c-parse.in

gcc库的原代码,对编程有很大帮助.

		  emit_line_note ($<filename>-1, $<lineno>0);
		  /* The emit_nop used to come before emit_line_note,
		     but that made the nop seem like part of the preceding line.
		     And that was confusing when the preceding line was
		     inside of an if statement and was not really executed.
		     I think it ought to work to put the nop after the line number.
		     We will see.  --rms, July 15, 1991.  */
		  emit_nop (); }
	  '(' expr ')'
		{ /* Don't start the loop till we have succeeded
		     in parsing the end test.  This is to make sure
		     that we end every loop we start.  */
		  expand_start_loop (1);
		  emit_line_note (input_filename, lineno);
		  expand_exit_loop_if_false (NULL_PTR,
					     truthvalue_conversion ($4));
		  position_after_white_space (); }
	  lineno_labeled_stmt
		{ expand_end_loop (); }
	| do_stmt_start
	  '(' expr ')' ';'
		{ emit_line_note (input_filename, lineno);
		  expand_exit_loop_if_false (NULL_PTR,
					     truthvalue_conversion ($3));
		  expand_end_loop ();
		  clear_momentary (); }
/* This rule is needed to make sure we end every loop we start.  */
	| do_stmt_start error
		{ expand_end_loop ();
		  clear_momentary (); }
	| FOR
	  '(' xexpr ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  /* See comment in `while' alternative, above.  */
		  emit_nop ();
		  if ($3) c_expand_expr_stmt ($3);
		  /* Next step is to call expand_start_loop_continue_elsewhere,
		     but wait till after we parse the entire for (...).
		     Otherwise, invalid input might cause us to call that
		     fn without calling expand_end_loop.  */
		}
	  xexpr ';'
		/* Can't emit now; wait till after expand_start_loop...  */
		{ $<lineno>7 = lineno;
		  $<filename>$ = input_filename; }
	  xexpr ')'
		{ 
		  /* Start the loop.  Doing this after parsing
		     all the expressions ensures we will end the loop.  */
		  expand_start_loop_continue_elsewhere (1);
		  /* Emit the end-test, with a line number.  */
		  emit_line_note ($<filename>8, $<lineno>7);
		  if ($6)
		    expand_exit_loop_if_false (NULL_PTR,
					       truthvalue_conversion ($6));
		  /* Don't let the tree nodes for $9 be discarded by
		     clear_momentary during the parsing of the next stmt.  */
		  push_momentary ();
		  $<lineno>7 = lineno;
		  $<filename>8 = input_filename;
		  position_after_white_space (); }
	  lineno_labeled_stmt
		{ /* Emit the increment expression, with a line number.  */
		  emit_line_note ($<filename>8, $<lineno>7);
		  expand_loop_continue_here ();
		  if ($9)
		    c_expand_expr_stmt ($9);
		  if (yychar == CONSTANT || yychar == STRING)
		    pop_momentary_nofree ();
		  else
		    pop_momentary ();
		  expand_end_loop (); }
	| SWITCH '(' expr ')'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_start_case ($3);
		  /* Don't let the tree nodes for $3 be discarded by
		     clear_momentary during the parsing of the next stmt.  */
		  push_momentary ();
		  position_after_white_space (); }
	  lineno_labeled_stmt
		{ expand_end_case ($3);
		  if (yychar == CONSTANT || yychar == STRING)
		    pop_momentary_nofree ();
		  else
		    pop_momentary (); }
	| BREAK ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  if ( ! expand_exit_something ())
		    error ("break statement not within loop or switch"); }
	| CONTINUE ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  if (! expand_continue_loop (NULL_PTR))
		    error ("continue statement not within a loop"); }
	| RETURN ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_return (NULL_TREE); }
	| RETURN expr ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_return ($2); }
	| ASM_KEYWORD maybe_type_qual '(' expr ')' ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  STRIP_NOPS ($4);
		  if ((TREE_CODE ($4) == ADDR_EXPR
		       && TREE_CODE (TREE_OPERAND ($4, 0)) == STRING_CST)
		      || TREE_CODE ($4) == STRING_CST)
		    expand_asm ($4);
		  else
		    error ("argument of `asm' is not a constant string"); }
	/* This is the case with just output operands.  */
	| ASM_KEYWORD maybe_type_qual '(' expr ':' asm_operands ')' ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_asm_operands ($4, $6, NULL_TREE, NULL_TREE,
					 $2 == ridpointers[(int)RID_VOLATILE],
					 input_filename, lineno); }
	/* This is the case with input operands as well.  */
	| ASM_KEYWORD maybe_type_qual '(' expr ':' asm_operands ':' asm_operands ')' ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_asm_operands ($4, $6, $8, NULL_TREE,
					 $2 == ridpointers[(int)RID_VOLATILE],
					 input_filename, lineno); }
	/* This is the case with clobbered registers as well.  */
	| ASM_KEYWORD maybe_type_qual '(' expr ':' asm_operands ':'
  	  asm_operands ':' asm_clobbers ')' ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  c_expand_asm_operands ($4, $6, $8, $10,
					 $2 == ridpointers[(int)RID_VOLATILE],
					 input_filename, lineno); }
	| GOTO identifier ';'
		{ tree decl;
		  stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  decl = lookup_label ($2);
		  if (decl != 0)
		    {
		      TREE_USED (decl) = 1;
		      expand_goto (decl);
		    }
		}
	| GOTO '*' expr ';'
		{ stmt_count++;
		  emit_line_note ($<filename>-1, $<lineno>0);
		  expand_computed_goto (convert (ptr_type_node, $3)); }
	| ';'
	;

