re PR target/23071 (Darwin alignment ignores "attribute packed" for first…

re PR target/23071 (Darwin alignment ignores "attribute packed" for first 'double' element of a struct)

	PR target/23071
	* config/rs6000/rs6000.c (darwin_rs6000_special_round_type_align):
	Don't overly align based upon packed packed fields.

From-SVN: r157654

gcc/ChangeLog

+2010-03-22  Mike Stump  <mikestump@comcast.net>
+
+	PR target/23071
+	* config/rs6000/rs6000.c (darwin_rs6000_special_round_type_align):
+	Don't overly align based upon packed packed fields.
+
 2010-03-22  Jason Merrill  <jason@redhat.com>
 
 	* c-pretty-print.c (pp_c_specifier_qualifier_list) [VECTOR_TYPE]:

gcc/config/rs6000/rs6000.c

@@ -4653,6 +4653,9 @@ darwin_rs6000_special_round_type_align (tree type, unsigned int computed,
       field = TREE_CHAIN (field);
     if (! field)
       break;
+    /* A packed field does not contribute any extra alignment.  */
+    if (DECL_PACKED (field))
+      return align;
     type = TREE_TYPE (field);
     while (TREE_CODE (type) == ARRAY_TYPE)
       type = TREE_TYPE (type);

gcc/testsuite/gcc.target/powerpc/darwin-abi-12.c

+/* { dg-do compile { target powerpc*-*-darwin* } } */
+/* { dg-final { scan-assembler ".comm _x,12,2" } } */
+/* { dg-final { scan-assembler-not ".space 7" } } */
+/* PR 23071 */
+
+struct Test {
+  double D __attribute__((packed,aligned(4)));
+  short X;
+} x;
+
+struct {
+  char x;
+  struct Test t;
+} b = { 1, { 2, 3 } };