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1 | //===-- llvm/Support/WinARMEH.h - Windows on ARM EH Constants ---*- C++ -*-===// |
2 | // | |
3 | // The LLVM Compiler Infrastructure | |
4 | // | |
5 | // This file is distributed under the University of Illinois Open Source | |
6 | // License. See LICENSE.TXT for details. | |
7 | // | |
8 | //===----------------------------------------------------------------------===// | |
9 | ||
10 | #ifndef LLVM_SUPPORT_ARMWINEH_H | |
11 | #define LLVM_SUPPORT_ARMWINEH_H | |
12 | ||
13 | #include "llvm/ADT/ArrayRef.h" | |
14 | #include "llvm/Support/Endian.h" | |
15 | ||
16 | namespace llvm { | |
17 | namespace ARM { | |
18 | namespace WinEH { | |
19 | enum class RuntimeFunctionFlag { | |
20 | RFF_Unpacked, /// unpacked entry | |
21 | RFF_Packed, /// packed entry | |
22 | RFF_PackedFragment, /// packed entry representing a fragment | |
23 | RFF_Reserved, /// reserved | |
24 | }; | |
25 | ||
26 | enum class ReturnType { | |
27 | RT_POP, /// return via pop {pc} (L flag must be set) | |
28 | RT_B, /// 16-bit branch | |
29 | RT_BW, /// 32-bit branch | |
30 | RT_NoEpilogue, /// no epilogue (fragment) | |
31 | }; | |
32 | ||
33 | /// RuntimeFunction - An entry in the table of procedure data (.pdata) | |
34 | /// | |
35 | /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 | |
36 | /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | |
37 | /// +---------------------------------------------------------------+ | |
38 | /// | Function Start RVA | | |
39 | /// +-------------------+-+-+-+-----+-+---+---------------------+---+ | |
40 | /// | Stack Adjust |C|L|R| Reg |H|Ret| Function Length |Flg| | |
41 | /// +-------------------+-+-+-+-----+-+---+---------------------+---+ | |
42 | /// | |
43 | /// Flag : 2-bit field with the following meanings: | |
44 | /// - 00 = packed unwind data not used; reamining bits point to .xdata record | |
45 | /// - 01 = packed unwind data | |
46 | /// - 10 = packed unwind data, function assumed to have no prologue; useful | |
47 | /// for function fragments that are discontiguous with the start of the | |
48 | /// function | |
49 | /// - 11 = reserved | |
50 | /// Function Length : 11-bit field providing the length of the entire function | |
51 | /// in bytes, divided by 2; if the function is greater than | |
52 | /// 4KB, a full .xdata record must be used instead | |
53 | /// Ret : 2-bit field indicating how the function returns | |
54 | /// - 00 = return via pop {pc} (the L bit must be set) | |
55 | /// - 01 = return via 16-bit branch | |
56 | /// - 10 = return via 32-bit branch | |
57 | /// - 11 = no epilogue; useful for function fragments that may only contain a | |
58 | /// prologue but the epilogue is elsewhere | |
59 | /// H : 1-bit flag indicating whether the function "homes" the integer parameter | |
60 | /// registers (r0-r3), allocating 16-bytes on the stack | |
61 | /// Reg : 3-bit field indicating the index of the last saved non-volatile | |
62 | /// register. If the R bit is set to 0, then only integer registers are | |
63 | /// saved (r4-rN, where N is 4 + Reg). If the R bit is set to 1, then | |
64 | /// only floating-point registers are being saved (d8-dN, where N is | |
65 | /// 8 + Reg). The special case of the R bit being set to 1 and Reg equal | |
66 | /// to 7 indicates that no registers are saved. | |
67 | /// R : 1-bit flag indicating whether the non-volatile registers are integer or | |
68 | /// floating-point. 0 indicates integer, 1 indicates floating-point. The | |
69 | /// special case of the R-flag being set and Reg being set to 7 indicates | |
70 | /// that no non-volatile registers are saved. | |
71 | /// L : 1-bit flag indicating whether the function saves/restores the link | |
