tm.texi (FUNCTION_ARG_REG_LITTLE_ENDIAN): New.

2001-12-11  Steve Ellcey  <sje@cup.hp.com>

	* doc/tm.texi (FUNCTION_ARG_REG_LITTLE_ENDIAN): New.
	* defaults.h (FUNCTION_ARG_REG_LITTLE_ENDIAN): New.
	* calls.c (store_unaligned_arguments_into_pseudos): Check
	FUNCTION_ARG_REG_LITTLE_ENDIAN to see how structures
	are passed/returned.
	* expr.c (move_block_from_reg): Ditto.
	(move_block_from_reg): Ditto.
	(copy_blkmode_from_reg): Ditto.
	* stmt.c (expand_return): Ditto.
	* stor-layout.c (compute_record_mode): If
	FUNCTION_ARG_REG_LITTLE_ENDIAN is set then check
	MEMBER_TYPE_FORCES_BLK even if mode == VOIDmode.
	* config/ia64/hpux.h (MEMBER_TYPE_FORCES_BLK): Set to true
	so that Structures of one field are still treated as structures.
	(FUNCTION_ARG_REG_LITTLE_ENDIAN): New, set it to true.
	(FUNCTION_ARG_PADDING): Set to ia64_hpux_function_arg_padding().
	(PAD_VARARGS_DOWN): Modify from default to not pad structures down.
	* config/ia64/ia64-protos.h (ia64_hpux_function_arg_padding): New.
	* config/ia64/ia64.c (ia64_hpux_function_arg_padding): New function
	to special case handling of structure padding.

From-SVN: r47904

gcc/ChangeLog

+2001-12-11  Steve Ellcey  <sje@cup.hp.com>
+
+	* doc/tm.texi (FUNCTION_ARG_REG_LITTLE_ENDIAN): New.
+	* defaults.h (FUNCTION_ARG_REG_LITTLE_ENDIAN): New.
+	* calls.c (store_unaligned_arguments_into_pseudos): Check
+	FUNCTION_ARG_REG_LITTLE_ENDIAN to see how structures
+	are passed/returned.
+	* expr.c (move_block_from_reg): Ditto.
+	(move_block_from_reg): Ditto.
+	(copy_blkmode_from_reg): Ditto.
+	* stmt.c (expand_return): Ditto.
+	* stor-layout.c (compute_record_mode): If
+	FUNCTION_ARG_REG_LITTLE_ENDIAN is set then check 
+	MEMBER_TYPE_FORCES_BLK even if mode == VOIDmode.
+	* config/ia64/hpux.h (MEMBER_TYPE_FORCES_BLK): Set to true
+	so that Structures of one field are still treated as structures.
+	(FUNCTION_ARG_REG_LITTLE_ENDIAN): New, set it to true.
+	(FUNCTION_ARG_PADDING): Set to ia64_hpux_function_arg_padding().
+	(PAD_VARARGS_DOWN): Modify from default to not pad structures down.
+	* config/ia64/ia64-protos.h (ia64_hpux_function_arg_padding): New.
+	* config/ia64/ia64.c (ia64_hpux_function_arg_padding): New function
+	to special case handling of structure padding.
+
 2001-12-11  Daniel Berlin  <dan@cgsoftware.com>
 
 	* sched-rgn.c (CONST_BASED_ADDRESS_P): CONST_INT -> CONSTANT_P.

gcc/calls.c

@@ -1029,7 +1029,9 @@ store_unaligned_arguments_into_pseudos (args, num_actuals)
 	   significant byte (to the right).  On a BYTES_BIG_ENDIAN machine,
 	   this means we must skip the empty high order bytes when
 	   calculating the bit offset.  */
-	if (BYTES_BIG_ENDIAN && bytes < UNITS_PER_WORD)
+	if (BYTES_BIG_ENDIAN
+	    && !FUNCTION_ARG_REG_LITTLE_ENDIAN
+	    && bytes < UNITS_PER_WORD)
 	  big_endian_correction = (BITS_PER_WORD  - (bytes * BITS_PER_UNIT));
 
 	for (j = 0; j < args[i].n_aligned_regs; j++)

