stmt.c

GUN开源阻止下的编译器GCC

  struct bc_label *bc_target;

  /* The label we use for the fixup patch */
  struct bc_label *label;

  /* True (non-0) if fixup has been handled */
  int bc_handled:1;

  /* Like stack_level above, except refers to the interpreter stack */
  int bc_stack_level;
};

static struct goto_fixup *goto_fixup_chain;

/* Within any binding contour that must restore a stack level,
   all labels are recorded with a chain of these structures.  */

struct label_chain
{
  /* Points to following fixup.  */
  struct label_chain *next;
  tree label;
};
static void expand_goto_internal	PROTO((tree, rtx, rtx));
static void bc_expand_goto_internal	PROTO((enum bytecode_opcode,
					       struct bc_label *, tree));
static int expand_fixup			PROTO((tree, rtx, rtx));
static void bc_expand_fixup		PROTO((enum bytecode_opcode,
					       struct bc_label *, int));
static void fixup_gotos			PROTO((struct nesting *, rtx, tree,
					       rtx, int));
static void bc_fixup_gotos		PROTO((struct nesting *, int, tree,
					       rtx, int));
static void bc_expand_start_cond	PROTO((tree, int));
static void bc_expand_end_cond		PROTO((void));
static void bc_expand_start_else	PROTO((void));
static void bc_expand_end_loop		PROTO((void));
static void bc_expand_end_bindings	PROTO((tree, int, int));
static void bc_expand_decl		PROTO((tree, tree));
static void bc_expand_variable_local_init PROTO((tree));
static void bc_expand_decl_init		PROTO((tree));
static void expand_null_return_1	PROTO((rtx, int));
static void expand_value_return		PROTO((rtx));
static int tail_recursion_args		PROTO((tree, tree));
static void expand_cleanups		PROTO((tree, tree, int, int));
static void bc_expand_start_case	PROTO((struct nesting *, tree,
					       tree, char *));
static int bc_pushcase			PROTO((tree, tree));
static void bc_check_for_full_enumeration_handling PROTO((tree));
static void bc_expand_end_case		PROTO((tree));
static void do_jump_if_equal		PROTO((rtx, rtx, rtx, int));
static int estimate_case_costs		PROTO((case_node_ptr));
static void group_case_nodes		PROTO((case_node_ptr));
static void balance_case_nodes		PROTO((case_node_ptr *,
					       case_node_ptr));
static int node_has_low_bound		PROTO((case_node_ptr, tree));
static int node_has_high_bound		PROTO((case_node_ptr, tree));
static int node_is_bounded		PROTO((case_node_ptr, tree));
static void emit_jump_if_reachable	PROTO((rtx));
static void emit_case_nodes		PROTO((rtx, case_node_ptr, rtx, tree));

extern rtx bc_allocate_local ();
extern rtx bc_allocate_variable_array ();

void
init_stmt ()
{
  gcc_obstack_init (&stmt_obstack);
#if 0
  empty_cleanup_list = build_tree_list (NULL_TREE, NULL_TREE);
#endif
}

void
init_stmt_for_function ()
{
  /* We are not currently within any block, conditional, loop or case.  */
  block_stack = 0;
  stack_block_stack = 0;
  loop_stack = 0;
  case_stack = 0;
  cond_stack = 0;
  nesting_stack = 0;
  nesting_depth = 0;

  block_start_count = 0;

  /* No gotos have been expanded yet.  */
  goto_fixup_chain = 0;

  /* We are not processing a ({...}) grouping.  */
  expr_stmts_for_value = 0;
  last_expr_type = 0;
}

void
save_stmt_status (p)
     struct function *p;
{
  p->block_stack = block_stack;
  p->stack_block_stack = stack_block_stack;
  p->cond_stack = cond_stack;
  p->loop_stack = loop_stack;
  p->case_stack = case_stack;
  p->nesting_stack = nesting_stack;
  p->nesting_depth = nesting_depth;
  p->block_start_count = block_start_count;
  p->last_expr_type = last_expr_type;
  p->last_expr_value = last_expr_value;
  p->expr_stmts_for_value = expr_stmts_for_value;
  p->emit_filename = emit_filename;
  p->emit_lineno = emit_lineno;
  p->goto_fixup_chain = goto_fixup_chain;
}

void
restore_stmt_status (p)
     struct function *p;
{
  block_stack = p->block_stack;
  stack_block_stack = p->stack_block_stack;
  cond_stack = p->cond_stack;
  loop_stack = p->loop_stack;
  case_stack = p->case_stack;
  nesting_stack = p->nesting_stack;
  nesting_depth = p->nesting_depth;
  block_start_count = p->block_start_count;
  last_expr_type = p->last_expr_type;
  last_expr_value = p->last_expr_value;
  expr_stmts_for_value = p->expr_stmts_for_value;
  emit_filename = p->emit_filename;
  emit_lineno = p->emit_lineno;
  goto_fixup_chain = p->goto_fixup_chain;
}

