Bug Summary

File:build/source/llvm/include/llvm/Bitstream/BitstreamReader.h
Warning:line 217, column 39
The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'word_t'

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name BitstreamReader.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Bitstream/Reader -I /build/source/llvm/lib/Bitstream/Reader -I include -I /build/source/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -source-date-epoch 1679915782 -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-03-27-130437-16335-1 -x c++ /build/source/llvm/lib/Bitstream/Reader/BitstreamReader.cpp

/build/source/llvm/lib/Bitstream/Reader/BitstreamReader.cpp

→
1//===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/Bitstream/BitstreamReader.h"
10#include "llvm/ADT/StringRef.h"
11#include <cassert>
12#include <optional>
13#include <string>
14
15using namespace llvm;
16
17//===----------------------------------------------------------------------===//
18// BitstreamCursor implementation
19//===----------------------------------------------------------------------===//
20//
21static Error error(const char *Message) {
22 return createStringError(std::errc::illegal_byte_sequence, Message);
23}
24
25/// Having read the ENTER_SUBBLOCK abbrevid, enter the block.
26Error BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
27 // Save the current block's state on BlockScope.
28 BlockScope.push_back(Block(CurCodeSize));
29 BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
30
31 // Add the abbrevs specific to this block to the CurAbbrevs list.
32 if (BlockInfo) {
33 if (const BitstreamBlockInfo::BlockInfo *Info =
34 BlockInfo->getBlockInfo(BlockID)) {
35 llvm::append_range(CurAbbrevs, Info->Abbrevs);
36 }
37 }
38
39 // Get the codesize of this block.
40 Expected<uint32_t> MaybeVBR = ReadVBR(bitc::CodeLenWidth);
41 if (!MaybeVBR)
42 return MaybeVBR.takeError();
43 CurCodeSize = MaybeVBR.get();
44
45 if (CurCodeSize > MaxChunkSize)
46 return llvm::createStringError(
47 std::errc::illegal_byte_sequence,
48 "can't read more than %zu at a time, trying to read %u", +MaxChunkSize,
49 CurCodeSize);
50
51 SkipToFourByteBoundary();
52 Expected<word_t> MaybeNum = Read(bitc::BlockSizeWidth);
53 if (!MaybeNum)
54 return MaybeNum.takeError();
55 word_t NumWords = MaybeNum.get();
56 if (NumWordsP)
57 *NumWordsP = NumWords;
58
59 if (CurCodeSize == 0)
60 return llvm::createStringError(
61 std::errc::illegal_byte_sequence,
62 "can't enter sub-block: current code size is 0");
63 if (AtEndOfStream())
64 return llvm::createStringError(
65 std::errc::illegal_byte_sequence,
66 "can't enter sub block: already at end of stream");
67
68 return Error::success();
69}
70
71static Expected<uint64_t> readAbbreviatedField(BitstreamCursor &Cursor,
72 const BitCodeAbbrevOp &Op) {
73 assert(!Op.isLiteral() && "Not to be used with literals!")(static_cast <bool> (!Op.isLiteral() && "Not to be used with literals!"
) ? void (0) : __assert_fail ("!Op.isLiteral() && \"Not to be used with literals!\""
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 73, __extension__
__PRETTY_FUNCTION__));
74
75 // Decode the value as we are commanded.
76 switch (Op.getEncoding()) {
77 case BitCodeAbbrevOp::Array:
78 case BitCodeAbbrevOp::Blob:
79 llvm_unreachable("Should not reach here")::llvm::llvm_unreachable_internal("Should not reach here", "llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 79);
80 case BitCodeAbbrevOp::Fixed:
81 assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize)(static_cast <bool> ((unsigned)Op.getEncodingData() <=
Cursor.MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 81, __extension__
__PRETTY_FUNCTION__));
82 return Cursor.Read((unsigned)Op.getEncodingData());
83 case BitCodeAbbrevOp::VBR:
84 assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize)(static_cast <bool> ((unsigned)Op.getEncodingData() <=
Cursor.MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 84, __extension__
__PRETTY_FUNCTION__));
85 return Cursor.ReadVBR64((unsigned)Op.getEncodingData());
86 case BitCodeAbbrevOp::Char6:
87 if (Expected<unsigned> Res = Cursor.Read(6))
88 return BitCodeAbbrevOp::DecodeChar6(Res.get());
89 else
90 return Res.takeError();
91 }
92 llvm_unreachable("invalid abbreviation encoding")::llvm::llvm_unreachable_internal("invalid abbreviation encoding"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 92);
93}
94
95/// skipRecord - Read the current record and discard it.
96Expected<unsigned> BitstreamCursor::skipRecord(unsigned AbbrevID) {
97 // Skip unabbreviated records by reading past their entries.
98 if (AbbrevID == bitc::UNABBREV_RECORD) {
99 Expected<uint32_t> MaybeCode = ReadVBR(6);
100 if (!MaybeCode)
101 return MaybeCode.takeError();
102 unsigned Code = MaybeCode.get();
103 Expected<uint32_t> MaybeVBR = ReadVBR(6);
104 if (!MaybeVBR)
105 return MaybeVBR.takeError();
106 unsigned NumElts = MaybeVBR.get();
107 for (unsigned i = 0; i != NumElts; ++i)
108 if (Expected<uint64_t> Res = ReadVBR64(6))
109 ; // Skip!
