Bug Summary

File:llvm/include/llvm/Bitstream/BitstreamReader.h
Warning:line 221, 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 'llvm::SimpleBitstreamCursor::word_t'

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name BitstreamReader.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -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 -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/build-llvm/lib/Bitstream/Reader -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/build-llvm/lib/Bitstream/Reader -I /build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader -I /build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/include -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-14/lib/clang/14.0.0/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 -O2 -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 -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/build-llvm/lib/Bitstream/Reader -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -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-2021-08-28-193554-24367-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp

/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/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 <string>
13
14using namespace llvm;
15
16//===----------------------------------------------------------------------===//
17// BitstreamCursor implementation
18//===----------------------------------------------------------------------===//
19
20/// Having read the ENTER_SUBBLOCK abbrevid, enter the block.
21Error BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
22 // Save the current block's state on BlockScope.
23 BlockScope.push_back(Block(CurCodeSize));
24 BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
25
26 // Add the abbrevs specific to this block to the CurAbbrevs list.
27 if (BlockInfo) {
28 if (const BitstreamBlockInfo::BlockInfo *Info =
29 BlockInfo->getBlockInfo(BlockID)) {
30 llvm::append_range(CurAbbrevs, Info->Abbrevs);
31 }
32 }
33
34 // Get the codesize of this block.
35 Expected<uint32_t> MaybeVBR = ReadVBR(bitc::CodeLenWidth);
36 if (!MaybeVBR)
37 return MaybeVBR.takeError();
38 CurCodeSize = MaybeVBR.get();
39
40 if (CurCodeSize > MaxChunkSize)
41 return llvm::createStringError(
42 std::errc::illegal_byte_sequence,
43 "can't read more than %zu at a time, trying to read %u", +MaxChunkSize,
44 CurCodeSize);
45
46 SkipToFourByteBoundary();
47 Expected<word_t> MaybeNum = Read(bitc::BlockSizeWidth);
48 if (!MaybeNum)
49 return MaybeNum.takeError();
50 word_t NumWords = MaybeNum.get();
51 if (NumWordsP)
52 *NumWordsP = NumWords;
53
54 if (CurCodeSize == 0)
55 return llvm::createStringError(
56 std::errc::illegal_byte_sequence,
57 "can't enter sub-block: current code size is 0");
58 if (AtEndOfStream())
59 return llvm::createStringError(
60 std::errc::illegal_byte_sequence,
61 "can't enter sub block: already at end of stream");
62
63 return Error::success();
64}
65
66static Expected<uint64_t> readAbbreviatedField(BitstreamCursor &Cursor,
67 const BitCodeAbbrevOp &Op) {
68 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!\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 68, __extension__ __PRETTY_FUNCTION__));
69
70 // Decode the value as we are commanded.
71 switch (Op.getEncoding()) {
72 case BitCodeAbbrevOp::Array:
73 case BitCodeAbbrevOp::Blob:
74 llvm_unreachable("Should not reach here")::llvm::llvm_unreachable_internal("Should not reach here", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 74);
75 case BitCodeAbbrevOp::Fixed:
76 assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize)(static_cast <bool> ((unsigned)Op.getEncodingData() <=
Cursor.MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 76, __extension__ __PRETTY_FUNCTION__));
77 return Cursor.Read((unsigned)Op.getEncodingData());
78 case BitCodeAbbrevOp::VBR:
79 assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize)(static_cast <bool> ((unsigned)Op.getEncodingData() <=
Cursor.MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 79, __extension__ __PRETTY_FUNCTION__));
80 return Cursor.ReadVBR64((unsigned)Op.getEncodingData());
81 case BitCodeAbbrevOp::Char6:
82 if (Expected<unsigned> Res = Cursor.Read(6))
83 return BitCodeAbbrevOp::DecodeChar6(Res.get());
84 else
85 return Res.takeError();
86 }
87 llvm_unreachable("invalid abbreviation encoding")::llvm::llvm_unreachable_internal("invalid abbreviation encoding"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 87);
88}
89
90/// skipRecord - Read the current record and discard it.
91Expected<unsigned> BitstreamCursor::skipRecord(unsigned AbbrevID) {
92 // Skip unabbreviated records by reading past their entries.
93 if (AbbrevID == bitc::UNABBREV_RECORD) {
94 Expected<uint32_t> MaybeCode = ReadVBR(6);
95 if (!MaybeCode)
96 return MaybeCode.takeError();
97 unsigned Code = MaybeCode.get();
98 Expected<uint32_t> MaybeVBR = ReadVBR(6);
99 if (!MaybeVBR)
100 return MaybeVBR.get();
101 unsigned NumElts = MaybeVBR.get();
102 for (unsigned i = 0; i != NumElts; ++i)
103 if (Expected<uint64_t> Res = ReadVBR64(6))
104 ; // Skip!
