avr.c

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

/* Subroutines for insn-output.c for ATMEL AVR micro controllers
   Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
   Contributed by Denis Chertykov ([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.  */

#include "config.h"
#include "system.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "real.h"
#include "insn-config.h"
#include "conditions.h"
#include "insn-attr.h"
#include "flags.h"
#include "reload.h"
#include "tree.h"
#include "output.h"
#include "expr.h"
#include "toplev.h"
#include "obstack.h"
#include "function.h"
#include "recog.h"
#include "tm_p.h"
#include "target.h"
#include "target-def.h"

/* Maximal allowed offset for an address in the LD command */
#define MAX_LD_OFFSET(MODE) (64 - (signed)GET_MODE_SIZE (MODE))

static int    avr_naked_function_p PARAMS ((tree));
static int    interrupt_function_p PARAMS ((tree));
static int    signal_function_p    PARAMS ((tree));
static int    avr_regs_to_save     PARAMS ((HARD_REG_SET *));
static int    sequent_regs_live    PARAMS ((void));
static const char * ptrreg_to_str  PARAMS ((int));
static const char * cond_string    PARAMS ((enum rtx_code));
static int    avr_num_arg_regs     PARAMS ((enum machine_mode, tree));
static int    out_adj_frame_ptr    PARAMS ((FILE *, int));
static int    out_set_stack_ptr    PARAMS ((FILE *, int, int));
static RTX_CODE compare_condition  PARAMS ((rtx insn));
static int    compare_sign_p       PARAMS ((rtx insn));
static int    reg_was_0            PARAMS ((rtx insn, rtx op));
static tree   avr_handle_progmem_attribute PARAMS ((tree *, tree, tree, int, bool *));
static tree   avr_handle_fndecl_attribute PARAMS ((tree *, tree, tree, int, bool *));
const struct attribute_spec avr_attribute_table[];
static bool   avr_assemble_integer PARAMS ((rtx, unsigned int, int));
static void   avr_output_function_prologue PARAMS ((FILE *, HOST_WIDE_INT));
static void   avr_output_function_epilogue PARAMS ((FILE *, HOST_WIDE_INT));
static void   avr_unique_section PARAMS ((tree, int));
static void   avr_encode_section_info PARAMS ((tree, int));
static unsigned int avr_section_type_flags PARAMS ((tree, const char *, int));

static void   avr_asm_out_ctor PARAMS ((rtx, int));
static void   avr_asm_out_dtor PARAMS ((rtx, int));

/* Allocate registers from r25 to r8 for parameters for function calls */
#define FIRST_CUM_REG 26

/* Temporary register RTX (gen_rtx (REG,QImode,TMP_REGNO)) */
rtx tmp_reg_rtx;

/* Zeroed register RTX (gen_rtx (REG,QImode,ZERO_REGNO)) */
rtx zero_reg_rtx;

/* RTX for register which will be used for loading immediate values to
   r0-r15 registers.  */
rtx ldi_reg_rtx;

/* AVR register names {"r0", "r1", ..., "r31"} */
static const char *const avr_regnames[] = REGISTER_NAMES;

/* This holds the last insn address.  */
static int last_insn_address = 0;

/* Commands count in the compiled file */
static int commands_in_file;

/* Commands in the functions prologues in the compiled file */
static int commands_in_prologues;

/* Commands in the functions epilogues in the compiled file */
static int commands_in_epilogues;

/* Prologue/Epilogue size in words */
static int prologue_size;
static int epilogue_size;

/* Size of all jump tables in the current function, in words.  */
static int jump_tables_size;

/* Initial stack value specified by the `-minit-stack=' option */
const char *avr_init_stack = "__stack";

/* Default MCU name */
const char *avr_mcu_name = "avr2";

/* Preprocessor macros to define depending on MCU type.  */
const char *avr_base_arch_macro;
const char *avr_extra_arch_macro;

/* More than 8K of program memory: use "call" and "jmp".  */
int avr_mega_p = 0;

/* Enhanced core: use "movw", "mul", ...  */
int avr_enhanced_p = 0;