110 else
111 return Res.takeError();
112 return Code;
113 }
114
115 Expected<const BitCodeAbbrev *> MaybeAbbv = getAbbrev(AbbrevID);
116 if (!MaybeAbbv)
117 return MaybeAbbv.takeError();
118
119 const BitCodeAbbrev *Abbv = MaybeAbbv.get();
120 const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
121 unsigned Code;
122 if (CodeOp.isLiteral())
123 Code = CodeOp.getLiteralValue();
124 else {
125 if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
126 CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
127 return llvm::createStringError(
128 std::errc::illegal_byte_sequence,
129 "Abbreviation starts with an Array or a Blob");
130 Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp);
131 if (!MaybeCode)
132 return MaybeCode.takeError();
133 Code = MaybeCode.get();
134 }
135
136 for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i < e; ++i) {
137 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
138 if (Op.isLiteral())
139 continue;
140
141 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
142 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
143 if (Expected<uint64_t> MaybeField = readAbbreviatedField(*this, Op))
144 continue;
145 else
146 return MaybeField.takeError();
147 }
148
149 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
150 // Array case. Read the number of elements as a vbr6.
151 Expected<uint32_t> MaybeNum = ReadVBR(6);
152 if (!MaybeNum)
153 return MaybeNum.takeError();
154 unsigned NumElts = MaybeNum.get();
155
156 // Get the element encoding.
157 assert(i+2 == e && "array op not second to last?")(static_cast <bool> (i+2 == e && "array op not second to last?"
) ? void (0) : __assert_fail ("i+2 == e && \"array op not second to last?\""
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 157, __extension__
__PRETTY_FUNCTION__));
158 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
159
160 // Read all the elements.
161 // Decode the value as we are commanded.
162 switch (EltEnc.getEncoding()) {
163 default:
164 return error("Array element type can't be an Array or a Blob");
165 case BitCodeAbbrevOp::Fixed:
166 assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize)(static_cast <bool> ((unsigned)EltEnc.getEncodingData()
<= MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)EltEnc.getEncodingData() <= MaxChunkSize"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 166, __extension__
__PRETTY_FUNCTION__));
167 if (Error Err =
168 JumpToBit(GetCurrentBitNo() + static_cast<uint64_t>(NumElts) *
169 EltEnc.getEncodingData()))
170 return std::move(Err);
171 break;
172 case BitCodeAbbrevOp::VBR:
173 assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize)(static_cast <bool> ((unsigned)EltEnc.getEncodingData()
<= MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)EltEnc.getEncodingData() <= MaxChunkSize"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 173, __extension__
__PRETTY_FUNCTION__));
174 for (; NumElts; --NumElts)
175 if (Expected<uint64_t> Res =
176 ReadVBR64((unsigned)EltEnc.getEncodingData()))
177 ; // Skip!
178 else
179 return Res.takeError();
180 break;
181 case BitCodeAbbrevOp::Char6:
182 if (Error Err = JumpToBit(GetCurrentBitNo() + NumElts * 6))
183 return std::move(Err);
184 break;
185 }
186 continue;
187 }
188
189 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob)(static_cast <bool> (Op.getEncoding() == BitCodeAbbrevOp
::Blob) ? void (0) : __assert_fail ("Op.getEncoding() == BitCodeAbbrevOp::Blob"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 189, __extension__
__PRETTY_FUNCTION__));
190 // Blob case. Read the number of bytes as a vbr6.
191 Expected<uint32_t> MaybeNum = ReadVBR(6);
192 if (!MaybeNum)
193 return MaybeNum.takeError();
194 unsigned NumElts = MaybeNum.get();
195 SkipToFourByteBoundary(); // 32-bit alignment
196
197 // Figure out where the end of this blob will be including tail padding.
198 const size_t NewEnd = GetCurrentBitNo() + alignTo(NumElts, 4) * 8;
199
200 // If this would read off the end of the bitcode file, just set the
201 // record to empty and return.
202 if (!canSkipToPos(NewEnd/8)) {
203 skipToEnd();
204 break;
205 }
206
207 // Skip over the blob.
208 if (Error Err = JumpToBit(NewEnd))
209 return std::move(Err);
210 }
211 return Code;
212}
213
214Expected<unsigned> BitstreamCursor::readRecord(unsigned AbbrevID,
215 SmallVectorImpl<uint64_t> &Vals,
216 StringRef *Blob) {
217 if (AbbrevID == bitc::UNABBREV_RECORD) {
218 Expected<uint32_t> MaybeCode = ReadVBR(6);
219 if (!MaybeCode)
220 return MaybeCode.takeError();
221 uint32_t Code = MaybeCode.get();
222 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
223 if (!MaybeNumElts)
224 return error(
225 ("Failed to read size: " + toString(MaybeNumElts.takeError()))
226 .c_str());
227 uint32_t NumElts = MaybeNumElts.get();
228 if (!isSizePlausible(NumElts))
229 return error("Size is not plausible");
230 Vals.reserve(Vals.size() + NumElts);
231
232 for (unsigned i = 0; i != NumElts; ++i)
233 if (Expected<uint64_t> MaybeVal = ReadVBR64(6))
234 Vals.push_back(MaybeVal.get());
235 else
236 return MaybeVal.takeError();
237 return Code;
238 }
239
240 Expected<const BitCodeAbbrev *> MaybeAbbv = getAbbrev(AbbrevID);
241 if (!MaybeAbbv)
242 return MaybeAbbv.takeError();
243 const BitCodeAbbrev *Abbv = MaybeAbbv.get();
244
245 // Read the record code first.