72 | /// register (LR) | |
73 | /// C : 1-bit flag indicating whether the function includes extra instructions | |
74 | /// to setup a frame chain for fast walking. If this flag is set, r11 is | |
75 | /// implicitly added to the list of saved non-volatile integer registers. | |
76 | /// Stack Adjust : 10-bit field indicating the number of bytes of stack that are | |
77 | /// allocated for this function. Only values between 0x000 and | |
78 | /// 0x3f3 can be directly encoded. If the value is 0x3f4 or | |
79 | /// greater, then the low 4 bits have special meaning as follows: | |
80 | /// - Bit 0-1 | |
81 | /// indicate the number of words' of adjustment (1-4), minus 1 | |
82 | /// - Bit 2 | |
83 | /// indicates if the prologue combined adjustment into push | |
84 | /// - Bit 3 | |
85 | /// indicates if the epilogue combined adjustment into pop | |
86 | /// | |
87 | /// RESTRICTIONS: | |
88 | /// - IF C is SET: | |
89 | /// + L flag must be set since frame chaining requires r11 and lr | |
90 | /// + r11 must NOT be included in the set of registers described by Reg | |
91 | /// - IF Ret is 0: | |
92 | /// + L flag must be set | |
93 | ||
94 | // NOTE: RuntimeFunction is meant to be a simple class that provides raw access | |
95 | // to all fields in the structure. The accessor methods reflect the names of | |
96 | // the bitfields that they correspond to. Although some obvious simplifications | |
97 | // are possible via merging of methods, it would prevent the use of this class | |
98 | // to fully inspect the contents of the data structure which is particularly | |
99 | // useful for scenarios such as llvm-readobj to aid in testing. | |
100 | ||
101 | class RuntimeFunction { | |
102 | public: | |
103 | const support::ulittle32_t BeginAddress; | |
104 | const support::ulittle32_t UnwindData; | |
105 | ||
106 | RuntimeFunction(const support::ulittle32_t *Data) | |
107 | : BeginAddress(Data[0]), UnwindData(Data[1]) {} | |
108 | ||
109 | RuntimeFunction(const support::ulittle32_t BeginAddress, | |
110 | const support::ulittle32_t UnwindData) | |
111 | : BeginAddress(BeginAddress), UnwindData(UnwindData) {} | |
112 | ||
113 | RuntimeFunctionFlag Flag() const { | |
114 | return RuntimeFunctionFlag(UnwindData & 0x3); | |
115 | } | |
116 | ||
117 | uint32_t ExceptionInformationRVA() const { | |
118 | assert(Flag() == RuntimeFunctionFlag::RFF_Unpacked && | |
119 | "unpacked form required for this operation"); | |
120 | return (UnwindData & ~0x3); | |
121 | } | |
122 | ||
123 | uint32_t PackedUnwindData() const { | |
124 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
125 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
126 | "packed form required for this operation"); | |
127 | return (UnwindData & ~0x3); | |
128 | } | |
129 | uint32_t FunctionLength() const { | |
130 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
131 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
132 | "packed form required for this operation"); | |
133 | return (((UnwindData & 0x00001ffc) >> 2) << 1); | |
134 | } | |
135 | ReturnType Ret() const { | |
136 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
137 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
138 | "packed form required for this operation"); | |
139 | assert(((UnwindData & 0x00006000) || L()) && "L must be set to 1"); | |
140 | return ReturnType((UnwindData & 0x00006000) >> 13); | |
141 | } | |
142 | bool H() const { | |
143 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
144 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
145 | "packed form required for this operation"); | |
146 | return ((UnwindData & 0x00008000) >> 15); | |
147 | } | |
148 | uint8_t Reg() const { | |
