source: rtems-tools/rtemstoolkit/elftoolchain/libdwarf/dwarf_new_expr.3 @ 4bb3996

5
Last change on this file since 4bb3996 was 4bb3996, checked in by Chris Johns <chrisj@…>, on 04/30/18 at 05:34:48

rtemstoolkit: Add libdwarf from elftoolchain.

The code is taken from:

https://svn.code.sf.net/p/elftoolchain/code/trunk

Update #3417

  • Property mode set to 100644
File size: 3.9 KB
Line 
1.\" Copyright (c) 2011 Kai Wang
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\"    notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\"    notice, this list of conditions and the following disclaimer in the
11.\"    documentation and/or other materials provided with the distribution.
12.\"
13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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25.\" $Id: dwarf_new_expr.3 2074 2011-10-27 03:34:33Z jkoshy $
26.\"
27.Dd September 8, 2011
28.Os
29.Dt DWARF_NEW_EXPR 3
30.Sh NAME
31.Nm dwarf_new_expr
32.Nd create a location expression descriptor
33.Sh LIBRARY
34.Lb libdwarf
35.Sh SYNOPSIS
36.In libdwarf.h
37.Ft "Dwarf_P_Expr"
38.Fo dwarf_new_expr
39.Fa "Dwarf_P_Debug dbg"
40.Fa "Dwarf_Error *err"
41.Fc
42.Sh DESCRIPTION
43Function
44.Fn dwarf_new_expr
45allocates a DWARF location expression descriptor used to build up a
46location expression stream.
47.Pp
48The application can use the functions
49.Xr dwarf_add_expr_gen 3
50and
51.Xr dwarf_add_expr_addr_b 3
52to add location expression operators to the created descriptor.
53When done, the application can call the function
54.Xr dwarf_expr_into_block 3
55to retrieve the generated byte stream for the location expression,
56or call the function
57.Xr dwarf_add_AT_location_expr 3
58to create an attribute with the location expression stream as its
59value.
60.Pp
61Argument
62.Ar dbg
63should reference a DWARF producer instance allocated using
64.Xr dwarf_producer_init 3
65or
66.Xr dwarf_producer_init_b 3 .
67.Pp
68If argument
69.Ar err
70is not NULL, it will be used to store error information in case
71of an error.
72.Sh RETURN VALUES
73On success, function
74.Fn dwarf_new_expr
75returns the created location expression descriptor.
76In case of an error, function
77.Fn dwarf_new_expr
78returns
79.Dv DW_DLV_BADADDR
80and sets the argument
81.Ar err .
82.Sh ERRORS
83Function
84.Fn dwarf_new_expr
85can fail with:
86.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
87.It Bq Er DW_DLE_ARGUMENT
88Argument
89.Ar dbg
90was NULL.
91.It Bq Er DW_DLE_MEMORY
92An out of memory condition was encountered during the execution of
93the function.
94.El
95.Sh EXAMPLES
96To create a location expression descriptor, add location expression
97operators to it and to retrieve the generated byte stream,
98use:
99.Bd -literal -offset indent
100Dwarf_P_Debug dbg;
101Dwarf_Error de;
102Dwarf_P_Expr pe;
103Dwarf_Addr buf;
104Dwarf_Unsigned len;
105
106/* ...Assume that `dbg' refers to a DWARF producer instance... */
107
108if ((pe = dwarf_new_expr(dbg, &de)) == DW_DLV_BADADDR) {
109        warnx("dwarf_new_expr failed: %s", dwarf_errmsg(-1));
110        return;
111}
112
113if (dwarf_add_expr_gen(pe, DW_OP_regx, 55, 0, &de) ==
114    DW_DLV_NOCOUNT) {
115        warnx("dwarf_add_expr_gen failed: %s", dwarf_errmsg(-1));
116        return;
117}
118
119if ((buf = dwarf_expr_into_block(pe, &len, &de)) ==
120    DW_DLV_BADADDR) {
121        warnx("dwarf_expr_into_block failed: %s",
122            dwarf_errmsg(-1));
123        return;
124}
125.Ed
126.Sh SEE ALSO
127.Xr dwarf 3 ,
128.Xr dwarf_add_AT_location_expr 3 ,
129.Xr dwarf_add_expr_gen 3 ,
130.Xr dwarf_add_expr_addr 3 ,
131.Xr dwarf_add_expr_addr_b 3 ,
132.Xr dwarf_expr_current_offset 3 ,
133.Xr dwarf_expr_into_block 3 ,
134.Xr dwarf_producer_init 3 ,
135.Xr dwarf_producer_init_b 3
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