246 assert(Abbv->getNumOperandInfos() != 0 && "no record code in abbreviation?")(static_cast <bool> (Abbv->getNumOperandInfos() != 0
&& "no record code in abbreviation?") ? void (0) : __assert_fail
("Abbv->getNumOperandInfos() != 0 && \"no record code in abbreviation?\""
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 246, __extension__
__PRETTY_FUNCTION__));
247 const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
248 unsigned Code;
249 if (CodeOp.isLiteral())
250 Code = CodeOp.getLiteralValue();
251 else {
252 if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
253 CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
254 return error("Abbreviation starts with an Array or a Blob");
255 if (Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp))
256 Code = MaybeCode.get();
257 else
258 return MaybeCode.takeError();
259 }
260
261 for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
262 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
263 if (Op.isLiteral()) {
264 Vals.push_back(Op.getLiteralValue());
265 continue;
266 }
267
268 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
269 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
270 if (Expected<uint64_t> MaybeVal = readAbbreviatedField(*this, Op))
271 Vals.push_back(MaybeVal.get());
272 else
273 return MaybeVal.takeError();
274 continue;
275 }
276
277 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
278 // Array case. Read the number of elements as a vbr6.
279 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
280 if (!MaybeNumElts)
281 return error(
282 ("Failed to read size: " + toString(MaybeNumElts.takeError()))
283 .c_str());
284 uint32_t NumElts = MaybeNumElts.get();
285 if (!isSizePlausible(NumElts))
286 return error("Size is not plausible");
287 Vals.reserve(Vals.size() + NumElts);
288
289 // Get the element encoding.
290 if (i + 2 != e)
291 return error("Array op not second to last");
292 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
293 if (!EltEnc.isEncoding())
294 return error(
295 "Array element type has to be an encoding of a type");
296
297 // Read all the elements.
298 switch (EltEnc.getEncoding()) {
299 default:
300 return error("Array element type can't be an Array or a Blob");
301 case BitCodeAbbrevOp::Fixed:
302 for (; NumElts; --NumElts)
303 if (Expected<SimpleBitstreamCursor::word_t> MaybeVal =
304 Read((unsigned)EltEnc.getEncodingData()))
305 Vals.push_back(MaybeVal.get());
306 else
307 return MaybeVal.takeError();
308 break;
309 case BitCodeAbbrevOp::VBR:
310 for (; NumElts; --NumElts)
311 if (Expected<uint64_t> MaybeVal =
312 ReadVBR64((unsigned)EltEnc.getEncodingData()))
313 Vals.push_back(MaybeVal.get());
314 else
315 return MaybeVal.takeError();
316 break;
317 case BitCodeAbbrevOp::Char6:
318 for (; NumElts; --NumElts)
319 if (Expected<SimpleBitstreamCursor::word_t> MaybeVal = Read(6))
320 Vals.push_back(BitCodeAbbrevOp::DecodeChar6(MaybeVal.get()));
321 else
322 return MaybeVal.takeError();
323 }
324 continue;
325 }
326
327 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob)(static_cast <bool> (Op.getEncoding() == BitCodeAbbrevOp
::Blob) ? void (0) : __assert_fail ("Op.getEncoding() == BitCodeAbbrevOp::Blob"
, "llvm/lib/Bitstream/Reader/BitstreamReader.cpp", 327, __extension__
__PRETTY_FUNCTION__));
328 // Blob case. Read the number of bytes as a vbr6.
329 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
330 if (!MaybeNumElts)
331 return MaybeNumElts.takeError();
332 uint32_t NumElts = MaybeNumElts.get();
333 SkipToFourByteBoundary(); // 32-bit alignment
334
335 // Figure out where the end of this blob will be including tail padding.
336 size_t CurBitPos = GetCurrentBitNo();
337 const size_t NewEnd = CurBitPos + alignTo(NumElts, 4) * 8;
338
339 // Make sure the bitstream is large enough to contain the blob.
340 if (!canSkipToPos(NewEnd/8))
341 return error("Blob ends too soon");
342
343 // Otherwise, inform the streamer that we need these bytes in memory. Skip
344 // over tail padding first, in case jumping to NewEnd invalidates the Blob
345 // pointer.
346 if (Error Err = JumpToBit(NewEnd))
347 return std::move(Err);
348 const char *Ptr = (const char *)getPointerToBit(CurBitPos, NumElts);
349
350 // If we can return a reference to the data, do so to avoid copying it.
351 if (Blob) {
352 *Blob = StringRef(Ptr, NumElts);
353 } else {
354 // Otherwise, unpack into Vals with zero extension.