/* Assembler only.  */
int avr_asm_only_p = 0;

struct base_arch_s {
  int asm_only;
  int enhanced;
  int mega;
  const char *const macro;
};

static const struct base_arch_s avr_arch_types[] = {
  { 1, 0, 0, NULL },  /* unknown device specified */
  { 1, 0, 0, "__AVR_ARCH__=1" },
  { 0, 0, 0, "__AVR_ARCH__=2" },
  { 0, 0, 1, "__AVR_ARCH__=3" },
  { 0, 1, 0, "__AVR_ARCH__=4" },
  { 0, 1, 1, "__AVR_ARCH__=5" }
};

struct mcu_type_s {
  const char *const name;
  int arch;  /* index in avr_arch_types[] */
  /* Must lie outside user's namespace.  NULL == no macro.  */
  const char *const macro;
};

/* List of all known AVR MCU types - if updated, it has to be kept
   in sync in several places (FIXME: is there a better way?):
    - here
    - avr.h (CPP_SPEC, LINK_SPEC, CRT_BINUTILS_SPECS)
    - t-avr (MULTILIB_MATCHES)
    - gas/config/tc-avr.c
    - avr-libc  */

static const struct mcu_type_s avr_mcu_types[] = {
    /* Classic, <= 8K.  */
  { "avr2",      2, NULL },
  { "at90s2313", 2, "__AVR_AT90S2313__" },
  { "at90s2323", 2, "__AVR_AT90S2323__" },
  { "at90s2333", 2, "__AVR_AT90S2333__" },
  { "at90s2343", 2, "__AVR_AT90S2343__" },
  { "attiny22",  2, "__AVR_ATtiny22__" },
  { "attiny26",  2, "__AVR_ATtiny26__" },
  { "at90s4414", 2, "__AVR_AT90S4414__" },
  { "at90s4433", 2, "__AVR_AT90S4433__" },
  { "at90s4434", 2, "__AVR_AT90S4434__" },
  { "at90s8515", 2, "__AVR_AT90S8515__" },
  { "at90c8534", 2, "__AVR_AT90C8534__" },
  { "at90s8535", 2, "__AVR_AT90S8535__" },
  { "at86rf401", 2, "__AVR_AT86RF401__" },
    /* Classic, > 8K.  */
  { "avr3",      3, NULL },
  { "atmega103", 3, "__AVR_ATmega103__" },
  { "atmega603", 3, "__AVR_ATmega603__" },
  { "at43usb320", 3, "__AVR_AT43USB320__" },
  { "at43usb355", 3, "__AVR_AT43USB355__" },
  { "at76c711",  3, "__AVR_AT76C711__" },
    /* Enhanced, <= 8K.  */
  { "avr4",      4, NULL },
  { "atmega8",   4, "__AVR_ATmega8__" },
  { "atmega8515", 4, "__AVR_ATmega8515__" },
  { "atmega8535", 4, "__AVR_ATmega8535__" },
    /* Enhanced, > 8K.  */
  { "avr5",      5, NULL },
  { "atmega16",  5, "__AVR_ATmega16__" },
  { "atmega161", 5, "__AVR_ATmega161__" },
  { "atmega162", 5, "__AVR_ATmega162__" },
  { "atmega163", 5, "__AVR_ATmega163__" },
  { "atmega169", 5, "__AVR_ATmega169__" },
  { "atmega32",  5, "__AVR_ATmega32__" },
  { "atmega323", 5, "__AVR_ATmega323__" },
  { "atmega64",  5, "__AVR_ATmega64__" },
  { "atmega128", 5, "__AVR_ATmega128__" },
  { "at94k",     5, "__AVR_AT94K__" },
    /* Assembler only.  */
  { "avr1",      1, NULL },
  { "at90s1200", 1, "__AVR_AT90S1200__" },
  { "attiny11",  1, "__AVR_ATtiny11__" },
  { "attiny12",  1, "__AVR_ATtiny12__" },
  { "attiny15",  1, "__AVR_ATtiny15__" },
  { "attiny28",  1, "__AVR_ATtiny28__" },
  { NULL,        0, NULL }
};

int avr_case_values_threshold = 30000;

/* Initialize the GCC target structure.  */
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.word\t"
#undef TARGET_ASM_INTEGER
#define TARGET_ASM_INTEGER avr_assemble_integer

