1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#include <err.h>
34#include "gprof.h"
35
36#define	DFN_DEPTH	100
37struct dfnstruct {
38    nltype	*nlentryp;
39    int		cycletop;
40};
41typedef struct dfnstruct	dfntype;
42
43dfntype	dfn_stack[ DFN_DEPTH ];
44int	dfn_depth;
45
46int	dfn_counter;
47
48void
49dfn_init(void)
50{
51
52    dfn_depth = 0;
53    dfn_counter = DFN_NAN;
54}
55
56    /*
57     *	given this parent, depth first number its children.
58     */
59void
60dfn(nltype *parentp)
61{
62    arctype	*arcp;
63
64#   ifdef DEBUG
65	if ( debug & DFNDEBUG ) {
66	    printf( "[dfn] dfn(" );
67	    printname( parentp );
68	    printf( ")\n" );
69	}
70#   endif /* DEBUG */
71	/*
72	 *	if we're already numbered, no need to look any further.
73	 */
74    if ( dfn_numbered( parentp ) ) {
75	return;
76    }
77	/*
78	 *	if we're already busy, must be a cycle
79	 */
80    if ( dfn_busy( parentp ) ) {
81	dfn_findcycle( parentp );
82	return;
83    }
84	/*
85	 *	visit yourself before your children
86	 */
87    dfn_pre_visit( parentp );
88	/*
89	 *	visit children
90	 */
91    for ( arcp = parentp -> children ; arcp ; arcp = arcp -> arc_childlist ) {
92	    if ( arcp -> arc_flags & DEADARC )
93		continue;
94	    dfn( arcp -> arc_childp );
95    }
96	/*
97	 *	visit yourself after your children
98	 */
99    dfn_post_visit( parentp );
100}
101
102    /*
103     *	push a parent onto the stack and mark it busy
104     */
105void
106dfn_pre_visit(nltype *parentp)
107{
108
109    dfn_depth += 1;
110    if ( dfn_depth >= DFN_DEPTH )
111	errx( 1 , "[dfn] out of my depth (dfn_stack overflow)" );
112    dfn_stack[ dfn_depth ].nlentryp = parentp;
113    dfn_stack[ dfn_depth ].cycletop = dfn_depth;
114    parentp -> toporder = DFN_BUSY;
115#   ifdef DEBUG
116	if ( debug & DFNDEBUG ) {
117	    printf( "[dfn_pre_visit]\t\t%d:" , dfn_depth );
118	    printname( parentp );
119	    printf( "\n" );
120	}
121#   endif /* DEBUG */
122}
123
124    /*
125     *	are we already numbered?
126     */
127bool
128dfn_numbered(nltype *childp)
129{
130
131    return ( childp -> toporder != DFN_NAN && childp -> toporder != DFN_BUSY );
132}
133
134    /*
135     *	are we already busy?
136     */
137bool
138dfn_busy(nltype *childp)
139{
140
141    if ( childp -> toporder == DFN_NAN ) {
142	return FALSE;
143    }
144    return TRUE;
145}
146
147    /*
148     *	MISSING: an explanation
149     */
150void
151dfn_findcycle(nltype *childp)
152{
153    int		cycletop;
154    nltype	*cycleheadp;
155    nltype	*tailp;
156    int		index;
157
158    for ( cycletop = dfn_depth ; cycletop > 0 ; cycletop -= 1 ) {
159	cycleheadp = dfn_stack[ cycletop ].nlentryp;
160	if ( childp == cycleheadp ) {
161	    break;
162	}
163	if ( childp -> cyclehead != childp &&
164	    childp -> cyclehead == cycleheadp ) {
165	    break;
166	}
167    }
168    if ( cycletop <= 0 )
169	errx( 1 , "[dfn_findcycle] couldn't find head of cycle" );
170#   ifdef DEBUG
171	if ( debug & DFNDEBUG ) {
172	    printf( "[dfn_findcycle] dfn_depth %d cycletop %d " ,
173		    dfn_depth , cycletop  );
174	    printname( cycleheadp );
175	    printf( "\n" );
176	}
177#   endif /* DEBUG */
178    if ( cycletop == dfn_depth ) {
179	    /*
180	     *	this is previous function, e.g. this calls itself
181	     *	sort of boring
182	     */
183	dfn_self_cycle( childp );
184    } else {
185	    /*
186	     *	glom intervening functions that aren't already
187	     *	glommed into this cycle.
188	     *	things have been glommed when their cyclehead field
189	     *	points to the head of the cycle they are glommed into.