355 auto *UPtr = reinterpret_cast<const unsigned char *>(Ptr);
356 Vals.append(UPtr, UPtr + NumElts);
357 }
358 }
359
360 return Code;
361}
362
363Error BitstreamCursor::ReadAbbrevRecord() {
364 auto Abbv = std::make_shared<BitCodeAbbrev>();
365 Expected<uint32_t> MaybeNumOpInfo = ReadVBR(5);
366 if (!MaybeNumOpInfo)
367 return MaybeNumOpInfo.takeError();
368 unsigned NumOpInfo = MaybeNumOpInfo.get();
369 for (unsigned i = 0; i != NumOpInfo; ++i) {
370 Expected<word_t> MaybeIsLiteral = Read(1);
371 if (!MaybeIsLiteral)
372 return MaybeIsLiteral.takeError();
373 bool IsLiteral = MaybeIsLiteral.get();
374 if (IsLiteral) {
375 Expected<uint64_t> MaybeOp = ReadVBR64(8);
376 if (!MaybeOp)
377 return MaybeOp.takeError();
378 Abbv->Add(BitCodeAbbrevOp(MaybeOp.get()));
379 continue;
380 }
381
382 Expected<word_t> MaybeEncoding = Read(3);
383 if (!MaybeEncoding)
384 return MaybeEncoding.takeError();
385 if (!BitCodeAbbrevOp::isValidEncoding(MaybeEncoding.get()))
386 return error("Invalid encoding");
387
388 BitCodeAbbrevOp::Encoding E =
389 (BitCodeAbbrevOp::Encoding)MaybeEncoding.get();
390 if (BitCodeAbbrevOp::hasEncodingData(E)) {
391 Expected<uint64_t> MaybeData = ReadVBR64(5);
392 if (!MaybeData)
393 return MaybeData.takeError();
394 uint64_t Data = MaybeData.get();
395
396 // As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
397 // and vbr(0) as a literal zero. This is decoded the same way, and avoids
398 // a slow path in Read() to have to handle reading zero bits.
399 if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
400 Data == 0) {
401 Abbv->Add(BitCodeAbbrevOp(0));
402 continue;
403 }
404
405 if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
406 Data > MaxChunkSize)
407 return error("Fixed or VBR abbrev record with size > MaxChunkData");
408
409 Abbv->Add(BitCodeAbbrevOp(E, Data));
410 } else
411 Abbv->Add(BitCodeAbbrevOp(E));
412 }
413
414 if (Abbv->getNumOperandInfos() == 0)
415 return error("Abbrev record with no operands");
416 CurAbbrevs.push_back(std::move(Abbv));
417
418 return Error::success();
419}
420
421Expected<std::optional<BitstreamBlockInfo>>
422BitstreamCursor::ReadBlockInfoBlock(bool ReadBlockInfoNames) {
423 if (llvm::Error Err = EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID))
1
Assuming the condition is false
→
2
←
Taking false branch
→
424 return std::move(Err);
425
426 BitstreamBlockInfo NewBlockInfo;
427
428 SmallVector<uint64_t, 64> Record;
429 BitstreamBlockInfo::BlockInfo *CurBlockInfo = nullptr;
430
431 // Read all the records for this module.
432 while (true) {
3
←
Loop condition is true. Entering loop body
→
433 Expected<BitstreamEntry> MaybeEntry =
434 advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
4
←
Calling 'BitstreamCursor::advanceSkippingSubblocks'
→
435 if (!MaybeEntry)
436 return MaybeEntry.takeError();
437 BitstreamEntry Entry = MaybeEntry.get();
438
439 switch (Entry.Kind) {
440 case llvm::BitstreamEntry::SubBlock: // Handled for us already.
441 case llvm::BitstreamEntry::Error:
442 return std::nullopt;
443 case llvm::BitstreamEntry::EndBlock:
444 return std::move(NewBlockInfo);
445 case llvm::BitstreamEntry::Record:
446 // The interesting case.
447 break;
448 }
449
450 // Read abbrev records, associate them with CurBID.
451 if (Entry.ID == bitc::DEFINE_ABBREV) {
452 if (!CurBlockInfo)
453 return std::nullopt;
454 if (Error Err = ReadAbbrevRecord())
455 return std::move(Err);
456
457 // ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
458 // appropriate BlockInfo.
459 CurBlockInfo->Abbrevs.push_back(std::move(CurAbbrevs.back()));
460 CurAbbrevs.pop_back();
461 continue;
462 }
463
464 // Read a record.
465 Record.clear();
466 Expected<unsigned> MaybeBlockInfo = readRecord(Entry.ID, Record);
467 if (!MaybeBlockInfo)
468 return MaybeBlockInfo.takeError();
469 switch (MaybeBlockInfo.get()) {
470 default:
471 break; // Default behavior, ignore unknown content.
472 case bitc::BLOCKINFO_CODE_SETBID:
473 if (Record.size() < 1)
474 return std::nullopt;
475 CurBlockInfo = &NewBlockInfo.getOrCreateBlockInfo((unsigned)Record[0]);
476 break;
477 case bitc::BLOCKINFO_CODE_BLOCKNAME: {
478 if (!CurBlockInfo)
479 return std::nullopt;
480 if (!ReadBlockInfoNames)
481 break; // Ignore name.
482 CurBlockInfo->Name = std::string(Record.begin(), Record.end());
483 break;
484 }
485 case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
486 if (!CurBlockInfo)
487 return std::nullopt;
488 if (!ReadBlockInfoNames)
489 break; // Ignore name.
490 CurBlockInfo->RecordNames.emplace_back(
491 (unsigned)Record[0], std::string(Record.begin() + 1, Record.end()));
492 break;
493 }
494 }
495 }
496}
←

/build/source/llvm/include/llvm/Bitstream/BitstreamReader.h

1//===- BitstreamReader.h - Low-level bitstream reader interface -*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This header defines the BitstreamReader class. This class can be used to
10// read an arbitrary bitstream, regardless of its contents.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_BITSTREAM_BITSTREAMREADER_H
15#define LLVM_BITSTREAM_BITSTREAMREADER_H
16
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/Bitstream/BitCodes.h"
20#include "llvm/Support/Endian.h"
21#include "llvm/Support/Error.h"
22#include "llvm/Support/MemoryBufferRef.h"
23#include <algorithm>
24#include <cassert>
25#include <climits>
26#include <cstddef>
27#include <cstdint>
28#include <memory>
29#include <optional>
30#include <string>
31#include <utility>
32#include <vector>
33
34namespace llvm {
35
36/// This class maintains the abbreviations read from a block info block.
