jcf-write.c

gcc-2.95.3 Linux下最常用的C编译器

/* Write out a Java(TM) class file.
   Copyright (C) 1998, 1999 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. 

Java and all Java-based marks are trademarks or registered trademarks
of Sun Microsystems, Inc. in the United States and other countries.
The Free Software Foundation is independent of Sun Microsystems, Inc.  */

#include "config.h"
#include "system.h"
#include "jcf.h"
#include "tree.h"
#include "java-tree.h"
#include "obstack.h"
#undef AND
#include "rtl.h"
#include "flags.h"
#include "java-opcodes.h"
#include "parse.h" /* for BLOCK_EXPR_BODY */
#include "buffer.h"
#include "toplev.h"

#ifndef DIR_SEPARATOR
#define DIR_SEPARATOR '/'
#endif

extern struct obstack temporary_obstack;

/* Base directory in which `.class' files should be written.
   NULL means to put the file into the same directory as the
   corresponding .java file.  */
char *jcf_write_base_directory = NULL;

/* Make sure bytecode.data is big enough for at least N more bytes. */

#define RESERVE(N) \
  do { CHECK_OP(state); \
    if (state->bytecode.ptr + (N) > state->bytecode.limit) \
    buffer_grow (&state->bytecode, N); } while (0)

/* Add a 1-byte instruction/operand I to bytecode.data,
   assuming space has already been RESERVE'd. */

#define OP1(I) (*state->bytecode.ptr++ = (I), CHECK_OP(state))

/* Like OP1, but I is a 2-byte big endian integer. */

#define OP2(I) \
  do { int _i = (I); OP1 (_i >> 8);  OP1 (_i); CHECK_OP(state); } while (0)

/* Like OP1, but I is a 4-byte big endian integer. */

#define OP4(I) \
  do { int _i = (I);  OP1 (_i >> 24);  OP1 (_i >> 16); \
       OP1 (_i >> 8); OP1 (_i); CHECK_OP(state); } while (0)

/* Macro to call each time we push I words on the JVM stack. */

#define NOTE_PUSH(I) \
  do { state->code_SP += (I); \
    if (state->code_SP > state->code_SP_max) \
      state->code_SP_max = state->code_SP; } while (0)

/* Macro to call each time we pop I words from the JVM stack. */

#define NOTE_POP(I) \
  do { state->code_SP -= (I); if (state->code_SP < 0) abort(); } while (0)

/* A chunk or segment of a .class file. */

struct chunk
{
  /* The next segment of this .class file. */
  struct chunk *next;

  /* The actual data in this segment to be written to the .class file. */
  unsigned char *data;

  /* The size of the segment to be written to the .class file. */
  int size;
};

#define PENDING_CLEANUP_PC (-3)
#define PENDING_EXIT_PC (-2)
#define UNDEFINED_PC (-1)

/* Each "block" represents a label plus the bytecode instructions following.
   There may be branches out of the block, but no incoming jumps, except
   to the beginning of the block.

   If (pc < 0), the jcf_block is not an actual block (i.e. it has no
   assocated code yet), but it is an undefined label.
*/

struct jcf_block
{
  /* For blocks that that are defined, the next block (in pc order).
     For blocks that are the not-yet-defined end label of a LABELED_BLOCK_EXPR
     or a cleanup expression (from a WITH_CLEANUP_EXPR),
     this is the next (outer) such end label, in a stack headed by
     labeled_blocks in jcf_partial. */
  struct jcf_block *next;

  /* In the not-yet-defined end label for an unfinished EXIT_BLOCK_EXPR.
     pc is PENDING_EXIT_PC.
     In the not-yet-defined end label for pending cleanup subroutine,
     pc is PENDING_CLEANUP_PC.
     For other not-yet-defined labels, pc is UNDEFINED_PC.

     If the label has been defined:
     Until perform_relocations is finished, this is the maximum possible
     value of the bytecode offset at the begnning of this block.
     After perform_relocations, it is the actual offset (pc). */
  int pc;

  int linenumber;

  /* After finish_jcf_block is called, The actual instructions contained in this block.
     Before than NULL, and the instructions are in state->bytecode. */
  union {
    struct chunk *chunk;

    /* If pc==PENDING_CLEANUP_PC, start_label is the start of the region
       coveed by the cleanup. */
    struct jcf_block *start_label;
  } v;

  union {
    /* Set of relocations (in reverse offset order) for this block. */
    struct jcf_relocation *relocations;

    /* If this block is that of the not-yet-defined end label of
       a LABELED_BLOCK_EXPR, where LABELED_BLOCK is that LABELED_BLOCK_EXPR.
       If pc==PENDING_CLEANUP_PC, the cleanup that needs to be run. */
    tree labeled_block;
  } u;
};

/* A "relocation" type for the 0-3 bytes of padding at the start
   of a tableswitch or a lookupswitch. */
#define SWITCH_ALIGN_RELOC 4

