1 /* Exception handling and frame unwind runtime interface routines.
2 Copyright (C) 2001, 2002 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 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 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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 #ifndef NO_BASE_OF_ENCODED_VALUE
81 /* Given an encoding and an _Unwind_Context, return the base to which
82 the encoding is relative. This base may then be passed to
83 read_encoded_value_with_base for use when the _Unwind_Context is
87 base_of_encoded_value (unsigned char encoding, struct _Unwind_Context *context)
89 if (encoding == DW_EH_PE_omit)
92 switch (encoding & 0x70)
96 case DW_EH_PE_aligned:
99 case DW_EH_PE_textrel:
100 return _Unwind_GetTextRelBase (context);
101 case DW_EH_PE_datarel:
102 return _Unwind_GetDataRelBase (context);
103 case DW_EH_PE_funcrel:
104 return _Unwind_GetRegionStart (context);
111 /* Read an unsigned leb128 value from P, store the value in VAL, return
112 P incremented past the value. We assume that a word is large enough to
113 hold any value so encoded; if it is smaller than a pointer on some target,
114 pointers should not be leb128 encoded on that target. */
116 static const unsigned char *
117 read_uleb128 (const unsigned char *p, _Unwind_Word *val)
119 unsigned int shift = 0;
127 result |= (byte & 0x7f) << shift;
136 /* Similar, but read a signed leb128 value. */
138 static const unsigned char *
139 read_sleb128 (const unsigned char *p, _Unwind_Sword *val)
141 unsigned int shift = 0;
149 result |= (byte & 0x7f) << shift;
154 /* Sign-extend a negative value. */
155 if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
156 result |= -(1L << shift);
158 *val = (_Unwind_Sword) result;
162 /* Load an encoded value from memory at P. The value is returned in VAL;
163 The function returns P incremented past the value. BASE is as given
164 by base_of_encoded_value for this encoding in the appropriate context. */
166 static const unsigned char *
167 read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,
168 const unsigned char *p, _Unwind_Ptr *val)
173 unsigned u2 __attribute__ ((mode (HI)));
174 unsigned u4 __attribute__ ((mode (SI)));
175 unsigned u8 __attribute__ ((mode (DI)));
176 signed s2 __attribute__ ((mode (HI)));
177 signed s4 __attribute__ ((mode (SI)));
178 signed s8 __attribute__ ((mode (DI)));
179 } __attribute__((__packed__));
181 union unaligned *u = (union unaligned *) p;
184 if (encoding == DW_EH_PE_aligned)
186 _Unwind_Ptr a = (_Unwind_Ptr) p;
187 a = (a + sizeof (void *) - 1) & - sizeof(void *);
188 result = *(_Unwind_Ptr *) a;
189 p = (const unsigned char *) (a + sizeof (void *));
193 switch (encoding & 0x0f)
195 case DW_EH_PE_absptr:
196 result = (_Unwind_Ptr) u->ptr;
197 p += sizeof (void *);
200 case DW_EH_PE_uleb128:
203 p = read_uleb128 (p, &tmp);
204 result = (_Unwind_Ptr) tmp;
208 case DW_EH_PE_sleb128:
211 p = read_sleb128 (p, &tmp);
212 result = (_Unwind_Ptr) tmp;
216 case DW_EH_PE_udata2:
220 case DW_EH_PE_udata4:
224 case DW_EH_PE_udata8:
229 case DW_EH_PE_sdata2:
233 case DW_EH_PE_sdata4:
237 case DW_EH_PE_sdata8:
248 result += ((encoding & 0x70) == DW_EH_PE_pcrel
249 ? (_Unwind_Ptr) u : base);
250 if (encoding & DW_EH_PE_indirect)
251 result = *(_Unwind_Ptr *) result;
259 #ifndef NO_BASE_OF_ENCODED_VALUE
261 /* Like read_encoded_value_with_base, but get the base from the context
262 rather than providing it directly. */
264 static inline const unsigned char *
265 read_encoded_value (struct _Unwind_Context *context, unsigned char encoding,
266 const unsigned char *p, _Unwind_Ptr *val)
268 return read_encoded_value_with_base (encoding,
269 base_of_encoded_value (encoding, context),