149 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
150 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
151 | "packed form required for this operation"); | |
152 | return ((UnwindData & 0x00070000) >> 16); | |
153 | } | |
154 | bool R() const { | |
155 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
156 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
157 | "packed form required for this operation"); | |
158 | return ((UnwindData & 0x00080000) >> 19); | |
159 | } | |
160 | bool L() const { | |
161 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
162 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
163 | "packed form required for this operation"); | |
164 | return ((UnwindData & 0x00100000) >> 20); | |
165 | } | |
166 | bool C() const { | |
167 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
168 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
169 | "packed form required for this operation"); | |
170 | assert(((~UnwindData & 0x00200000) || L()) && | |
171 | "L flag must be set, chaining requires r11 and LR"); | |
172 | assert(((~UnwindData & 0x00200000) || (Reg() < 7) || R()) && | |
173 | "r11 must not be included in Reg; C implies r11"); | |
174 | return ((UnwindData & 0x00200000) >> 21); | |
175 | } | |
176 | uint16_t StackAdjust() const { | |
177 | assert((Flag() == RuntimeFunctionFlag::RFF_Packed || | |
178 | Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && | |
179 | "packed form required for this operation"); | |
180 | return ((UnwindData & 0xffc00000) >> 22); | |
181 | } | |
182 | }; | |
183 | ||
184 | /// PrologueFolding - pseudo-flag derived from Stack Adjust indicating that the | |
185 | /// prologue has stack adjustment combined into the push | |
186 | inline bool PrologueFolding(const RuntimeFunction &RF) { | |
187 | return RF.StackAdjust() >= 0x3f4 && (RF.StackAdjust() & 0x4); | |
188 | } | |
189 | /// Epilogue - pseudo-flag derived from Stack Adjust indicating that the | |
190 | /// epilogue has stack adjustment combined into the pop | |
191 | inline bool EpilogueFolding(const RuntimeFunction &RF) { | |
192 | return RF.StackAdjust() >= 0x3f4 && (RF.StackAdjust() & 0x8); | |
193 | } | |
194 | /// StackAdjustment - calculated stack adjustment in words. The stack | |
195 | /// adjustment should be determined via this function to account for the special | |
196 | /// handling the special encoding when the value is >= 0x3f4. | |
197 | inline uint16_t StackAdjustment(const RuntimeFunction &RF) { | |
198 | uint16_t Adjustment = RF.StackAdjust(); | |
199 | if (Adjustment >= 0x3f4) | |
200 | return (Adjustment & 0x3) ? ((Adjustment & 0x3) << 2) - 1 : 0; | |
201 | return Adjustment; | |
202 | } | |
203 | ||
204 | /// SavedRegisterMask - Utility function to calculate the set of saved general | |
205 | /// purpose (r0-r15) and VFP (d0-d31) registers. | |
206 | std::pair<uint16_t, uint32_t> SavedRegisterMask(const RuntimeFunction &RF); | |
207 | ||
208 | /// ExceptionDataRecord - An entry in the table of exception data (.xdata) | |
209 | /// | |
210 | /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 | |
211 | /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | |
212 | /// +-------+---------+-+-+-+---+-----------------------------------+ | |
213 | /// | C Wrd | Epi Cnt |F|E|X|Ver| Function Length | | |
214 | /// +-------+--------+'-'-'-'---'---+-------------------------------+ | |
215 | /// | Reserved |Ex. Code Words| (Extended Epilogue Count) | | |
216 | /// +-------+--------+--------------+-------------------------------+ | |
217 | /// | |
218 | /// Function Length : 18-bit field indicating the total length of the function | |
219 | /// in bytes divided by 2. If a function is larger than | |
220 | /// 512KB, then multiple pdata and xdata records must be used. | |
