mips.c

gcc-2.95.3 Linux下最常用的C编译器

/* Subroutines for insn-output.c for MIPS
   Copyright (C) 1989, 90, 91, 93-98, 1999 Free Software Foundation, Inc.
   Contributed by A. Lichnewsky, [e-mail].
   Changes by Michael Meissner, [e-mail].
   64 bit r4000 support by Ian Lance Taylor, [e-mail], and
   Brendan Eich, [e-mail].

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.  */

/* ??? The TARGET_FP_CALL_32 macros are intended to simulate a 32 bit
   calling convention in 64 bit mode.  It doesn't work though, and should
   be replaced with something better designed.  */

#include "config.h"
#include "system.h"
#include <signal.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 "insn-attr.h"
#include "insn-codes.h"
#include "recog.h"
#include "toplev.h"

#undef MAX			/* sys/param.h may also define these */
#undef MIN

#include "tree.h"
#include "expr.h"
#include "flags.h"
#include "reload.h"
#include "output.h"

#if defined(USG) || !defined(HAVE_STAB_H)
#include "gstab.h"  /* If doing DBX on sysV, use our own stab.h.  */
#else
#include <stab.h>  /* On BSD, use the system's stab.h.  */
#endif /* not USG */

#ifdef __GNU_STAB__
#define STAB_CODE_TYPE enum __stab_debug_code
#else
#define STAB_CODE_TYPE int
#endif

extern char  *mktemp ();
extern tree   lookup_name ();

/* Enumeration for all of the relational tests, so that we can build
   arrays indexed by the test type, and not worry about the order
   of EQ, NE, etc. */

enum internal_test {
    ITEST_EQ,
    ITEST_NE,
    ITEST_GT,
    ITEST_GE,
    ITEST_LT,
    ITEST_LE,
    ITEST_GTU,
    ITEST_GEU,
    ITEST_LTU,
    ITEST_LEU,
    ITEST_MAX
  };


struct constant;
static enum internal_test map_test_to_internal_test	PROTO ((enum rtx_code));
static int mips16_simple_memory_operand		PROTO ((rtx, rtx,
							enum machine_mode));
static int m16_check_op				PROTO ((rtx, int, int, int));
static void block_move_loop			PROTO ((rtx, rtx, int, int,
							rtx, rtx));
static void block_move_call			PROTO ((rtx, rtx, rtx));
static FILE *make_temp_file			PROTO ((void));
static void save_restore_insns			PROTO ((int, rtx,
							long, FILE *));
static void mips16_output_gp_offset		PROTO ((FILE *, rtx));
static void mips16_fp_args			PROTO ((FILE *, int, int));
static void build_mips16_function_stub		PROTO ((FILE *));
static void mips16_optimize_gp			PROTO ((rtx));
static rtx add_constant				PROTO ((struct constant **,
							rtx,
							enum machine_mode));
static void dump_constants			PROTO ((struct constant *,
							rtx));
static rtx mips_find_symbol			PROTO ((rtx));
static void abort_with_insn			PROTO ((rtx, const char *))
  ATTRIBUTE_NORETURN;


/* Global variables for machine-dependent things.  */

/* Threshold for data being put into the small data/bss area, instead
   of the normal data area (references to the small data/bss area take
   1 instruction, and use the global pointer, references to the normal
   data area takes 2 instructions).  */
int mips_section_threshold = -1;

/* Count the number of .file directives, so that .loc is up to date.  */
int num_source_filenames = 0;

/* Count the number of sdb related labels are generated (to find block
   start and end boundaries).  */
int sdb_label_count = 0;

/* Next label # for each statement for Silicon Graphics IRIS systems. */
int sym_lineno = 0;

/* Non-zero if inside of a function, because the stupid MIPS asm can't
   handle .files inside of functions.  */
int inside_function = 0;

/* Files to separate the text and the data output, so that all of the data
   can be emitted before the text, which will mean that the assembler will
   generate smaller code, based on the global pointer.  */
FILE *asm_out_data_file;
FILE *asm_out_text_file;

/* Linked list of all externals that are to be emitted when optimizing
   for the global pointer if they haven't been declared by the end of
   the program with an appropriate .comm or initialization.  */

struct extern_list
{
  struct extern_list *next;	/* next external */
  char *name;			/* name of the external */
  int size;			/* size in bytes */
} *extern_head = 0;

/* Name of the file containing the current function.  */
const char *current_function_file = "";

/* Warning given that Mips ECOFF can't support changing files
   within a function.  */
int file_in_function_warning = FALSE;

/* Whether to suppress issuing .loc's because the user attempted
   to change the filename within a function.  */
int ignore_line_number = FALSE;

/* Number of nested .set noreorder, noat, nomacro, and volatile requests.  */
int set_noreorder;
int set_noat;
int set_nomacro;
int set_volatile;

/* The next branch instruction is a branch likely, not branch normal.  */
int mips_branch_likely;

/* Count of delay slots and how many are filled.  */
int dslots_load_total;
int dslots_load_filled;
int dslots_jump_total;
int dslots_jump_filled;