37class BitstreamBlockInfo {
38public:
39 /// This contains information emitted to BLOCKINFO_BLOCK blocks. These
40 /// describe abbreviations that all blocks of the specified ID inherit.
41 struct BlockInfo {
42 unsigned BlockID = 0;
43 std::vector<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
44 std::string Name;
45 std::vector<std::pair<unsigned, std::string>> RecordNames;
46 };
47
48private:
49 std::vector<BlockInfo> BlockInfoRecords;
50
51public:
52 /// If there is block info for the specified ID, return it, otherwise return
53 /// null.
54 const BlockInfo *getBlockInfo(unsigned BlockID) const {
55 // Common case, the most recent entry matches BlockID.
56 if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
57 return &BlockInfoRecords.back();
58
59 for (const BlockInfo &BI : BlockInfoRecords)
60 if (BI.BlockID == BlockID)
61 return &BI;
62 return nullptr;
63 }
64
65 BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
66 if (const BlockInfo *BI = getBlockInfo(BlockID))
67 return *const_cast<BlockInfo*>(BI);
68
69 // Otherwise, add a new record.
70 BlockInfoRecords.emplace_back();
71 BlockInfoRecords.back().BlockID = BlockID;
72 return BlockInfoRecords.back();
73 }
74};
75
76/// This represents a position within a bitstream. There may be multiple
77/// independent cursors reading within one bitstream, each maintaining their
78/// own local state.
79class SimpleBitstreamCursor {
80 ArrayRef<uint8_t> BitcodeBytes;
81 size_t NextChar = 0;
82
83public:
84 /// This is the current data we have pulled from the stream but have not
85 /// returned to the client. This is specifically and intentionally defined to
86 /// follow the word size of the host machine for efficiency. We use word_t in
87 /// places that are aware of this to make it perfectly explicit what is going
88 /// on.
89 using word_t = size_t;
90
91private:
92 word_t CurWord = 0;
93
94 /// This is the number of bits in CurWord that are valid. This is always from
95 /// [0...bits_of(size_t)-1] inclusive.
96 unsigned BitsInCurWord = 0;
97
98public:
99 SimpleBitstreamCursor() = default;
100 explicit SimpleBitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
101 : BitcodeBytes(BitcodeBytes) {}
102 explicit SimpleBitstreamCursor(StringRef BitcodeBytes)
103 : BitcodeBytes(arrayRefFromStringRef(BitcodeBytes)) {}
104 explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
105 : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}
106
107 bool canSkipToPos(size_t pos) const {
108 // pos can be skipped to if it is a valid address or one byte past the end.
109 return pos <= BitcodeBytes.size();
110 }
111
112 bool AtEndOfStream() {
113 return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
114 }
115
116 /// Return the bit # of the bit we are reading.
117 uint64_t GetCurrentBitNo() const {
118 return NextChar*CHAR_BIT8 - BitsInCurWord;
119 }
120
121 // Return the byte # of the current bit.
122 uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }
123
124 ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }
125
126 /// Reset the stream to the specified bit number.
127 Error JumpToBit(uint64_t BitNo) {
128 size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
129 unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
130 assert(canSkipToPos(ByteNo) && "Invalid location")(static_cast <bool> (canSkipToPos(ByteNo) && "Invalid location"
) ? void (0) : __assert_fail ("canSkipToPos(ByteNo) && \"Invalid location\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 130, __extension__
__PRETTY_FUNCTION__));
131
132 // Move the cursor to the right word.
133 NextChar = ByteNo;
134 BitsInCurWord = 0;
135
136 // Skip over any bits that are already consumed.
137 if (WordBitNo) {
138 if (Expected<word_t> Res = Read(WordBitNo))
139 return Error::success();
140 else
141 return Res.takeError();
142 }
143
144 return Error::success();
145 }
146
147 /// Get a pointer into the bitstream at the specified byte offset.
148 const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
149 return BitcodeBytes.data() + ByteNo;
150 }
151
152 /// Get a pointer into the bitstream at the specified bit offset.
153 ///
154 /// The bit offset must be on a byte boundary.
155 const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
156 assert(!(BitNo % 8) && "Expected bit on byte boundary")(static_cast <bool> (!(BitNo % 8) && "Expected bit on byte boundary"
) ? void (0) : __assert_fail ("!(BitNo % 8) && \"Expected bit on byte boundary\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 156, __extension__
__PRETTY_FUNCTION__));
157 return getPointerToByte(BitNo / 8, NumBytes);
158 }
159
160 Error fillCurWord() {
161 if (NextChar >= BitcodeBytes.size())
162 return createStringError(std::errc::io_error,
163 "Unexpected end of file reading %u of %u bytes",
164 NextChar, BitcodeBytes.size());
165
166 // Read the next word from the stream.
167 const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
168 unsigned BytesRead;
169 if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
170 BytesRead = sizeof(word_t);
171 CurWord =
172 support::endian::read<word_t, support::little, support::unaligned>(
173 NextCharPtr);
174 } else {
175 // Short read.
