stormy16.c

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/* Xstormy16 target functions.
   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
   Free Software Foundation, Inc.
   Contributed by Red Hat, Inc.

This file is part of GCC.

GCC 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, or (at your option)
any later version.

GCC 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 GCC; see the file COPYING.  If not, write to
the Free Software Foundation, 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-flags.h"
#include "output.h"
#include "insn-attr.h"
#include "flags.h"
#include "recog.h"
#include "toplev.h"
#include "obstack.h"
#include "tree.h"
#include "expr.h"
#include "optabs.h"
#include "except.h"
#include "function.h"
#include "target.h"
#include "target-def.h"
#include "tm_p.h"
#include "langhooks.h"
#include "tree-gimple.h"

static rtx emit_addhi3_postreload (rtx, rtx, rtx);
static void xstormy16_asm_out_constructor (rtx, int);
static void xstormy16_asm_out_destructor (rtx, int);
static void xstormy16_asm_output_mi_thunk (FILE *, tree, HOST_WIDE_INT,
					   HOST_WIDE_INT, tree);

static void xstormy16_init_builtins (void);
static rtx xstormy16_expand_builtin (tree, rtx, rtx, enum machine_mode, int);
static bool xstormy16_rtx_costs (rtx, int, int, int *);
static int xstormy16_address_cost (rtx);
static bool xstormy16_return_in_memory (tree, tree);

/* Define the information needed to generate branch and scc insns.  This is
   stored from the compare operation.  */
struct rtx_def * xstormy16_compare_op0;
struct rtx_def * xstormy16_compare_op1;

/* Compute a (partial) cost for rtx X.  Return true if the complete
   cost has been computed, and false if subexpressions should be
   scanned.  In either case, *TOTAL contains the cost result.  */

static bool
xstormy16_rtx_costs (rtx x, int code, int outer_code ATTRIBUTE_UNUSED,
		     int *total)
{
  switch (code)
    {
    case CONST_INT:
      if (INTVAL (x) < 16 && INTVAL (x) >= 0)
        *total = COSTS_N_INSNS (1) / 2;
      else if (INTVAL (x) < 256 && INTVAL (x) >= 0)
	*total = COSTS_N_INSNS (1);
      else
	*total = COSTS_N_INSNS (2);
      return true;

    case CONST_DOUBLE:
    case CONST:
    case SYMBOL_REF:
    case LABEL_REF:
      *total = COSTS_N_INSNS(2);
      return true;

    case MULT:
      *total = COSTS_N_INSNS (35 + 6);
      return true;
    case DIV:
      *total = COSTS_N_INSNS (51 - 6);
      return true;

    default:
      return false;
    }
}

static int
xstormy16_address_cost (rtx x)
{
  return (GET_CODE (x) == CONST_INT ? 2
	  : GET_CODE (x) == PLUS ? 7
	  : 5);
}

/* Branches are handled as follows:

   1. HImode compare-and-branches.  The machine supports these
      natively, so the appropriate pattern is emitted directly.

   2. SImode EQ and NE.  These are emitted as pairs of HImode
      compare-and-branches.      

   3. SImode LT, GE, LTU and GEU.  These are emitted as a sequence
      of a SImode subtract followed by a branch (not a compare-and-branch),
      like this:
      sub
      sbc
      blt

   4. SImode GT, LE, GTU, LEU.  These are emitted as a sequence like:
      sub
      sbc
      blt
      or
      bne
*/

/* Emit a branch of kind CODE to location LOC.  */

void
xstormy16_emit_cbranch (enum rtx_code code, rtx loc)
{
  rtx op0 = xstormy16_compare_op0;
  rtx op1 = xstormy16_compare_op1;
  rtx condition_rtx, loc_ref, branch, cy_clobber;
  rtvec vec;
  enum machine_mode mode;
  
  mode = GET_MODE (op0);
  gcc_assert (mode == HImode || mode == SImode);

  if (mode == SImode
      && (code == GT || code == LE || code == GTU || code == LEU))
    {
      int unsigned_p = (code == GTU || code == LEU);
      int gt_p = (code == GT || code == GTU);
      rtx lab = NULL_RTX;
      
      if (gt_p)
	lab = gen_label_rtx ();
      xstormy16_emit_cbranch (unsigned_p ? LTU : LT, gt_p ? lab : loc);
      /* This should be generated as a comparison against the temporary
	 created by the previous insn, but reload can't handle that.  */
      xstormy16_emit_cbranch (gt_p ? NE : EQ, loc);
      if (gt_p)
	emit_label (lab);
      return;
    }
  else if (mode == SImode 
	   && (code == NE || code == EQ)
	   && op1 != const0_rtx)
    {
      rtx lab = NULL_RTX;
      int num_words = GET_MODE_BITSIZE (mode) / BITS_PER_WORD;
      int i;
      
