path: root/gdb/ppc-sysv-tdep.c

/* Target-dependent code for PowerPC systems using the SVR4 ABI
   for GDB, the GNU debugger.

   Copyright 2000, 2001, 2002 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "gdbcore.h"
#include "inferior.h"
#include "regcache.h"
#include "value.h"
#include "gdb_string.h"

#include "ppc-tdep.h"

/* Pass the arguments in either registers, or in the stack. Using the
   ppc sysv ABI, the first eight words of the argument list (that might
   be less than eight parameters if some parameters occupy more than one
   word) are passed in r3..r10 registers.  float and double parameters are
   passed in fpr's, in addition to that. Rest of the parameters if any
   are passed in user stack. 

   If the function is returning a structure, then the return address is passed
   in r3, then the first 7 words of the parametes can be passed in registers,
   starting from r4. */

CORE_ADDR
ppc_sysv_abi_push_dummy_call (struct gdbarch *gdbarch, CORE_ADDR func_addr,
			      struct regcache *regcache, CORE_ADDR bp_addr,
			      int nargs, struct value **args, CORE_ADDR sp,
			      int struct_return, CORE_ADDR struct_addr)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  const CORE_ADDR saved_sp = read_sp ();
  int argspace = 0;		/* 0 is an initial wrong guess.  */
  int write_pass;

  /* Go through the argument list twice.

     Pass 1: Figure out how much new stack space is required for
     arguments and pushed values.  Unlike the PowerOpen ABI, the SysV
     ABI doesn't reserve any extra space for parameters which are put
     in registers, but does always push structures and then pass their
     address.

     Pass 2: Replay the same computation but this time also write the
     values out to the target.  */

  for (write_pass = 0; write_pass < 2; write_pass++)
    {
      int argno;
      /* Next available floating point register for float and double
         arguments.  */
      int freg = 1;
      /* Next available general register for non-float, non-vector
         arguments.  */
      int greg = 3;
      /* Next available vector register for vector arguments.  */
      int vreg = 2;
      /* Arguments start above the "LR save word" and "Back chain".  */
      int argoffset = 2 * tdep->wordsize;
      /* Structures start after the arguments.  */
      int structoffset = argoffset + argspace;

      /* If the function is returning a `struct', then the first word
         (which will be passed in r3) is used for struct return
         address.  In that case we should advance one word and start
         from r4 register to copy parameters.  */
      if (struct_return)
	{
	  if (write_pass)
	    regcache_cooked_write_signed (regcache,
					  tdep->ppc_gp0_regnum + greg,
					  struct_addr);
	  greg++;
	}

      for (argno = 0; argno < nargs; argno++)
	{
	  struct value *arg = args[argno];
	  struct type *type = check_typedef (VALUE_TYPE (arg));
	  int len = TYPE_LENGTH (type);
	  char *val = VALUE_CONTENTS (arg);

