gcc/
[official-gcc.git] / gcc / unwind-c.c
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1 /* Supporting functions for C exception handling.
2 Copyright (C) 2002, 2003, 2009 Free Software Foundation, Inc.
3 Contributed by Aldy Hernandez <aldy@quesejoda.com>.
4 Shamelessly stolen from the Java front end.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 Under Section 7 of GPL version 3, you are granted additional
19 permissions described in the GCC Runtime Library Exception, version
20 3.1, as published by the Free Software Foundation.
22 You should have received a copy of the GNU General Public License and
23 a copy of the GCC Runtime Library Exception along with this program;
24 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 <http://www.gnu.org/licenses/>. */
27 #include "tconfig.h"
28 #include "tsystem.h"
29 #include "unwind.h"
30 #define NO_SIZE_OF_ENCODED_VALUE
31 #include "unwind-pe.h"
33 typedef struct
35 _Unwind_Ptr Start;
36 _Unwind_Ptr LPStart;
37 _Unwind_Ptr ttype_base;
38 const unsigned char *TType;
39 const unsigned char *action_table;
40 unsigned char ttype_encoding;
41 unsigned char call_site_encoding;
42 } lsda_header_info;
44 static const unsigned char *
45 parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p,
46 lsda_header_info *info)
48 _uleb128_t tmp;
49 unsigned char lpstart_encoding;
51 info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
53 /* Find @LPStart, the base to which landing pad offsets are relative. */
54 lpstart_encoding = *p++;
55 if (lpstart_encoding != DW_EH_PE_omit)
56 p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
57 else
58 info->LPStart = info->Start;
60 /* Find @TType, the base of the handler and exception spec type data. */
61 info->ttype_encoding = *p++;
62 if (info->ttype_encoding != DW_EH_PE_omit)
64 p = read_uleb128 (p, &tmp);
65 info->TType = p + tmp;
67 else
68 info->TType = 0;
70 /* The encoding and length of the call-site table; the action table
71 immediately follows. */
72 info->call_site_encoding = *p++;
73 p = read_uleb128 (p, &tmp);
74 info->action_table = p + tmp;
76 return p;
79 #ifdef __ARM_EABI_UNWINDER__
80 /* ARM EABI personality routines must also unwind the stack. */
81 #define CONTINUE_UNWINDING \
82 do \
83 { \
84 if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \
85 return _URC_FAILURE; \
86 return _URC_CONTINUE_UNWIND; \
87 } \
88 while (0)
89 #else
90 #define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND
91 #endif
93 #ifdef __USING_SJLJ_EXCEPTIONS__
94 #define PERSONALITY_FUNCTION __gcc_personality_sj0
95 #define __builtin_eh_return_data_regno(x) x
96 #else
97 #define PERSONALITY_FUNCTION __gcc_personality_v0
98 #endif
100 #ifdef __ARM_EABI_UNWINDER__
101 _Unwind_Reason_Code
102 PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *,
103 struct _Unwind_Context *);
105 _Unwind_Reason_Code
106 PERSONALITY_FUNCTION (_Unwind_State state,
107 struct _Unwind_Exception * ue_header,
108 struct _Unwind_Context * context)
109 #else
110 _Unwind_Reason_Code
111 PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class,
112 struct _Unwind_Exception *, struct _Unwind_Context *);
114 _Unwind_Reason_Code
115 PERSONALITY_FUNCTION (int version,
116 _Unwind_Action actions,
117 _Unwind_Exception_Class exception_class ATTRIBUTE_UNUSED,
118 struct _Unwind_Exception *ue_header,
119 struct _Unwind_Context *context)
120 #endif
122 lsda_header_info info;
123 const unsigned char *language_specific_data, *p;
124 _Unwind_Ptr landing_pad, ip;
125 int ip_before_insn = 0;
127 #ifdef __ARM_EABI_UNWINDER__
128 if ((state & _US_ACTION_MASK) != _US_UNWIND_FRAME_STARTING)
129 CONTINUE_UNWINDING;
131 /* The dwarf unwinder assumes the context structure holds things like the
132 function and LSDA pointers. The ARM implementation caches these in
133 the exception header (UCB). To avoid rewriting everything we make the
134 virtual IP register point at the UCB. */
135 ip = (_Unwind_Ptr) ue_header;
136 _Unwind_SetGR (context, 12, ip);
137 #else
138 if (version != 1)
139 return _URC_FATAL_PHASE1_ERROR;
141 /* Currently we only support cleanups for C. */
142 if ((actions & _UA_CLEANUP_PHASE) == 0)
143 CONTINUE_UNWINDING;
144 #endif
146 language_specific_data = (const unsigned char *)
147 _Unwind_GetLanguageSpecificData (context);
149 /* If no LSDA, then there are no handlers or cleanups. */
150 if (! language_specific_data)
151 CONTINUE_UNWINDING;
153 /* Parse the LSDA header. */
154 p = parse_lsda_header (context, language_specific_data, &info);
155 #ifdef HAVE_GETIPINFO
156 ip = _Unwind_GetIPInfo (context, &ip_before_insn);
157 #else
158 ip = _Unwind_GetIP (context);
159 #endif
160 if (! ip_before_insn)
161 --ip;
162 landing_pad = 0;
164 #ifdef __USING_SJLJ_EXCEPTIONS__
165 /* The given "IP" is an index into the call-site table, with two
166 exceptions -- -1 means no-action, and 0 means terminate. But
167 since we're using uleb128 values, we've not got random access
168 to the array. */
169 if ((int) ip <= 0)
170 return _URC_CONTINUE_UNWIND;
171 else
173 _uleb128_t cs_lp, cs_action;
176 p = read_uleb128 (p, &cs_lp);
177 p = read_uleb128 (p, &cs_action);
179 while (--ip);
181 /* Can never have null landing pad for sjlj -- that would have
182 been indicated by a -1 call site index. */
183 landing_pad = (_Unwind_Ptr)cs_lp + 1;
184 goto found_something;
186 #else
187 /* Search the call-site table for the action associated with this IP. */
188 while (p < info.action_table)
190 _Unwind_Ptr cs_start, cs_len, cs_lp;
191 _uleb128_t cs_action;
193 /* Note that all call-site encodings are "absolute" displacements. */
194 p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
195 p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
196 p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
197 p = read_uleb128 (p, &cs_action);
199 /* The table is sorted, so if we've passed the ip, stop. */
200 if (ip < info.Start + cs_start)
201 p = info.action_table;
202 else if (ip < info.Start + cs_start + cs_len)
204 if (cs_lp)
205 landing_pad = info.LPStart + cs_lp;
206 goto found_something;
209 #endif
211 /* IP is not in table. No associated cleanups. */
212 /* ??? This is where C++ calls std::terminate to catch throw
213 from a destructor. */
214 CONTINUE_UNWINDING;
216 found_something:
217 if (landing_pad == 0)
219 /* IP is present, but has a null landing pad.
220 No handler to be run. */
221 CONTINUE_UNWINDING;
224 _Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
225 (_Unwind_Ptr) ue_header);
226 _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0);
227 _Unwind_SetIP (context, landing_pad);
228 return _URC_INSTALL_CONTEXT;