/* A relocation type for the labels in a tableswitch or a lookupswitch;
   these are relative to the start of the instruction, but (due to
   th 0-3 bytes of padding), we don't know the offset before relocation. */
#define BLOCK_START_RELOC 1

struct jcf_relocation
{
  /* Next relocation for the current jcf_block. */
  struct jcf_relocation *next;

  /* The (byte) offset within the current block that needs to be relocated. */
  HOST_WIDE_INT offset;

  /* 0 if offset is a 4-byte relative offset.
     4 (SWITCH_ALIGN_RELOC) if offset points to 0-3 padding bytes inserted
     for proper alignment in tableswitch/lookupswitch instructions.
     1 (BLOCK_START_RELOC) if offset points to a 4-byte offset relative
     to the start of the containing block.
     -1 if offset is a 2-byte relative offset.
     < -1 if offset is the address of an instruction with a 2-byte offset
     that does not have a corresponding 4-byte offset version, in which
     case the absolute value of kind is the inverted opcode.
     > 4 if offset is the address of an instruction (such as jsr) with a
     2-byte offset that does have a corresponding 4-byte offset version,
     in which case kind is the opcode of the 4-byte version (such as jsr_w). */
  int kind;

  /* The label the relocation wants to actually transfer to. */
  struct jcf_block *label;
};

/* State for single catch clause. */

struct jcf_handler
{
  struct jcf_handler *next;

  struct jcf_block *start_label;
  struct jcf_block *end_label;
  struct jcf_block *handler_label;

  /* The sub-class of Throwable handled, or NULL_TREE (for finally). */
  tree type;
};

/* State for the current switch statement. */

struct jcf_switch_state
{
  struct jcf_switch_state *prev;
  struct jcf_block *default_label;

  struct jcf_relocation *cases;
  int num_cases;
  HOST_WIDE_INT min_case, max_case;
};

/* This structure is used to contain the various pieces that will
   become a .class file. */

struct jcf_partial
{
  struct chunk *first;
  struct chunk *chunk;
  struct obstack *chunk_obstack;
  tree current_method;

  /* List of basic blocks for the current method. */
  struct jcf_block *blocks;
  struct jcf_block *last_block;

  struct localvar_info *first_lvar;
  struct localvar_info *last_lvar;
  int lvar_count;

  CPool cpool;

  int linenumber_count;

  /* Until perform_relocations, this is a upper bound on the number
     of bytes (so far) in the instructions for the current method. */
  int code_length;

  /* Stack of undefined ending labels for LABELED_BLOCK_EXPR. */
  struct jcf_block *labeled_blocks;
  
  /* The current stack size (stack pointer) in the current method. */
  int code_SP;

  /* The largest extent of stack size (stack pointer) in the current method. */
  int code_SP_max;

  /* Contains a mapping from local var slot number to localvar_info. */
  struct buffer localvars;

  /* The buffer allocated for bytecode for the current jcf_block. */
  struct buffer bytecode;

  /* Chain of exception handlers for the current method. */
  struct jcf_handler *handlers;

  /* Last element in handlers chain. */
  struct jcf_handler *last_handler;

  /* Number of exception handlers for the current method. */
  int num_handlers;

  /* Number of finalizers we are currently nested within. */
  int num_finalizers;

  /* If non-NULL, use this for the return value. */
  tree return_value_decl;

  /* Information about the current switch statemenet. */
  struct jcf_switch_state *sw_state;
};

static void generate_bytecode_insns PROTO ((tree, int, struct jcf_partial *));
static struct chunk * alloc_chunk PROTO ((struct chunk *, unsigned char *,
					  int, struct obstack *));
static unsigned char * append_chunk PROTO ((unsigned char *, int,
					    struct jcf_partial *));
static void append_chunk_copy PROTO ((unsigned char *, int,
				      struct jcf_partial *));
static struct jcf_block * gen_jcf_label PROTO ((struct jcf_partial *));
static void finish_jcf_block PROTO ((struct jcf_partial *));
static void define_jcf_label PROTO ((struct jcf_block *,
				     struct jcf_partial *));
static struct jcf_block * get_jcf_label_here PROTO ((struct jcf_partial *));
static void put_linenumber PROTO ((int, struct jcf_partial *));
static void localvar_alloc PROTO ((tree, struct jcf_partial *));
static int localvar_free PROTO ((tree, struct jcf_partial *));
static int get_access_flags PROTO ((tree));
static void write_chunks PROTO ((FILE *, struct chunk *));
static int adjust_typed_op PROTO ((tree, int));
static void generate_bytecode_conditional PROTO ((tree, struct jcf_block *,
						  struct jcf_block *, int,
						  struct jcf_partial *));
static void generate_bytecode_return PROTO ((tree, struct jcf_partial *));
static void perform_relocations PROTO ((struct jcf_partial *));
static void init_jcf_state PROTO ((struct jcf_partial *, struct obstack *));
static void init_jcf_method PROTO ((struct jcf_partial *, tree));
static void release_jcf_state PROTO ((struct jcf_partial *));
static struct chunk * generate_classfile PROTO ((tree, struct jcf_partial *));


