expmed.h

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/* Target-dependent costs for expmed.c.
   Copyright (C) 1987-2013 Free Software Foundation, 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 3, 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 COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef EXPMED_H
#define EXPMED_H 1

enum alg_code {
  alg_unknown,
  alg_zero,
  alg_m, alg_shift,
  alg_add_t_m2,
  alg_sub_t_m2,
  alg_add_factor,
  alg_sub_factor,
  alg_add_t2_m,
  alg_sub_t2_m,
  alg_impossible
};

/* This structure holds the "cost" of a multiply sequence.  The
   "cost" field holds the total rtx_cost of every operator in the
   synthetic multiplication sequence, hence cost(a op b) is defined
   as rtx_cost(op) + cost(a) + cost(b), where cost(leaf) is zero.
   The "latency" field holds the minimum possible latency of the
   synthetic multiply, on a hypothetical infinitely parallel CPU.
   This is the critical path, or the maximum height, of the expression
   tree which is the sum of rtx_costs on the most expensive path from
   any leaf to the root.  Hence latency(a op b) is defined as zero for
   leaves and rtx_cost(op) + max(latency(a), latency(b)) otherwise.  */

struct mult_cost {
  short cost;     /* Total rtx_cost of the multiplication sequence.  */
  short latency;  /* The latency of the multiplication sequence.  */
};

/* This macro is used to compare a pointer to a mult_cost against an
   single integer "rtx_cost" value.  This is equivalent to the macro
   CHEAPER_MULT_COST(X,Z) where Z = {Y,Y}.  */
#define MULT_COST_LESS(X,Y) ((X)->cost < (Y)    \
                             || ((X)->cost == (Y) && (X)->latency < (Y)))

/* This macro is used to compare two pointers to mult_costs against
   each other.  The macro returns true if X is cheaper than Y.
   Currently, the cheaper of two mult_costs is the one with the
   lower "cost".  If "cost"s are tied, the lower latency is cheaper.  */
#define CHEAPER_MULT_COST(X,Y)  ((X)->cost < (Y)->cost          \
                                 || ((X)->cost == (Y)->cost     \
                                     && (X)->latency < (Y)->latency))

/* This structure records a sequence of operations.
   `ops' is the number of operations recorded.
   `cost' is their total cost.
   The operations are stored in `op' and the corresponding
   logarithms of the integer coefficients in `log'.

   These are the operations:
   alg_zero             total := 0;
   alg_m                total := multiplicand;
   alg_shift            total := total * coeff
   alg_add_t_m2         total := total + multiplicand * coeff;
   alg_sub_t_m2         total := total - multiplicand * coeff;
   alg_add_factor       total := total * coeff + total;
   alg_sub_factor       total := total * coeff - total;
   alg_add_t2_m         total := total * coeff + multiplicand;
   alg_sub_t2_m         total := total * coeff - multiplicand;

   The first operand must be either alg_zero or alg_m.  */

struct algorithm
{
  struct mult_cost cost;
  short ops;
  /* The size of the OP and LOG fields are not directly related to the
     word size, but the worst-case algorithms will be if we have few
     consecutive ones or zeros, i.e., a multiplicand like 10101010101...
     In that case we will generate shift-by-2, add, shift-by-2, add,...,
     in total wordsize operations.  */
  enum alg_code op[MAX_BITS_PER_WORD];
  char log[MAX_BITS_PER_WORD];
};

/* The entry for our multiplication cache/hash table.  */
struct alg_hash_entry {
  /* The number we are multiplying by.  */
  unsigned HOST_WIDE_INT t;

  /* The mode in which we are multiplying something by T.  */
  enum machine_mode mode;

  /* The best multiplication algorithm for t.  */
  enum alg_code alg;

  /* The cost of multiplication if ALG_CODE is not alg_impossible.
     Otherwise, the cost within which multiplication by T is
     impossible.  */
  struct mult_cost cost;

  /* Optimized for speed? */
  bool speed;
};

/* The number of cache/hash entries.  */
#if HOST_BITS_PER_WIDE_INT == 64
#define NUM_ALG_HASH_ENTRIES 1031
#else
#define NUM_ALG_HASH_ENTRIES 307
#endif