105 else
106 return Res.takeError();
107 return Code;
108 }
109
110 const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
111 const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
112 unsigned Code;
113 if (CodeOp.isLiteral())
114 Code = CodeOp.getLiteralValue();
115 else {
116 if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
117 CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
118 return llvm::createStringError(
119 std::errc::illegal_byte_sequence,
120 "Abbreviation starts with an Array or a Blob");
121 Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp);
122 if (!MaybeCode)
123 return MaybeCode.takeError();
124 Code = MaybeCode.get();
125 }
126
127 for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i < e; ++i) {
128 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
129 if (Op.isLiteral())
130 continue;
131
132 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
133 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
134 if (Expected<uint64_t> MaybeField = readAbbreviatedField(*this, Op))
135 continue;
136 else
137 return MaybeField.takeError();
138 }
139
140 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
141 // Array case. Read the number of elements as a vbr6.
142 Expected<uint32_t> MaybeNum = ReadVBR(6);
143 if (!MaybeNum)
144 return MaybeNum.takeError();
145 unsigned NumElts = MaybeNum.get();
146
147 // Get the element encoding.
148 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?\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 148, __extension__ __PRETTY_FUNCTION__));
149 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
150
151 // Read all the elements.
152 // Decode the value as we are commanded.
153 switch (EltEnc.getEncoding()) {
154 default:
155 report_fatal_error("Array element type can't be an Array or a Blob");
156 case BitCodeAbbrevOp::Fixed:
157 assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize)(static_cast <bool> ((unsigned)EltEnc.getEncodingData()
<= MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)EltEnc.getEncodingData() <= MaxChunkSize"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 157, __extension__ __PRETTY_FUNCTION__));
158 if (Error Err =
159 JumpToBit(GetCurrentBitNo() + static_cast<uint64_t>(NumElts) *
160 EltEnc.getEncodingData()))
161 return std::move(Err);
162 break;
163 case BitCodeAbbrevOp::VBR:
164 assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize)(static_cast <bool> ((unsigned)EltEnc.getEncodingData()
<= MaxChunkSize) ? void (0) : __assert_fail ("(unsigned)EltEnc.getEncodingData() <= MaxChunkSize"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 164, __extension__ __PRETTY_FUNCTION__));
165 for (; NumElts; --NumElts)
166 if (Expected<uint64_t> Res =
167 ReadVBR64((unsigned)EltEnc.getEncodingData()))
168 ; // Skip!
169 else
170 return Res.takeError();
171 break;
172 case BitCodeAbbrevOp::Char6:
173 if (Error Err = JumpToBit(GetCurrentBitNo() + NumElts * 6))
174 return std::move(Err);
175 break;
176 }
177 continue;
178 }
179
180 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob)(static_cast <bool> (Op.getEncoding() == BitCodeAbbrevOp
::Blob) ? void (0) : __assert_fail ("Op.getEncoding() == BitCodeAbbrevOp::Blob"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 180, __extension__ __PRETTY_FUNCTION__));
181 // Blob case. Read the number of bytes as a vbr6.
182 Expected<uint32_t> MaybeNum = ReadVBR(6);
183 if (!MaybeNum)
184 return MaybeNum.takeError();
185 unsigned NumElts = MaybeNum.get();
186 SkipToFourByteBoundary(); // 32-bit alignment
187
188 // Figure out where the end of this blob will be including tail padding.
189 const size_t NewEnd = GetCurrentBitNo() + alignTo(NumElts, 4) * 8;
190
191 // If this would read off the end of the bitcode file, just set the
192 // record to empty and return.
193 if (!canSkipToPos(NewEnd/8)) {
194 skipToEnd();
195 break;
196 }
197
198 // Skip over the blob.
199 if (Error Err = JumpToBit(NewEnd))
200 return std::move(Err);
201 }
202 return Code;
203}
204
205Expected<unsigned> BitstreamCursor::readRecord(unsigned AbbrevID,
206 SmallVectorImpl<uint64_t> &Vals,
207 StringRef *Blob) {
208 if (AbbrevID == bitc::UNABBREV_RECORD) {
209 Expected<uint32_t> MaybeCode = ReadVBR(6);
210 if (!MaybeCode)
211 return MaybeCode.takeError();
212 uint32_t Code = MaybeCode.get();
213 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
214 if (!MaybeNumElts)
215 return MaybeNumElts.takeError();
216 uint32_t NumElts = MaybeNumElts.get();
217 Vals.reserve(Vals.size() + NumElts);
218
219 for (unsigned i = 0; i != NumElts; ++i)
220 if (Expected<uint64_t> MaybeVal = ReadVBR64(6))
221 Vals.push_back(MaybeVal.get());
222 else
223 return MaybeVal.takeError();
224 return Code;
225 }
226
227 const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
228
229 // Read the record code first.
