regs.h

/* Define per-register tables for data flow info and register allocation.
   Copyright (C) 1987, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2003, 2004, 2005, 2006, 2007, 2008 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 GCC_REGS_H
#define GCC_REGS_H

#include "varray.h"
#include "obstack.h"
#include "hard-reg-set.h"
#include "basic-block.h"

#define REG_BYTES(R) mode_size[(int) GET_MODE (R)]

/* When you only have the mode of a pseudo register before it has a hard
   register chosen for it, this reports the size of each hard register
   a pseudo in such a mode would get allocated to.  A target may
   override this.  */

#ifndef REGMODE_NATURAL_SIZE
#define REGMODE_NATURAL_SIZE(MODE)	UNITS_PER_WORD
#endif

#ifndef SMALL_REGISTER_CLASSES
#define SMALL_REGISTER_CLASSES 0
#endif

/* Maximum register number used in this function, plus one.  */

extern int max_regno;

/* REG_N_REFS and REG_N_SETS are initialized by a call to
   regstat_init_n_sets_and_refs from the current values of
   DF_REG_DEF_COUNT and DF_REG_USE_COUNT.  REG_N_REFS and REG_N_SETS
   should only be used if a pass need to change these values in some
   magical way or or the pass needs to have accurate values for these
   and is not using incremental df scanning.

   At the end of a pass that uses REG_N_REFS and REG_N_SETS, a call
   should be made to regstat_free_n_sets_and_refs.  

   Local alloc seems to play pretty loose with these values.
   REG_N_REFS is set to 0 if the register is used in an asm.
   Furthermore, local_alloc calls regclass to hack both REG_N_REFS and
   REG_N_SETS for three address insns.  Other passes seem to have
   other special values.  */



/* Structure to hold values for REG_N_SETS (i) and REG_N_REFS (i). */

struct regstat_n_sets_and_refs_t
{
  int sets;			/* # of times (REG n) is set */
  int refs;			/* # of times (REG n) is used or set */
};

extern struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;

/* Indexed by n, gives number of times (REG n) is used or set.  */
static inline int
REG_N_REFS(int regno)
{
  return regstat_n_sets_and_refs[regno].refs;
}

/* Indexed by n, gives number of times (REG n) is used or set.  */
#define SET_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs = V)
#define INC_REG_N_REFS(N,V) (regstat_n_sets_and_refs[N].refs += V)

/* Indexed by n, gives number of times (REG n) is set.  */
static inline int
REG_N_SETS (int regno)
{
  return regstat_n_sets_and_refs[regno].sets;
}

/* Indexed by n, gives number of times (REG n) is set.  */
#define SET_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets = V)
#define INC_REG_N_SETS(N,V) (regstat_n_sets_and_refs[N].sets += V)


/* Functions defined in reg-stat.c.  */
extern void regstat_init_n_sets_and_refs (void);
extern void regstat_free_n_sets_and_refs (void);
extern void regstat_compute_ri (void);
extern void regstat_free_ri (void);
extern bitmap regstat_get_setjmp_crosses (void);
extern void regstat_compute_calls_crossed (void);
extern void regstat_free_calls_crossed (void);


/* Register information indexed by register number.  This structure is
   initialized by calling regstat_compute_ri and is destroyed by
   calling regstat_free_ri.  */
struct reg_info_t
{
  int freq;			/* # estimated frequency (REG n) is used or set */
  int deaths;			/* # of times (REG n) dies */
  int live_length;		/* # of instructions (REG n) is live */
  int calls_crossed;		/* # of calls (REG n) is live across */
  int freq_calls_crossed;	/* # estimated frequency (REG n) crosses call */
  int throw_calls_crossed;	/* # of calls that may throw (REG n) is live across */
  int basic_block;		/* # of basic blocks (REG n) is used in */
};

extern struct reg_info_t *reg_info_p;

/* The number allocated elements of reg_info_p.  */
extern size_t reg_info_p_size;

/* Estimate frequency of references to register N.  */

#define REG_FREQ(N) (reg_info_p[N].freq)

/* The weights for each insn varies from 0 to REG_FREQ_BASE.
   This constant does not need to be high, as in infrequently executed
   regions we want to count instructions equivalently to optimize for
   size instead of speed.  */
#define REG_FREQ_MAX 1000

