bc-emit.c

GCC编译器源代码

/* Output bytecodes for GNU C-compiler.
   Copyright (C) 1993, 1994, 1996, 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.  */


#include "config.h"
#include <stdio.h>
#ifdef __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#include "machmode.h"
#include "rtl.h"
#include "real.h"
#include "obstack.h"
#include "bytecode.h"
#ifdef __GNUC__
#include "bytetypes.h"
#endif
#include "bc-emit.h"
#include "bc-opcode.h"
#include "bc-typecd.h"
#include "bi-run.h"

extern char *xmalloc (), *xrealloc ();

extern struct obstack *rtl_obstack;

/* Indexed by mode class, gives the narrowest mode for each class.  */

extern enum machine_mode class_narrowest_mode[(int) MAX_MODE_CLASS];

/* Commonly used modes.  */
/* Mode whose width is BITS_PER_UNIT */
extern enum machine_mode byte_mode;

/* Mode whose width is BITS_PER_WORD */
extern enum machine_mode word_mode;

/* Vector indexed by opcode giving info about the args for each opcode.  */
static struct arityvec arityvec[] = {
#include "bc-arity.h"
};

/* How to print a symbol name for the assembler.  */

static void
prsym (file, s)
     FILE *file;
     char *s;
{
  if (*s == '*')
    fprintf (file, "%s", s + 1);
  else

#ifdef NAMES_HAVE_UNDERSCORES
    fprintf (file, "_%s", s);
#else
    fprintf (file, "%s", s);
#endif

}

/* Maintain a bucket hash table for symbol names.  */

#define HASH_BITS 32
#define HASH_SIZE 509

static struct bc_sym *hashtab[HASH_SIZE];

static unsigned int
hash (name)
     char *name;
{
  unsigned int hash = 0;

  while (*name)
    {
      hash = hash << 3 | hash >> HASH_BITS - 3;
      hash += *name++;
    }

  return hash % HASH_SIZE;
}


/* Look up the named symbol, creating it if it doesn't exist.  */

struct bc_sym *
sym_lookup (name)
     char *name;
{
  int i;
  struct bc_sym *s;

  i = hash (name);
  for (s = hashtab[i]; s; s = s->next)
    if (!strcmp (s->name, name))
      return s;

  s = (struct bc_sym *) xmalloc (sizeof (struct bc_sym));
  s->name = xmalloc (strlen (name) + 1);
  strcpy (s->name, name);
  s->defined = s->global = s->common = 0;
  s->val = 0;
  s->next = hashtab[i];
  hashtab[i] = s;
  return s;
}


/* Write out .globl and common symbols to the named file.  */

static void
bc_sym_write (file)
     FILE *file;
{
  int i;
  struct bc_sym *s;

  for (i = 0; i < HASH_SIZE; ++i)
    for (s = hashtab[i]; s; s = s->next)
      {
	if (s->global)
	  {
	    fprintf (file, "\n\t.globl ");
	    prsym (file, s->name);
	    putc ('\n', file);
	    if (s->common)
	      {
		fprintf (file, "\n\t.comm ");
		prsym (file, s->name);
		fprintf (file, ", %lu\n", s->val);
	      }
	  }
	else if (s->common)
	  {
	    fprintf (file, "\n\t.lcomm ");
	    prsym (file, s->name);
	    fprintf (file, ", %lu\n", s->val);
	  }
      }
}




/* Create and initialize a new segment.  */

static struct bc_seg *
seg_create ()
{
  struct bc_seg *result;

  result = (struct bc_seg *) xmalloc (sizeof (struct bc_seg));
  result->alloc = 256;
  result->data = xmalloc (result->alloc);
  result->size = 0;
  result->syms = 0;
  result->relocs = 0;
  return result;
}


/* Advance the segment index to the next alignment boundary.  */

static void
seg_align (seg, log)
     struct bc_seg *seg;
     int log;
{
  unsigned int oldsize = seg->size;

  seg->size = seg->size + (1 << log) - 1 & ~((1 << log) - 1);
  if (seg->size > seg->alloc)
    {
      while (seg->size > seg->alloc)
	seg->alloc *= 2;
      seg->data = xrealloc (seg->data, seg->alloc);
    }
  bzero (seg->data + oldsize, seg->size - oldsize);
}