230 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?\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 230, __extension__ __PRETTY_FUNCTION__));
231 const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
232 unsigned Code;
233 if (CodeOp.isLiteral())
234 Code = CodeOp.getLiteralValue();
235 else {
236 if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
237 CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
238 report_fatal_error("Abbreviation starts with an Array or a Blob");
239 if (Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp))
240 Code = MaybeCode.get();
241 else
242 return MaybeCode.takeError();
243 }
244
245 for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
246 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
247 if (Op.isLiteral()) {
248 Vals.push_back(Op.getLiteralValue());
249 continue;
250 }
251
252 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
253 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
254 if (Expected<uint64_t> MaybeVal = readAbbreviatedField(*this, Op))
255 Vals.push_back(MaybeVal.get());
256 else
257 return MaybeVal.takeError();
258 continue;
259 }
260
261 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
262 // Array case. Read the number of elements as a vbr6.
263 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
264 if (!MaybeNumElts)
265 return MaybeNumElts.takeError();
266 uint32_t NumElts = MaybeNumElts.get();
267 Vals.reserve(Vals.size() + NumElts);
268
269 // Get the element encoding.
270 if (i + 2 != e)
271 report_fatal_error("Array op not second to last");
272 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
273 if (!EltEnc.isEncoding())
274 report_fatal_error(
275 "Array element type has to be an encoding of a type");
276
277 // Read all the elements.
278 switch (EltEnc.getEncoding()) {
279 default:
280 report_fatal_error("Array element type can't be an Array or a Blob");
281 case BitCodeAbbrevOp::Fixed:
282 for (; NumElts; --NumElts)
283 if (Expected<SimpleBitstreamCursor::word_t> MaybeVal =
284 Read((unsigned)EltEnc.getEncodingData()))
285 Vals.push_back(MaybeVal.get());
286 else
287 return MaybeVal.takeError();
288 break;
289 case BitCodeAbbrevOp::VBR:
290 for (; NumElts; --NumElts)
291 if (Expected<uint64_t> MaybeVal =
292 ReadVBR64((unsigned)EltEnc.getEncodingData()))
293 Vals.push_back(MaybeVal.get());
294 else
295 return MaybeVal.takeError();
296 break;
297 case BitCodeAbbrevOp::Char6:
298 for (; NumElts; --NumElts)
299 if (Expected<SimpleBitstreamCursor::word_t> MaybeVal = Read(6))
300 Vals.push_back(BitCodeAbbrevOp::DecodeChar6(MaybeVal.get()));
301 else
302 return MaybeVal.takeError();
303 }
304 continue;
305 }
306
307 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob)(static_cast <bool> (Op.getEncoding() == BitCodeAbbrevOp
::Blob) ? void (0) : __assert_fail ("Op.getEncoding() == BitCodeAbbrevOp::Blob"
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Bitstream/Reader/BitstreamReader.cpp"
, 307, __extension__ __PRETTY_FUNCTION__));
308 // Blob case. Read the number of bytes as a vbr6.
309 Expected<uint32_t> MaybeNumElts = ReadVBR(6);
310 if (!MaybeNumElts)
311 return MaybeNumElts.takeError();
312 uint32_t NumElts = MaybeNumElts.get();
313 SkipToFourByteBoundary(); // 32-bit alignment
314
315 // Figure out where the end of this blob will be including tail padding.
316 size_t CurBitPos = GetCurrentBitNo();
317 const size_t NewEnd = CurBitPos + alignTo(NumElts, 4) * 8;
318
319 // If this would read off the end of the bitcode file, just set the
320 // record to empty and return.
321 if (!canSkipToPos(NewEnd/8)) {
322 Vals.append(NumElts, 0);
323 skipToEnd();
324 break;
325 }
326
327 // Otherwise, inform the streamer that we need these bytes in memory. Skip
328 // over tail padding first, in case jumping to NewEnd invalidates the Blob
329 // pointer.
330 if (Error Err = JumpToBit(NewEnd))
331 return std::move(Err);
332 const char *Ptr = (const char *)getPointerToBit(CurBitPos, NumElts);
333
334 // If we can return a reference to the data, do so to avoid copying it.
335 if (Blob) {
336 *Blob = StringRef(Ptr, NumElts);
337 } else {
338 // Otherwise, unpack into Vals with zero extension.