	  if (TYPE_CODE (type) == TYPE_CODE_FLT
	      && ppc_floating_point_unit_p (current_gdbarch) && len <= 8)
	    {
	      /* Floating point value converted to "double" then
	         passed in an FP register, when the registers run out,
	         8 byte aligned stack is used.  */
	      if (freg <= 8)
		{
		  if (write_pass)
		    {
		      /* Always store the floating point value using
		         the register's floating-point format.  */
		      char regval[MAX_REGISTER_SIZE];
		      struct type *regtype
			= register_type (gdbarch, FP0_REGNUM + freg);
		      convert_typed_floating (val, type, regval, regtype);
		      regcache_cooked_write (regcache, FP0_REGNUM + freg,
					     regval);
		    }
		  freg++;
		}
	      else
		{
		  /* SysV ABI converts floats to doubles before
		     writing them to an 8 byte aligned stack location.  */
		  argoffset = align_up (argoffset, 8);
		  if (write_pass)
		    {
		      char memval[8];
		      struct type *memtype;
		      switch (TARGET_BYTE_ORDER)
			{
			case BFD_ENDIAN_BIG:
			  memtype = builtin_type_ieee_double_big;
			  break;
			case BFD_ENDIAN_LITTLE:
			  memtype = builtin_type_ieee_double_little;
			  break;
			default:
			  internal_error (__FILE__, __LINE__, "bad switch");
			}
		      convert_typed_floating (val, type, memval, memtype);
		      write_memory (sp + argoffset, val, len);
		    }
		  argoffset += 8;
		}
	    }
	  else if (len == 8 && (TYPE_CODE (type) == TYPE_CODE_INT	/* long long */
				|| (!ppc_floating_point_unit_p (current_gdbarch) && TYPE_CODE (type) == TYPE_CODE_FLT)))	/* double */
	    {
	      /* "long long" or "double" passed in an odd/even
	         register pair with the low addressed word in the odd
	         register and the high addressed word in the even
	         register, or when the registers run out an 8 byte
	         aligned stack location.  */
	      if (greg > 9)
		{
		  /* Just in case GREG was 10.  */
		  greg = 11;
		  argoffset = align_up (argoffset, 8);
		  if (write_pass)
		    write_memory (sp + argoffset, val, len);
		  argoffset += 8;
		}
	      else if (tdep->wordsize == 8)
		{
		  if (write_pass)
		    regcache_cooked_write (regcache,
					   tdep->ppc_gp0_regnum + greg, val);
		  greg += 1;
		}
	      else
		{
		  /* Must start on an odd register - r3/r4 etc.  */
		  if ((greg & 1) == 0)
		    greg++;
		  if (write_pass)
		    {
		      regcache_cooked_write (regcache,
					     tdep->ppc_gp0_regnum + greg + 0,
					     val + 0);
		      regcache_cooked_write (regcache,
					     tdep->ppc_gp0_regnum + greg + 1,
					     val + 4);
		    }
		  greg += 2;
		}
	    }
	  else if (len == 16
		   && TYPE_CODE (type) == TYPE_CODE_ARRAY
		   && TYPE_VECTOR (type) && tdep->ppc_vr0_regnum >= 0)
	    {
	      /* Vector parameter passed in an Altivec register, or
	         when that runs out, 16 byte aligned stack location.  */
	      if (vreg <= 13)
		{
		  if (write_pass)
		    regcache_cooked_write (current_regcache,
					   tdep->ppc_vr0_regnum + vreg, val);
		  vreg++;
		}
	      else
		{
		  argoffset = align_up (argoffset, 16);
		  if (write_pass)
		    write_memory (sp + argoffset, val, 16);
		  argoffset += 16;
		}
	    }
	  else if (len == 8
		   && TYPE_CODE (type) == TYPE_CODE_ARRAY
		   && TYPE_VECTOR (type) && tdep->ppc_ev0_regnum >= 0)
	    {
	      /* Vector parameter passed in an e500 register, or when
	         that runs out, 8 byte aligned stack location.  Note
	         that since e500 vector and general purpose registers
	         both map onto the same underlying register set, a
	         "greg" and not a "vreg" is consumed here.  A cooked
	         write stores the value in the correct locations
	         within the raw register cache.  */
	      if (greg <= 10)
		{
		  if (write_pass)
		    regcache_cooked_write (current_regcache,
					   tdep->ppc_ev0_regnum + greg, val);
		  greg++;
		}
	      else
		{
		  argoffset = align_up (argoffset, 8);
		  if (write_pass)
		    write_memory (sp + argoffset, val, 8);
		  argoffset += 8;
		}
	    }
	  else
	    {
	      /* Reduce the parameter down to something that fits in a
	         "word".  */
	      char word[MAX_REGISTER_SIZE];
	      memset (word, 0, MAX_REGISTER_SIZE);
	      if (len > tdep->wordsize
		  || TYPE_CODE (type) == TYPE_CODE_STRUCT
		  || TYPE_CODE (type) == TYPE_CODE_UNION)
		{
		  /* Structs and large values are put on an 8 byte
		     aligned stack ... */
		  structoffset = align_up (structoffset, 8);
		  if (write_pass)
		    write_memory (sp + structoffset, val, len);
		  /* ... and then a "word" pointing to that address is
		     passed as the parameter.  */
		  store_unsigned_integer (word, tdep->wordsize,
					  sp + structoffset);
		  structoffset += len;
		}
	      else if (TYPE_CODE (type) == TYPE_CODE_INT)
		/* Sign or zero extend the "int" into a "word".  */
		store_unsigned_integer (word, tdep->wordsize,
					unpack_long (type, val));
	      else
		/* Always goes in the low address.  */
		memcpy (word, val, len);
	      /* Store that "word" in a register, or on the stack.
	         The words have "4" byte alignment.  */
	      if (greg <= 10)
		{
		  if (write_pass)
		    regcache_cooked_write (regcache,
					   tdep->ppc_gp0_regnum + greg, word);
		  greg++;
		}
	      else
		{
		  argoffset = align_up (argoffset, tdep->wordsize);
		  if (write_pass)
		    write_memory (sp + argoffset, word, tdep->wordsize);
		  argoffset += tdep->wordsize;
		}
	    }
	}