/* Emit a no-op instruction.  */

void
emit_nop ()
{
  rtx last_insn;

  if (!output_bytecode)
    {
      last_insn = get_last_insn ();
      if (!optimize
	  && (GET_CODE (last_insn) == CODE_LABEL
	      || (GET_CODE (last_insn) == NOTE
		  && prev_real_insn (last_insn) == 0)))
	emit_insn (gen_nop ());
    }
}

/* Return the rtx-label that corresponds to a LABEL_DECL,
   creating it if necessary.  */

rtx
label_rtx (label)
     tree label;
{
  if (TREE_CODE (label) != LABEL_DECL)
    abort ();

  if (DECL_RTL (label))
    return DECL_RTL (label);

  return DECL_RTL (label) = gen_label_rtx ();
}

/* Add an unconditional jump to LABEL as the next sequential instruction.  */

void
emit_jump (label)
     rtx label;
{
  do_pending_stack_adjust ();
  emit_jump_insn (gen_jump (label));
  emit_barrier ();
}

/* Emit code to jump to the address
   specified by the pointer expression EXP.  */

void
expand_computed_goto (exp)
     tree exp;
{
  if (output_bytecode)
    {
      bc_expand_expr (exp);
      bc_emit_instruction (jumpP);
    }
  else
    {
      rtx x = expand_expr (exp, NULL_RTX, VOIDmode, 0);

#ifdef POINTERS_EXTEND_UNSIGNED
      x = convert_memory_address (Pmode, x);
#endif

      emit_queue ();
      do_pending_stack_adjust ();
      emit_indirect_jump (x);
    }
}

/* Handle goto statements and the labels that they can go to.  */

/* Specify the location in the RTL code of a label LABEL,
   which is a LABEL_DECL tree node.

   This is used for the kind of label that the user can jump to with a
   goto statement, and for alternatives of a switch or case statement.
   RTL labels generated for loops and conditionals don't go through here;
   they are generated directly at the RTL level, by other functions below.

   Note that this has nothing to do with defining label *names*.
   Languages vary in how they do that and what that even means.  */

void
expand_label (label)
     tree label;
{
  struct label_chain *p;

  if (output_bytecode)
    {
      if (! DECL_RTL (label))
	DECL_RTL (label) = bc_gen_rtx ((char *) 0, 0, bc_get_bytecode_label ());
      if (! bc_emit_bytecode_labeldef (BYTECODE_BC_LABEL (DECL_RTL (label))))
	error ("multiply defined label");
      return;
    }

  do_pending_stack_adjust ();
  emit_label (label_rtx (label));
  if (DECL_NAME (label))
    LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));

  if (stack_block_stack != 0)
    {
      p = (struct label_chain *) oballoc (sizeof (struct label_chain));
      p->next = stack_block_stack->data.block.label_chain;
      stack_block_stack->data.block.label_chain = p;
      p->label = label;
    }
}

/* Declare that LABEL (a LABEL_DECL) may be used for nonlocal gotos
   from nested functions.  */

void
declare_nonlocal_label (label)
     tree label;
{
  nonlocal_labels = tree_cons (NULL_TREE, label, nonlocal_labels);
  LABEL_PRESERVE_P (label_rtx (label)) = 1;
  if (nonlocal_goto_handler_slot == 0)
    {
      nonlocal_goto_handler_slot
	= assign_stack_local (Pmode, GET_MODE_SIZE (Pmode), 0);
      emit_stack_save (SAVE_NONLOCAL,
		       &nonlocal_goto_stack_level,
		       PREV_INSN (tail_recursion_reentry));
    }
}

/* Generate RTL code for a `goto' statement with target label LABEL.
   LABEL should be a LABEL_DECL tree node that was or will later be
   defined with `expand_label'.  */

void
expand_goto (label)
     tree label;
{
  tree context;

  if (output_bytecode)
    {
      expand_goto_internal (label, label_rtx (label), NULL_RTX);
      return;
    }

  /* Check for a nonlocal goto to a containing function.  */
  context = decl_function_context (label);
  if (context != 0 && context != current_function_decl)
    {
      struct function *p = find_function_data (context);
      rtx label_ref = gen_rtx (LABEL_REF, Pmode, label_rtx (label));
      rtx temp;

      p->has_nonlocal_label = 1;
      current_function_has_nonlocal_goto = 1;
      LABEL_REF_NONLOCAL_P (label_ref) = 1;