#define NUM_MODE_INT \
  (MAX_MODE_INT - MIN_MODE_INT + 1)
#define NUM_MODE_PARTIAL_INT \
  (MIN_MODE_PARTIAL_INT == VOIDmode ? 0 \
   : MAX_MODE_PARTIAL_INT - MIN_MODE_PARTIAL_INT + 1)
#define NUM_MODE_VECTOR_INT \
  (MIN_MODE_VECTOR_INT == VOIDmode ? 0 \
   : MAX_MODE_VECTOR_INT - MIN_MODE_VECTOR_INT + 1)

#define NUM_MODE_IP_INT (NUM_MODE_INT + NUM_MODE_PARTIAL_INT)
#define NUM_MODE_IPV_INT (NUM_MODE_IP_INT + NUM_MODE_VECTOR_INT)

struct expmed_op_cheap {
  bool cheap[2][NUM_MODE_IPV_INT];
};

struct expmed_op_costs {
  int cost[2][NUM_MODE_IPV_INT];
};

/* Target-dependent globals.  */
struct target_expmed {
  /* Each entry of ALG_HASH caches alg_code for some integer.  This is
     actually a hash table.  If we have a collision, that the older
     entry is kicked out.  */
  struct alg_hash_entry x_alg_hash[NUM_ALG_HASH_ENTRIES];

  /* True if x_alg_hash might already have been used.  */
  bool x_alg_hash_used_p;

  /* Nonzero means divides or modulus operations are relatively cheap for
     powers of two, so don't use branches; emit the operation instead.
     Usually, this will mean that the MD file will emit non-branch
     sequences.  */
  struct expmed_op_cheap x_sdiv_pow2_cheap;
  struct expmed_op_cheap x_smod_pow2_cheap;

  /* Cost of various pieces of RTL.  Note that some of these are indexed by
     shift count and some by mode.  */
  int x_zero_cost[2];
  struct expmed_op_costs x_add_cost;
  struct expmed_op_costs x_neg_cost;
  struct expmed_op_costs x_shift_cost[MAX_BITS_PER_WORD];
  struct expmed_op_costs x_shiftadd_cost[MAX_BITS_PER_WORD];
  struct expmed_op_costs x_shiftsub0_cost[MAX_BITS_PER_WORD];
  struct expmed_op_costs x_shiftsub1_cost[MAX_BITS_PER_WORD];
  struct expmed_op_costs x_mul_cost;
  struct expmed_op_costs x_sdiv_cost;
  struct expmed_op_costs x_udiv_cost;
  int x_mul_widen_cost[2][NUM_MODE_INT];
  int x_mul_highpart_cost[2][NUM_MODE_INT];

  /* Conversion costs are only defined between two scalar integer modes
     of different sizes.  The first machine mode is the destination mode,
     and the second is the source mode.  */
  int x_convert_cost[2][NUM_MODE_IP_INT][NUM_MODE_IP_INT];
};

extern struct target_expmed default_target_expmed;
#if SWITCHABLE_TARGET
extern struct target_expmed *this_target_expmed;
#else
#define this_target_expmed (&default_target_expmed)
#endif

/* Return a pointer to the alg_hash_entry at IDX.  */

static inline struct alg_hash_entry *
alg_hash_entry_ptr (int idx)
{
  return &this_target_expmed->x_alg_hash[idx];
}

/* Return true if the x_alg_hash field might have been used.  */

static inline bool
alg_hash_used_p (void)
{
  return this_target_expmed->x_alg_hash_used_p;
}

/* Set whether the x_alg_hash field might have been used.  */

static inline void
set_alg_hash_used_p (bool usedp)
{
  this_target_expmed->x_alg_hash_used_p = usedp;
}

/* Compute an index into the cost arrays by mode class.  */

static inline int
expmed_mode_index (enum machine_mode mode)
{
  switch (GET_MODE_CLASS (mode))
    {
    case MODE_INT:
      return mode - MIN_MODE_INT;
    case MODE_PARTIAL_INT:
      return mode - MIN_MODE_PARTIAL_INT + NUM_MODE_INT;
    case MODE_VECTOR_INT:
      return mode - MIN_MODE_VECTOR_INT + NUM_MODE_IP_INT;
    default:
      gcc_unreachable ();
    }
}