#undef TARGET_ASM_FUNCTION_PROLOGUE
#define TARGET_ASM_FUNCTION_PROLOGUE avr_output_function_prologue
#undef TARGET_ASM_FUNCTION_EPILOGUE
#define TARGET_ASM_FUNCTION_EPILOGUE avr_output_function_epilogue
#undef TARGET_ATTRIBUTE_TABLE
#define TARGET_ATTRIBUTE_TABLE avr_attribute_table
#undef TARGET_ASM_UNIQUE_SECTION
#define TARGET_ASM_UNIQUE_SECTION avr_unique_section
#undef TARGET_ENCODE_SECTION_INFO
#define TARGET_ENCODE_SECTION_INFO avr_encode_section_info
#undef TARGET_SECTION_TYPE_FLAGS
#define TARGET_SECTION_TYPE_FLAGS avr_section_type_flags

struct gcc_target targetm = TARGET_INITIALIZER;

void
avr_override_options ()
{
  const struct mcu_type_s *t;
  const struct base_arch_s *base;

  for (t = avr_mcu_types; t->name; t++)
    if (strcmp (t->name, avr_mcu_name) == 0)
      break;

  if (!t->name)
    {
      fprintf (stderr, "unknown MCU `%s' specified\nKnown MCU names:\n",
	       avr_mcu_name);
      for (t = avr_mcu_types; t->name; t++)
	fprintf (stderr,"   %s\n", t->name);
    }

  base = &avr_arch_types[t->arch];
  avr_asm_only_p = base->asm_only;
  avr_enhanced_p = base->enhanced;
  avr_mega_p = base->mega;
  avr_base_arch_macro = base->macro;
  avr_extra_arch_macro = t->macro;

  if (optimize && !TARGET_NO_TABLEJUMP)
    avr_case_values_threshold = (!AVR_MEGA || TARGET_CALL_PROLOGUES) ? 8 : 17;
}


/* Initialize TMP_REG_RTX and ZERO_REG_RTX */
void
avr_init_once ()
{
  tmp_reg_rtx = xmalloc (sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  memset (tmp_reg_rtx, 0, sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  PUT_CODE (tmp_reg_rtx, REG);
  PUT_MODE (tmp_reg_rtx, QImode);
  XINT (tmp_reg_rtx, 0) = TMP_REGNO;

  zero_reg_rtx = xmalloc (sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  memset (zero_reg_rtx, 0, sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  PUT_CODE (zero_reg_rtx, REG);
  PUT_MODE (zero_reg_rtx, QImode);
  XINT (zero_reg_rtx, 0) = ZERO_REGNO;

  ldi_reg_rtx = xmalloc (sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  memset (ldi_reg_rtx, 0, sizeof (struct rtx_def) + 1 * sizeof (rtunion));
  PUT_CODE (ldi_reg_rtx, REG);
  PUT_MODE (ldi_reg_rtx, QImode);
  XINT (ldi_reg_rtx, 0) = LDI_REG_REGNO;
}

/*  return register class from register number */

static const int reg_class_tab[]={
  GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,
  GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,
  GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,GENERAL_REGS,
  GENERAL_REGS, /* r0 - r15 */
  LD_REGS,LD_REGS,LD_REGS,LD_REGS,LD_REGS,LD_REGS,LD_REGS,
  LD_REGS,                      /* r16 - 23 */
  ADDW_REGS,ADDW_REGS,          /* r24,r25 */
  POINTER_X_REGS,POINTER_X_REGS, /* r26,27 */
  POINTER_Y_REGS,POINTER_Y_REGS, /* r28,r29 */
  POINTER_Z_REGS,POINTER_Z_REGS, /* r30,r31 */
  STACK_REG,STACK_REG           /* SPL,SPH */
};

/* Return register class for register R */

enum reg_class
avr_regno_reg_class (r)
     int r;
{
  if (r <= 33)
    return reg_class_tab[r];
  return ALL_REGS;
}


/* A C expression which defines the machine-dependent operand
   constraint letters for register classes.  If C is such a
   letter, the value should be the register class corresponding to
   it.  Otherwise, the value should be `NO_REGS'.  The register
   letter `r', corresponding to class `GENERAL_REGS', will not be
   passed to this macro; you do not need to handle it.  */

enum reg_class
avr_reg_class_from_letter  (c)
     int c;
{
  switch (c)
    {
    case 't' : return R0_REG;
    case 'b' : return BASE_POINTER_REGS;
    case 'e' : return POINTER_REGS;
    case 'w' : return ADDW_REGS;
    case 'd' : return LD_REGS;
    case 'l' : return NO_LD_REGS;
    case 'a' : return SIMPLE_LD_REGS;
    case 'x' : return POINTER_X_REGS;
    case 'y' : return POINTER_Y_REGS;
    case 'z' : return POINTER_Z_REGS;
    case 'q' : return STACK_REG;
    default: break;
    }
  return NO_REGS;
}