/* # of nops needed by previous insn */
int dslots_number_nops;

/* Number of 1/2/3 word references to data items (ie, not jal's).  */
int num_refs[3];

/* registers to check for load delay */
rtx mips_load_reg, mips_load_reg2, mips_load_reg3, mips_load_reg4;

/* Cached operands, and operator to compare for use in set/branch on
   condition codes.  */
rtx branch_cmp[2];

/* what type of branch to use */
enum cmp_type branch_type;

/* Number of previously seen half-pic pointers and references.  */
static int prev_half_pic_ptrs = 0;
static int prev_half_pic_refs = 0;

/* which cpu are we scheduling for */
enum processor_type mips_cpu;

/* which instruction set architecture to use.  */
int mips_isa;

#ifdef MIPS_ABI_DEFAULT
/* Which ABI to use.  This is defined to a constant in mips.h if the target
   doesn't support multiple ABIs.  */
int mips_abi;
#endif

/* Strings to hold which cpu and instruction set architecture to use.  */
const char *mips_cpu_string;	/* for -mcpu=<xxx> */
const char *mips_isa_string;	/* for -mips{1,2,3,4} */
const char *mips_abi_string;	/* for -mabi={32,n32,64,eabi} */

/* Whether we are generating mips16 code.  This is a synonym for
   TARGET_MIPS16, and exists for use as an attribute.  */
int mips16;

/* This variable is set by -mno-mips16.  We only care whether
   -mno-mips16 appears or not, and using a string in this fashion is
   just a way to avoid using up another bit in target_flags.  */
const char *mips_no_mips16_string;

/* This is only used to determine if an type size setting option was 
   explicitly specified (-mlong64, -mint64, -mlong32).  The specs
   set this option if such an option is used. */
const char *mips_explicit_type_size_string;

/* Whether we are generating mips16 hard float code.  In mips16 mode
   we always set TARGET_SOFT_FLOAT; this variable is nonzero if
   -msoft-float was not specified by the user, which means that we
   should arrange to call mips32 hard floating point code.  */
int mips16_hard_float;

/* This variable is set by -mentry.  We only care whether -mentry
   appears or not, and using a string in this fashion is just a way to
   avoid using up another bit in target_flags.  */
const char *mips_entry_string;

/* Whether we should entry and exit pseudo-ops in mips16 mode.  */
int mips_entry;

/* If TRUE, we split addresses into their high and low parts in the RTL.  */
int mips_split_addresses;

/* Generating calls to position independent functions?  */
enum mips_abicalls_type mips_abicalls;

/* High and low marks for floating point values which we will accept
   as legitimate constants for LEGITIMATE_CONSTANT_P.  These are
   initialized in override_options.  */
REAL_VALUE_TYPE dfhigh, dflow, sfhigh, sflow;

/* Mode used for saving/restoring general purpose registers.  */
static enum machine_mode gpr_mode;

/* Array giving truth value on whether or not a given hard register
   can support a given mode.  */
char mips_hard_regno_mode_ok[(int)MAX_MACHINE_MODE][FIRST_PSEUDO_REGISTER];

/* Current frame information calculated by compute_frame_size.  */
struct mips_frame_info current_frame_info;

/* Zero structure to initialize current_frame_info.  */
struct mips_frame_info zero_frame_info;

/* Temporary filename used to buffer .text until end of program
   for -mgpopt.  */
static char *temp_filename;

/* Pseudo-reg holding the address of the current function when
   generating embedded PIC code.  Created by LEGITIMIZE_ADDRESS, used
   by mips_finalize_pic if it was created.  */
rtx embedded_pic_fnaddr_rtx;

/* The length of all strings seen when compiling for the mips16.  This
   is used to tell how many strings are in the constant pool, so that
   we can see if we may have an overflow.  This is reset each time the
   constant pool is output.  */
int mips_string_length;

/* Pseudo-reg holding the value of $28 in a mips16 function which
   refers to GP relative global variables.  */
rtx mips16_gp_pseudo_rtx;

/* In mips16 mode, we build a list of all the string constants we see
   in a particular function.  */

struct string_constant
{
  struct string_constant *next;
  char *label;
};

static struct string_constant *string_constants;

/* List of all MIPS punctuation characters used by print_operand.  */
char mips_print_operand_punct[256];

/* Map GCC register number to debugger register number.  */
int mips_dbx_regno[FIRST_PSEUDO_REGISTER];

/* Buffer to use to enclose a load/store operation with %{ %} to
   turn on .set volatile.  */
static char volatile_buffer[60];