      /* Compute the actual stack space requirements.  */
      if (!write_pass)
	{
	  /* Remember the amount of space needed by the arguments.  */
	  argspace = argoffset;
	  /* Allocate space for both the arguments and the structures.  */
	  sp -= (argoffset + structoffset);
	  /* Ensure that the stack is still 16 byte aligned.  */
	  sp = align_down (sp, 16);
	}
    }

  /* Update %sp.   */
  regcache_cooked_write_signed (regcache, SP_REGNUM, sp);

  /* Write the backchain (it occupies WORDSIZED bytes).  */
  write_memory_signed_integer (sp, tdep->wordsize, saved_sp);

  /* Point the inferior function call's return address at the dummy's
     breakpoint.  */
  regcache_cooked_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);

  return sp;
}

/* Structures 8 bytes or less long are returned in the r3 & r4
   registers, according to the SYSV ABI. */
int
ppc_sysv_abi_use_struct_convention (int gcc_p, struct type *value_type)
{
  if ((TYPE_LENGTH (value_type) == 16 || TYPE_LENGTH (value_type) == 8)
      && TYPE_VECTOR (value_type))
    return 0;

  return (TYPE_LENGTH (value_type) > 8);
}


/* The 64 bit ABI retun value convention.

   Return non-zero if the return-value is stored in a register, return
   0 if the return-value is instead stored on the stack (a.k.a.,
   struct return convention).

   For a return-value stored in a register: when INVAL is non-NULL,
   copy the buffer to the corresponding register return-value location
   location; when OUTVAL is non-NULL, fill the buffer from the
   corresponding register return-value location.  */

/* Potential ways that a function can return a value of a given type.  */
enum return_value_convention
{
  /* Where the return value has been squeezed into one or more
     registers.  */
  RETURN_VALUE_REGISTER_CONVENTION,
  /* Commonly known as the "struct return convention".  The caller
     passes an additional hidden first parameter to the caller.  That
     parameter contains the address at which the value being returned
     should be stored.  While typically, and historically, used for
     large structs, this is convention is applied to values of many
     different types.  */
  RETURN_VALUE_STRUCT_CONVENTION
};