/* Append the given data to the given segment.  */

static void
seg_data (seg, data, size)
     struct bc_seg *seg;
     char *data;
     unsigned int size;
{
  if (seg->size + size > seg->alloc)
    {
      while (seg->size + size > seg->alloc)
	seg->alloc *= 2;
      seg->data = xrealloc (seg->data, seg->alloc);
    }

  bcopy (data, seg->data + seg->size, size);
  seg->size += size;
}


/* Append a zero-filled skip to the given segment.  */

static void
seg_skip (seg, size)
     struct bc_seg *seg;
     unsigned int size;
{
  if (seg->size + size > seg->alloc)
    {
      while (seg->size + size > seg->alloc)
	seg->alloc *= 2;
      seg->data = xrealloc (seg->data, seg->alloc);
    }

  memset (seg->data + seg->size, 0, size);
  seg->size += size;
}


/* Define the given name as the current offset in the given segment.  It
   is an error if the name is already defined.  Return 0 or 1 indicating
   failure or success respectively.  */

static int
seg_defsym (seg, name)
     struct bc_seg *seg;
     char *name;
{
  struct bc_sym *sym;
  struct bc_segsym *segsym;

  sym = sym_lookup (name);
  if (sym->defined)
    return 0;

  sym->defined = 1;
  sym->val = seg->size;
  segsym = (struct bc_segsym *) xmalloc (sizeof (struct bc_segsym));
  segsym->sym = sym;
  segsym->next = seg->syms;
  seg->syms = segsym;
  return 1;
}


/* Generate in seg's data a reference to the given sym, adjusted by
   the given offset.  */

static void
seg_refsym (seg, name, offset)
     struct bc_seg *seg;
     char *name;
     int offset;
{
  struct bc_sym *sym;
  struct bc_segreloc *segreloc;

  sym = sym_lookup (name);
  segreloc = (struct bc_segreloc *) xmalloc (sizeof (struct bc_segreloc));
  segreloc->offset = seg->size;
  segreloc->sym = sym;
  segreloc->next = seg->relocs;
  seg->relocs = segreloc;
  seg_data (seg, (char *) &offset, sizeof offset);
}


/* Concatenate the contents of given segments into the first argument.  */

static void
seg_concat (result, seg)
     struct bc_seg *result, *seg;
{
  unsigned int fix;
  struct bc_segsym *segsym;
  struct bc_segreloc *segreloc;

  seg_align (result, MACHINE_SEG_ALIGN);
  fix = result->size;
  seg_data (result, seg->data, seg->size);
  free (seg->data);

  /* Go through the symbols and relocs of SEG, adjusting their offsets
     for their new location in RESULT.  */
  if (seg->syms)
    {
      segsym = seg->syms;
      do
	segsym->sym->val += fix;
      while (segsym->next && (segsym = segsym->next));
      segsym->next = result->syms;
      result->syms = seg->syms;
    }
  if (seg->relocs)
    {
      segreloc = seg->relocs;
      do
	segreloc->offset += fix;
      while (segreloc->next && (segreloc = segreloc->next));
      segreloc->next = result->relocs;
      result->relocs = seg->relocs;
    }

  free ((char *) seg);
}

/* Write a segment to a file.  */

static void
bc_seg_write (seg, file)
     struct bc_seg *seg;
     FILE *file;
{
  struct bc_segsym *segsym, *nsegsym, *psegsym;
  struct bc_segreloc *segreloc, *nsegreloc, *psegreloc;
  int i, offset, flag;

  /* Reverse the list of symbols.  */
  for (psegsym = 0, segsym = seg->syms; segsym; segsym = nsegsym)
    {
      nsegsym = segsym->next;
      segsym->next = psegsym;
      psegsym = segsym;
    }
  seg->syms = psegsym;

  /* Reverse the list of relocs.  */
  for (psegreloc = 0, segreloc = seg->relocs; segreloc; segreloc = nsegreloc)
    {
      nsegreloc = segreloc->next;
      segreloc->next = psegreloc;
      psegreloc = segreloc;
    }
  seg->relocs = psegreloc;

  /* Output each byte of the segment.  */
  for (i = 0, segsym = seg->syms, segreloc = seg->relocs; i < seg->size; ++i)
    {
      while (segsym && segsym->sym->val == i)
	{
	  if (i % 8 != 0)
	    putc ('\n', file);