190	     */
191	for ( tailp = cycleheadp ; tailp -> cnext ; tailp = tailp -> cnext ) {
192	    /* void: chase down to tail of things already glommed */
193#	    ifdef DEBUG
194		if ( debug & DFNDEBUG ) {
195		    printf( "[dfn_findcycle] tail " );
196		    printname( tailp );
197		    printf( "\n" );
198		}
199#	    endif /* DEBUG */
200	}
201	    /*
202	     *	if what we think is the top of the cycle
203	     *	has a cyclehead field, then it's not really the
204	     *	head of the cycle, which is really what we want
205	     */
206	if ( cycleheadp -> cyclehead != cycleheadp ) {
207	    cycleheadp = cycleheadp -> cyclehead;
208#	    ifdef DEBUG
209		if ( debug & DFNDEBUG ) {
210		    printf( "[dfn_findcycle] new cyclehead " );
211		    printname( cycleheadp );
212		    printf( "\n" );
213		}
214#	    endif /* DEBUG */
215	}
216	for ( index = cycletop + 1 ; index <= dfn_depth ; index += 1 ) {
217	    childp = dfn_stack[ index ].nlentryp;
218	    if ( childp -> cyclehead == childp ) {
219		    /*
220		     *	not yet glommed anywhere, glom it
221		     *	and fix any children it has glommed
222		     */
223		tailp -> cnext = childp;
224		childp -> cyclehead = cycleheadp;
225#		ifdef DEBUG
226		    if ( debug & DFNDEBUG ) {
227			printf( "[dfn_findcycle] glomming " );
228			printname( childp );
229			printf( " onto " );
230			printname( cycleheadp );
231			printf( "\n" );
232		    }
233#		endif /* DEBUG */
234		for ( tailp = childp ; tailp->cnext ; tailp = tailp->cnext ) {
235		    tailp -> cnext -> cyclehead = cycleheadp;
236#		    ifdef DEBUG
237			if ( debug & DFNDEBUG ) {
238			    printf( "[dfn_findcycle] and its tail " );
239			    printname( tailp -> cnext );
240			    printf( " onto " );
241			    printname( cycleheadp );
242			    printf( "\n" );
243			}
244#		    endif /* DEBUG */
245		}
246	    } else if ( childp -> cyclehead != cycleheadp /* firewall */ ) {
247		fprintf( stderr ,
248			"[dfn_busy] glommed, but not to cyclehead\n" );
249	    }
250	}
251    }
252}
253
254    /*
255     *	deal with self-cycles
256     *	for lint: ARGSUSED
257     */
258void
259dfn_self_cycle(nltype *parentp)
260{
261	/*
262	 *	since we are taking out self-cycles elsewhere
263	 *	no need for the special case, here.
264	 */
265#   ifdef DEBUG
266	if ( debug & DFNDEBUG ) {
267	    printf( "[dfn_self_cycle] " );
268	    printname( parentp );
269	    printf( "\n" );
270	}
271#   endif /* DEBUG */
272}
273
274    /*
275     *	visit a node after all its children
276     *	[MISSING: an explanation]
277     *	and pop it off the stack
278     */
279void
280dfn_post_visit(nltype *parentp)
281{
282    nltype	*memberp;
283
284#   ifdef DEBUG
285	if ( debug & DFNDEBUG ) {
286	    printf( "[dfn_post_visit]\t%d: " , dfn_depth );
287	    printname( parentp );
288	    printf( "\n" );
289	}
290#   endif /* DEBUG */
291	/*
292	 *	number functions and things in their cycles
293	 *	unless the function is itself part of a cycle
294	 */
295    if ( parentp -> cyclehead == parentp ) {
296	dfn_counter += 1;
297	for ( memberp = parentp ; memberp ; memberp = memberp -> cnext ) {
298	    memberp -> toporder = dfn_counter;
299#	    ifdef DEBUG
300		if ( debug & DFNDEBUG ) {
301		    printf( "[dfn_post_visit]\t\tmember " );
302		    printname( memberp );
303		    printf( " -> toporder = %d\n" , dfn_counter );
304		}
305#	    endif /* DEBUG */
306	}
307    } else {
308#	ifdef DEBUG
309	    if ( debug & DFNDEBUG ) {
310		printf( "[dfn_post_visit]\t\tis part of a cycle\n" );
311	    }
312#	endif /* DEBUG */
313    }
314    dfn_depth -= 1;
315}
316