gcc/config/ia64/hpux.h

@@ -95,3 +95,30 @@ Boston, MA 02111-1307, USA.  */
 
 #undef TARGET_DEFAULT
 #define TARGET_DEFAULT (MASK_DWARF2_ASM | MASK_BIG_ENDIAN)
+
+/* This needs to be set to force structure arguments with a single
+   field to be treated as structures and not as the type of their
+   field.  Without this a structure with a single char will be
+   returned just like a char variable and that is wrong on HP-UX
+   IA64.  TARGET_STRUCT_ARG_REG_LITTLE_ENDIAN triggers the special
+   structure handling, this macro simply ensures that single field
+   structures are always treated like structures.  */
+
+#define MEMBER_TYPE_FORCES_BLK(FIELD) 1
+
+/* Override the setting of FUNCTION_ARG_REG_LITTLE_ENDIAN in
+   defaults.h.  Setting this to true means that we are not passing
+   structures in registers in the "normal" big-endian way.  See
+   See section 8.5 of the "Itanium Software Conventions and Runtime
+   Architecture", specifically Table 8-1 and the explanation of Byte 0
+   alignment and LSB alignment and a description of how structures
+   are passed.  */
+
+#define FUNCTION_ARG_REG_LITTLE_ENDIAN 1
+
+#undef FUNCTION_ARG_PADDING
+#define FUNCTION_ARG_PADDING(MODE, TYPE) \
+	ia64_hpux_function_arg_padding ((MODE), (TYPE))
+
+#undef PAD_VARARGS_DOWN
+#define PAD_VARARGS_DOWN (!AGGREGATE_TYPE_P (type))

gcc/config/ia64/ia64-protos.h

@@ -134,3 +134,8 @@ extern void sdata_section PARAMS ((void));
 #ifdef SBSS_SECTION_ASM_OP
 extern void sbss_section PARAMS ((void));
 #endif
+
+#ifdef ARGS_SIZE_RTX
+/* expr.h defines ARGS_SIZE_RTX and `enum direction'.  */
+extern enum direction ia64_hpux_function_arg_padding PARAMS ((enum machine_mode, tree));
+#endif /* ARGS_SIZE_RTX */

gcc/config/ia64/ia64.c

@@ -7724,3 +7724,27 @@ ia64_expand_builtin (exp, target, subtarget, mode, ignore)
 
   return NULL_RTX;
 }
+
+/* For the HP-UX IA64 aggregate parameters are passed stored in the
+   most significant bits of the stack slot.  */
+
+enum direction
+ia64_hpux_function_arg_padding (mode, type)
+     enum machine_mode mode;
+     tree type;
+{
+   /* Exception to normal case for structures/unions/etc. */
+
+   if (type && AGGREGATE_TYPE_P (type)
+       && int_size_in_bytes (type) < UNITS_PER_WORD)
+     return upward;
+
+   /* This is the standard FUNCTION_ARG_PADDING with !BYTES_BIG_ENDIAN
+      hardwired to be true. */
+
+   return((mode == BLKmode
+       ? (type && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
+          && int_size_in_bytes (type) < (PARM_BOUNDARY / BITS_PER_UNIT))
+       : GET_MODE_BITSIZE (mode) < PARM_BOUNDARY)
+      ? downward : upward);
+}

gcc/defaults.h

@@ -457,4 +457,14 @@ You Lose!  You must define PREFERRED_DEBUGGING_TYPE!
 #define PREFERRED_DEBUGGING_TYPE NO_DEBUG
 #endif
 
+/* This is set to 1 if BYTES_BIG_ENDIAN is defined but the target uses a
+   little-endian method of passing and returning structures in registers.
+   On the HP-UX IA64 and PA64 platforms structures are aligned differently
+   then integral values and setting this value to 1 will allow for the
+   special handling of structure arguments and return values in regs.  */
+
+#ifndef FUNCTION_ARG_REG_LITTLE_ENDIAN
+#define FUNCTION_ARG_REG_LITTLE_ENDIAN 0
+#endif
+
 #endif  /* ! GCC_DEFAULTS_H */

gcc/doc/tm.texi

@@ -3435,6 +3435,14 @@ nonzero, the caller does not make a copy.  Instead, it passes a pointer to the
 determined that the value won't be modified, it need not make a copy;
 otherwise a copy must be made.
 