static enum return_value_convention
ppc64_sysv_abi_return_value (struct type *valtype, struct regcache *regcache,
			     const void *inval, void *outval)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
  /* Floats and doubles in F1.  */
  if (TYPE_CODE (valtype) == TYPE_CODE_FLT && TYPE_LENGTH (valtype) <= 8)
    {
      char regval[MAX_REGISTER_SIZE];
      struct type *regtype = register_type (current_gdbarch, FP0_REGNUM);
      if (inval != NULL)
	{
	  convert_typed_floating (inval, valtype, regval, regtype);
	  regcache_cooked_write (regcache, FP0_REGNUM + 1, regval);
	}
      if (outval != NULL)
	{
	  regcache_cooked_read (regcache, FP0_REGNUM + 1, regval);
	  convert_typed_floating (regval, regtype, outval, valtype);
	}
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  if (TYPE_CODE (valtype) == TYPE_CODE_INT && TYPE_LENGTH (valtype) <= 8)
    {
      /* Integers in r3.  */
      if (inval != NULL)
	{
	  /* Be careful to sign extend the value.  */
	  regcache_cooked_write_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
					  unpack_long (valtype, inval));
	}
      if (outval != NULL)
	{
	  /* Extract the integer from r3.  Since this is truncating the
	     value, there isn't a sign extension problem.  */
	  ULONGEST regval;
	  regcache_cooked_read_unsigned (regcache, tdep->ppc_gp0_regnum + 3,
					 &regval);
	  store_unsigned_integer (outval, TYPE_LENGTH (valtype), regval);
	}
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  /* All pointers live in r3.  */
  if (TYPE_CODE (valtype) == TYPE_CODE_PTR)
    {
      /* All pointers live in r3.  */
      if (inval != NULL)
	regcache_cooked_write (regcache, tdep->ppc_gp0_regnum + 3, inval);
      if (outval != NULL)
	regcache_cooked_read (regcache, tdep->ppc_gp0_regnum + 3, outval);
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY
      && TYPE_LENGTH (valtype) <= 8
      && TYPE_CODE (TYPE_TARGET_TYPE (valtype)) == TYPE_CODE_INT
      && TYPE_LENGTH (TYPE_TARGET_TYPE (valtype)) == 1)
    {
      /* Small character arrays are returned, right justified, in r3.  */
      int offset = (register_size (current_gdbarch, tdep->ppc_gp0_regnum + 3)
		    - TYPE_LENGTH (valtype));
      if (inval != NULL)
	regcache_cooked_write_part (regcache, tdep->ppc_gp0_regnum + 3,
				    offset, TYPE_LENGTH (valtype), inval);
      if (outval != NULL)
	regcache_cooked_read_part (regcache, tdep->ppc_gp0_regnum + 3,
				   offset, TYPE_LENGTH (valtype), outval);
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  /* Big floating point values get stored in adjacent floating
     point registers.  */
  if (TYPE_CODE (valtype) == TYPE_CODE_FLT
      && (TYPE_LENGTH (valtype) == 16 || TYPE_LENGTH (valtype) == 32))
    {
      if (inval || outval != NULL)
	{
	  int i;
	  for (i = 0; i < TYPE_LENGTH (valtype) / 8; i++)
	    {
	      if (inval != NULL)
		regcache_cooked_write (regcache, FP0_REGNUM + 1 + i,
				       (const bfd_byte *) inval + i * 8);
	      if (outval != NULL)
		regcache_cooked_read (regcache, FP0_REGNUM + 1 + i,
				      (bfd_byte *) outval + i * 8);
	    }
	}
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  /* Complex values get returned in f1:f2, need to convert.  */
  if (TYPE_CODE (valtype) == TYPE_CODE_COMPLEX
      && (TYPE_LENGTH (valtype) == 8 || TYPE_LENGTH (valtype) == 16))
    {
      if (regcache != NULL)
	{
	  int i;
	  for (i = 0; i < 2; i++)
	    {
	      char regval[MAX_REGISTER_SIZE];
	      struct type *regtype =
		register_type (current_gdbarch, FP0_REGNUM);
	      if (inval != NULL)
		{
		  convert_typed_floating ((const bfd_byte *) inval +
					  i * (TYPE_LENGTH (valtype) / 2),
					  valtype, regval, regtype);
		  regcache_cooked_write (regcache, FP0_REGNUM + 1 + i,
					 regval);
		}
	      if (outval != NULL)
		{
		  regcache_cooked_read (regcache, FP0_REGNUM + 1 + i, regval);
		  convert_typed_floating (regval, regtype,
					  (bfd_byte *) outval +
					  i * (TYPE_LENGTH (valtype) / 2),
					  valtype);
		}
	    }
	}
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  /* Big complex values get stored in f1:f4.  */
  if (TYPE_CODE (valtype) == TYPE_CODE_COMPLEX && TYPE_LENGTH (valtype) == 32)
    {
      if (regcache != NULL)
	{
	  int i;
	  for (i = 0; i < 4; i++)
	    {
	      if (inval != NULL)
		regcache_cooked_write (regcache, FP0_REGNUM + 1 + i,
				       (const bfd_byte *) inval + i * 8);
	      if (outval != NULL)
		regcache_cooked_read (regcache, FP0_REGNUM + 1 + i,
				      (bfd_byte *) outval + i * 8);
	    }
	}
      return RETURN_VALUE_REGISTER_CONVENTION;
    }
  return RETURN_VALUE_STRUCT_CONVENTION;
}

int
ppc64_sysv_abi_use_struct_convention (int gcc_p, struct type *value_type)
{
  return (ppc64_sysv_abi_return_value (value_type, NULL, NULL, NULL)
	  == RETURN_VALUE_STRUCT_CONVENTION);
}

void
ppc64_sysv_abi_extract_return_value (struct type *valtype,
				     struct regcache *regbuf, void *valbuf)
{
  if (ppc64_sysv_abi_return_value (valtype, regbuf, NULL, valbuf)
      != RETURN_VALUE_REGISTER_CONVENTION)
    error ("Function return value unknown");
}

void
ppc64_sysv_abi_store_return_value (struct type *valtype,
				   struct regcache *regbuf,
				   const void *valbuf)
{
  if (!ppc64_sysv_abi_return_value (valtype, regbuf, valbuf, NULL))
    error ("Function return value location unknown");
}