bfin.c

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/* Return true when register may be used to pass function parameters.  */

bool 
function_arg_regno_p (int n)
{
  int i;
  for (i = 0; arg_regs[i] != -1; i++)
    if (n == arg_regs[i])
      return true;
  return false;
}

/* Returns 1 if OP contains a symbol reference */

int
symbolic_reference_mentioned_p (rtx op)
{
  register const char *fmt;
  register int i;

  if (GET_CODE (op) == SYMBOL_REF || GET_CODE (op) == LABEL_REF)
    return 1;

  fmt = GET_RTX_FORMAT (GET_CODE (op));
  for (i = GET_RTX_LENGTH (GET_CODE (op)) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'E')
	{
	  register int j;

	  for (j = XVECLEN (op, i) - 1; j >= 0; j--)
	    if (symbolic_reference_mentioned_p (XVECEXP (op, i, j)))
	      return 1;
	}

      else if (fmt[i] == 'e' && symbolic_reference_mentioned_p (XEXP (op, i)))
	return 1;
    }

  return 0;
}

/* Decide whether we can make a sibling call to a function.  DECL is the
   declaration of the function being targeted by the call and EXP is the
   CALL_EXPR representing the call.  */

static bool
bfin_function_ok_for_sibcall (tree decl ATTRIBUTE_UNUSED,
			      tree exp ATTRIBUTE_UNUSED)
{
  e_funkind fkind = funkind (TREE_TYPE (current_function_decl));
  return fkind == SUBROUTINE;
}

/* Emit RTL insns to initialize the variable parts of a trampoline at
   TRAMP. FNADDR is an RTX for the address of the function's pure
   code.  CXT is an RTX for the static chain value for the function.  */

void
initialize_trampoline (tramp, fnaddr, cxt)
     rtx tramp, fnaddr, cxt;
{
  rtx t1 = copy_to_reg (fnaddr);
  rtx t2 = copy_to_reg (cxt);
  rtx addr;

  addr = memory_address (Pmode, plus_constant (tramp, 2));
  emit_move_insn (gen_rtx_MEM (HImode, addr), gen_lowpart (HImode, t1));
  emit_insn (gen_ashrsi3 (t1, t1, GEN_INT (16)));
  addr = memory_address (Pmode, plus_constant (tramp, 6));
  emit_move_insn (gen_rtx_MEM (HImode, addr), gen_lowpart (HImode, t1));

  addr = memory_address (Pmode, plus_constant (tramp, 10));
  emit_move_insn (gen_rtx_MEM (HImode, addr), gen_lowpart (HImode, t2));
  emit_insn (gen_ashrsi3 (t2, t2, GEN_INT (16)));
  addr = memory_address (Pmode, plus_constant (tramp, 14));
  emit_move_insn (gen_rtx_MEM (HImode, addr), gen_lowpart (HImode, t2));
}

/* Emit insns to move operands[1] into operands[0].  */

void
emit_pic_move (rtx *operands, enum machine_mode mode ATTRIBUTE_UNUSED)
{
  rtx temp = reload_in_progress ? operands[0] : gen_reg_rtx (Pmode);

  if (GET_CODE (operands[0]) == MEM && SYMBOLIC_CONST (operands[1]))
    operands[1] = force_reg (SImode, operands[1]);
  else
    operands[1] = legitimize_pic_address (operands[1], temp,
					  pic_offset_table_rtx);
}

/* Expand a move operation in mode MODE.  The operands are in OPERANDS.  */

void
expand_move (rtx *operands, enum machine_mode mode)
{
  if (flag_pic && SYMBOLIC_CONST (operands[1]))
    emit_pic_move (operands, mode);

  /* Don't generate memory->memory or constant->memory moves, go through a
     register */
  else if ((reload_in_progress | reload_completed) == 0
	   && GET_CODE (operands[0]) == MEM
    	   && GET_CODE (operands[1]) != REG)
    operands[1] = force_reg (mode, operands[1]);
}

/* Split one or more DImode RTL references into pairs of SImode
   references.  The RTL can be REG, offsettable MEM, integer constant, or
   CONST_DOUBLE.  "operands" is a pointer to an array of DImode RTL to
   split and "num" is its length.  lo_half and hi_half are output arrays
   that parallel "operands".  */

void
split_di (rtx operands[], int num, rtx lo_half[], rtx hi_half[])
{
  while (num--)
    {
      rtx op = operands[num];