/* Utility macros for appending (big-endian) data to a buffer.
   We assume a local variable 'ptr' points into where we want to
   write next, and we assume enoygh space has been allocated. */

#ifdef ENABLE_CHECKING
int
CHECK_PUT(ptr, state, i)
     void *ptr;
     struct jcf_partial *state;
     int i;
{
  if (ptr < state->chunk->data
      || (char*)ptr + i > state->chunk->data + state->chunk->size)
    fatal ("internal error - CHECK_PUT failed");
  return 0;
}
#else
#define CHECK_PUT(PTR, STATE, I) ((void)0)
#endif

#define PUT1(X)  (CHECK_PUT(ptr, state, 1), *ptr++ = (X))
#define PUT2(X)  (PUT1((X) >> 8), PUT1((X) & 0xFF))
#define PUT4(X)  (PUT2((X) >> 16), PUT2((X) & 0xFFFF))
#define PUTN(P, N)  (CHECK_PUT(ptr, state, N), memcpy(ptr, P, N), ptr += (N))


/* Allocate a new chunk on obstack WORK, and link it in after LAST.
   Set the data and size fields to DATA and SIZE, respectively.
   However, if DATA is NULL and SIZE>0, allocate a buffer as well. */

static struct chunk *
alloc_chunk (last, data, size, work)
     struct chunk *last;
     unsigned char *data;
     int size;
     struct obstack *work;
{
  struct chunk *chunk = (struct chunk *)
    obstack_alloc (work, sizeof(struct chunk));

  if (data == NULL && size > 0)
    data = obstack_alloc (work, size);

  chunk->next = NULL;
  chunk->data = data;
  chunk->size = size;
  if (last != NULL)
    last->next = chunk;
  return chunk;
}

#ifdef ENABLE_CHECKING
int
CHECK_OP(struct jcf_partial *state)
{
  if (state->bytecode.ptr > state->bytecode.limit)
    {
      fatal("internal error - CHECK_OP failed");
    }
  return 0;
}
#else
#define CHECK_OP(STATE) ((void)0)
#endif

static unsigned char *
append_chunk (data, size, state)
     unsigned char *data;
     int size;
     struct jcf_partial *state;
{
  state->chunk = alloc_chunk (state->chunk, data, size, state->chunk_obstack);
  if (state->first == NULL)
    state->first = state->chunk;
  return state->chunk->data;
}

static void
append_chunk_copy (data, size, state)
     unsigned char *data;
     int size;
     struct jcf_partial *state;
{
  unsigned char *ptr = append_chunk (NULL, size, state);
  memcpy (ptr, data, size);
}

static struct jcf_block *
gen_jcf_label (state)
     struct jcf_partial *state;
{
  struct jcf_block *block = (struct jcf_block *)
    obstack_alloc (state->chunk_obstack, sizeof (struct jcf_block));
  block->next =	NULL;
  block->linenumber = -1;
  block->pc = UNDEFINED_PC;
  return block;
}

static void
finish_jcf_block (state)
     struct jcf_partial *state;
{
  struct jcf_block *block = state->last_block;
  struct jcf_relocation *reloc;
  int code_length = BUFFER_LENGTH (&state->bytecode);
  int pc = state->code_length;
  append_chunk_copy (state->bytecode.data, code_length, state);
  BUFFER_RESET (&state->bytecode);
  block->v.chunk = state->chunk;

  /* Calculate code_length to the maximum value it can have. */
  pc += block->v.chunk->size;
  for (reloc = block->u.relocations;  reloc != NULL;  reloc = reloc->next)
    {
      int kind = reloc->kind;
      if (kind == SWITCH_ALIGN_RELOC)
	pc += 3;
      else if (kind > BLOCK_START_RELOC)
	pc += 2; /* 2-byte offset may grow to 4-byte offset */
      else if (kind < -1)
	pc += 5; /* May need to add a goto_w. */
    }
  state->code_length = pc;
}

static void
define_jcf_label (label, state)
     struct jcf_block *label;
     struct jcf_partial *state;
{
  if (state->last_block != NULL)
    finish_jcf_block (state);
  label->pc = state->code_length;
  if (state->blocks == NULL)
    state->blocks = label;
  else
    state->last_block->next = label;
  state->last_block = label;
  label->next = NULL;
  label->u.relocations = NULL;
}

static struct jcf_block *
get_jcf_label_here (state)
     struct jcf_partial *state;
{
  if (state->last_block != NULL && BUFFER_LENGTH (&state->bytecode) == 0)
    return state->last_block;
  else
    {