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/*
* Copyright (c) 2002-2005 The TenDRA Project <http://www.tendra.org/>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of The TenDRA Project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
*/
/*
Crown Copyright (c) 1997
This TenDRA(r) Computer Program is subject to Copyright
owned by the United Kingdom Secretary of State for Defence
acting through the Defence Evaluation and Research Agency
(DERA). It is made available to Recipients with a
royalty-free licence for its use, reproduction, transfer
to other parties and amendment for any purpose not excluding
product development provided that any such use et cetera
shall be deemed to be acceptance of the following conditions:-
(1) Its Recipients shall ensure that this Notice is
reproduced upon any copies or amended versions of it;
(2) Any amended version of it shall be clearly marked to
show both the nature of and the organisation responsible
for the relevant amendment or amendments;
(3) Its onward transfer from a recipient to another
party shall be deemed to be that party's acceptance of
these conditions;
(4) DERA gives no warranty or assurance as to its
quality or suitability for any purpose and DERA accepts
no liability whatsoever in relation to any use to which
it may be put.
*/
/**********************************************************************
$Author: release $
$Date: 1998/01/17 15:55:47 $
$Revision: 1.1.1.1 $
$Log: label_ops.c,v $
* Revision 1.1.1.1 1998/01/17 15:55:47 release
* First version to be checked into rolling release.
*
* Revision 1.5 1997/08/06 10:58:32 currie
* Catch overflowed constants, PlumHall requirement
*
* Revision 1.4 1997/04/18 10:58:47 currie
* another pathelogical case
*
* Revision 1.3 1996/05/21 12:53:54 currie
* Pathological gotos
*
* Revision 1.2 1995/10/11 17:10:07 currie
* avs errors
*
* Revision 1.1 1995/04/06 10:44:05 currie
* Initial revision
*
***********************************************************************/
#include "config.h"
#include "common_types.h"
#include "expmacs.h"
#include "tags.h"
#include "label_ops.h"
#include "check.h"
#include "externs.h"
#include "exp.h"
#include "installglob.h"
#include "shapemacs.h"
/* label_is_next returns 1 if lab is a labst which immediately
follows e, otherwise 0. e will not be nilexp
*/
int
label_is_next(exp lab, exp e)
{
if (!indirect_jumps) {
return 0;
}
while (last(e)) {
e = bro(e);
if (e == nilexp || name(e) >= ass_tag || name(sh(e)) != bothd) {
return 0;
}
}
if (name(bro(e)) == labst_tag) {
return bro(e) == lab;
}
return 0;
}
static exp
is_jumper(exp e)
{
if (name(e) == test_tag || name(e) == goto_tag ||
name(e) == testbit_tag || name(e) == res_tag) {
return e;
}
return nilexp;
}
static exp
down(exp e)
{
if (name(e) == seq_tag) {
return down(son(son(e)));
}
if (name(e) == cond_tag) {
return down(son(e));
}
return e;
}
/* next_jump delivers a goto, res, test or testbit exp if this
is certain to be the next thing obeyed after e. nilexp
otherwise.
*/
static exp
next_jump(exp e)
{
if (!indirect_jumps) {
return nilexp;
}
do {
while (last(e)) {
e = bro(e);
if (e == nilexp || name(e) >= goto_tag) {
return nilexp;
}
}
e = bro(e);
} while (name(e) == labst_tag && (e = father(e), name(e) !=rep_tag));
if (is_jumper(e)) {
return e;
}
if (name(e) == seq_tag || name(e) == cond_tag) {
return is_jumper(down(e));
}
if (name(e) == top_tag) {
return next_jump(e);
}
return nilexp;
}
/* next_jump delivers a goto, res, test or testbit exp if this
is certain to be the next thing obeyed after e and there is no
other route to the goto (etc.). nilexp otherwise.
*/
exp
short_next_jump(exp e)
{
if (!indirect_jumps) {
return nilexp;
}
while (last(e)) {
e = bro(e);
if (e == nilexp || name(e) >= cond_tag) {
return nilexp;
}
}
e = bro(e);
if (is_jumper(e)) {
return e;
}
if (name(e) == seq_tag || name(e) == cond_tag) {
return is_jumper(down(e));
}
if (name(e) == top_tag) {
return short_next_jump(e);
}
return nilexp;
}
exp
jump_dest(exp lab)
{
return next_jump(son(lab));
}
exp
final_dest(exp lab)
{
exp final = lab;
exp temp, ll;
while (name(final) == labst_tag) {
temp = jump_dest(final);
if (temp != nilexp && name(temp) == goto_tag &&
pt(temp) != final) {
ll = lab;
while (ll != final) {
if (pt(temp) == ll) {
/* pathological loop */
return final;
}
ll = pt(jump_dest(ll));
}
final = pt(temp);
} else {
break;
}
}
return final;
}
/* delivers 1 iff when a jumps, b also jumps
a and b will be test or testbit */
static int
subsumes(exp a, exp b)
{
if (name(a) == name(b) && test_number(a) == test_number(b) &&
eq_exp(son(a), son(b)) && eq_exp(bro(son(a)), bro(son(b)))) {
return 1;
}
return 0;
}
exp
final_dest_test(exp lab, exp e)
{
exp final = lab;
exp temp, ll;
while (name(final) == labst_tag) {
temp = jump_dest(final);
if (temp == nilexp || final == pt(temp)) {
return final;
}
if (name(temp) == goto_tag ||
(name(temp) == name(e) && subsumes(e, temp))) {
ll = lab;
while (ll != final) {
if (pt(temp) == ll) {
/* pathological loop */
return final;
}
ll = pt(jump_dest(ll));
}
final = pt(temp);
} else {
break;
}
}
return final;
}