      /* simplify_subreg refuse to split volatile memory addresses,
         but we still have to handle it.  */
      if (GET_CODE (op) == MEM)
	{
	  lo_half[num] = adjust_address (op, SImode, 0);
	  hi_half[num] = adjust_address (op, SImode, 4);
	}
      else
	{
	  lo_half[num] = simplify_gen_subreg (SImode, op,
					      GET_MODE (op) == VOIDmode
					      ? DImode : GET_MODE (op), 0);
	  hi_half[num] = simplify_gen_subreg (SImode, op,
					      GET_MODE (op) == VOIDmode
					      ? DImode : GET_MODE (op), 4);
	}
    }
}

bool
bfin_longcall_p (rtx op, int call_cookie)
{
  gcc_assert (GET_CODE (op) == SYMBOL_REF);
  if (call_cookie & CALL_SHORT)
    return 0;
  if (call_cookie & CALL_LONG)
    return 1;
  if (TARGET_LONG_CALLS)
    return 1;
  return 0;
}

/* Expand a call instruction.  FNADDR is the call target, RETVAL the return value.
   COOKIE is a CONST_INT holding the call_cookie prepared init_cumulative_args.
   SIBCALL is nonzero if this is a sibling call.  */

void
bfin_expand_call (rtx retval, rtx fnaddr, rtx callarg1, rtx cookie, int sibcall)
{
  rtx use = NULL, call;
  rtx callee = XEXP (fnaddr, 0);
  rtx pat = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (sibcall ? 3 : 2));

  /* In an untyped call, we can get NULL for operand 2.  */
  if (cookie == NULL_RTX)
    cookie = const0_rtx;

  /* Static functions and indirect calls don't need the pic register.  */
  if (flag_pic
      && GET_CODE (callee) == SYMBOL_REF
      && !SYMBOL_REF_LOCAL_P (callee))
    use_reg (&use, pic_offset_table_rtx);

  if ((!register_no_elim_operand (callee, Pmode)
       && GET_CODE (callee) != SYMBOL_REF)
      || (GET_CODE (callee) == SYMBOL_REF
	  && (flag_pic
	      || bfin_longcall_p (callee, INTVAL (cookie)))))
    {
      callee = copy_to_mode_reg (Pmode, callee);
      fnaddr = gen_rtx_MEM (Pmode, callee);
    }
  call = gen_rtx_CALL (VOIDmode, fnaddr, callarg1);

  if (retval)
    call = gen_rtx_SET (VOIDmode, retval, call);

  XVECEXP (pat, 0, 0) = call;
  XVECEXP (pat, 0, 1) = gen_rtx_USE (VOIDmode, cookie);
  if (sibcall)
    XVECEXP (pat, 0, 2) = gen_rtx_RETURN (VOIDmode);
  call = emit_call_insn (pat);
  if (use)
    CALL_INSN_FUNCTION_USAGE (call) = use;
}

/* Return 1 if hard register REGNO can hold a value of machine-mode MODE.  */

int
hard_regno_mode_ok (int regno, enum machine_mode mode)
{
  /* Allow only dregs to store value of mode HI or QI */
  enum reg_class class = REGNO_REG_CLASS (regno);

  if (mode == CCmode)
    return 0;

  if (mode == V2HImode)
    return D_REGNO_P (regno);
  if (class == CCREGS)
    return mode == BImode;
  if (mode == PDImode)
    return regno == REG_A0 || regno == REG_A1;
  if (mode == SImode
      && TEST_HARD_REG_BIT (reg_class_contents[PROLOGUE_REGS], regno))
    return 1;
      
  return TEST_HARD_REG_BIT (reg_class_contents[MOST_REGS], regno);
}

/* Implements target hook vector_mode_supported_p.  */

static bool
bfin_vector_mode_supported_p (enum machine_mode mode)
{
  return mode == V2HImode;
}

/* Return the cost of moving data from a register in class CLASS1 to
   one in class CLASS2.  A cost of 2 is the default.  */

int
bfin_register_move_cost (enum machine_mode mode ATTRIBUTE_UNUSED,
			 enum reg_class class1, enum reg_class class2)
{
  /* If optimizing for size, always prefer reg-reg over reg-memory moves.  */
  if (optimize_size)
    return 2;

  /* There are some stalls involved when moving from a DREG to a different
     class reg, and using the value in one of the following instructions.
     Attempt to model this by slightly discouraging such moves.  */
  if (class1 == DREGS && class2 != DREGS)
    return 2 * 2;

  return 2;
}

/* Return the cost of moving data of mode M between a
   register and memory.  A value of 2 is the default; this cost is
   relative to those in `REGISTER_MOVE_COST'.