176 BytesRead = BitcodeBytes.size() - NextChar;
177 CurWord = 0;
178 for (unsigned B = 0; B != BytesRead; ++B)
179 CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
180 }
181 NextChar += BytesRead;
182 BitsInCurWord = BytesRead * 8;
183 return Error::success();
184 }
185
186 Expected<word_t> Read(unsigned NumBits) {
187 static const unsigned BitsInWord = sizeof(word_t) * 8;
188
189 assert(NumBits && NumBits <= BitsInWord &&(static_cast <bool> (NumBits && NumBits <= BitsInWord
&& "Cannot return zero or more than BitsInWord bits!"
) ? void (0) : __assert_fail ("NumBits && NumBits <= BitsInWord && \"Cannot return zero or more than BitsInWord bits!\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 190, __extension__
__PRETTY_FUNCTION__))
11
←
Assuming 'NumBits' is not equal to 0
→
12
←
Assuming 'NumBits' is <= 'BitsInWord'
→
13
←
'?' condition is true
→
190 "Cannot return zero or more than BitsInWord bits!")(static_cast <bool> (NumBits && NumBits <= BitsInWord
&& "Cannot return zero or more than BitsInWord bits!"
) ? void (0) : __assert_fail ("NumBits && NumBits <= BitsInWord && \"Cannot return zero or more than BitsInWord bits!\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 190, __extension__
__PRETTY_FUNCTION__));
191
192 static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
193
194 // If the field is fully contained by CurWord, return it quickly.
195 if (BitsInCurWord >= NumBits) {
14
←
Assuming 'NumBits' is > field 'BitsInCurWord'
→
196 word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
197
198 // Use a mask to avoid undefined behavior.
199 CurWord >>= (NumBits & Mask);
200
201 BitsInCurWord -= NumBits;
202 return R;
203 }
204
205 word_t R = BitsInCurWord
15.1
Field 'BitsInCurWord' is not equal to 0
15.1
Field 'BitsInCurWord' is not equal to 0
 ? CurWord : 0;
15
←
Taking false branch
→
16
←
'?' condition is true
→
206 unsigned BitsLeft = NumBits - BitsInCurWord;
207
208 if (Error fillResult = fillCurWord())
17
←
Assuming the condition is false
→
18
←
Taking false branch
→
209 return std::move(fillResult);
210
211 // If we run out of data, abort.
212 if (BitsLeft > BitsInCurWord)
19
←
Assuming 'BitsLeft' is <= field 'BitsInCurWord'
→
20
←
Taking false branch
→
213 return createStringError(std::errc::io_error,
214 "Unexpected end of file reading %u of %u bits",
215 BitsInCurWord, BitsLeft);
216
217 word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
21
←
The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'word_t'
218
219 // Use a mask to avoid undefined behavior.
220 CurWord >>= (BitsLeft & Mask);
221
222 BitsInCurWord -= BitsLeft;
223
224 R |= R2 << (NumBits - BitsLeft);
225
226 return R;
227 }
228
229 Expected<uint32_t> ReadVBR(const unsigned NumBits) {
230 Expected<unsigned> MaybeRead = Read(NumBits);
231 if (!MaybeRead)
232 return MaybeRead;
233 uint32_t Piece = MaybeRead.get();
234
235 assert(NumBits <= 32 && NumBits >= 1 && "Invalid NumBits value")(static_cast <bool> (NumBits <= 32 && NumBits
>= 1 && "Invalid NumBits value") ? void (0) : __assert_fail
("NumBits <= 32 && NumBits >= 1 && \"Invalid NumBits value\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 235, __extension__
__PRETTY_FUNCTION__));
236 const uint32_t MaskBitOrder = (NumBits - 1);
237 const uint32_t Mask = 1UL << MaskBitOrder;
238
239 if ((Piece & Mask) == 0)
240 return Piece;
241
242 uint32_t Result = 0;
243 unsigned NextBit = 0;
244 while (true) {
245 Result |= (Piece & (Mask - 1)) << NextBit;
246
247 if ((Piece & Mask) == 0)
248 return Result;
249
250 NextBit += NumBits-1;
251 if (NextBit >= 32)
252 return createStringError(std::errc::illegal_byte_sequence,
253 "Unterminated VBR");
254
255 MaybeRead = Read(NumBits);
256 if (!MaybeRead)
257 return MaybeRead;
258 Piece = MaybeRead.get();
259 }
260 }
261
262 // Read a VBR that may have a value up to 64-bits in size. The chunk size of
263 // the VBR must still be <= 32 bits though.
264 Expected<uint64_t> ReadVBR64(const unsigned NumBits) {
265 Expected<uint64_t> MaybeRead = Read(NumBits);
266 if (!MaybeRead)
267 return MaybeRead;
268 uint32_t Piece = MaybeRead.get();
269 assert(NumBits <= 32 && NumBits >= 1 && "Invalid NumBits value")(static_cast <bool> (NumBits <= 32 && NumBits
>= 1 && "Invalid NumBits value") ? void (0) : __assert_fail
("NumBits <= 32 && NumBits >= 1 && \"Invalid NumBits value\""
, "llvm/include/llvm/Bitstream/BitstreamReader.h", 269, __extension__
__PRETTY_FUNCTION__));
270 const uint32_t MaskBitOrder = (NumBits - 1);
271 const uint32_t Mask = 1UL << MaskBitOrder;
272
273 if ((Piece & Mask) == 0)
274 return uint64_t(Piece);
275
276 uint64_t Result = 0;
277 unsigned NextBit = 0;
278 while (true) {
279 Result |= uint64_t(Piece & (Mask - 1)) << NextBit;
280
281 if ((Piece & Mask) == 0)
282 return Result;
283
284 NextBit += NumBits-1;
285 if (NextBit >= 64)
286 return createStringError(std::errc::illegal_byte_sequence,
287 "Unterminated VBR");
288
289 MaybeRead = Read(NumBits);
290 if (!MaybeRead)
291 return MaybeRead;
292 Piece = MaybeRead.get();
293 }
294 }
295
296 void SkipToFourByteBoundary() {
297 // If word_t is 64-bits and if we've read less than 32 bits, just dump
298 // the bits we have up to the next 32-bit boundary.