339 auto *UPtr = reinterpret_cast<const unsigned char *>(Ptr);
340 Vals.append(UPtr, UPtr + NumElts);
341 }
342 }
343
344 return Code;
345}
346
347Error BitstreamCursor::ReadAbbrevRecord() {
348 auto Abbv = std::make_shared<BitCodeAbbrev>();
349 Expected<uint32_t> MaybeNumOpInfo = ReadVBR(5);
350 if (!MaybeNumOpInfo)
351 return MaybeNumOpInfo.takeError();
352 unsigned NumOpInfo = MaybeNumOpInfo.get();
353 for (unsigned i = 0; i != NumOpInfo; ++i) {
354 Expected<word_t> MaybeIsLiteral = Read(1);
355 if (!MaybeIsLiteral)
356 return MaybeIsLiteral.takeError();
357 bool IsLiteral = MaybeIsLiteral.get();
358 if (IsLiteral) {
359 Expected<uint64_t> MaybeOp = ReadVBR64(8);
360 if (!MaybeOp)
361 return MaybeOp.takeError();
362 Abbv->Add(BitCodeAbbrevOp(MaybeOp.get()));
363 continue;
364 }
365
366 Expected<word_t> MaybeEncoding = Read(3);
367 if (!MaybeEncoding)
368 return MaybeEncoding.takeError();
369 BitCodeAbbrevOp::Encoding E =
370 (BitCodeAbbrevOp::Encoding)MaybeEncoding.get();
371 if (BitCodeAbbrevOp::hasEncodingData(E)) {
372 Expected<uint64_t> MaybeData = ReadVBR64(5);
373 if (!MaybeData)
374 return MaybeData.takeError();
375 uint64_t Data = MaybeData.get();
376
377 // As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
378 // and vbr(0) as a literal zero. This is decoded the same way, and avoids
379 // a slow path in Read() to have to handle reading zero bits.
380 if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
381 Data == 0) {
382 Abbv->Add(BitCodeAbbrevOp(0));
383 continue;
384 }
385
386 if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
387 Data > MaxChunkSize)
388 report_fatal_error(
389 "Fixed or VBR abbrev record with size > MaxChunkData");
390
391 Abbv->Add(BitCodeAbbrevOp(E, Data));
392 } else
393 Abbv->Add(BitCodeAbbrevOp(E));
394 }
395
396 if (Abbv->getNumOperandInfos() == 0)
397 report_fatal_error("Abbrev record with no operands");
398 CurAbbrevs.push_back(std::move(Abbv));
399
400 return Error::success();
401}
402
403Expected<Optional<BitstreamBlockInfo>>
404BitstreamCursor::ReadBlockInfoBlock(bool ReadBlockInfoNames) {
405 if (llvm::Error Err = EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID))
1
Assuming the condition is false
→
2
←
Taking false branch
→
406 return std::move(Err);
407
408 BitstreamBlockInfo NewBlockInfo;
409
410 SmallVector<uint64_t, 64> Record;
411 BitstreamBlockInfo::BlockInfo *CurBlockInfo = nullptr;
412
413 // Read all the records for this module.
414 while (true) {
3
←
Loop condition is true. Entering loop body
→
415 Expected<BitstreamEntry> MaybeEntry =
416 advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
4
←
Calling 'BitstreamCursor::advanceSkippingSubblocks'
→
417 if (!MaybeEntry)
418 return MaybeEntry.takeError();
419 BitstreamEntry Entry = MaybeEntry.get();
420
421 switch (Entry.Kind) {
422 case llvm::BitstreamEntry::SubBlock: // Handled for us already.
423 case llvm::BitstreamEntry::Error:
424 return None;
425 case llvm::BitstreamEntry::EndBlock:
426 return std::move(NewBlockInfo);
427 case llvm::BitstreamEntry::Record:
428 // The interesting case.
429 break;
430 }
431
432 // Read abbrev records, associate them with CurBID.
433 if (Entry.ID == bitc::DEFINE_ABBREV) {
434 if (!CurBlockInfo) return None;
435 if (Error Err = ReadAbbrevRecord())
436 return std::move(Err);
437
438 // ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
439 // appropriate BlockInfo.
440 CurBlockInfo->Abbrevs.push_back(std::move(CurAbbrevs.back()));
441 CurAbbrevs.pop_back();
442 continue;
443 }
444
445 // Read a record.
446 Record.clear();
447 Expected<unsigned> MaybeBlockInfo = readRecord(Entry.ID, Record);
448 if (!MaybeBlockInfo)
449 return MaybeBlockInfo.takeError();
450 switch (MaybeBlockInfo.get()) {
451 default:
452 break; // Default behavior, ignore unknown content.
453 case bitc::BLOCKINFO_CODE_SETBID:
454 if (Record.size() < 1)
455 return None;
456 CurBlockInfo = &NewBlockInfo.getOrCreateBlockInfo((unsigned)Record[0]);
457 break;
458 case bitc::BLOCKINFO_CODE_BLOCKNAME: {
459 if (!CurBlockInfo)
460 return None;
461 if (!ReadBlockInfoNames)
462 break; // Ignore name.
463 CurBlockInfo->Name = std::string(Record.begin(), Record.end());
464 break;
465 }
466 case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
467 if (!CurBlockInfo) return None;
468 if (!ReadBlockInfoNames)
469 break; // Ignore name.