   ??? In theory L1 memory has single-cycle latency.  We should add a switch
   that tells the compiler whether we expect to use only L1 memory for the
   program; it'll make the costs more accurate.  */

int
bfin_memory_move_cost (enum machine_mode mode ATTRIBUTE_UNUSED,
		       enum reg_class class,
		       int in ATTRIBUTE_UNUSED)
{
  /* Make memory accesses slightly more expensive than any register-register
     move.  Also, penalize non-DP registers, since they need secondary
     reloads to load and store.  */
  if (! reg_class_subset_p (class, DPREGS))
    return 10;

  return 8;
}

/* Inform reload about cases where moving X with a mode MODE to a register in
   CLASS requires an extra scratch register.  Return the class needed for the
   scratch register.  */

enum reg_class
secondary_input_reload_class (enum reg_class class, enum machine_mode mode,
			      rtx x)
{
  /* If we have HImode or QImode, we can only use DREGS as secondary registers;
     in most other cases we can also use PREGS.  */
  enum reg_class default_class = GET_MODE_SIZE (mode) >= 4 ? DPREGS : DREGS;
  enum reg_class x_class = NO_REGS;
  enum rtx_code code = GET_CODE (x);

  if (code == SUBREG)
    x = SUBREG_REG (x), code = GET_CODE (x);
  if (REG_P (x))
    {
      int regno = REGNO (x);
      if (regno >= FIRST_PSEUDO_REGISTER)
	regno = reg_renumber[regno];

      if (regno == -1)
	code = MEM;
      else
	x_class = REGNO_REG_CLASS (regno);
    }

  /* We can be asked to reload (plus (FP) (large_constant)) into a DREG.
     This happens as a side effect of register elimination, and we need
     a scratch register to do it.  */
  if (fp_plus_const_operand (x, mode))
    {
      rtx op2 = XEXP (x, 1);
      int large_constant_p = ! CONST_7BIT_IMM_P (INTVAL (op2));

      if (class == PREGS || class == PREGS_CLOBBERED)
	return NO_REGS;
      /* If destination is a DREG, we can do this without a scratch register
	 if the constant is valid for an add instruction.  */
      if (class == DREGS || class == DPREGS)
	return large_constant_p ? PREGS : NO_REGS;
      /* Reloading to anything other than a DREG?  Use a PREG scratch
	 register.  */
      return PREGS;
    }

  /* Data can usually be moved freely between registers of most classes.
     AREGS are an exception; they can only move to or from another register
     in AREGS or one in DREGS.  They can also be assigned the constant 0.  */
  if (x_class == AREGS)
    return class == DREGS || class == AREGS ? NO_REGS : DREGS;

  if (class == AREGS)
    {
      if (x != const0_rtx && x_class != DREGS)
	return DREGS;
      else
	return NO_REGS;
    }

  /* CCREGS can only be moved from/to DREGS.  */
  if (class == CCREGS && x_class != DREGS)
    return DREGS;
  if (x_class == CCREGS && class != DREGS)
    return DREGS;
  /* All registers other than AREGS can load arbitrary constants.  The only
     case that remains is MEM.  */
  if (code == MEM)
    if (! reg_class_subset_p (class, default_class))
      return default_class;
  return NO_REGS;
}

/* Like secondary_input_reload_class; and all we do is call that function.  */

enum reg_class
secondary_output_reload_class (enum reg_class class, enum machine_mode mode,
			       rtx x)
{
  return secondary_input_reload_class (class, mode, x);
}

/* Implement TARGET_HANDLE_OPTION.  */

static bool
bfin_handle_option (size_t code, const char *arg, int value)
{
  switch (code)
    {
    case OPT_mshared_library_id_:
      if (value > MAX_LIBRARY_ID)
	error ("-mshared-library-id=%s is not between 0 and %d",
	       arg, MAX_LIBRARY_ID);
      bfin_lib_id_given = 1;
      return true;

    default:
      return true;
    }
}

/* Implement the macro OVERRIDE_OPTIONS.  */

void
override_options (void)
{
  if (TARGET_OMIT_LEAF_FRAME_POINTER)
    flag_omit_frame_pointer = 1;

