re PR ada/35186 (implicit assumption about alignment of DImode)

	PR ada/35186
	* decl.c (maybe_pad_type): Avoid padding an integral type when
	bumping its alignment is sufficient.

From-SVN: r132963

gcc/ada/ChangeLog

+2008-03-05  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR ada/35186
+	* decl.c (maybe_pad_type): Avoid padding an integral type when
+	bumping its alignment is sufficient.
+
 2008-03-02  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
 	* gnatfind.adb, gnatxref.adb: Fix argument parsing typos.

gcc/ada/decl.c

@@ -5301,7 +5301,6 @@ maybe_pad_type (tree type, tree size, unsigned int align,
      off the padding, since we will either be returning the inner type
      or repadding it.  If no size or alignment is specified, use that of
      the original padded type.  */
-
   if (TREE_CODE (type) == RECORD_TYPE && TYPE_IS_PADDING_P (type))
     {
       if ((!size
@@ -5326,7 +5325,6 @@ maybe_pad_type (tree type, tree size, unsigned int align,
      is not done here (and is only valid for bitfields anyway), show the size
      isn't changing.  Likewise, clear the alignment if it isn't being
      changed.  Then return if we aren't doing anything.  */
-
   if (size
       && (operand_equal_p (size, orig_size, 0)
 	  || (TREE_CODE (orig_size) == INTEGER_CST
@@ -5339,6 +5337,19 @@ maybe_pad_type (tree type, tree size, unsigned int align,
   if (align == 0 && !size)
     return type;
 
+  /* If no size is specified and we have an integral type, and changing
+     the alignment won't change its size, return a copy of the type
+     with the specified alignment.  */
+  if (!size
+      && INTEGRAL_TYPE_P (type)
+      && host_integerp (orig_size, 1)
+      && (TREE_INT_CST_LOW (orig_size) % align) == 0)
+    {
+      type = copy_type (type);
+      TYPE_ALIGN (type) = align;
+      return type;
+    }
+
   /* We used to modify the record in place in some cases, but that could
      generate incorrect debugging information.  So make a new record
      type and name.  */

gcc/testsuite/ChangeLog

+2008-03-05  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/specs/pack33.ads: New test.
+
 2008-03-05  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/35472

gcc/testsuite/gnat.dg/specs/pack33.ads

+-- { dg-do compile }
+
+package Pack33 is
+
+   Bits : constant := 33;
+
+   type Bits_33 is mod 2 ** Bits;
+   for Bits_33'Size use Bits;
+
+   type Cluster is record
+      E0, E1, E2, E3, E4, E5, E6, E7 : Bits_33;
+   end record;
+
+   for Cluster use record
+      E0 at 0 range 0 * Bits .. 0 * Bits + Bits - 1;
+      E1 at 0 range 1 * Bits .. 1 * Bits + Bits - 1;
+      E2 at 0 range 2 * Bits .. 2 * Bits + Bits - 1;
+      E3 at 0 range 3 * Bits .. 3 * Bits + Bits - 1;
+      E4 at 0 range 4 * Bits .. 4 * Bits + Bits - 1;
+      E5 at 0 range 5 * Bits .. 5 * Bits + Bits - 1;
+      E6 at 0 range 6 * Bits .. 6 * Bits + Bits - 1;
+      E7 at 0 range 7 * Bits .. 7 * Bits + Bits - 1;
+   end record;
+
+   for Cluster'Size use Bits * 8;
+
+end Pack33;