221 | /// Vers : 2-bit field describing the version of the remaining structure. Only | |
222 | /// version 0 is currently defined (values 1-3 are not permitted). | |
223 | /// X : 1-bit field indicating the presence of exception data | |
224 | /// E : 1-bit field indicating that the single epilogue is packed into the | |
225 | /// header | |
226 | /// F : 1-bit field indicating that the record describes a function fragment | |
227 | /// (implies that no prologue is present, and prologue processing should be | |
228 | /// skipped) | |
229 | /// Epilogue Count : 5-bit field that differs in meaning based on the E field. | |
230 | /// | |
231 | /// If E is set, then this field specifies the index of the | |
232 | /// first unwind code describing the (only) epilogue. | |
233 | /// | |
234 | /// Otherwise, this field indicates the number of exception | |
235 | /// scopes. If more than 31 scopes exist, then this field and | |
236 | /// the Code Words field must both be set to 0 to indicate that | |
237 | /// an extension word is required. | |
238 | /// Code Words : 4-bit field that species the number of 32-bit words needed to | |
239 | /// contain all the unwind codes. If more than 15 words (63 code | |
240 | /// bytes) are required, then this field and the Epilogue Count | |
241 | /// field must both be set to 0 to indicate that an extension word | |
242 | /// is required. | |
243 | /// Extended Epilogue Count, Extended Code Words : | |
244 | /// Valid only if Epilog Count and Code Words are both | |
245 | /// set to 0. Provides an 8-bit extended code word | |
246 | /// count and 16-bits for epilogue count | |
247 | /// | |
248 | /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 | |
249 | /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | |
250 | /// +----------------+------+---+---+-------------------------------+ | |
251 | /// | Ep Start Idx | Cond |Res| Epilogue Start Offset | | |
252 | /// +----------------+------+---+-----------------------------------+ | |
253 | /// | |
254 | /// If the E bit is unset in the header, the header is followed by a series of | |
255 | /// epilogue scopes, which are sorted by their offset. | |
256 | /// | |
257 | /// Epilogue Start Offset: 18-bit field encoding the offset of epilogue relative | |
258 | /// to the start of the function in bytes divided by two | |
259 | /// Res : 2-bit field reserved for future expansion (must be set to 0) | |
260 | /// Condition : 4-bit field providing the condition under which the epilogue is | |
261 | /// executed. Unconditional epilogues should set this field to 0xe. | |
262 | /// Epilogues must be entirely conditional or unconditional, and in | |
263 | /// Thumb-2 mode. The epilogue beings with the first instruction | |
264 | /// after the IT opcode. | |
265 | /// Epilogue Start Index : 8-bit field indicating the byte index of the first | |
266 | /// unwind code describing the epilogue | |
267 | /// | |
268 | /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 | |
269 | /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | |
270 | /// +---------------+---------------+---------------+---------------+ | |
271 | /// | Unwind Code 3 | Unwind Code 2 | Unwind Code 1 | Unwind Code 0 | | |
272 | /// +---------------+---------------+---------------+---------------+ | |
273 | /// | |
274 | /// Following the epilogue scopes, the byte code describing the unwinding | |
275 | /// follows. This is padded to align up to word alignment. Bytes are stored in | |
276 | /// little endian. | |
277 | /// | |
278 | /// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 | |
279 | /// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 | |