/* Compute register frequency from the BB frequency.  When optimizing for size,
   or profile driven feedback is available and the function is never executed,
   frequency is always equivalent.  Otherwise rescale the basic block
   frequency.  */
#define REG_FREQ_FROM_BB(bb) (optimize_size				      \
			      || (flag_branch_probabilities		      \
				  && !ENTRY_BLOCK_PTR->count)		      \
			      ? REG_FREQ_MAX				      \
			      : ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
			      ? ((bb)->frequency * REG_FREQ_MAX / BB_FREQ_MAX)\
			      : 1)

/* Indexed by N, gives number of insns in which register N dies.
   Note that if register N is live around loops, it can die
   in transitions between basic blocks, and that is not counted here.
   So this is only a reliable indicator of how many regions of life there are
   for registers that are contained in one basic block.  */

#define REG_N_DEATHS(N) (reg_info_p[N].deaths)

/* Get the number of consecutive words required to hold pseudo-reg N.  */

#define PSEUDO_REGNO_SIZE(N) \
  ((GET_MODE_SIZE (PSEUDO_REGNO_MODE (N)) + UNITS_PER_WORD - 1)		\
   / UNITS_PER_WORD)

/* Get the number of bytes required to hold pseudo-reg N.  */

#define PSEUDO_REGNO_BYTES(N) \
  GET_MODE_SIZE (PSEUDO_REGNO_MODE (N))

/* Get the machine mode of pseudo-reg N.  */

#define PSEUDO_REGNO_MODE(N) GET_MODE (regno_reg_rtx[N])

/* Indexed by N, gives number of CALL_INSNS across which (REG n) is live.  */

#define REG_N_CALLS_CROSSED(N)  (reg_info_p[N].calls_crossed)
#define REG_FREQ_CALLS_CROSSED(N)  (reg_info_p[N].freq_calls_crossed)

/* Indexed by N, gives number of CALL_INSNS that may throw, across which
   (REG n) is live.  */

#define REG_N_THROWING_CALLS_CROSSED(N) (reg_info_p[N].throw_calls_crossed)

/* Total number of instructions at which (REG n) is live.  The larger
   this is, the less priority (REG n) gets for allocation in a hard
   register (in global-alloc).  This is set in df-problems.c whenever
   register info is requested and remains valid for the rest of the
   compilation of the function; it is used to control register
   allocation.

   local-alloc.c may alter this number to change the priority.

   Negative values are special.
   -1 is used to mark a pseudo reg which has a constant or memory equivalent
   and is used infrequently enough that it should not get a hard register.
   -2 is used to mark a pseudo reg for a parameter, when a frame pointer
   is not required.  global.c makes an allocno for this but does
   not try to assign a hard register to it.  */

#define REG_LIVE_LENGTH(N)  (reg_info_p[N].live_length)

/* Indexed by n, gives number of basic block that  (REG n) is used in.
   If the value is REG_BLOCK_GLOBAL (-1),
   it means (REG n) is used in more than one basic block.
   REG_BLOCK_UNKNOWN (0) means it hasn't been seen yet so we don't know.
   This information remains valid for the rest of the compilation
   of the current function; it is used to control register allocation.  */

#define REG_BLOCK_UNKNOWN 0
#define REG_BLOCK_GLOBAL -1

#define REG_BASIC_BLOCK(N) (reg_info_p[N].basic_block)

/* Vector of substitutions of register numbers,
   used to map pseudo regs into hardware regs.

   This can't be folded into reg_n_info without changing all of the
   machine dependent directories, since the reload functions
   in the machine dependent files access it.  */

extern short *reg_renumber;

/* Vector indexed by machine mode saying whether there are regs of that mode.  */

extern bool have_regs_of_mode [MAX_MACHINE_MODE];

/* For each hard register, the widest mode object that it can contain.
   This will be a MODE_INT mode if the register can hold integers.  Otherwise
   it will be a MODE_FLOAT or a MODE_CC mode, whichever is valid for the
   register.  */

extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];

/* Flag set by local-alloc or global-alloc if they decide to allocate
   something in a call-clobbered register.  */

extern int caller_save_needed;