all_iter_stmt:
	  all_iter_stmt_simple
/*	| all_iter_stmt_with_decl */
	;

all_iter_stmt_simple:
	  FOR '(' primary ')' 
	  {
	    /* The value returned by this action is  */
	    /*      1 if everything is OK */ 
	    /*      0 in case of error or already bound iterator */

	    $<itype>$ = 0;
	    if (TREE_CODE ($3) != VAR_DECL)
	      error ("invalid `for (ITERATOR)' syntax");
	    else if (! ITERATOR_P ($3))
	      error ("`%s' is not an iterator",
		     IDENTIFIER_POINTER (DECL_NAME ($3)));
	    else if (ITERATOR_BOUND_P ($3))
	      error ("`for (%s)' inside expansion of same iterator",
		     IDENTIFIER_POINTER (DECL_NAME ($3)));
	    else
	      {
		$<itype>$ = 1;
		iterator_for_loop_start ($3);
	      }
	  }
	  lineno_labeled_stmt
	  {
	    if ($<itype>5)
	      iterator_for_loop_end ($3);
	  }

/*  This really should allow any kind of declaration,
    for generality.  Fix it before turning it back on.

all_iter_stmt_with_decl:
	  FOR '(' ITERATOR pushlevel setspecs iterator_spec ')' 
	  {
*/	    /* The value returned by this action is  */
	    /*      1 if everything is OK */ 
	    /*      0 in case of error or already bound iterator */
/*
	    iterator_for_loop_start ($6);
	  }
	  lineno_labeled_stmt
	  {
	    iterator_for_loop_end ($6);
	    emit_line_note (input_filename, lineno);
	    expand_end_bindings (getdecls (), 1, 0);
	    $<ttype>$ = poplevel (1, 1, 0);
	    if (yychar == CONSTANT || yychar == STRING)
	      pop_momentary_nofree ();
	    else
	      pop_momentary ();	    
	  }
*/

/* Any kind of label, including jump labels and case labels.
   ANSI C accepts labels only before statements, but we allow them
   also at the end of a compound statement.  */

label:	  CASE expr_no_commas ':'
		{ register tree value = check_case_value ($2);
		  register tree label
		    = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);

		  stmt_count++;

		  if (value != error_mark_node)
		    {
		      tree duplicate;
		      int success = pushcase (value, convert_and_check,
					      label, &duplicate);
		      if (success == 1)
			error ("case label not within a switch statement");
		      else if (success == 2)
			{
			  error ("duplicate case value");
			  error_with_decl (duplicate, "this is the first entry for that value");
			}
		      else if (success == 3)
			warning ("case value out of range");
		      else if (success == 5)
			error ("case label within scope of cleanup or variable array");
		    }
		  position_after_white_space (); }
	| CASE expr_no_commas ELLIPSIS expr_no_commas ':'
		{ register tree value1 = check_case_value ($2);
		  register tree value2 = check_case_value ($4);
		  register tree label
		    = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);

		  stmt_count++;

		  if (value1 != error_mark_node && value2 != error_mark_node)
		    {
		      tree duplicate;
		      int success = pushcase_range (value1, value2,
						    convert_and_check, label,
						    &duplicate);
		      if (success == 1)
			error ("case label not within a switch statement");
		      else if (success == 2)
			{
			  error ("duplicate case value");
			  error_with_decl (duplicate, "this is the first entry for that value");
			}
		      else if (success == 3)
			warning ("case value out of range");
		      else if (success == 4)
			warning ("empty case range");
		      else if (success == 5)
			error ("case label within scope of cleanup or variable array");
		    }
		  position_after_white_space (); }
	| DEFAULT ':'
		{
		  tree duplicate;
		  register tree label
		    = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
		  int success = pushcase (NULL_TREE, 0, label, &duplicate);
		  stmt_count++;
		  if (success == 1)
		    error ("default label not within a switch statement");
		  else if (success == 2)
		    {
		      error ("multiple default labels in one switch");
		      error_with_decl (duplicate, "this is the first default label");
		    }
		  position_after_white_space (); }
	| identifier ':'
		{ tree label = define_label (input_filename, lineno, $1);
		  stmt_count++;
		  emit_nop ();
		  if (label)
		    expand_label (label);
		  position_after_white_space (); }
	;