299 if (sizeof(word_t) > 4 &&
300 BitsInCurWord >= 32) {
301 CurWord >>= BitsInCurWord-32;
302 BitsInCurWord = 32;
303 return;
304 }
305
306 BitsInCurWord = 0;
307 }
308
309 /// Return the size of the stream in bytes.
310 size_t SizeInBytes() const { return BitcodeBytes.size(); }
311
312 /// Skip to the end of the file.
313 void skipToEnd() { NextChar = BitcodeBytes.size(); }
314
315 /// Check whether a reservation of Size elements is plausible.
316 bool isSizePlausible(size_t Size) const {
317 // Don't allow reserving more elements than the number of bits, assuming
318 // at least one bit is needed to encode an element.
319 return Size < BitcodeBytes.size() * 8;
320 }
321};
322
323/// When advancing through a bitstream cursor, each advance can discover a few
324/// different kinds of entries:
325struct BitstreamEntry {
326 enum {
327 Error, // Malformed bitcode was found.
328 EndBlock, // We've reached the end of the current block, (or the end of the
329 // file, which is treated like a series of EndBlock records.
330 SubBlock, // This is the start of a new subblock of a specific ID.
331 Record // This is a record with a specific AbbrevID.
332 } Kind;
333
334 unsigned ID;
335
336 static BitstreamEntry getError() {
337 BitstreamEntry E; E.Kind = Error; return E;
338 }
339
340 static BitstreamEntry getEndBlock() {
341 BitstreamEntry E; E.Kind = EndBlock; return E;
342 }
343
344 static BitstreamEntry getSubBlock(unsigned ID) {
345 BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
346 }
347
348 static BitstreamEntry getRecord(unsigned AbbrevID) {
349 BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
350 }
351};
352
353/// This represents a position within a bitcode file, implemented on top of a
354/// SimpleBitstreamCursor.
355///
356/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
357/// be passed by value.
358class BitstreamCursor : SimpleBitstreamCursor {
359 // This is the declared size of code values used for the current block, in
360 // bits.
361 unsigned CurCodeSize = 2;
362
363 /// Abbrevs installed at in this block.
364 std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
365
366 struct Block {
367 unsigned PrevCodeSize;
368 std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
369
370 explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
371 };
372
373 /// This tracks the codesize of parent blocks.
374 SmallVector<Block, 8> BlockScope;
375
376 BitstreamBlockInfo *BlockInfo = nullptr;
377
378public:
379 static const size_t MaxChunkSize = 32;
380
381 BitstreamCursor() = default;
382 explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
383 : SimpleBitstreamCursor(BitcodeBytes) {}
384 explicit BitstreamCursor(StringRef BitcodeBytes)
385 : SimpleBitstreamCursor(BitcodeBytes) {}
386 explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
387 : SimpleBitstreamCursor(BitcodeBytes) {}
388
389 using SimpleBitstreamCursor::AtEndOfStream;
390 using SimpleBitstreamCursor::canSkipToPos;
391 using SimpleBitstreamCursor::fillCurWord;
392 using SimpleBitstreamCursor::getBitcodeBytes;
393 using SimpleBitstreamCursor::GetCurrentBitNo;
394 using SimpleBitstreamCursor::getCurrentByteNo;
395 using SimpleBitstreamCursor::getPointerToByte;
396 using SimpleBitstreamCursor::JumpToBit;
397 using SimpleBitstreamCursor::Read;
398 using SimpleBitstreamCursor::ReadVBR;
399 using SimpleBitstreamCursor::ReadVBR64;
400 using SimpleBitstreamCursor::SizeInBytes;
401 using SimpleBitstreamCursor::skipToEnd;
402
403 /// Return the number of bits used to encode an abbrev #.
404 unsigned getAbbrevIDWidth() const { return CurCodeSize; }
405
406 /// Flags that modify the behavior of advance().
407 enum {
408 /// If this flag is used, the advance() method does not automatically pop
409 /// the block scope when the end of a block is reached.
410 AF_DontPopBlockAtEnd = 1,
411
412 /// If this flag is used, abbrev entries are returned just like normal
413 /// records.
414 AF_DontAutoprocessAbbrevs = 2
415 };
416
417 /// Advance the current bitstream, returning the next entry in the stream.
418 Expected<BitstreamEntry> advance(unsigned Flags = 0) {
419 while (true) {
7
←
Loop condition is true. Entering loop body
→
420 if (AtEndOfStream())
8
←
Taking false branch
→
421 return BitstreamEntry::getError();
422
423 Expected<unsigned> MaybeCode = ReadCode();
9
←
Calling 'BitstreamCursor::ReadCode'
→
424 if (!MaybeCode)
425 return MaybeCode.takeError();
426 unsigned Code = MaybeCode.get();
427
428 if (Code == bitc::END_BLOCK) {
429 // Pop the end of the block unless Flags tells us not to.