470 CurBlockInfo->RecordNames.emplace_back(
471 (unsigned)Record[0], std::string(Record.begin() + 1, Record.end()));
472 break;
473 }
474 }
475 }
476}
←

/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/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/ErrorHandling.h"
23#include "llvm/Support/MathExtras.h"
24#include "llvm/Support/MemoryBuffer.h"
25#include <algorithm>
26#include <cassert>
27#include <climits>
28#include <cstddef>
29#include <cstdint>
30#include <memory>
31#include <string>
32#include <utility>
33#include <vector>
34
35namespace llvm {
36
37/// This class maintains the abbreviations read from a block info block.
38class BitstreamBlockInfo {
39public:
40 /// This contains information emitted to BLOCKINFO_BLOCK blocks. These
41 /// describe abbreviations that all blocks of the specified ID inherit.
42 struct BlockInfo {
43 unsigned BlockID = 0;
44 std::vector<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
45 std::string Name;
46 std::vector<std::pair<unsigned, std::string>> RecordNames;
47 };
48
49private:
50 std::vector<BlockInfo> BlockInfoRecords;
51
52public:
53 /// If there is block info for the specified ID, return it, otherwise return
54 /// null.
55 const BlockInfo *getBlockInfo(unsigned BlockID) const {
56 // Common case, the most recent entry matches BlockID.
57 if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
58 return &BlockInfoRecords.back();
59
60 for (unsigned i = 0, e = static_cast<unsigned>(BlockInfoRecords.size());
61 i != e; ++i)
62 if (BlockInfoRecords[i].BlockID == BlockID)
63 return &BlockInfoRecords[i];
64 return nullptr;
65 }
66
67 BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
68 if (const BlockInfo *BI = getBlockInfo(BlockID))
69 return *const_cast<BlockInfo*>(BI);
70
71 // Otherwise, add a new record.
72 BlockInfoRecords.emplace_back();
73 BlockInfoRecords.back().BlockID = BlockID;
74 return BlockInfoRecords.back();
75 }
76};
77
78/// This represents a position within a bitstream. There may be multiple
79/// independent cursors reading within one bitstream, each maintaining their
80/// own local state.
81class SimpleBitstreamCursor {
82 ArrayRef<uint8_t> BitcodeBytes;
83 size_t NextChar = 0;
84
85public:
86 /// This is the current data we have pulled from the stream but have not
87 /// returned to the client. This is specifically and intentionally defined to
88 /// follow the word size of the host machine for efficiency. We use word_t in
89 /// places that are aware of this to make it perfectly explicit what is going
90 /// on.
91 using word_t = size_t;
92
93private:
94 word_t CurWord = 0;
95
96 /// This is the number of bits in CurWord that are valid. This is always from
97 /// [0...bits_of(size_t)-1] inclusive.
98 unsigned BitsInCurWord = 0;
99
100public:
101 static const constexpr size_t MaxChunkSize = sizeof(word_t) * 8;
102
103 SimpleBitstreamCursor() = default;
104 explicit SimpleBitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
105 : BitcodeBytes(BitcodeBytes) {}
106 explicit SimpleBitstreamCursor(StringRef BitcodeBytes)
107 : BitcodeBytes(arrayRefFromStringRef(BitcodeBytes)) {}
108 explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
109 : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}
110
111 bool canSkipToPos(size_t pos) const {
112 // pos can be skipped to if it is a valid address or one byte past the end.
113 return pos <= BitcodeBytes.size();
114 }
115
116 bool AtEndOfStream() {
117 return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
118 }
119
120 /// Return the bit # of the bit we are reading.
121 uint64_t GetCurrentBitNo() const {
122 return NextChar*CHAR_BIT8 - BitsInCurWord;
123 }
124
125 // Return the byte # of the current bit.
126 uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }
127
128 ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }
129
130 /// Reset the stream to the specified bit number.
131 Error JumpToBit(uint64_t BitNo) {
132 size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
133 unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
134 assert(canSkipToPos(ByteNo) && "Invalid location")(static_cast <bool> (canSkipToPos(ByteNo) && "Invalid location"
) ? void (0) : __assert_fail ("canSkipToPos(ByteNo) && \"Invalid location\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/include/llvm/Bitstream/BitstreamReader.h"
, 134, __extension__ __PRETTY_FUNCTION__));
135
136 // Move the cursor to the right word.
137 NextChar = ByteNo;
138 BitsInCurWord = 0;
139
140 // Skip over any bits that are already consumed.
141 if (WordBitNo) {
142 if (Expected<word_t> Res = Read(WordBitNo))
143 return Error::success();
144 else
145 return Res.takeError();
146 }
147
148 return Error::success();
149 }
150
151 /// Get a pointer into the bitstream at the specified byte offset.
152 const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
153 return BitcodeBytes.data() + ByteNo;
154 }
155
156 /// Get a pointer into the bitstream at the specified bit offset.
157 ///
158 /// The bit offset must be on a byte boundary.