	  BC_WRITE_SEGSYM (segsym, file);
	  segsym = segsym->next;
	  flag = 1;
	}
      if (segreloc && segreloc->offset == i)
	{
	  if (i % 8 != 0)
	    putc ('\n', file);

	  bcopy (seg->data + i, (char *) &offset, sizeof (int));
	  i += sizeof (int) - 1;

	  BC_WRITE_RELOC_ENTRY (segreloc, file, offset);
	  segreloc = segreloc->next;
	  flag = 1;
	}
      else
	{
	  if (i % 8 == 0 || flag)
	    BC_START_BYTECODE_LINE (file);

	  BC_WRITE_BYTECODE (i % 8 == 0 || flag ? ' ' : ',',
			     seg->data[i] & 0xFF,
			     file);
	  flag = 0;
	  if (i % 8 == 7)
	    putc ('\n', file);
	}
    }

  /* Paranoia check--we should have visited all syms and relocs during
     the output pass.  */

  if (segsym || segreloc)
    abort ();
}



/* Text and data segments of the object file in making.  */
static struct bc_seg *bc_text_seg;
static struct bc_seg *bc_data_seg;

/* Called before anything else in this module.  */

void
bc_initialize ()
{
  int min_class_size[(int) MAX_MODE_CLASS];
  enum machine_mode mode;
  int i;

  bc_init_mode_to_code_map ();

  bc_text_seg = seg_create ();
  bc_data_seg = seg_create ();

  dconst0 = REAL_VALUE_ATOF ("0", DFmode);
  dconst1 = REAL_VALUE_ATOF ("1", DFmode);
  dconst2 = REAL_VALUE_ATOF ("2", DFmode);
  dconstm1 = REAL_VALUE_ATOF ("-1", DFmode);

  /* Find the narrowest mode for each class and compute the word and byte
     modes.  */

  for (i = 0; i < (int) MAX_MODE_CLASS; i++)
    min_class_size[i] = 1000;

  for (mode = VOIDmode; (int) mode < (int) MAX_MACHINE_MODE;
       mode = (enum machine_mode) ((int) mode + 1))
    {
      if (GET_MODE_SIZE (mode) < min_class_size[(int) GET_MODE_CLASS (mode)])
	{
	  class_narrowest_mode[(int) GET_MODE_CLASS (mode)] = mode;
	  min_class_size[(int) GET_MODE_CLASS (mode)] = GET_MODE_SIZE (mode);
	}
      if (GET_MODE_CLASS (mode) == MODE_INT
	  && GET_MODE_BITSIZE (mode) == BITS_PER_UNIT)
	byte_mode = mode;

      if (GET_MODE_CLASS (mode) == MODE_INT
	  && GET_MODE_BITSIZE (mode) == BITS_PER_WORD)
	word_mode = mode;
    }
}


/* External addresses referenced in a function.  Rather than trying to
   work relocatable address directly into bytecoded functions (which would
   require us to provide hairy location info and possibly obey alignment
   rules imposed by the architecture) we build an auxiliary table of
   pointer constants, and encode just offsets into this table into the
   actual bytecode.  */
static struct bc_seg *ptrconsts;

/* Trampoline code for the function entry.  */
struct bc_seg *trampoline;

/* Actual byte code of the function.  */
struct bc_seg *bytecode;

/* List of labels defined in the function.  */
struct bc_label *labels;

/* List of label references in the function.  */
struct bc_labelref *labelrefs;


/* Add symbol to pointer table.  Return offset into table where
   pointer was stored.  The offset usually goes into the bytecode
   stream as a constP literal.  */

int
bc_define_pointer (p)
     char *p;
{
  int offset = ptrconsts->size;

  seg_refsym (ptrconsts, p, 0);
  return offset;
}


/* Begin a bytecoded function.  */

int
bc_begin_function (name)
    char *name;
{
  ptrconsts = seg_create ();
  trampoline = seg_create ();
  bytecode = seg_create ();
  return seg_defsym (trampoline, name);
}


/* Force alignment in inline bytecode.  */

void
bc_align_bytecode (align)
    int align;
{
  seg_align (bytecode, align);
}