      if (code == EQ)
	lab = gen_label_rtx ();
      
      for (i = 0; i < num_words - 1; i++)
	{
	  xstormy16_compare_op0 = simplify_gen_subreg (word_mode, op0, mode, 
						      i * UNITS_PER_WORD);
	  xstormy16_compare_op1 = simplify_gen_subreg (word_mode, op1, mode, 
						      i * UNITS_PER_WORD);
	  xstormy16_emit_cbranch (NE, code == EQ ? lab : loc);
	}
      xstormy16_compare_op0 = simplify_gen_subreg (word_mode, op0, mode, 
						  i * UNITS_PER_WORD);
      xstormy16_compare_op1 = simplify_gen_subreg (word_mode, op1, mode, 
						  i * UNITS_PER_WORD);
      xstormy16_emit_cbranch (code, loc);

      if (code == EQ)
	emit_label (lab);
      return;
    }

  /* We can't allow reload to try to generate any reload after a branch,
     so when some register must match we must make the temporary ourselves.  */
  if (mode != HImode)
    {
      rtx tmp;
      tmp = gen_reg_rtx (mode);
      emit_move_insn (tmp, op0);
      op0 = tmp;
    }

  condition_rtx = gen_rtx_fmt_ee (code, mode, op0, op1);
  loc_ref = gen_rtx_LABEL_REF (VOIDmode, loc);
  branch = gen_rtx_SET (VOIDmode, pc_rtx,
			gen_rtx_IF_THEN_ELSE (VOIDmode, condition_rtx,
					      loc_ref, pc_rtx));

  cy_clobber = gen_rtx_CLOBBER (VOIDmode, gen_rtx_SCRATCH (BImode));

  if (mode == HImode)
    vec = gen_rtvec (2, branch, cy_clobber);
  else if (code == NE || code == EQ)
    vec = gen_rtvec (2, branch, gen_rtx_CLOBBER (VOIDmode, op0));
  else
    {
      rtx sub;
#if 0
      sub = gen_rtx_SET (VOIDmode, op0, gen_rtx_MINUS (SImode, op0, op1));
#else
      sub = gen_rtx_CLOBBER (SImode, op0);
#endif
      vec = gen_rtvec (3, branch, sub, cy_clobber);
    }

  emit_jump_insn (gen_rtx_PARALLEL (VOIDmode, vec));
}

/* Take a SImode conditional branch, one of GT/LE/GTU/LEU, and split
   the arithmetic operation.  Most of the work is done by
   xstormy16_expand_arith.  */

void
xstormy16_split_cbranch (enum machine_mode mode, rtx label, rtx comparison,
			 rtx dest, rtx carry)
{
  rtx op0 = XEXP (comparison, 0);
  rtx op1 = XEXP (comparison, 1);
  rtx seq, last_insn;
  rtx compare;
  
  start_sequence ();
  xstormy16_expand_arith (mode, COMPARE, dest, op0, op1, carry);
  seq = get_insns ();
  end_sequence ();

  gcc_assert (INSN_P (seq));

  last_insn = seq;
  while (NEXT_INSN (last_insn) != NULL_RTX)
    last_insn = NEXT_INSN (last_insn);

  compare = SET_SRC (XVECEXP (PATTERN (last_insn), 0, 0));
  PUT_CODE (XEXP (compare, 0), GET_CODE (comparison));
  XEXP (compare, 1) = gen_rtx_LABEL_REF (VOIDmode, label);
  emit_insn (seq);
}


/* Return the string to output a conditional branch to LABEL, which is
   the operand number of the label.

   OP is the conditional expression, or NULL for branch-always.

   REVERSED is nonzero if we should reverse the sense of the comparison.