159 const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
160 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\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/include/llvm/Bitstream/BitstreamReader.h"
, 160, __extension__ __PRETTY_FUNCTION__));
161 return getPointerToByte(BitNo / 8, NumBytes);
162 }
163
164 Error fillCurWord() {
165 if (NextChar >= BitcodeBytes.size())
166 return createStringError(std::errc::io_error,
167 "Unexpected end of file reading %u of %u bytes",
168 NextChar, BitcodeBytes.size());
169
170 // Read the next word from the stream.
171 const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
172 unsigned BytesRead;
173 if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
174 BytesRead = sizeof(word_t);
175 CurWord =
176 support::endian::read<word_t, support::little, support::unaligned>(
177 NextCharPtr);
178 } else {
179 // Short read.
180 BytesRead = BitcodeBytes.size() - NextChar;
181 CurWord = 0;
182 for (unsigned B = 0; B != BytesRead; ++B)
183 CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
184 }
185 NextChar += BytesRead;
186 BitsInCurWord = BytesRead * 8;
187 return Error::success();
188 }
189
190 Expected<word_t> Read(unsigned NumBits) {
191 static const unsigned BitsInWord = MaxChunkSize;
192
193 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!\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/include/llvm/Bitstream/BitstreamReader.h"
, 194, __extension__ __PRETTY_FUNCTION__))
11
←
Assuming 'NumBits' is not equal to 0
→
12
←
Assuming 'NumBits' is <= 'BitsInWord'
→
13
←
'?' condition is true
→
194 "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!\""
, "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/include/llvm/Bitstream/BitstreamReader.h"
, 194, __extension__ __PRETTY_FUNCTION__));
195
196 static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
197
198 // If the field is fully contained by CurWord, return it quickly.
199 if (BitsInCurWord >= NumBits) {
14
←
Assuming 'NumBits' is > field 'BitsInCurWord'
→
200 word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
201
202 // Use a mask to avoid undefined behavior.
203 CurWord >>= (NumBits & Mask);
204
205 BitsInCurWord -= NumBits;
206 return R;
207 }
208
209 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
→
210 unsigned BitsLeft = NumBits - BitsInCurWord;
211
212 if (Error fillResult = fillCurWord())
17
←
Assuming the condition is false
→
18
←
Taking false branch
→
213 return std::move(fillResult);
214
215 // If we run out of data, abort.
216 if (BitsLeft > BitsInCurWord)
19
←
Assuming 'BitsLeft' is <= field 'BitsInCurWord'
→
20
←
Taking false branch
→
217 return createStringError(std::errc::io_error,
218 "Unexpected end of file reading %u of %u bits",
219 BitsInCurWord, BitsLeft);
220
221 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 'llvm::SimpleBitstreamCursor::word_t'
222
223 // Use a mask to avoid undefined behavior.
224 CurWord >>= (BitsLeft & Mask);
225
226 BitsInCurWord -= BitsLeft;
227
228 R |= R2 << (NumBits - BitsLeft);
229
230 return R;
231 }
232
233 Expected<uint32_t> ReadVBR(unsigned NumBits) {
234 Expected<unsigned> MaybeRead = Read(NumBits);
235 if (!MaybeRead)
236 return MaybeRead;
237 uint32_t Piece = MaybeRead.get();
238
239 if ((Piece & (1U << (NumBits-1))) == 0)
240 return Piece;
241
242 uint32_t Result = 0;
243 unsigned NextBit = 0;
244 while (true) {
245 Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
246
247 if ((Piece & (1U << (NumBits-1))) == 0)
248 return Result;
249
250 NextBit += NumBits-1;
251 MaybeRead = Read(NumBits);
252 if (!MaybeRead)
253 return MaybeRead;
254 Piece = MaybeRead.get();
255 }
256 }
257
258 // Read a VBR that may have a value up to 64-bits in size. The chunk size of
259 // the VBR must still be <= 32 bits though.
260 Expected<uint64_t> ReadVBR64(unsigned NumBits) {
261 Expected<uint64_t> MaybeRead = Read(NumBits);
262 if (!MaybeRead)
263 return MaybeRead;
264 uint32_t Piece = MaybeRead.get();
265
266 if ((Piece & (1U << (NumBits-1))) == 0)
267 return uint64_t(Piece);
268
269 uint64_t Result = 0;
270 unsigned NextBit = 0;
271 while (true) {
272 Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;
273
274 if ((Piece & (1U << (NumBits-1))) == 0)
275 return Result;
276
277 NextBit += NumBits-1;
278 MaybeRead = Read(NumBits);
279 if (!MaybeRead)
280 return MaybeRead;
281 Piece = MaybeRead.get();
282 }
283 }
284
285 void SkipToFourByteBoundary() {
286 // If word_t is 64-bits and if we've read less than 32 bits, just dump
287 // the bits we have up to the next 32-bit boundary.
288 if (sizeof(word_t) > 4 &&
289 BitsInCurWord >= 32) {
290 CurWord >>= BitsInCurWord-32;
291 BitsInCurWord = 32;
292 return;
293 }
294
295 BitsInCurWord = 0;
296 }
297
298 /// Return the size of the stream in bytes.
