re PR target/28207 (128-bit IBM long double misaligned on stack)

	PR target/28207
	* config/rs6000/rs6000.c (function_arg_boundary): Double-word align
	128-bit IBM long doubles for ABI_V4.

From-SVN: r115170

gcc/ChangeLog

+2006-07-04  Alan Modra  <amodra@bigpond.net.au>
+
+	PR target/28207
+	* config/rs6000/rs6000.c (function_arg_boundary): Double-word align
+	128-bit IBM long doubles for ABI_V4.
+
 2006-07-03  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* tree.c (range_in_array_bounds_p): New predicate.

gcc/config/rs6000/rs6000.c

@@ -4485,7 +4485,12 @@ function_arg_padding (enum machine_mode mode, tree type)
    of an argument with the specified mode and type.  If it is not defined,
    PARM_BOUNDARY is used for all arguments.
 
-   V.4 wants long longs to be double word aligned.
+   V.4 wants long longs and doubles to be double word aligned.  Just
+   testing the mode size is a boneheaded way to do this as it means
+   that other types such as complex int are also double word aligned.
+   However, we're stuck with this because changing the ABI might break
+   existing library interfaces.
+
    Doubleword align SPE vectors.
    Quadword align Altivec vectors.
    Quadword align large synthetic vector types.   */
@@ -4493,7 +4498,11 @@ function_arg_padding (enum machine_mode mode, tree type)
 int
 function_arg_boundary (enum machine_mode mode, tree type)
 {
-  if (DEFAULT_ABI == ABI_V4 && GET_MODE_SIZE (mode) == 8)
+  if (DEFAULT_ABI == ABI_V4
+      && (GET_MODE_SIZE (mode) == 8
+	  || (TARGET_HARD_FLOAT
+	      && TARGET_FPRS
+	      && mode == TFmode)))
     return 64;
   else if (SPE_VECTOR_MODE (mode)
 	   || (type && TREE_CODE (type) == VECTOR_TYPE