      /* Copy the rtl for the slots so that they won't be shared in
	 case the virtual stack vars register gets instantiated differently
	 in the parent than in the child.  */

#if HAVE_nonlocal_goto
      if (HAVE_nonlocal_goto)
	emit_insn (gen_nonlocal_goto (lookup_static_chain (label),
				      copy_rtx (p->nonlocal_goto_handler_slot),
				      copy_rtx (p->nonlocal_goto_stack_level),
				      label_ref));
      else
#endif
	{
	  rtx addr;

	  /* Restore frame pointer for containing function.
	     This sets the actual hard register used for the frame pointer
	     to the location of the function's incoming static chain info.
	     The non-local goto handler will then adjust it to contain the
	     proper value and reload the argument pointer, if needed.  */
	  emit_move_insn (hard_frame_pointer_rtx, lookup_static_chain (label));

	  /* We have now loaded the frame pointer hardware register with
	     the address of that corresponds to the start of the virtual
	     stack vars.  So replace virtual_stack_vars_rtx in all
	     addresses we use with stack_pointer_rtx.  */

	  /* Get addr of containing function's current nonlocal goto handler,
	     which will do any cleanups and then jump to the label.  */
	  addr = copy_rtx (p->nonlocal_goto_handler_slot);
	  temp = copy_to_reg (replace_rtx (addr, virtual_stack_vars_rtx,
					   hard_frame_pointer_rtx));
	  
	  /* Restore the stack pointer.  Note this uses fp just restored.  */
	  addr = p->nonlocal_goto_stack_level;
	  if (addr)
	    addr = replace_rtx (copy_rtx (addr),
				virtual_stack_vars_rtx,
				hard_frame_pointer_rtx);

	  emit_stack_restore (SAVE_NONLOCAL, addr, NULL_RTX);

	  /* Put in the static chain register the nonlocal label address.  */
	  emit_move_insn (static_chain_rtx, label_ref);
	  /* USE of hard_frame_pointer_rtx added for consistency; not clear if
	     really needed.  */
	  emit_insn (gen_rtx (USE, VOIDmode, hard_frame_pointer_rtx));
	  emit_insn (gen_rtx (USE, VOIDmode, stack_pointer_rtx));
	  emit_insn (gen_rtx (USE, VOIDmode, static_chain_rtx));
	  emit_indirect_jump (temp);
	}
     }
  else
    expand_goto_internal (label, label_rtx (label), NULL_RTX);
}

/* Generate RTL code for a `goto' statement with target label BODY.
   LABEL should be a LABEL_REF.
   LAST_INSN, if non-0, is the rtx we should consider as the last
   insn emitted (for the purposes of cleaning up a return).  */

static void
expand_goto_internal (body, label, last_insn)
     tree body;
     rtx label;
     rtx last_insn;
{
  struct nesting *block;
  rtx stack_level = 0;

  /* NOTICE!  If a bytecode instruction other than `jump' is needed,
     then the caller has to call bc_expand_goto_internal()
     directly. This is rather an exceptional case, and there aren't
     that many places where this is necessary. */
  if (output_bytecode)
    {
      expand_goto_internal (body, label, last_insn);
      return;
    }

  if (GET_CODE (label) != CODE_LABEL)
    abort ();

  /* If label has already been defined, we can tell now
     whether and how we must alter the stack level.  */

  if (PREV_INSN (label) != 0)
    {
      /* Find the innermost pending block that contains the label.
	 (Check containment by comparing insn-uids.)
	 Then restore the outermost stack level within that block,
	 and do cleanups of all blocks contained in it.  */
      for (block = block_stack; block; block = block->next)
	{
	  if (INSN_UID (block->data.block.first_insn) < INSN_UID (label))
	    break;
	  if (block->data.block.stack_level != 0)
	    stack_level = block->data.block.stack_level;
	  /* Execute the cleanups for blocks we are exiting.  */
	  if (block->data.block.cleanups != 0)
	    {
	      expand_cleanups (block->data.block.cleanups, NULL_TREE, 1, 1);
	      do_pending_stack_adjust ();
	    }
	}

      if (stack_level)
	{
	  /* Ensure stack adjust isn't done by emit_jump, as this would clobber
	     the stack pointer.  This one should be deleted as dead by flow. */
	  clear_pending_stack_adjust ();
	  do_pending_stack_adjust ();
	  emit_stack_restore (SAVE_BLOCK, stack_level, NULL_RTX);