299 size_t SizeInBytes() const { return BitcodeBytes.size(); }
300
301 /// Skip to the end of the file.
302 void skipToEnd() { NextChar = BitcodeBytes.size(); }
303};
304
305/// When advancing through a bitstream cursor, each advance can discover a few
306/// different kinds of entries:
307struct BitstreamEntry {
308 enum {
309 Error, // Malformed bitcode was found.
310 EndBlock, // We've reached the end of the current block, (or the end of the
311 // file, which is treated like a series of EndBlock records.
312 SubBlock, // This is the start of a new subblock of a specific ID.
313 Record // This is a record with a specific AbbrevID.
314 } Kind;
315
316 unsigned ID;
317
318 static BitstreamEntry getError() {
319 BitstreamEntry E; E.Kind = Error; return E;
320 }
321
322 static BitstreamEntry getEndBlock() {
323 BitstreamEntry E; E.Kind = EndBlock; return E;
324 }
325
326 static BitstreamEntry getSubBlock(unsigned ID) {
327 BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
328 }
329
330 static BitstreamEntry getRecord(unsigned AbbrevID) {
331 BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
332 }
333};
334
335/// This represents a position within a bitcode file, implemented on top of a
336/// SimpleBitstreamCursor.
337///
338/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
339/// be passed by value.
340class BitstreamCursor : SimpleBitstreamCursor {
341 // This is the declared size of code values used for the current block, in
342 // bits.
343 unsigned CurCodeSize = 2;
344
345 /// Abbrevs installed at in this block.
346 std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
347
348 struct Block {
349 unsigned PrevCodeSize;
350 std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
351
352 explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
353 };
354
355 /// This tracks the codesize of parent blocks.
356 SmallVector<Block, 8> BlockScope;
357
358 BitstreamBlockInfo *BlockInfo = nullptr;
359
360public:
361 static const size_t MaxChunkSize = sizeof(word_t) * 8;
362
363 BitstreamCursor() = default;
364 explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
365 : SimpleBitstreamCursor(BitcodeBytes) {}
366 explicit BitstreamCursor(StringRef BitcodeBytes)
367 : SimpleBitstreamCursor(BitcodeBytes) {}
368 explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
369 : SimpleBitstreamCursor(BitcodeBytes) {}
370
371 using SimpleBitstreamCursor::AtEndOfStream;
372 using SimpleBitstreamCursor::canSkipToPos;
373 using SimpleBitstreamCursor::fillCurWord;
374 using SimpleBitstreamCursor::getBitcodeBytes;
375 using SimpleBitstreamCursor::GetCurrentBitNo;
376 using SimpleBitstreamCursor::getCurrentByteNo;
377 using SimpleBitstreamCursor::getPointerToByte;
378 using SimpleBitstreamCursor::JumpToBit;
379 using SimpleBitstreamCursor::Read;
380 using SimpleBitstreamCursor::ReadVBR;
381 using SimpleBitstreamCursor::ReadVBR64;
382 using SimpleBitstreamCursor::SizeInBytes;
383 using SimpleBitstreamCursor::skipToEnd;
384
385 /// Return the number of bits used to encode an abbrev #.
386 unsigned getAbbrevIDWidth() const { return CurCodeSize; }
387
388 /// Flags that modify the behavior of advance().
389 enum {
390 /// If this flag is used, the advance() method does not automatically pop
391 /// the block scope when the end of a block is reached.
392 AF_DontPopBlockAtEnd = 1,
393
394 /// If this flag is used, abbrev entries are returned just like normal
395 /// records.
396 AF_DontAutoprocessAbbrevs = 2
397 };
398
399 /// Advance the current bitstream, returning the next entry in the stream.
400 Expected<BitstreamEntry> advance(unsigned Flags = 0) {
401 while (true) {
7
←
Loop condition is true. Entering loop body
→
402 if (AtEndOfStream())
8
←
Taking false branch
→
403 return BitstreamEntry::getError();
404
405 Expected<unsigned> MaybeCode = ReadCode();
9
←
Calling 'BitstreamCursor::ReadCode'
→
406 if (!MaybeCode)
407 return MaybeCode.takeError();
408 unsigned Code = MaybeCode.get();
409
410 if (Code == bitc::END_BLOCK) {
411 // Pop the end of the block unless Flags tells us not to.
412 if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
413 return BitstreamEntry::getError();
414 return BitstreamEntry::getEndBlock();
415 }
416
417 if (Code == bitc::ENTER_SUBBLOCK) {
418 if (Expected<unsigned> MaybeSubBlock = ReadSubBlockID())
419 return BitstreamEntry::getSubBlock(MaybeSubBlock.get());
420 else
421 return MaybeSubBlock.takeError();
422 }
423
424 if (Code == bitc::DEFINE_ABBREV &&
425 !(Flags & AF_DontAutoprocessAbbrevs)) {
426 // We read and accumulate abbrev's, the client can't do anything with
427 // them anyway.