  /* Library identification */
  if (bfin_lib_id_given && ! TARGET_ID_SHARED_LIBRARY)
    error ("-mshared-library-id= specified without -mid-shared-library");

  if (TARGET_ID_SHARED_LIBRARY)
    /* ??? Provide a way to use a bigger GOT.  */
    flag_pic = 1;

  flag_schedule_insns = 0;
}

/* Return the destination address of BRANCH.
   We need to use this instead of get_attr_length, because the
   cbranch_with_nops pattern conservatively sets its length to 6, and
   we still prefer to use shorter sequences.  */

static int
branch_dest (rtx branch)
{
  rtx dest;
  int dest_uid;
  rtx pat = PATTERN (branch);
  if (GET_CODE (pat) == PARALLEL)
    pat = XVECEXP (pat, 0, 0);
  dest = SET_SRC (pat);
  if (GET_CODE (dest) == IF_THEN_ELSE)
    dest = XEXP (dest, 1);
  dest = XEXP (dest, 0);
  dest_uid = INSN_UID (dest);
  return INSN_ADDRESSES (dest_uid);
}

/* Return nonzero if INSN is annotated with a REG_BR_PROB note that indicates
   it's a branch that's predicted taken.  */

static int
cbranch_predicted_taken_p (rtx insn)
{
  rtx x = find_reg_note (insn, REG_BR_PROB, 0);

  if (x)
    {
      int pred_val = INTVAL (XEXP (x, 0));

      return pred_val >= REG_BR_PROB_BASE / 2;
    }

  return 0;
}

/* Templates for use by asm_conditional_branch.  */

static const char *ccbranch_templates[][3] = {
  { "if !cc jump %3;",  "if cc jump 4 (bp); jump.s %3;",  "if cc jump 6 (bp); jump.l %3;" },
  { "if cc jump %3;",   "if !cc jump 4 (bp); jump.s %3;", "if !cc jump 6 (bp); jump.l %3;" },
  { "if !cc jump %3 (bp);",  "if cc jump 4; jump.s %3;",  "if cc jump 6; jump.l %3;" },
  { "if cc jump %3 (bp);",  "if !cc jump 4; jump.s %3;",  "if !cc jump 6; jump.l %3;" },
};

/* Output INSN, which is a conditional branch instruction with operands
   OPERANDS.

   We deal with the various forms of conditional branches that can be generated
   by bfin_reorg to prevent the hardware from doing speculative loads, by
   - emitting a sufficient number of nops, if N_NOPS is nonzero, or
   - always emitting the branch as predicted taken, if PREDICT_TAKEN is true.
   Either of these is only necessary if the branch is short, otherwise the
   template we use ends in an unconditional jump which flushes the pipeline
   anyway.  */

void
asm_conditional_branch (rtx insn, rtx *operands, int n_nops, int predict_taken)
{
  int offset = branch_dest (insn) - INSN_ADDRESSES (INSN_UID (insn));
  /* Note : offset for instructions like if cc jmp; jump.[sl] offset
            is to be taken from start of if cc rather than jump.
            Range for jump.s is (-4094, 4096) instead of (-4096, 4094)
  */
  int len = (offset >= -1024 && offset <= 1022 ? 0
	     : offset >= -4094 && offset <= 4096 ? 1
	     : 2);
  int bp = predict_taken && len == 0 ? 1 : cbranch_predicted_taken_p (insn);
  int idx = (bp << 1) | (GET_CODE (operands[0]) == EQ ? BRF : BRT);
  output_asm_insn (ccbranch_templates[idx][len], operands);
  gcc_assert (n_nops == 0 || !bp);
  if (len == 0)
    while (n_nops-- > 0)
      output_asm_insn ("nop;", NULL);
}

/* Emit rtl for a comparison operation CMP in mode MODE.  Operands have been
   stored in bfin_compare_op0 and bfin_compare_op1 already.  */

rtx
bfin_gen_compare (rtx cmp, enum machine_mode mode ATTRIBUTE_UNUSED)
{
  enum rtx_code code1, code2;
  rtx op0 = bfin_compare_op0, op1 = bfin_compare_op1;
  rtx tem = bfin_cc_rtx;
  enum rtx_code code = GET_CODE (cmp);