1 /* Exception handling and frame unwind runtime interface routines.
2 Copyright (C) 2001 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 /* @@@ Really this should be out of line, but this also causes link
22 compatibility problems with the base ABI. This is slightly better
23 than duplicating code, however. */
25 /* If using C++, references to abort have to be qualified with std::. */
27 #define __gxx_abort std::abort
29 #define __gxx_abort abort
32 /* Pointer encodings, from dwarf2.h. */
33 #define DW_EH_PE_absptr 0x00
34 #define DW_EH_PE_omit 0xff
36 #define DW_EH_PE_uleb128 0x01
37 #define DW_EH_PE_udata2 0x02
38 #define DW_EH_PE_udata4 0x03
39 #define DW_EH_PE_udata8 0x04
40 #define DW_EH_PE_sleb128 0x09
41 #define DW_EH_PE_sdata2 0x0A
42 #define DW_EH_PE_sdata4 0x0B
43 #define DW_EH_PE_sdata8 0x0C
44 #define DW_EH_PE_signed 0x08
46 #define DW_EH_PE_pcrel 0x10
47 #define DW_EH_PE_textrel 0x20
48 #define DW_EH_PE_datarel 0x30
49 #define DW_EH_PE_funcrel 0x40
50 #define DW_EH_PE_aligned 0x50
52 #define DW_EH_PE_indirect 0x80
55 /* Given an encoding, return the number of bytes the format occupies.
56 This is only defined for fixed-size encodings, and so does not
60 size_of_encoded_value (unsigned char encoding)
62 if (encoding == DW_EH_PE_omit)
65 switch (encoding & 0x07)
68 return sizeof (void *);
79 /* Given an encoding and an _Unwind_Context, return the base to which
80 the encoding is relative. This base may then be passed to
81 read_encoded_value_with_base for use when the _Unwind_Context is
85 base_of_encoded_value (unsigned char encoding, struct _Unwind_Context *context)
87 if (encoding == DW_EH_PE_omit)
90 switch (encoding & 0x70)
94 case DW_EH_PE_aligned:
97 case DW_EH_PE_textrel:
98 return _Unwind_GetTextRelBase (context);
99 case DW_EH_PE_datarel:
100 return _Unwind_GetDataRelBase (context);
101 case DW_EH_PE_funcrel:
102 return _Unwind_GetRegionStart (context);
107 /* Load an encoded value from memory at P. The value is returned in VAL;
108 The function returns P incremented past the value. BASE is as given
109 by base_of_encoded_value for this encoding in the appropriate context. */
111 static const unsigned char *
112 read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,
113 const unsigned char *p, _Unwind_Ptr *val)
118 unsigned u2 __attribute__ ((mode (HI)));
119 unsigned u4 __attribute__ ((mode (SI)));
120 unsigned u8 __attribute__ ((mode (DI)));
121 signed s2 __attribute__ ((mode (HI)));
122 signed s4 __attribute__ ((mode (SI)));
123 signed s8 __attribute__ ((mode (DI)));
124 } __attribute__((__packed__));
126 union unaligned *u = (union unaligned *) p;
129 if (encoding == DW_EH_PE_aligned)
131 _Unwind_Ptr a = (_Unwind_Ptr)p;
132 a = (a + sizeof (void *) - 1) & - sizeof(void *);
133 result = *(_Unwind_Ptr *) a;
134 p = (const unsigned char *)(a + sizeof (void *));
138 switch (encoding & 0x0f)
140 case DW_EH_PE_absptr:
141 result = (_Unwind_Ptr) u->ptr;
142 p += sizeof (void *);
145 case DW_EH_PE_uleb128:
147 unsigned int shift = 0;
154 result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
161 case DW_EH_PE_sleb128:
163 unsigned int shift = 0;
170 result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
175 if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
176 result |= -(1L << shift);
180 case DW_EH_PE_udata2:
184 case DW_EH_PE_udata4:
188 case DW_EH_PE_udata8:
193 case DW_EH_PE_sdata2:
197 case DW_EH_PE_sdata4:
201 case DW_EH_PE_sdata8:
212 result += ((encoding & 0x70) == DW_EH_PE_pcrel
213 ? (_Unwind_Ptr)u : base);
214 if (encoding & DW_EH_PE_indirect)
215 result = *(_Unwind_Ptr *)result;
223 /* Like read_encoded_value_with_base, but get the base from the context
224 rather than providing it directly. */
226 static inline const unsigned char *
227 read_encoded_value (struct _Unwind_Context *context, unsigned char encoding,
228 const unsigned char *p, _Unwind_Ptr *val)
230 return read_encoded_value_with_base (encoding,
231 base_of_encoded_value (encoding, context),
235 /* Read an unsigned leb128 value from P, store the value in VAL, return
236 P incremented past the value. */
238 static inline const unsigned char *
239 read_uleb128 (const unsigned char *p, _Unwind_Ptr *val)
241 return read_encoded_value_with_base (DW_EH_PE_uleb128, 0, p, val);
244 /* Similar, but read a signed leb128 value. */
246 static inline const unsigned char *
247 read_sleb128 (const unsigned char *p, _Unwind_Ptr *val)
249 return read_encoded_value_with_base (DW_EH_PE_sleb128, 0, p, val);