1 /* Exception handling and frame unwind runtime interface routines.
2 Copyright (C) 2001 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 /* Load an encoded value from memory at P. The value is returned in VAL;
112 The function returns P incremented past the value. BASE is as given
113 by base_of_encoded_value for this encoding in the appropriate context. */
115 static const unsigned char *
116 read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,
117 const unsigned char *p, _Unwind_Ptr *val)
122 unsigned u2 __attribute__ ((mode (HI)));
123 unsigned u4 __attribute__ ((mode (SI)));
124 unsigned u8 __attribute__ ((mode (DI)));
125 signed s2 __attribute__ ((mode (HI)));
126 signed s4 __attribute__ ((mode (SI)));
127 signed s8 __attribute__ ((mode (DI)));
128 } __attribute__((__packed__));
130 union unaligned *u = (union unaligned *) p;
133 if (encoding == DW_EH_PE_aligned)
135 _Unwind_Ptr a = (_Unwind_Ptr)p;
136 a = (a + sizeof (void *) - 1) & - sizeof(void *);
137 result = *(_Unwind_Ptr *) a;
138 p = (const unsigned char *)(a + sizeof (void *));
142 switch (encoding & 0x0f)
144 case DW_EH_PE_absptr:
145 result = (_Unwind_Ptr) u->ptr;
146 p += sizeof (void *);
149 case DW_EH_PE_uleb128:
151 unsigned int shift = 0;
158 result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
165 case DW_EH_PE_sleb128:
167 unsigned int shift = 0;
174 result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
179 if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
180 result |= -(1L << shift);
184 case DW_EH_PE_udata2:
188 case DW_EH_PE_udata4:
192 case DW_EH_PE_udata8:
197 case DW_EH_PE_sdata2:
201 case DW_EH_PE_sdata4:
205 case DW_EH_PE_sdata8:
216 result += ((encoding & 0x70) == DW_EH_PE_pcrel
217 ? (_Unwind_Ptr)u : base);
218 if (encoding & DW_EH_PE_indirect)
219 result = *(_Unwind_Ptr *)result;
227 #ifndef NO_BASE_OF_ENCODED_VALUE
229 /* Like read_encoded_value_with_base, but get the base from the context
230 rather than providing it directly. */
232 static inline const unsigned char *
233 read_encoded_value (struct _Unwind_Context *context, unsigned char encoding,
234 const unsigned char *p, _Unwind_Ptr *val)
236 return read_encoded_value_with_base (encoding,
237 base_of_encoded_value (encoding, context),
243 /* Read an unsigned leb128 value from P, store the value in VAL, return
244 P incremented past the value. */
246 static inline const unsigned char *
247 read_uleb128 (const unsigned char *p, _Unwind_Ptr *val)
249 return read_encoded_value_with_base (DW_EH_PE_uleb128, 0, p, val);
252 /* Similar, but read a signed leb128 value. */
254 static inline const unsigned char *
255 read_sleb128 (const unsigned char *p, _Unwind_Ptr *val)
257 return read_encoded_value_with_base (DW_EH_PE_sleb128, 0, p, val);