From patchwork Thu Jan 12 23:09:29 2012
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Subject: useless_type_conversion_p vs pointer sizes
Date: Thu, 12 Jan 2012 13:09:29 -0000
From: DJ Delorie <dj@redhat.com>
X-Patchwork-Id: 135695
Message-Id: <201201122309.q0CN9T8o027553@greed.delorie.com>
To: gcc-patches@gcc.gnu.org

Another case where one address space may support multiple pointer
sizes, so conversions between such must be preserved.

	* tree-ssa.c (useless_type_conversion_p): Conversions between
	different-sized pointers aren't useless.


Index: tree-ssa.c
===================================================================
--- tree-ssa.c	(revision 183139)
+++ tree-ssa.c	(working copy)
@@ -1192,12 +1192,17 @@ bool
 useless_type_conversion_p (tree outer_type, tree inner_type)
 {
   /* Do the following before stripping toplevel qualifiers.  */
   if (POINTER_TYPE_P (inner_type)
       && POINTER_TYPE_P (outer_type))
     {
+      /* Do not lose casts between pointers of different precision.  */
+      if (TYPE_PRECISION (outer_type)
+	  != TYPE_PRECISION (inner_type))
+	return false;
+
       /* Do not lose casts between pointers to different address spaces.  */
       if (TYPE_ADDR_SPACE (TREE_TYPE (outer_type))
 	  != TYPE_ADDR_SPACE (TREE_TYPE (inner_type)))
 	return false;
 
       /* If the outer type is (void *), the conversion is not necessary.  */