Re: new argument macro: INITIAL_ARGS_SIZE

[Aldy Hernandez <aldyh at redhat dot com>]

>>>>> "David" == David Edelsohn <dje@watson.ibm.com> writes:

 > 	This type of patch defining macros to a value or zero depending on
 > TARGET_ALTIVEC_ABI is a reasonable approach for the GCC 3.1 branch.  If
 > the macros are defined wrong for PowerPC, we need to define them correctly
 > for GCC 3.2 trunk, not this type of kludge.  I would prefer to not put a
 > kludge in the GCC 3.1 branch without a correct fix for GCC 3.2 trunk also
 > ready. 

Richard mentioned that the definitions apply to both altivec and non
altivec.

I don't understand the code to be of much use here, but here's the
updated patch making the changes for altivec AND non-altivec-- in
a non kludgey manner ;-).  I still need to test more variants though.

IMO, this should go in both 3.1 and the trunk.

Finally, there's an additional patchlet for instantiate_virtual_regs
to take into account INITIAL_ARGS_SIZE, since with the latest
proposed changes, in_arg_offset was off and unaligned things.

Aldy

2002-02-28  Richard Henderson  <rth@redhat.com>
	    Secretary: Aldy Hernandez  <aldyh@redhat.com>

	* doc/tm.texi (INITIAL_ARGS_SIZE): Document.

	* defaults.h (INITIAL_ARGS_SIZE): New.

	* calls.c (initialize_argument_information): Initialize
	args_size->constant to INITIAL_ARGS_SIZE.

	* function.c (assign_parms): Initialize stack_args_size.constant to
	FIRST_PARM_OFFSET.
	(instantiate_virtual_regs): Subtract INITIAL_ARGS_SIZE from
	in_arg_offset.

2002-02-28  Aldy Hernandez  <aldyh@redhat.com>

	* config/rs6000/rs6000.h (STACK_POINTER_OFFSET): Set to 0.
	(INITIAL_ARGS_SIZE): Define.

	* config/rs6000/rs6000.c (setup_incoming_varargs): Adjust memory
	offset in which to put registers by INITIAL_ARGS_SIZE.


Index: doc/tm.texi
===================================================================
RCS file: /cvs/uberbaum/gcc/doc/tm.texi,v
retrieving revision 1.102
diff -c -p -r1.102 tm.texi
*** tm.texi	2002/02/23 12:59:09	1.102
--- tm.texi	2002/02/28 05:48:43
*************** function.
*** 2609,2614 ****
--- 2609,2625 ----
  If @code{ARGS_GROW_DOWNWARD}, this is the offset to the location above
  the first argument's address.
  
+ @findex INITIAL_ARGS_SIZE
+ @item INITIAL_ARGS_SIZE (@var{fundecl})
+ Offset from @code{virtual_outgoing_args} and
+ @code{virtual_incoming_args} to the first argument's address.
+ 
+ On some machines, the natural definition of
+ @code{virtual_outgoing_args} and
+ @code{virtual_incoming_args} are not as aligned as the stack pointer.
+ In these cases, use @code{INITIAL_ARGS_SIZE} and set
+ @code{STACK_POINTER_OFFSET} to zero.
+ 
  @findex STACK_DYNAMIC_OFFSET
  @item STACK_DYNAMIC_OFFSET (@var{fundecl})
  Offset from the stack pointer register to an item dynamically allocated
Index: defaults.h
===================================================================
RCS file: /cvs/uberbaum/gcc/defaults.h,v
retrieving revision 1.64
diff -c -p -r1.64 defaults.h
*** defaults.h	2001/12/17 16:46:09	1.64
--- defaults.h	2002/02/28 05:48:43
*************** do {								\
*** 365,370 ****
--- 365,377 ----
  #define PREFERRED_STACK_BOUNDARY STACK_BOUNDARY
  #endif
  
+ /* Offset from virtual_outgoing_args or virtual_incoming_args to the
+    first argument's address.  If this is nonzero, STACK_POINTER_OFFSET
+    should be set to 0.  */
+ #ifndef INITIAL_ARGS_SIZE
+ #define INITIAL_ARGS_SIZE(x) 0
+ #endif
+ 
  /* By default, the C++ compiler will use function addresses in the
     vtable entries.  Setting this non-zero tells the compiler to use
     function descriptors instead.  The value of this macro says how
Index: calls.c
===================================================================
RCS file: /cvs/uberbaum/gcc/calls.c,v
retrieving revision 1.221
diff -c -p -r1.221 calls.c
*** calls.c	2002/02/11 13:33:07	1.221
--- calls.c	2002/02/28 05:48:45
*************** initialize_argument_information (num_act
*** 1136,1142 ****
    int i;
    tree p;
  
!   args_size->constant = 0;
    args_size->var = 0;
  
    /* In this loop, we consider args in the order they are written.
--- 1136,1142 ----
    int i;
    tree p;
  