   INSN is the insn.  */

char *
xstormy16_output_cbranch_hi (rtx op, const char *label, int reversed, rtx insn)
{
  static char string[64];
  int need_longbranch = (op != NULL_RTX
			 ? get_attr_length (insn) == 8
			 : get_attr_length (insn) == 4);
  int really_reversed = reversed ^ need_longbranch;
  const char *ccode;
  const char *template;
  const char *operands;
  enum rtx_code code;
  
  if (! op)
    {
      if (need_longbranch)
	ccode = "jmpf";
      else
	ccode = "br";
      sprintf (string, "%s %s", ccode, label);
      return string;
    }

  code = GET_CODE (op);

  if (GET_CODE (XEXP (op, 0)) != REG)
    {
      code = swap_condition (code);
      operands = "%3,%2";
    }
  else
      operands = "%2,%3";

  /* Work out which way this really branches.  */
  if (really_reversed)
    code = reverse_condition (code);

  switch (code)
    {
    case EQ:   ccode = "z";   break;
    case NE:   ccode = "nz";  break;
    case GE:   ccode = "ge";  break;
    case LT:   ccode = "lt";  break;
    case GT:   ccode = "gt";  break;
    case LE:   ccode = "le";  break;
    case GEU:  ccode = "nc";  break;
    case LTU:  ccode = "c";   break;
    case GTU:  ccode = "hi";  break;
    case LEU:  ccode = "ls";  break;
      
    default:
      gcc_unreachable ();
    }

  if (need_longbranch)
    template = "b%s %s,.+8 | jmpf %s";
  else
    template = "b%s %s,%s";
  sprintf (string, template, ccode, operands, label);
  
  return string;
}

/* Return the string to output a conditional branch to LABEL, which is
   the operand number of the label, but suitable for the tail of a
   SImode branch.

   OP is the conditional expression (OP is never NULL_RTX).

   REVERSED is nonzero if we should reverse the sense of the comparison.

   INSN is the insn.  */

char *
xstormy16_output_cbranch_si (rtx op, const char *label, int reversed, rtx insn)
{
  static char string[64];
  int need_longbranch = get_attr_length (insn) >= 8;
  int really_reversed = reversed ^ need_longbranch;
  const char *ccode;
  const char *template;
  char prevop[16];
  enum rtx_code code;
  
  code = GET_CODE (op);

  /* Work out which way this really branches.  */
  if (really_reversed)
    code = reverse_condition (code);

  switch (code)
    {
    case EQ:   ccode = "z";   break;
    case NE:   ccode = "nz";  break;
    case GE:   ccode = "ge";  break;
    case LT:   ccode = "lt";  break;
    case GEU:  ccode = "nc";  break;
    case LTU:  ccode = "c";   break;

      /* The missing codes above should never be generated.  */
    default:
      gcc_unreachable ();
    }

  switch (code)
    {
    case EQ: case NE:
      {
	int regnum;
	
	gcc_assert (GET_CODE (XEXP (op, 0)) == REG);
      
	regnum = REGNO (XEXP (op, 0));
	sprintf (prevop, "or %s,%s", reg_names[regnum], reg_names[regnum+1]);
      }
      break;

    case GE: case LT: case GEU: case LTU:
      strcpy (prevop, "sbc %2,%3");
      break;

    default:
      gcc_unreachable ();
    }

  if (need_longbranch)
    template = "%s | b%s .+6 | jmpf %s";
  else
    template = "%s | b%s %s";
  sprintf (string, template, prevop, ccode, label);
  
  return string;
}

/* Many machines have some registers that cannot be copied directly to or from
   memory or even from other types of registers.  An example is the `MQ'
   register, which on most machines, can only be copied to or from general
   registers, but not memory.  Some machines allow copying all registers to and
   from memory, but require a scratch register for stores to some memory
   locations (e.g., those with symbolic address on the RT, and those with
   certain symbolic address on the SPARC when compiling PIC).  In some cases,
   both an intermediate and a scratch register are required.

   You should define these macros to indicate to the reload phase that it may
   need to allocate at least one register for a reload in addition to the
   register to contain the data.  Specifically, if copying X to a register
   CLASS in MODE requires an intermediate register, you should define
   `SECONDARY_INPUT_RELOAD_CLASS' to return the largest register class all of
   whose registers can be used as intermediate registers or scratch registers.

   If copying a register CLASS in MODE to X requires an intermediate or scratch
   register, `SECONDARY_OUTPUT_RELOAD_CLASS' should be defined to return the
   largest register class required.  If the requirements for input and output
   reloads are the same, the macro `SECONDARY_RELOAD_CLASS' should be used
   instead of defining both macros identically.

   The values returned by these macros are often `GENERAL_REGS'.  Return
   `NO_REGS' if no spare register is needed; i.e., if X can be directly copied
   to or from a register of CLASS in MODE without requiring a scratch register.
   Do not define this macro if it would always return `NO_REGS'.

   If a scratch register is required (either with or without an intermediate