-07-09 21:20:07.000000000 +0200
+++ gcc/cfgexpand.c	2005-07-09 21:40:41.000000000 +0200
@@ -770,15 +770,14 @@ stack_protect_classify_type (tree type)
 	  || t == signed_char_type_node
 	  || t == unsigned_char_type_node)
 	{
-	  HOST_WIDE_INT max = PARAM_VALUE (PARAM_SSP_BUFFER_SIZE);
-	  HOST_WIDE_INT len;
+	  unsigned HOST_WIDE_INT max = PARAM_VALUE (PARAM_SSP_BUFFER_SIZE);
+	  unsigned HOST_WIDE_INT len;
 
-	  if (!TYPE_DOMAIN (type)
-	      || !TYPE_MAX_VALUE (TYPE_DOMAIN (type))
-	      || !host_integerp (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 1))
-	    len = max + 1;
+	  if (!TYPE_SIZE_UNIT (type)
+	      || !host_integerp (TYPE_SIZE_UNIT (type), 1))
+	    len = max;
 	  else
-	    len = tree_low_cst (TYPE_MAX_VALUE (TYPE_DOMAIN (type)), 1);
+	    len = tree_low_cst (TYPE_SIZE_UNIT (type), 1);
 
 	  if (len < max)
 	    ret = SPCT_HAS_SMALL_CHAR_ARRAY | SPCT_HAS_ARRAY;

	Jakub