Update.
[glibc.git] / gmon / mcount.c
blobf6eb229e2e77ec69fc78caa21a0edfd48dc62b6b
1 /*-
2 * Copyright (c) 1983, 1992, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
30 #if !defined(lint) && !defined(KERNEL) && defined(LIBC_SCCS)
31 static char sccsid[] = "@(#)mcount.c 8.1 (Berkeley) 6/4/93";
32 #endif
34 #include <sys/param.h>
35 #include <sys/gmon.h>
37 /* This file provides the machine-dependent definitions of the _MCOUNT_DECL
38 and MCOUNT macros. */
39 #include "machine-gmon.h"
41 #include <atomicity.h>
44 * mcount is called on entry to each function compiled with the profiling
45 * switch set. _mcount(), which is declared in a machine-dependent way
46 * with _MCOUNT_DECL, does the actual work and is either inlined into a
47 * C routine or called by an assembly stub. In any case, this magic is
48 * taken care of by the MCOUNT definition in <machine/profile.h>.
50 * _mcount updates data structures that represent traversals of the
51 * program's call graph edges. frompc and selfpc are the return
52 * address and function address that represents the given call graph edge.
54 * Note: the original BSD code used the same variable (frompcindex) for
55 * both frompcindex and frompc. Any reasonable, modern compiler will
56 * perform this optimization.
58 _MCOUNT_DECL(frompc, selfpc) /* _mcount; may be static, inline, etc */
60 register u_short *frompcindex;
61 register struct tostruct *top, *prevtop;
62 register struct gmonparam *p;
63 register long toindex;
64 int i;
66 p = &_gmonparam;
68 * check that we are profiling
69 * and that we aren't recursively invoked.
71 if (! compare_and_swap (&p->state, GMON_PROF_ON, GMON_PROF_BUSY))
72 return;
75 * check that frompcindex is a reasonable pc value.
76 * for example: signal catchers get called from the stack,
77 * not from text space. too bad.
79 frompc -= p->lowpc;
80 if (frompc > p->textsize)
81 goto done;
83 /* The following test used to be
84 if (p->log_hashfraction >= 0)
85 But we can simplify this if we assume the profiling data
86 is always initialized by the functions in gmon.c. But
87 then it is possible to avoid a runtime check and use the
88 smae `if' as in gmon.c. So keep these tests in sync. */
89 if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) {
90 /* avoid integer divide if possible: */
91 i = frompc >> p->log_hashfraction;
92 } else {
93 i = frompc / (p->hashfraction * sizeof(*p->froms));
95 frompcindex = &p->froms[i];
96 toindex = *frompcindex;
97 if (toindex == 0) {
99 * first time traversing this arc
101 toindex = ++p->tos[0].link;
102 if (toindex >= p->tolimit)
103 /* halt further profiling */
104 goto overflow;
106 *frompcindex = toindex;
107 top = &p->tos[toindex];
108 top->selfpc = selfpc;
109 top->count = 1;
110 top->link = 0;
111 goto done;
113 top = &p->tos[toindex];
114 if (top->selfpc == selfpc) {
116 * arc at front of chain; usual case.
118 top->count++;
119 goto done;
122 * have to go looking down chain for it.
123 * top points to what we are looking at,
124 * prevtop points to previous top.
125 * we know it is not at the head of the chain.
127 for (; /* goto done */; ) {
128 if (top->link == 0) {
130 * top is end of the chain and none of the chain
131 * had top->selfpc == selfpc.
132 * so we allocate a new tostruct
133 * and link it to the head of the chain.
135 toindex = ++p->tos[0].link;
136 if (toindex >= p->tolimit)
137 goto overflow;
139 top = &p->tos[toindex];
140 top->selfpc = selfpc;
141 top->count = 1;
142 top->link = *frompcindex;
143 *frompcindex = toindex;
144 goto done;
147 * otherwise, check the next arc on the chain.
149 prevtop = top;
150 top = &p->tos[top->link];
151 if (top->selfpc == selfpc) {
153 * there it is.
154 * increment its count
155 * move it to the head of the chain.
157 top->count++;
158 toindex = prevtop->link;
159 prevtop->link = top->link;
160 top->link = *frompcindex;
161 *frompcindex = toindex;
162 goto done;
166 done:
167 p->state = GMON_PROF_ON;
168 return;
169 overflow:
170 p->state = GMON_PROF_ERROR;
171 return;
175 * Actual definition of mcount function. Defined in <machine/profile.h>,
176 * which is included by <sys/gmon.h>.
178 MCOUNT