428 if (Error Err = ReadAbbrevRecord())
429 return std::move(Err);
430 continue;
431 }
432
433 return BitstreamEntry::getRecord(Code);
434 }
435 }
436
437 /// This is a convenience function for clients that don't expect any
438 /// subblocks. This just skips over them automatically.
439 Expected<BitstreamEntry> advanceSkippingSubblocks(unsigned Flags = 0) {
440 while (true) {
5
←
Loop condition is true. Entering loop body
→
441 // If we found a normal entry, return it.
442 Expected<BitstreamEntry> MaybeEntry = advance(Flags);
6
←
Calling 'BitstreamCursor::advance'
→
443 if (!MaybeEntry)
444 return MaybeEntry;
445 BitstreamEntry Entry = MaybeEntry.get();
446
447 if (Entry.Kind != BitstreamEntry::SubBlock)
448 return Entry;
449
450 // If we found a sub-block, just skip over it and check the next entry.
451 if (Error Err = SkipBlock())
452 return std::move(Err);
453 }
454 }
455
456 Expected<unsigned> ReadCode() { return Read(CurCodeSize); }
10
←
Calling 'SimpleBitstreamCursor::Read'
→
457
458 // Block header:
459 // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
460
461 /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
462 Expected<unsigned> ReadSubBlockID() { return ReadVBR(bitc::BlockIDWidth); }
463
464 /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
465 /// of this block.
466 Error SkipBlock() {
467 // Read and ignore the codelen value.
468 if (Expected<uint32_t> Res = ReadVBR(bitc::CodeLenWidth))
469 ; // Since we are skipping this block, we don't care what code widths are
470 // used inside of it.
471 else
472 return Res.takeError();
473
474 SkipToFourByteBoundary();
475 Expected<unsigned> MaybeNum = Read(bitc::BlockSizeWidth);
476 if (!MaybeNum)
477 return MaybeNum.takeError();
478 size_t NumFourBytes = MaybeNum.get();
479
480 // Check that the block wasn't partially defined, and that the offset isn't
481 // bogus.
482 size_t SkipTo = GetCurrentBitNo() + NumFourBytes * 4 * 8;
483 if (AtEndOfStream())
484 return createStringError(std::errc::illegal_byte_sequence,
485 "can't skip block: already at end of stream");
486 if (!canSkipToPos(SkipTo / 8))
487 return createStringError(std::errc::illegal_byte_sequence,
488 "can't skip to bit %zu from %" PRIu64"l" "u", SkipTo,
489 GetCurrentBitNo());
490
491 if (Error Res = JumpToBit(SkipTo))
492 return Res;
493
494 return Error::success();
495 }
496
497 /// Having read the ENTER_SUBBLOCK abbrevid, and enter the block.
498 Error EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);
499
500 bool ReadBlockEnd() {
501 if (BlockScope.empty()) return true;
502
503 // Block tail:
504 // [END_BLOCK, <align4bytes>]
505 SkipToFourByteBoundary();
506
507 popBlockScope();
508 return false;
509 }
510
511private:
512 void popBlockScope() {
513 CurCodeSize = BlockScope.back().PrevCodeSize;
514
515 CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
516 BlockScope.pop_back();
517 }
518
519 //===--------------------------------------------------------------------===//
520 // Record Processing
521 //===--------------------------------------------------------------------===//
522
523public:
524 /// Return the abbreviation for the specified AbbrevId.
525 const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
526 unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
527 if (AbbrevNo >= CurAbbrevs.size())
528 report_fatal_error("Invalid abbrev number");
529 return CurAbbrevs[AbbrevNo].get();
530 }
531
532 /// Read the current record and discard it, returning the code for the record.
533 Expected<unsigned> skipRecord(unsigned AbbrevID);
534
535 Expected<unsigned> readRecord(unsigned AbbrevID,
536 SmallVectorImpl<uint64_t> &Vals,
537 StringRef *Blob = nullptr);
538
539 //===--------------------------------------------------------------------===//
540 // Abbrev Processing
541 //===--------------------------------------------------------------------===//
542 Error ReadAbbrevRecord();
543
544 /// Read and return a block info block from the bitstream. If an error was
545 /// encountered, return None.
546 ///
547 /// \param ReadBlockInfoNames Whether to read block/record name information in
548 /// the BlockInfo block. Only llvm-bcanalyzer uses this.
549 Expected<Optional<BitstreamBlockInfo>>
550 ReadBlockInfoBlock(bool ReadBlockInfoNames = false);
551
552 /// Set the block info to be used by this BitstreamCursor to interpret
553 /// abbreviated records.
554 void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
555};
556
557} // end llvm namespace
558
559#endif // LLVM_BITSTREAM_BITSTREAMREADER_H