/* Hardware names for the registers.  If -mrnames is used, this
   will be overwritten with mips_sw_reg_names.  */

char mips_reg_names[][8] =
{
 "$0",   "$1",   "$2",   "$3",   "$4",   "$5",   "$6",   "$7",
 "$8",   "$9",   "$10",  "$11",  "$12",  "$13",  "$14",  "$15",
 "$16",  "$17",  "$18",  "$19",  "$20",  "$21",  "$22",  "$23",
 "$24",  "$25",  "$26",  "$27",  "$28",  "$sp",  "$fp",  "$31",
 "$f0",  "$f1",  "$f2",  "$f3",  "$f4",  "$f5",  "$f6",  "$f7",
 "$f8",  "$f9",  "$f10", "$f11", "$f12", "$f13", "$f14", "$f15",
 "$f16", "$f17", "$f18", "$f19", "$f20", "$f21", "$f22", "$f23",
 "$f24", "$f25", "$f26", "$f27", "$f28", "$f29", "$f30", "$f31",
 "hi",   "lo",   "accum","$fcc0","$fcc1","$fcc2","$fcc3","$fcc4",
 "$fcc5","$fcc6","$fcc7","$rap"
};

/* Mips software names for the registers, used to overwrite the
   mips_reg_names array.  */

char mips_sw_reg_names[][8] =
{
  "$zero","$at",  "$v0",  "$v1",  "$a0",  "$a1",  "$a2",  "$a3",
  "$t0",  "$t1",  "$t2",  "$t3",  "$t4",  "$t5",  "$t6",  "$t7",
  "$s0",  "$s1",  "$s2",  "$s3",  "$s4",  "$s5",  "$s6",  "$s7",
  "$t8",  "$t9",  "$k0",  "$k1",  "$gp",  "$sp",  "$fp",  "$ra",
  "$f0",  "$f1",  "$f2",  "$f3",  "$f4",  "$f5",  "$f6",  "$f7",
  "$f8",  "$f9",  "$f10", "$f11", "$f12", "$f13", "$f14", "$f15",
  "$f16", "$f17", "$f18", "$f19", "$f20", "$f21", "$f22", "$f23",
  "$f24", "$f25", "$f26", "$f27", "$f28", "$f29", "$f30", "$f31",
  "hi",   "lo",   "accum","$fcc0","$fcc1","$fcc2","$fcc3","$fcc4",
  "$fcc5","$fcc6","$fcc7","$rap"
};

/* Map hard register number to register class */
enum reg_class mips_regno_to_class[] =
{
  GR_REGS,	GR_REGS,	M16_NA_REGS,	M16_NA_REGS,
  M16_REGS,	M16_REGS,	M16_REGS,	M16_REGS,
  GR_REGS,	GR_REGS,	GR_REGS,	GR_REGS,
  GR_REGS,	GR_REGS,	GR_REGS,	GR_REGS,
  M16_NA_REGS,	M16_NA_REGS,	GR_REGS,	GR_REGS,
  GR_REGS,	GR_REGS,	GR_REGS,	GR_REGS,
  T_REG,	GR_REGS,	GR_REGS,	GR_REGS,
  GR_REGS,	GR_REGS,	GR_REGS,	GR_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  FP_REGS,	FP_REGS,	FP_REGS,	FP_REGS,
  HI_REG,	LO_REG,		HILO_REG,	ST_REGS,
  ST_REGS,	ST_REGS,	ST_REGS,	ST_REGS,
  ST_REGS,	ST_REGS,	ST_REGS,	GR_REGS
};

/* Map register constraint character to register class.  */
enum reg_class mips_char_to_class[256] =
{
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
  NO_REGS,	NO_REGS,	NO_REGS,	NO_REGS,
};


/* Return truth value of whether OP can be used as an operands
   where a register or 16 bit unsigned integer is needed.  */

int
uns_arith_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  if (GET_CODE (op) == CONST_INT && SMALL_INT_UNSIGNED (op))
    return 1;

  return register_operand (op, mode);
}

/* Return truth value of whether OP can be used as an operands
   where a 16 bit integer is needed  */

int
arith_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  if (GET_CODE (op) == CONST_INT && SMALL_INT (op))
    return 1;

  /* On the mips16, a GP relative value is a signed 16 bit offset.  */
  if (TARGET_MIPS16 && GET_CODE (op) == CONST && mips16_gp_offset_p (op))
    return 1;

  return register_operand (op, mode);
}

/* Return truth value of whether OP can be used as an operand in a two
   address arithmetic insn (such as set 123456,%o4) of mode MODE.  */

int
arith32_operand (op, mode)
     rtx op;
     enum machine_mode mode;
{
  if (GET_CODE (op) == CONST_INT)
    return 1;

  return register_operand (op, mode);
}

/* Return truth value of whether OP is a integer which fits in 16 bits  */

int
small_int (op, mode)
     rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  return (GET_CODE (op) == CONST_INT && SMALL_INT (op));
}

/* Return truth value of whether OP is a 32 bit integer which is too big to
   be loaded with one instruction.  */

int
large_int (op, mode)
     rtx op;
     enum machine_mode mode ATTRIBUTE_UNUSED;
{
  HOST_WIDE_INT value;

  if (GET_CODE (op) != CONST_INT)
    return 0;

  value = INTVAL (op);

  /* ior reg,$r0,value */
  if ((value & ~ ((HOST_WIDE_INT) 0x0000ffff)) == 0)
    return 0;

  /* subu reg,$r0,value */
  if (((unsigned HOST_WIDE_INT) (value + 32768)) <= 32767)
    return 0;

  /* lui reg,value>>16 */