Re: [RFC/RFT] Tree-level lowering of generic vectors, part 2

[Paolo Bonzini <paolo dot bonzini at polimi dot it>]

> 	Any ideas on how to correct this problem?

This is caused by vector modes introducing a new beast: non-aggregate 
types of BLKmode.  This conflicts with the implementation of the 
return_in_memory target hook in a couple of targets, one of which is rs6000.

The attached patch is an update of 
http://gcc.gnu.org/ml/gcc-patches/2004-07/msg02197.html which takes care 
of this as well.  I checked manually that vector-2 now compiles at all 
optimization levels.

Here is the situation.

Target which are not ok
-----------------------

pdp11: ?? should we care ??

rs6000: aggregates are passed in memory if bigger than 8 bytes, but 
vectors are not.

Targets which are ok
--------------------

alpha: FP vectors passed in memory, int vectors only if bigger than a word

arc, arm, avr, h8300, ip2k, iq2000, m32r, m68hc11, mcore, pa, stormy16, 
xtensa: vectors passed in memory if bigger than a fixed threshold, 
typically 4/8/16 bytes

i386, mn10300, sh, sparc, v850: BLKmode stuff always passed in memory

mips: One of the above two depending on the ABI (no wonder...)

ia64: not sure about whether it is ok, but it has a fixed threshold 
above which values are passed in memory... from looking at 
function_value, it knows how to cope with BLKmode and it treats 
aggregates and non-aggregates the same

s390: vectors always passed in memory

Paolo

2004-07-22  Paolo Bonzini  <bonzini@gnu.org>

	* config/rs6000/rs6000.c (USE_ALTIVEC_FOR_ARG_P,
	init_cumulative_args, function_arg_boundary,
	function_arg_advance, function_arg,
	rs6000_pass_by_reference, rs6000_gimplify_va_arg):
	Look into the type instead of using
	ALTIVEC_VECTOR_MODE.
	(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 1.678
diff -u -p -r1.678 rs6000.c
--- rs6000.c	4 Aug 2004 23:38:34 -0000	1.678
+++ rs6000.c	6 Aug 2004 08:06:14 -0000
@@ -4432,7 +4432,9 @@ rs6000_emit_move (rtx dest, rtx source, 
 
 /* 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))
@@ -4465,6 +4467,9 @@ rs6000_return_in_memory (tree type, tree
       && (TARGET_AIX_STRUCT_RET
 	  || (unsigned HOST_WIDE_INT) int_size_in_bytes (type) > 8))
     return true;
+  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;
@@ -4527,7 +4532,8 @@ init_cumulative_args (CUMULATIVE_ARGS *c
     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"
@@ -4615,14 +4621,15 @@ function_arg_padding (enum machine_mode 
    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;
 }
@@ -4659,7 +4666,10 @@ function_arg_advance (CUMULATIVE_ARGS *c
 {
   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;
 
@@ -4962,7 +4972,10 @@ function_arg (CUMULATIVE_ARGS *cum, enum
       }
     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;
@@ -5195,13 +5208,17 @@ function_arg_partial_nregs (CUMULATIVE_A
 
 static bool
 rs6000_pass_by_reference (CUMULATIVE_ARGS *cum ATTRIBUTE_UNUSED, 
-			  enum machine_mode mode ATTRIBUTE_UNUSED, 
-			  tree type, bool named ATTRIBUTE_UNUSED)
+			  enum machine_mode mode, 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))
+      || (TARGET_32BIT
+	  && !TARGET_ALTIVEC_ABI
+	  && type
+	  && TREE_CODE (type) == VECTOR_TYPE
+	  && int_size_in_bytes (type) == 16)
       || (type && int_size_in_bytes (type) < 0))
     {
       if (TARGET_DEBUG_ARG)
@@ -5540,7 +5557,9 @@ rs6000_gimplify_va_arg (tree valist, tre
   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
     {