/* Return a pointer to a boolean contained in EOC indicating whether
   a particular operation performed in MODE is cheap when optimizing
   for SPEED.  */

static inline bool *
expmed_op_cheap_ptr (struct expmed_op_cheap *eoc, bool speed,
                     enum machine_mode mode)
{
  int idx = expmed_mode_index (mode);
  return &eoc->cheap[speed][idx];
}

/* Return a pointer to a cost contained in COSTS when a particular
   operation is performed in MODE when optimizing for SPEED.  */

static inline int *
expmed_op_cost_ptr (struct expmed_op_costs *costs, bool speed,
                    enum machine_mode mode)
{
  int idx = expmed_mode_index (mode);
  return &costs->cost[speed][idx];
}

/* Subroutine of {set_,}sdiv_pow2_cheap.  Not to be used otherwise.  */

static inline bool *
sdiv_pow2_cheap_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cheap_ptr (&this_target_expmed->x_sdiv_pow2_cheap,
                              speed, mode);
}

/* Set whether a signed division by a power of 2 is cheap in MODE
   when optimizing for SPEED.  */

static inline void
set_sdiv_pow2_cheap (bool speed, enum machine_mode mode, bool cheap_p)
{
  *sdiv_pow2_cheap_ptr (speed, mode) = cheap_p;
}

/* Return whether a signed division by a power of 2 is cheap in MODE
   when optimizing for SPEED.  */

static inline bool
sdiv_pow2_cheap (bool speed, enum machine_mode mode)
{
  return *sdiv_pow2_cheap_ptr (speed, mode);
}

/* Subroutine of {set_,}smod_pow2_cheap.  Not to be used otherwise.  */

static inline bool *
smod_pow2_cheap_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cheap_ptr (&this_target_expmed->x_smod_pow2_cheap,
                              speed, mode);
}

/* Set whether a signed modulo by a power of 2 is CHEAP in MODE when
   optimizing for SPEED.  */

static inline void
set_smod_pow2_cheap (bool speed, enum machine_mode mode, bool cheap)
{
  *smod_pow2_cheap_ptr (speed, mode) = cheap;
}

/* Return whether a signed modulo by a power of 2 is cheap in MODE
   when optimizing for SPEED.  */

static inline bool
smod_pow2_cheap (bool speed, enum machine_mode mode)
{
  return *smod_pow2_cheap_ptr (speed, mode);
}

/* Subroutine of {set_,}zero_cost.  Not to be used otherwise.  */

static inline int *
zero_cost_ptr (bool speed)
{
  return &this_target_expmed->x_zero_cost[speed];
}

/* Set the COST of loading zero when optimizing for SPEED.  */

static inline void
set_zero_cost (bool speed, int cost)
{
  *zero_cost_ptr (speed) = cost;
}

/* Return the COST of loading zero when optimizing for SPEED.  */

static inline int
zero_cost (bool speed)
{
  return *zero_cost_ptr (speed);
}

/* Subroutine of {set_,}add_cost.  Not to be used otherwise.  */

static inline int *
add_cost_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_add_cost, speed, mode);
}

/* Set the COST of computing an add in MODE when optimizing for SPEED.  */

static inline void
set_add_cost (bool speed, enum machine_mode mode, int cost)
{
  *add_cost_ptr (speed, mode) = cost;
}

/* Return the cost of computing an add in MODE when optimizing for SPEED.  */

static inline int
add_cost (bool speed, enum machine_mode mode)
{
  return *add_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}neg_cost.  Not to be used otherwise.  */

static inline int *
neg_cost_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_neg_cost, speed, mode);
}

/* Set the COST of computing a negation in MODE when optimizing for SPEED.  */

static inline void
set_neg_cost (bool speed, enum machine_mode mode, int cost)
{
  *neg_cost_ptr (speed, mode) = cost;
}