+@findex FUNCTION_ARG_REG_LITTLE_ENDIAN
+@item FUNCTION_ARG_REG_LITTLE_ENDIAN
+If defined TRUE on a big-endian system then structure arguments passed
+(and returned) in registers are passed in a little-endian manner instead of
+the big-endian manner.  On the HP-UX IA64 and PA64 platforms structures are
+aligned differently then integral values and setting this value to true will
+allow for the special handling of structure arguments and return values.
+
 @findex CUMULATIVE_ARGS
 @item CUMULATIVE_ARGS
 A C type for declaring a variable that is used as the first argument of

gcc/expr.c

@@ -1868,7 +1868,8 @@ move_block_from_reg (regno, x, nregs, size)
   /* If SIZE is that of a mode no bigger than a word, just use that
      mode's store operation.  */
   if (size <= UNITS_PER_WORD
-      && (mode = mode_for_size (size * BITS_PER_UNIT, MODE_INT, 0)) != BLKmode)
+      && (mode = mode_for_size (size * BITS_PER_UNIT, MODE_INT, 0)) != BLKmode
+      && !FUNCTION_ARG_REG_LITTLE_ENDIAN)
     {
       emit_move_insn (adjust_address (x, mode, 0), gen_rtx_REG (mode, regno));
       return;
@@ -1877,7 +1878,9 @@ move_block_from_reg (regno, x, nregs, size)
   /* Blocks smaller than a word on a BYTES_BIG_ENDIAN machine must be aligned
      to the left before storing to memory.  Note that the previous test
      doesn't handle all cases (e.g. SIZE == 3).  */
-  if (size < UNITS_PER_WORD && BYTES_BIG_ENDIAN)
+  if (size < UNITS_PER_WORD
+      && BYTES_BIG_ENDIAN
+      && !FUNCTION_ARG_REG_LITTLE_ENDIAN)
     {
       rtx tem = operand_subword (x, 0, 1, BLKmode);
       rtx shift;
@@ -2162,15 +2165,25 @@ copy_blkmode_from_reg (tgtblk, srcreg, type)
 
   /* This code assumes srcreg is at least a full word.  If it isn't,
      copy it into a new pseudo which is a full word.  */
+
+  /* If FUNCTION_ARG_REG_LITTLE_ENDIAN is set and convert_to_mode does
+     a copy, the wrong part of the register gets copied so we fake
+     a type conversion in place.  */
+     
   if (GET_MODE (srcreg) != BLKmode
       && GET_MODE_SIZE (GET_MODE (srcreg)) < UNITS_PER_WORD)
+    if (FUNCTION_ARG_REG_LITTLE_ENDIAN)
+       srcreg = simplify_gen_subreg (word_mode, srcreg, GET_MODE (srcreg), 0);
+    else
        srcreg = convert_to_mode (word_mode, srcreg, TREE_UNSIGNED (type));
 
   /* Structures whose size is not a multiple of a word are aligned
      to the least significant byte (to the right).  On a BYTES_BIG_ENDIAN
      machine, this means we must skip the empty high order bytes when
      calculating the bit offset.  */
-  if (BYTES_BIG_ENDIAN && bytes % UNITS_PER_WORD)
+  if (BYTES_BIG_ENDIAN
+      && !FUNCTION_ARG_REG_LITTLE_ENDIAN
+      && bytes % UNITS_PER_WORD)
     big_endian_correction
       = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD) * BITS_PER_UNIT));
 

gcc/stmt.c

@@ -3197,7 +3197,9 @@ expand_return (retval)
 	 to the least significant byte (to the right).  On a BYTES_BIG_ENDIAN
 	 machine, this means we must skip the empty high order bytes when
 	 calculating the bit offset.  */
-      if (BYTES_BIG_ENDIAN && bytes % UNITS_PER_WORD)
+      if (BYTES_BIG_ENDIAN
+	  && !FUNCTION_ARG_REG_LITTLE_ENDIAN
+	  && bytes % UNITS_PER_WORD)
 	big_endian_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD)
 						  * BITS_PER_UNIT));
 

gcc/stor-layout.c

@@ -1149,7 +1149,17 @@ compute_record_mode (type)
 #ifdef MEMBER_TYPE_FORCES_BLK
       /* With some targets, eg. c4x, it is sub-optimal
 	 to access an aligned BLKmode structure as a scalar.  */
-      if (mode == VOIDmode && MEMBER_TYPE_FORCES_BLK (field))
+
+      /* On ia64-*-hpux we need to ensure that we don't change the
+	 mode of a structure containing a single field or else we
+	 will pass it incorrectly.  Since a structure with a single
+	 field causes mode to get set above we can't allow the
+	 check for mode == VOIDmode in this case.  Perhaps
+	 MEMBER_TYPE_FORCES_BLK should be extended to include mode
+	 as an argument and the check could be put in there for c4x.  */
+
+      if ((mode == VOIDmode || FUNCTION_ARG_REG_LITTLE_ENDIAN)
+	  && MEMBER_TYPE_FORCES_BLK (field))
 	return;
 #endif /* MEMBER_TYPE_FORCES_BLK  */
     }