2004-10-06  Paolo Bonzini  <bonzini@gnu.org>

	PR target/17836

	* config/rs6000/rs6000.c (USE_ALTIVEC_FOR_ARG_P,
	init_cumulative_args, function_arg_boundary,
	function_arg_advance, function_arg, rs6000_gimplify_va_arg):
	Look into the type instead of using ALTIVEC_VECTOR_MODE.
	(rs6000_pass_by_reference): Same as above, plus warn
	for wide (>16 bytes) vector types and pass them by reference.
	(rs6000_return_in_memory): Return true for vectors
	above 16 bytes.

Index: rs6000.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/rs6000.c,v
retrieving revision 1.720
diff -u -r1.720 rs6000.c
--- rs6000.c	5 Oct 2004 12:43:53 -0000	1.720
+++ rs6000.c	7 Oct 2004 09:33:42 -0000
@@ -4531,7 +4531,9 @@
 
 /* Nonzero if we can use an AltiVec register to pass this arg.  */
 #define USE_ALTIVEC_FOR_ARG_P(CUM,MODE,TYPE,NAMED)	\
-  (ALTIVEC_VECTOR_MODE (MODE)				\
+  ((TYPE)						\
+   && TREE_CODE (TYPE) == VECTOR_TYPE			\
+   && int_size_in_bytes (TYPE) == 16			\
    && (CUM)->vregno <= ALTIVEC_ARG_MAX_REG		\
    && TARGET_ALTIVEC_ABI				\
    && (NAMED))
@@ -4564,6 +4566,12 @@
       && (TARGET_AIX_STRUCT_RET
 	  || (unsigned HOST_WIDE_INT) int_size_in_bytes (type) > 8))
     return true;
+  /* If TARGET_ALTIVEC is not set, we return 16-byte vectors in memory,
+     otherwise function.c tries to use a TImode register and we get
+     an unrecognizable insn.  */
+  if (TREE_CODE (type) == VECTOR_TYPE
+      && int_size_in_bytes (type) > (TARGET_ALTIVEC ? 16 : 8))
+    return true;
   if (DEFAULT_ABI == ABI_V4 && TYPE_MODE (type) == TFmode)
     return true;
   return false;
@@ -4626,7 +4634,8 @@
   if (fntype
       && !TARGET_ALTIVEC
       && TARGET_ALTIVEC_ABI
-      && ALTIVEC_VECTOR_MODE (TYPE_MODE (TREE_TYPE (fntype))))
+      && TREE_CODE (TREE_TYPE (fntype)) == VECTOR_TYPE
+      && int_size_in_bytes (TREE_TYPE (fntype)) == 16)
     {
       error ("Cannot return value in vector register because"
 	     " altivec instructions are disabled, use -maltivec"
@@ -4710,14 +4719,15 @@
    V.4 wants long longs to be double word aligned.  */
 
 int
-function_arg_boundary (enum machine_mode mode, tree type ATTRIBUTE_UNUSED)
+function_arg_boundary (enum machine_mode mode, tree type)
 {
   if (DEFAULT_ABI == ABI_V4 && GET_MODE_SIZE (mode) == 8)
     return 64;
-  else if (SPE_VECTOR_MODE (mode))
-    return 64;
-  else if (ALTIVEC_VECTOR_MODE (mode))
-    return 128;
+  else if (type
+	   && TREE_CODE (type) == VECTOR_TYPE
+	   && (int_size_in_bytes (type) == 8
+	       || int_size_in_bytes (type) == 16))
+    return 8 * int_size_in_bytes (type);
   else
     return PARM_BOUNDARY;
 }
@@ -4754,7 +4764,10 @@
 {
   cum->nargs_prototype--;
 
-  if (TARGET_ALTIVEC_ABI && ALTIVEC_VECTOR_MODE (mode))
+  if (TARGET_ALTIVEC_ABI
+      && type
+      && TREE_CODE (type) == VECTOR_TYPE
+      && int_size_in_bytes (type) == 16)
     {
       bool stack = false;
 