430 if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
431 return BitstreamEntry::getError();
432 return BitstreamEntry::getEndBlock();
433 }
434
435 if (Code == bitc::ENTER_SUBBLOCK) {
436 if (Expected<unsigned> MaybeSubBlock = ReadSubBlockID())
437 return BitstreamEntry::getSubBlock(MaybeSubBlock.get());
438 else
439 return MaybeSubBlock.takeError();
440 }
441
442 if (Code == bitc::DEFINE_ABBREV &&
443 !(Flags & AF_DontAutoprocessAbbrevs)) {
444 // We read and accumulate abbrev's, the client can't do anything with
445 // them anyway.
446 if (Error Err = ReadAbbrevRecord())
447 return std::move(Err);
448 continue;
449 }
450
451 return BitstreamEntry::getRecord(Code);
452 }
453 }
454
455 /// This is a convenience function for clients that don't expect any
456 /// subblocks. This just skips over them automatically.
457 Expected<BitstreamEntry> advanceSkippingSubblocks(unsigned Flags = 0) {
458 while (true) {
5
←
Loop condition is true. Entering loop body
→
459 // If we found a normal entry, return it.
460 Expected<BitstreamEntry> MaybeEntry = advance(Flags);
6
←
Calling 'BitstreamCursor::advance'
→
461 if (!MaybeEntry)
462 return MaybeEntry;
463 BitstreamEntry Entry = MaybeEntry.get();
464
465 if (Entry.Kind != BitstreamEntry::SubBlock)
466 return Entry;
467
468 // If we found a sub-block, just skip over it and check the next entry.
469 if (Error Err = SkipBlock())
470 return std::move(Err);
471 }
472 }
473
474 Expected<unsigned> ReadCode() { return Read(CurCodeSize); }
10
←
Calling 'SimpleBitstreamCursor::Read'
→
475
476 // Block header:
477 // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
478
479 /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
480 Expected<unsigned> ReadSubBlockID() { return ReadVBR(bitc::BlockIDWidth); }
481
482 /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
483 /// of this block.
484 Error SkipBlock() {
485 // Read and ignore the codelen value.
486 if (Expected<uint32_t> Res = ReadVBR(bitc::CodeLenWidth))
487 ; // Since we are skipping this block, we don't care what code widths are
488 // used inside of it.
489 else
490 return Res.takeError();
491
492 SkipToFourByteBoundary();
493 Expected<unsigned> MaybeNum = Read(bitc::BlockSizeWidth);
494 if (!MaybeNum)
495 return MaybeNum.takeError();
496 size_t NumFourBytes = MaybeNum.get();
497
498 // Check that the block wasn't partially defined, and that the offset isn't
499 // bogus.
500 size_t SkipTo = GetCurrentBitNo() + NumFourBytes * 4 * 8;
501 if (AtEndOfStream())
502 return createStringError(std::errc::illegal_byte_sequence,
503 "can't skip block: already at end of stream");
504 if (!canSkipToPos(SkipTo / 8))
505 return createStringError(std::errc::illegal_byte_sequence,
506 "can't skip to bit %zu from %" PRIu64"l" "u", SkipTo,
507 GetCurrentBitNo());
508
509 if (Error Res = JumpToBit(SkipTo))
510 return Res;
511
512 return Error::success();
513 }
514
515 /// Having read the ENTER_SUBBLOCK abbrevid, and enter the block.
516 Error EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);
517
518 bool ReadBlockEnd() {
519 if (BlockScope.empty()) return true;
520
521 // Block tail:
522 // [END_BLOCK, <align4bytes>]
523 SkipToFourByteBoundary();
524
525 popBlockScope();
526 return false;
527 }
528
529private:
530 void popBlockScope() {
531 CurCodeSize = BlockScope.back().PrevCodeSize;
532
533 CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
534 BlockScope.pop_back();
535 }
536
537 //===--------------------------------------------------------------------===//
538 // Record Processing
539 //===--------------------------------------------------------------------===//
540
541public:
542 /// Return the abbreviation for the specified AbbrevId.
543 Expected<const BitCodeAbbrev *> getAbbrev(unsigned AbbrevID) {
544 unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
545 if (AbbrevNo >= CurAbbrevs.size())
546 return createStringError(
547 std::errc::illegal_byte_sequence, "Invalid abbrev number");
548 return CurAbbrevs[AbbrevNo].get();
549 }
550
551 /// Read the current record and discard it, returning the code for the record.
552 Expected<unsigned> skipRecord(unsigned AbbrevID);
553
554 Expected<unsigned> readRecord(unsigned AbbrevID,
555 SmallVectorImpl<uint64_t> &Vals,
556 StringRef *Blob = nullptr);
557
558 //===--------------------------------------------------------------------===//
559 // Abbrev Processing
560 //===--------------------------------------------------------------------===//
561 Error ReadAbbrevRecord();
562
563 /// Read and return a block info block from the bitstream. If an error was
564 /// encountered, return std::nullopt.
565 ///
566 /// \param ReadBlockInfoNames Whether to read block/record name information in
567 /// the BlockInfo block. Only llvm-bcanalyzer uses this.
568 Expected<std::optional<BitstreamBlockInfo>>
569 ReadBlockInfoBlock(bool ReadBlockInfoNames = false);
570
571 /// Set the block info to be used by this BitstreamCursor to interpret
572 /// abbreviated records.
573 void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
574};
575
576} // end llvm namespace
577
578#endif // LLVM_BITSTREAM_BITSTREAMREADER_H