/* Return the cost of computing a negation in MODE when optimizing for
   SPEED.  */

static inline int
neg_cost (bool speed, enum machine_mode mode)
{
  return *neg_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}shift_cost.  Not to be used otherwise.  */

static inline int *
shift_cost_ptr (bool speed, enum machine_mode mode, int bits)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_shift_cost[bits],
                             speed, mode);
}

/* Set the COST of doing a shift in MODE by BITS when optimizing for SPEED.  */

static inline void
set_shift_cost (bool speed, enum machine_mode mode, int bits, int cost)
{
  *shift_cost_ptr (speed, mode, bits) = cost;
}

/* Return the cost of doing a shift in MODE by BITS when optimizing for
   SPEED.  */

static inline int
shift_cost (bool speed, enum machine_mode mode, int bits)
{
  return *shift_cost_ptr (speed, mode, bits);
}

/* Subroutine of {set_,}shiftadd_cost.  Not to be used otherwise.  */

static inline int *
shiftadd_cost_ptr (bool speed, enum machine_mode mode, int bits)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_shiftadd_cost[bits],
                             speed, mode);
}

/* Set the COST of doing a shift in MODE by BITS followed by an add when
   optimizing for SPEED.  */

static inline void
set_shiftadd_cost (bool speed, enum machine_mode mode, int bits, int cost)
{
  *shiftadd_cost_ptr (speed, mode, bits) = cost;
}

/* Return the cost of doing a shift in MODE by BITS followed by an add
   when optimizing for SPEED.  */

static inline int
shiftadd_cost (bool speed, enum machine_mode mode, int bits)
{
  return *shiftadd_cost_ptr (speed, mode, bits);
}

/* Subroutine of {set_,}shiftsub0_cost.  Not to be used otherwise.  */

static inline int *
shiftsub0_cost_ptr (bool speed, enum machine_mode mode, int bits)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_shiftsub0_cost[bits],
                             speed, mode);
}

/* Set the COST of doing a shift in MODE by BITS and then subtracting a
   value when optimizing for SPEED.  */

static inline void
set_shiftsub0_cost (bool speed, enum machine_mode mode, int bits, int cost)
{
  *shiftsub0_cost_ptr (speed, mode, bits) = cost;
}

/* Return the cost of doing a shift in MODE by BITS and then subtracting
   a value when optimizing for SPEED.  */

static inline int
shiftsub0_cost (bool speed, enum machine_mode mode, int bits)
{
  return *shiftsub0_cost_ptr (speed, mode, bits);
}

/* Subroutine of {set_,}shiftsub1_cost.  Not to be used otherwise.  */

static inline int *
shiftsub1_cost_ptr (bool speed, enum machine_mode mode, int bits)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_shiftsub1_cost[bits],
                             speed, mode);
}

/* Set the COST of subtracting a shift in MODE by BITS from a value when
   optimizing for SPEED.  */

static inline void
set_shiftsub1_cost (bool speed, enum machine_mode mode, int bits, int cost)
{
  *shiftsub1_cost_ptr (speed, mode, bits) = cost;
}

/* Return the cost of subtracting a shift in MODE by BITS from a value
   when optimizing for SPEED.  */

static inline int
shiftsub1_cost (bool speed, enum machine_mode mode, int bits)
{
  return *shiftsub1_cost_ptr (speed, mode, bits);
}

/* Subroutine of {set_,}mul_cost.  Not to be used otherwise.  */

static inline int *
mul_cost_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_mul_cost, speed, mode);
}

/* Set the COST of doing a multiplication in MODE when optimizing for
   SPEED.  */

static inline void
set_mul_cost (bool speed, enum machine_mode mode, int cost)
{
  *mul_cost_ptr (speed, mode) = cost;
}

/* Return the cost of doing a multiplication in MODE when optimizing
   for SPEED.  */

static inline int
mul_cost (bool speed, enum machine_mode mode)
{
  return *mul_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}sdiv_cost.  Not to be used otherwise.  */

static inline int *
sdiv_cost_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_sdiv_cost, speed, mode);
}