@@ -5057,7 +5070,10 @@
       }
     else
       return gen_rtx_REG (mode, cum->vregno);
-  else if (TARGET_ALTIVEC_ABI && ALTIVEC_VECTOR_MODE (mode))
+  else if (TARGET_ALTIVEC_ABI
+           && type
+	   && TREE_CODE (type) == VECTOR_TYPE
+	   && int_size_in_bytes (type) == 16)
     {
       if (named || abi == ABI_V4)
 	return NULL_RTX;
@@ -5296,25 +5312,64 @@
    As an extension to all 32-bit ABIs, AltiVec vectors are passed by
    reference unless the AltiVec vector extension ABI is in force.
 
-   As an extension to all ABIs, variable sized types are passed by
-   reference.  */
+   As an extension to all ABIs, variable sized types and vectors
+   wider than 16 bytes are passed by reference.  */
 
 static bool
-rs6000_pass_by_reference (CUMULATIVE_ARGS *cum ATTRIBUTE_UNUSED,
-			  enum machine_mode mode ATTRIBUTE_UNUSED,
-			  tree type, bool named ATTRIBUTE_UNUSED)
-{
-  if ((DEFAULT_ABI == ABI_V4
-       && ((type && AGGREGATE_TYPE_P (type))
-	   || mode == TFmode))
-      || (TARGET_32BIT && !TARGET_ALTIVEC_ABI && ALTIVEC_VECTOR_MODE (mode))
-      || (type && int_size_in_bytes (type) < 0))
+rs6000_pass_by_reference (CUMULATIVE_ARGS *cum ATTRIBUTE_UNUSED, 
+			  enum machine_mode mode, tree type,
+			  bool named ATTRIBUTE_UNUSED)
+{
+  if (DEFAULT_ABI == ABI_V4 && mode == TFmode)
+    {
+      if (TARGET_DEBUG_ARG)
+	fprintf (stderr, "function_arg_pass_by_reference: V4 long double\n");
+      return 1;
+    }
+
+  if (!type)
+    return 0;
+
+  if (DEFAULT_ABI == ABI_V4 && AGGREGATE_TYPE_P (type))
+    {
+      if (TARGET_DEBUG_ARG)
+	fprintf (stderr, "function_arg_pass_by_reference: V4 aggregates\n");
+      return 1;
+    }
+
+  if (TARGET_32BIT
+      && !TARGET_ALTIVEC_ABI
+      && TREE_CODE (type) == VECTOR_TYPE
+      && int_size_in_bytes (type) == 16)
     {
       if (TARGET_DEBUG_ARG)
-	fprintf (stderr, "function_arg_pass_by_reference\n");
+	fprintf (stderr, "function_arg_pass_by_reference: AltiVec\n");
+      return 1;
+    }
+
+  if (TREE_CODE (type) == VECTOR_TYPE
+      && int_size_in_bytes (type) > 16)
+    {
+      static int warned_for_big_vectors = false;
+      if (TARGET_DEBUG_ARG)
+	fprintf (stderr, "function_arg_pass_by_reference: vectors >16 bytes\n");
+      if (!warned_for_big_vectors)
+	{
+	  warning ("vectors bigger than 16 bytes are passed by reference: "
+		   "this may change in a future version of the ABI");
+	  warned_for_big_vectors = 1;
+	}
 
       return 1;
     }
+
+  if (int_size_in_bytes (type) == -1)
+    {
+      if (TARGET_DEBUG_ARG)
+	fprintf (stderr, "function_arg_pass_by_reference: variable size\n");
+      return 1;
+    }
+
   return 0;
 }
 
@@ -5646,7 +5701,9 @@
   DECL_POINTER_ALIAS_SET (addr) = get_varargs_alias_set ();
 
   /*  AltiVec vectors never go in registers when -mabi=altivec.  */
-  if (TARGET_ALTIVEC_ABI && ALTIVEC_VECTOR_MODE (TYPE_MODE (type)))
+  if (TARGET_ALTIVEC_ABI
+      && TREE_CODE (type) == VECTOR_TYPE
+      && int_size_in_bytes (type) == 16)
     align = 16;
   else
     {