/* Either a type-qualifier or nothing.  First thing in an `asm' statement.  */

maybe_type_qual:
	/* empty */
		{ emit_line_note (input_filename, lineno);
		  $$ = NULL_TREE; }
	| TYPE_QUAL
		{ emit_line_note (input_filename, lineno); }
	;

xexpr:
	/* empty */
		{ $$ = NULL_TREE; }
	| expr
	;

/* These are the operands other than the first string and colon
   in  asm ("addextend %2,%1": "=dm" (x), "0" (y), "g" (*x))  */
asm_operands: /* empty */
		{ $$ = NULL_TREE; }
	| nonnull_asm_operands
	;

nonnull_asm_operands:
	  asm_operand
	| nonnull_asm_operands ',' asm_operand
		{ $$ = chainon ($1, $3); }
	;

asm_operand:
	  STRING '(' expr ')'
		{ $$ = build_tree_list ($1, $3); }
	;

asm_clobbers:
	  string
		{ $$ = tree_cons (NULL_TREE, combine_strings ($1), NULL_TREE); }
	| asm_clobbers ',' string
		{ $$ = tree_cons (NULL_TREE, combine_strings ($3), $1); }
	;

/* This is what appears inside the parens in a function declarator.
   Its value is a list of ..._TYPE nodes.  */
parmlist:
		{ pushlevel (0);
		  clear_parm_order ();
		  declare_parm_level (0); }
	  parmlist_1
		{ $$ = $2;
		  parmlist_tags_warning ();
		  poplevel (0, 0, 0); }
	;

parmlist_1:
	  parmlist_2 ')'
	| parms ';'
		{ tree parm;
		  if (pedantic)
		    pedwarn ("ANSI C forbids forward parameter declarations");
		  /* Mark the forward decls as such.  */
		  for (parm = getdecls (); parm; parm = TREE_CHAIN (parm))
		    TREE_ASM_WRITTEN (parm) = 1;
		  clear_parm_order (); }
	  parmlist_1
		{ $$ = $4; }
	| error ')'
		{ $$ = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE); }
	;

/* This is what appears inside the parens in a function declarator.
   Is value is represented in the format that grokdeclarator expects.  */
parmlist_2:  /* empty */
		{ $$ = get_parm_info (0); }
	| ELLIPSIS
		{ $$ = get_parm_info (0);
		  /* Gcc used to allow this as an extension.  However, it does
		     not work for all targets, and thus has been disabled.
		     Also, since func (...) and func () are indistinguishable,
		     it caused problems with the code in expand_builtin which
		     tries to verify that BUILT_IN_NEXT_ARG is being used
		     correctly.  */
		  error ("ANSI C requires a named argument before `...'");
		}
	| parms
		{ $$ = get_parm_info (1); }
	| parms ',' ELLIPSIS
		{ $$ = get_parm_info (0); }
	;

parms:
	parm
		{ push_parm_decl ($1); }
	| parms ',' parm
		{ push_parm_decl ($3); }
	;

/* A single parameter declaration or parameter type name,
   as found in a parmlist.  */
parm:
	  typed_declspecs setspecs parm_declarator maybe_attribute
		{ $$ = build_tree_list (build_tree_list (current_declspecs,
							 $3),
					build_tree_list (prefix_attributes,
							 $4));
		  current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| typed_declspecs setspecs notype_declarator maybe_attribute
		{ $$ = build_tree_list (build_tree_list (current_declspecs,
							 $3),
					build_tree_list (prefix_attributes,
							 $4)); 
		  current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| typed_declspecs setspecs absdcl maybe_attribute
		{ $$ = build_tree_list (build_tree_list (current_declspecs,
							 $3),
					build_tree_list (prefix_attributes,
							 $4));
		  current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2); }
	| declmods setspecs notype_declarator maybe_attribute
		{ $$ = build_tree_list (build_tree_list (current_declspecs,
							 $3),
					build_tree_list (prefix_attributes,
							 $4));
		  current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (declspec_stack);
		  resume_momentary ($2);  }

	| declmods setspecs absdcl maybe_attribute
		{ $$ = build_tree_list (build_tree_list (current_declspecs,
							 $3),
					build_tree_list (prefix_attributes,
							 $4));
		  current_declspecs = TREE_VALUE (declspec_stack);
		  prefix_attributes = TREE_PURPOSE (declspec_stack);
		  declspec_stack = TREE_CHAIN (de