/* Set the COST of doing a signed division in MODE when optimizing
   for SPEED.  */

static inline void
set_sdiv_cost (bool speed, enum machine_mode mode, int cost)
{
  *sdiv_cost_ptr (speed, mode) = cost;
}

/* Return the cost of doing a signed division in MODE when optimizing
   for SPEED.  */

static inline int
sdiv_cost (bool speed, enum machine_mode mode)
{
  return *sdiv_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}udiv_cost.  Not to be used otherwise.  */

static inline int *
udiv_cost_ptr (bool speed, enum machine_mode mode)
{
  return expmed_op_cost_ptr (&this_target_expmed->x_udiv_cost, speed, mode);
}

/* Set the COST of doing an unsigned division in MODE when optimizing
   for SPEED.  */

static inline void
set_udiv_cost (bool speed, enum machine_mode mode, int cost)
{
  *udiv_cost_ptr (speed, mode) = cost;
}

/* Return the cost of doing an unsigned division in MODE when
   optimizing for SPEED.  */

static inline int
udiv_cost (bool speed, enum machine_mode mode)
{
  return *udiv_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}mul_widen_cost.  Not to be used otherwise.  */

static inline int *
mul_widen_cost_ptr (bool speed, enum machine_mode mode)
{
  gcc_assert (GET_MODE_CLASS (mode) == MODE_INT);

  return &this_target_expmed->x_mul_widen_cost[speed][mode - MIN_MODE_INT];
}

/* Set the COST for computing a widening multiplication in MODE when
   optimizing for SPEED.  */

static inline void
set_mul_widen_cost (bool speed, enum machine_mode mode, int cost)
{
  *mul_widen_cost_ptr (speed, mode) = cost;
}

/* Return the cost for computing a widening multiplication in MODE when
   optimizing for SPEED.  */

static inline int
mul_widen_cost (bool speed, enum machine_mode mode)
{
  return *mul_widen_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}mul_highpart_cost.  Not to be used otherwise.  */

static inline int *
mul_highpart_cost_ptr (bool speed, enum machine_mode mode)
{
  gcc_assert (GET_MODE_CLASS (mode) == MODE_INT);

  return &this_target_expmed->x_mul_highpart_cost[speed][mode - MIN_MODE_INT];
}

/* Set the COST for computing the high part of a multiplication in MODE
   when optimizing for SPEED.  */

static inline void
set_mul_highpart_cost (bool speed, enum machine_mode mode, int cost)
{
  *mul_highpart_cost_ptr (speed, mode) = cost;
}

/* Return the cost for computing the high part of a multiplication in MODE
   when optimizing for SPEED.  */

static inline int
mul_highpart_cost (bool speed, enum machine_mode mode)
{
  return *mul_highpart_cost_ptr (speed, mode);
}

/* Subroutine of {set_,}convert_cost.  Not to be used otherwise.  */

static inline int *
convert_cost_ptr (enum machine_mode to_mode, enum machine_mode from_mode,
                  bool speed)
{
  int to_idx = expmed_mode_index (to_mode);
  int from_idx = expmed_mode_index (from_mode);

  gcc_assert (IN_RANGE (to_idx, 0, NUM_MODE_IP_INT - 1));
  gcc_assert (IN_RANGE (from_idx, 0, NUM_MODE_IP_INT - 1));

  return &this_target_expmed->x_convert_cost[speed][to_idx][from_idx];
}

/* Set the COST for converting from FROM_MODE to TO_MODE when optimizing
   for SPEED.  */

static inline void
set_convert_cost (enum machine_mode to_mode, enum machine_mode from_mode,
                  bool speed, int cost)
{
  *convert_cost_ptr (to_mode, from_mode, speed) = cost;
}

/* Return the cost for converting from FROM_MODE to TO_MODE when optimizing
   for SPEED.  */

static inline int
convert_cost (enum machine_mode to_mode, enum machine_mode from_mode,
              bool speed)
{
  return *convert_cost_ptr (to_mode, from_mode, speed);
}

extern int mult_by_coeff_cost (HOST_WIDE_INT, enum machine_mode, bool);
#endif