280 | /// +---------------------------------------------------------------+ | |
281 | /// | Exception Handler RVA (requires X = 1) | | |
282 | /// +---------------------------------------------------------------+ | |
283 | /// | (possibly followed by data required for exception handler) | | |
284 | /// +---------------------------------------------------------------+ | |
285 | /// | |
286 | /// If the X bit is set in the header, the unwind byte code is followed by the | |
287 | /// exception handler information. This constants of one Exception Handler RVA | |
288 | /// which is the address to the exception handler, followed immediately by the | |
289 | /// variable length data associated with the exception handler. | |
290 | /// | |
291 | ||
292 | struct EpilogueScope { | |
293 | const support::ulittle32_t ES; | |
294 | ||
295 | EpilogueScope(const support::ulittle32_t Data) : ES(Data) {} | |
296 | uint32_t EpilogueStartOffset() const { | |
297 | return (ES & 0x0003ffff); | |
298 | } | |
299 | uint8_t Res() const { | |
300 | return ((ES & 0x000c0000) >> 18); | |
301 | } | |
302 | uint8_t Condition() const { | |
303 | return ((ES & 0x00f00000) >> 20); | |
304 | } | |
305 | uint8_t EpilogueStartIndex() const { | |
306 | return ((ES & 0xff000000) >> 24); | |
307 | } | |
308 | }; | |
309 | ||
310 | struct ExceptionDataRecord; | |
311 | inline size_t HeaderWords(const ExceptionDataRecord &XR); | |
312 | ||
313 | struct ExceptionDataRecord { | |
314 | const support::ulittle32_t *Data; | |
315 | ||
316 | ExceptionDataRecord(const support::ulittle32_t *Data) : Data(Data) {} | |
317 | ||
318 | uint32_t FunctionLength() const { | |
319 | return (Data[0] & 0x0003ffff); | |
320 | } | |
321 | ||
322 | uint8_t Vers() const { | |
323 | return (Data[0] & 0x000C0000) >> 18; | |
324 | } | |
325 | ||
326 | bool X() const { | |
327 | return ((Data[0] & 0x00100000) >> 20); | |
328 | } | |
329 | ||
330 | bool E() const { | |
331 | return ((Data[0] & 0x00200000) >> 21); | |
332 | } | |
333 | ||
334 | bool F() const { | |
335 | return ((Data[0] & 0x00400000) >> 22); | |
336 | } | |
337 | ||
338 | uint8_t EpilogueCount() const { | |
339 | if (HeaderWords(*this) == 1) | |
340 | return (Data[0] & 0x0f800000) >> 23; | |
341 | return Data[1] & 0x0000ffff; | |
342 | } | |
343 | ||
344 | uint8_t CodeWords() const { | |
345 | if (HeaderWords(*this) == 1) | |
346 | return (Data[0] & 0xf0000000) >> 28; | |
347 | return (Data[1] & 0x00ff0000) >> 16; | |
348 | } | |
349 | ||
350 | ArrayRef<support::ulittle32_t> EpilogueScopes() const { | |
351 | assert(E() == 0 && "epilogue scopes are only present when the E bit is 0"); | |
352 | size_t Offset = HeaderWords(*this); | |
353 | return makeArrayRef(&Data[Offset], EpilogueCount()); | |
354 | } | |
355 | ||
356 | ArrayRef<uint8_t> UnwindByteCode() const { | |
357 | const size_t Offset = HeaderWords(*this) | |
358 | + (E() ? 0 : EpilogueCount()); | |
359 | const uint8_t *ByteCode = | |
360 | reinterpret_cast<const uint8_t *>(&Data[Offset]); | |
361 | return makeArrayRef(ByteCode, CodeWords() * sizeof(uint32_t)); | |
362 | } | |
363 | ||
364 | uint32_t ExceptionHandlerRVA() const { | |
365 | assert(X() && "Exception Handler RVA is only valid if the X bit is set"); | |
366 | return Data[HeaderWords(*this) + EpilogueCount() + CodeWords()]; | |
367 | } | |
368 | ||
369 | uint32_t ExceptionHandlerParameter() const { | |
370 | assert(X() && "Exception Handler RVA is only valid if the X bit is set"); | |
371 | return Data[HeaderWords(*this) + EpilogueCount() + CodeWords() + 1]; | |
372 | } | |
373 | }; | |
374 | ||
375 | inline size_t HeaderWords(const ExceptionDataRecord &XR) { | |
376 | return (XR.Data[0] & 0xff800000) ? 1 : 2; | |
377 | } | |
378 | } | |
379 | } | |
380 | } | |
381 | ||
382 | #endif |