!   args_size->constant = INITIAL_ARGS_SIZE (fndecl);
    args_size->var = 0;
  
    /* In this loop, we consider args in the order they are written.
Index: function.c
===================================================================
RCS file: /cvs/uberbaum/gcc/function.c,v
retrieving revision 1.347
diff -c -p -r1.347 function.c
*** function.c	2002/02/19 02:53:15	1.347
--- function.c	2002/02/28 05:48:48
*************** instantiate_virtual_regs (fndecl, insns)
*** 3486,3492 ****
--- 3486,3496 ----
    unsigned int i;
  
    /* Compute the offsets to use for this function.  */
+ #ifdef INITIAL_ARGS_SIZE
+   in_arg_offset = FIRST_PARM_OFFSET (fndecl) - INITIAL_ARGS_SIZE (fndecl);
+ #else
    in_arg_offset = FIRST_PARM_OFFSET (fndecl);
+ #endif
    var_offset = STARTING_FRAME_OFFSET;
    dynamic_offset = STACK_DYNAMIC_OFFSET (fndecl);
    out_arg_offset = STACK_POINTER_OFFSET;
*************** assign_parms (fndecl)
*** 4269,4275 ****
--- 4273,4283 ----
      internal_arg_pointer = virtual_incoming_args_rtx;
    current_function_internal_arg_pointer = internal_arg_pointer;
  
+ #ifdef INITIAL_ARGS_SIZE
+   stack_args_size.constant = FIRST_PARM_OFFSET (context);
+ #else
    stack_args_size.constant = 0;
+ #endif
    stack_args_size.var = 0;
  
    /* If struct value address is treated as the first argument, make it so.  */
Index: config/rs6000/rs6000.h
===================================================================
RCS file: /cvs/uberbaum/gcc/config/rs6000/rs6000.h,v
retrieving revision 1.184
diff -c -p -r1.184 rs6000.h
*** rs6000.h	2002/02/21 02:34:20	1.184
--- rs6000.h	2002/02/28 05:48:50
*************** typedef struct rs6000_stack {
*** 1425,1432 ****
  
  /* This is the difference between the logical top of stack and the actual sp.
  
!    For the RS/6000, sp points past the fixed area.  */
! #define STACK_POINTER_OFFSET RS6000_SAVE_AREA
  
  /* Define this if the maximum size of all the outgoing args is to be
     accumulated and pushed during the prologue.  The amount can be
--- 1425,1438 ----
  
  /* This is the difference between the logical top of stack and the actual sp.
  
!    For the RS/6000, sp points past the fixed area, but we set to
!    0 because we defined INITIAL_ARGS_SIZE below.  */
! #define STACK_POINTER_OFFSET 0
! 
! /* Offset from virtual_outgoing_args or virtual_incoming_args to the
!    first argument's address.  If this is nonzero, STACK_POINTER_OFFSET
!    should be set to 0.  */
! #define INITIAL_ARGS_SIZE(FNDECL) RS6000_SAVE_AREA
  
  /* Define this if the maximum size of all the outgoing args is to be
     accumulated and pushed during the prologue.  The amount can be
Index: config/rs6000/rs6000.c
===================================================================
RCS file: /cvs/uberbaum/gcc/config/rs6000/rs6000.c,v
retrieving revision 1.291
diff -c -p -r1.291 rs6000.c
*** rs6000.c	2002/02/25 02:30:32	1.291
--- rs6000.c	2002/02/28 05:48:54
*************** setup_incoming_varargs (cum, mode, type,
*** 2909,2923 ****
  	 stack, or can we allocate this with assign_stack_local instead.  */
        cfun->machine->sysv_varargs_p = 1;
        if (! no_rtl)
! 	save_area = plus_constant (virtual_stack_vars_rtx,
! 				   - RS6000_VARARGS_SIZE);
  
        first_reg_offset = next_cum.sysv_gregno - GP_ARG_MIN_REG;
      }
    else
      {
        first_reg_offset = next_cum.words;
!       save_area = virtual_incoming_args_rtx;
        cfun->machine->sysv_varargs_p = 0;
  
        if (MUST_PASS_IN_STACK (mode, type))
--- 2909,2927 ----
  	 stack, or can we allocate this with assign_stack_local instead.  */
        cfun->machine->sysv_varargs_p = 1;
        if (! no_rtl)
! 	save_area
! 	  = plus_constant (virtual_stack_vars_rtx,
! 			   - RS6000_VARARGS_SIZE
! 			   + INITIAL_ARGS_SIZE (current_function_decl));
  
        first_reg_offset = next_cum.sysv_gregno - GP_ARG_MIN_REG;
      }
    else
      {
        first_reg_offset = next_cum.words;
!       save_area
! 	= plus_constant (virtual_incoming_args_rtx,
! 			 INITIAL_ARGS_SIZE (current_function_decl));
        cfun->machine->sysv_varargs_p = 0;
  
        if (MUST_PASS_IN_STACK (mode, type))