/* Return nonzero if FUNC is a naked function.  */

static int
avr_naked_function_p (func)
     tree func;
{
  tree a;

  if (TREE_CODE (func) != FUNCTION_DECL)
    abort ();
  
  a = lookup_attribute ("naked", DECL_ATTRIBUTES (func));
  return a != NULL_TREE;
}

/* Return nonzero if FUNC is an interrupt function as specified
   by the "interrupt" attribute.  */

static int
interrupt_function_p (func)
     tree func;
{
  tree a;

  if (TREE_CODE (func) != FUNCTION_DECL)
    return 0;

  a = lookup_attribute ("interrupt", DECL_ATTRIBUTES (func));
  return a != NULL_TREE;
}

/* Return nonzero if FUNC is a signal function as specified
   by the "signal" attribute.  */

static int
signal_function_p (func)
     tree func;
{
  tree a;

  if (TREE_CODE (func) != FUNCTION_DECL)
    return 0;

  a = lookup_attribute ("signal", DECL_ATTRIBUTES (func));
  return a != NULL_TREE;
}

/* Return the number of hard registers to push/pop in the prologue/epilogue
   of the current function, and optionally store these registers in SET.  */

static int
avr_regs_to_save (set)
     HARD_REG_SET *set;
{
  int reg, count;
  int int_or_sig_p = (interrupt_function_p (current_function_decl)
		      || signal_function_p (current_function_decl));
  int leaf_func_p = leaf_function_p ();

  if (set)
    CLEAR_HARD_REG_SET (*set);
  count = 0;

  /* No need to save any registers if the function never returns.  */
  if (TREE_THIS_VOLATILE (current_function_decl))
    return 0;

  for (reg = 0; reg < 32; reg++)
    {
      /* Do not push/pop __tmp_reg__, __zero_reg__, as well as
	 any global register variables.  */
      if (fixed_regs[reg])
	continue;

      if ((int_or_sig_p && !leaf_func_p && call_used_regs[reg])
	  || (regs_ever_live[reg]
	      && (int_or_sig_p || !call_used_regs[reg])
	      && !(frame_pointer_needed
		   && (reg == REG_Y || reg == (REG_Y+1)))))
	{
	  if (set)
	    SET_HARD_REG_BIT (*set, reg);
	  count++;
	}
    }
  return count;
}

/* Compute offset between arg_pointer and frame_pointer */

int
initial_elimination_offset (from, to)
     int from;
     int to;
{
  if (from == FRAME_POINTER_REGNUM && to == STACK_POINTER_REGNUM)
    return 0;
  else
    {
      int offset = frame_pointer_needed ? 2 : 0;

      offset += avr_regs_to_save (NULL);
      return get_frame_size () + 2 + 1 + offset;
    }
}

/* Return 1 if the function epilogue is just a single "ret".  */

int
avr_simple_epilogue ()
{
  return (! frame_pointer_needed
	  && get_frame_size () == 0
	  && avr_regs_to_save (NULL) == 0
	  && ! interrupt_function_p (current_function_decl)
	  && ! signal_function_p (current_function_decl)
	  && ! avr_naked_function_p (current_function_decl)
	  && ! MAIN_NAME_P (DECL_NAME (current_function_decl))
	  && ! TREE_THIS_VOLATILE (current_function_decl));
}

/* This function checks sequence of live registers */

static int
sequent_regs_live ()
{
  int reg;
  int live_seq=0;
  int cur_seq=0;

  for (reg = 0; reg < 18; ++reg)
    {
      if (!call_used_regs[reg])
	{
	  if (regs_ever_live[reg])
	    {
	      ++live_seq;
	      ++cur_seq;
	    }
	  else
	    cur_seq = 0;
	}
    }

  if (!frame_pointer_needed)
    {
      if (regs_ever_live[REG_Y])
	{
	  ++live_seq;
	  ++cur_seq;
	}
      else
	cur_seq = 0;

      if (regs_ever_live[REG_Y+1])
	{
	  ++live_seq;
	  ++cur_seq;
	}
      else
	cur_seq = 0;
    }
  else
    {
      cur_seq += 2;
      live_seq += 2;
    }
  return (cur_seq == live_seq) ? live_seq : 0;
}