gcc/regs.h

/* Define per-register tables for data flow info and register allocation.
   Copyright (C) 1987, 1993, 1994, 1995, 1997 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC 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.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */



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

/* Get the number of consecutive hard regs required to hold the REG rtx R.
   When something may be an explicit hard reg, REG_SIZE is the only
   valid way to get this value.  You cannot get it from the regno.  */

#define REG_SIZE(R) \
  ((mode_size[(int) GET_MODE (R)] + UNITS_PER_WORD - 1) / UNITS_PER_WORD)

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

extern int max_regno;

/* Maximum number of SCRATCH rtx's in each block of this function.  */

extern int max_scratch;

/* Register information indexed by register number */
typedef struct reg_info_def {
				/* fields set by reg_scan */
  int first_uid;		/* UID of first insn to use (REG n) */
  int last_uid;			/* UID of last insn to use (REG n) */
  int last_note_uid;		/* UID of last note to use (REG n) */

				/* fields set by both reg_scan and flow_analysis */
  int sets;			/* # of times (REG n) is set */

				/* fields set by flow_analysis */
  int refs;			/* # of times (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 basic_block;		/* # of basic blocks (REG n) is used in */
  char changes_size;		/* whether (SUBREG (REG n)) changes size */
} reg_info;

extern reg_info *reg_n_info;

/* Indexed by n, gives number of times (REG n) is used or set.
   References within loops may be counted more times.  */

#define REG_N_REFS(N) (reg_n_info[(N)].refs)

/* Indexed by n, gives number of times (REG n) is set.
   ??? both regscan and flow allocate space for this.  We should settle
   on just copy.  */

#define REG_N_SETS(N) (reg_n_info[(N)].sets)

/* 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_n_info[(N)].deaths)

/* Indexed by N; says whether a pseudo register N was ever used
   within a SUBREG that changes the size of the reg.  Some machines prohibit
   such objects to be in certain (usually floating-point) registers.  */

#define REG_CHANGES_SIZE(N) (reg_n_info[(N)].changes_size)

/* 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_n_info[(N)].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 flow.c 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_n_info[(N)].live_length)

/* 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 hardware reg
   saying whether that reg is ever used.  */

extern char regs_ever_live[FIRST_PSEUDO_REGISTER];

/* Vector indexed by hardware reg giving its name.  */

extern char *reg_names[FIRST_PSEUDO_REGISTER];

/* 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];

/* Vector indexed by regno; gives uid of first insn using that reg.
   This is computed by reg_scan for use by cse and loop.
   It is sometimes adjusted for subsequent changes during loop,
   but not adjusted by cse even if cse invalidates it.  */

#define REGNO_FIRST_UID(N) (reg_n_info[(N)].first_uid)

/* Vector indexed by regno; gives uid of last insn using that reg.
   This is computed by reg_scan for use by cse and loop.
   It is sometimes adjusted for subsequent changes during loop,
   but not adjusted by cse even if cse invalidates it.
   This is harmless since cse won't scan through a loop end.  */

#define REGNO_LAST_UID(N) (reg_n_info[(N)].last_uid)

/* Similar, but includes insns that mention the reg in their notes.  */

#define REGNO_LAST_NOTE_UID(N) (reg_n_info[(N)].last_note_uid)

/* This is reset to LAST_VIRTUAL_REGISTER + 1 at the start of each function.
   After rtl generation, it is 1 plus the largest register number used.  */

extern int reg_rtx_no;

/* Vector indexed by regno; contains 1 for a register is considered a pointer.
   Reloading, etc. will use a pointer register rather than a non-pointer
   as the base register in an address, when there is a choice of two regs.  */

extern char *regno_pointer_flag;
#define REGNO_POINTER_FLAG(REGNO) regno_pointer_flag[REGNO]
extern int regno_pointer_flag_length;

/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
   that have to go in the same hard reg.  */
extern rtx regs_may_share;

/* Vector mapping pseudo regno into the REG rtx for that register.
   This is computed by reg_scan.  */

extern rtx *regno_reg_rtx;

/* 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

/* Allocated in local_alloc.  */

/* A list of SCRATCH rtl allocated by local-alloc.  */
extern rtx *scratch_list;
/* The basic block in which each SCRATCH is used.  */
extern int *scratch_block;
/* The length of the arrays pointed to by scratch_block and scratch_list.  */
extern int scratch_list_length;

/* Allocate reg_n_info tables */
extern void allocate_reg_info PROTO((int, int, int));