/* Predicate to decide whether to give a hard reg to a pseudo which
   is referenced REFS times and would need to be saved and restored
   around a call CALLS times.  */

#ifndef CALLER_SAVE_PROFITABLE
#define CALLER_SAVE_PROFITABLE(REFS, CALLS)  (4 * (CALLS) < (REFS))
#endif

/* On most machines a register class is likely to be spilled if it
   only has one register.  */
#ifndef CLASS_LIKELY_SPILLED_P
#define CLASS_LIKELY_SPILLED_P(CLASS) (reg_class_size[(int) (CLASS)] == 1)
#endif

/* Select a register mode required for caller save of hard regno REGNO.  */
#ifndef HARD_REGNO_CALLER_SAVE_MODE
#define HARD_REGNO_CALLER_SAVE_MODE(REGNO, NREGS, MODE) \
  choose_hard_reg_mode (REGNO, NREGS, false)
#endif

/* Registers that get partially clobbered by a call in a given mode.
   These must not be call used registers.  */
#ifndef HARD_REGNO_CALL_PART_CLOBBERED
#define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
#endif

/* 1 if the corresponding class does contain register of given
   mode.  */
extern char contains_reg_of_mode [N_REG_CLASSES] [MAX_MACHINE_MODE];

typedef unsigned short move_table[N_REG_CLASSES];

/* Maximum cost of moving from a register in one class to a register
   in another class.  */
extern move_table *move_cost[MAX_MACHINE_MODE];

/* Specify number of hard registers given machine mode occupy.  */
extern unsigned char hard_regno_nregs[FIRST_PSEUDO_REGISTER][MAX_MACHINE_MODE];

/* Similar, but here we don't have to move if the first index is a
   subset of the second so in that case the cost is zero.  */
extern move_table *may_move_in_cost[MAX_MACHINE_MODE];

/* Similar, but here we don't have to move if the first index is a
   superset of the second so in that case the cost is zero.  */
extern move_table *may_move_out_cost[MAX_MACHINE_MODE];

/* Return an exclusive upper bound on the registers occupied by hard
   register (reg:MODE REGNO).  */

static inline unsigned int
end_hard_regno (enum machine_mode mode, unsigned int regno)
{
  return regno + hard_regno_nregs[regno][(int) mode];
}

/* Likewise for hard register X.  */

#define END_HARD_REGNO(X) end_hard_regno (GET_MODE (X), REGNO (X))

/* Likewise for hard or pseudo register X.  */

#define END_REGNO(X) (HARD_REGISTER_P (X) ? END_HARD_REGNO (X) : REGNO (X) + 1)

/* Add to REGS all the registers required to store a value of mode MODE
   in register REGNO.  */

static inline void
add_to_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
		     unsigned int regno)
{
  unsigned int end_regno;

  end_regno = end_hard_regno (mode, regno);
  do
    SET_HARD_REG_BIT (*regs, regno);
  while (++regno < end_regno);
}

/* Likewise, but remove the registers.  */

static inline void
remove_from_hard_reg_set (HARD_REG_SET *regs, enum machine_mode mode,
			  unsigned int regno)
{
  unsigned int end_regno;

  end_regno = end_hard_regno (mode, regno);
  do
    CLEAR_HARD_REG_BIT (*regs, regno);
  while (++regno < end_regno);
}

/* Return true if REGS contains the whole of (reg:MODE REGNO).  */

static inline bool
in_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
		   unsigned int regno)
{
  unsigned int end_regno;

  if (!TEST_HARD_REG_BIT (regs, regno))
    return false;

  end_regno = end_hard_regno (mode, regno);
  while (++regno < end_regno)
    if (!TEST_HARD_REG_BIT (regs, regno))
      return false;

  return true;
}

/* Return true if (reg:MODE REGNO) includes an element of REGS.  */

static inline bool
overlaps_hard_reg_set_p (const HARD_REG_SET regs, enum machine_mode mode,
			 unsigned int regno)
{
  unsigned int end_regno;

  if (TEST_HARD_REG_BIT (regs, regno))
    return true;

  end_regno = end_hard_regno (mode, regno);
  while (++regno < end_regno)
    if (TEST_HARD_REG_BIT (regs, regno))
      return true;

  return false;
}

#endif /* GCC_REGS_H */