Bug Summary

File:tools/clang/lib/Frontend/SerializedDiagnosticReader.cpp
Warning:line 210, 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

/build/llvm-toolchain-snapshot-6.0~svn318693/tools/clang/lib/Frontend/SerializedDiagnosticReader.cpp

1//===--- SerializedDiagnosticReader.cpp - Reads diagnostics ---------------===//
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#include "clang/Frontend/SerializedDiagnosticReader.h"
11#include "clang/Basic/FileManager.h"
12#include "clang/Frontend/SerializedDiagnostics.h"
13#include "llvm/Support/ManagedStatic.h"
14
15using namespace clang;
16using namespace clang::serialized_diags;
17
18std::error_code SerializedDiagnosticReader::readDiagnostics(StringRef File) {
19 // Open the diagnostics file.
20 FileSystemOptions FO;
21 FileManager FileMgr(FO);
22
23 auto Buffer = FileMgr.getBufferForFile(File);
24 if (!Buffer)
1
Taking false branch
25 return SDError::CouldNotLoad;
26
27 llvm::BitstreamCursor Stream(**Buffer);
28 Optional<llvm::BitstreamBlockInfo> BlockInfo;
29
30 if (Stream.AtEndOfStream())
2
Taking false branch
31 return SDError::InvalidSignature;
32
33 // Sniff for the signature.
34 if (Stream.Read(8) != 'D' ||
3
Calling 'SimpleBitstreamCursor::Read'
35 Stream.Read(8) != 'I' ||
36 Stream.Read(8) != 'A' ||
37 Stream.Read(8) != 'G')
38 return SDError::InvalidSignature;
39
40 // Read the top level blocks.
41 while (!Stream.AtEndOfStream()) {
42 if (Stream.ReadCode() != llvm::bitc::ENTER_SUBBLOCK)
43 return SDError::InvalidDiagnostics;
44
45 std::error_code EC;
46 switch (Stream.ReadSubBlockID()) {
47 case llvm::bitc::BLOCKINFO_BLOCK_ID: {
48 BlockInfo = Stream.ReadBlockInfoBlock();
49 if (!BlockInfo)
50 return SDError::MalformedBlockInfoBlock;
51 Stream.setBlockInfo(&*BlockInfo);
52 continue;
53 }
54 case BLOCK_META:
55 if ((EC = readMetaBlock(Stream)))
56 return EC;
57 continue;
58 case BLOCK_DIAG:
59 if ((EC = readDiagnosticBlock(Stream)))
60 return EC;
61 continue;
62 default:
63 if (!Stream.SkipBlock())
64 return SDError::MalformedTopLevelBlock;
65 continue;
66 }
67 }
68 return std::error_code();
69}
70
71enum class SerializedDiagnosticReader::Cursor {
72 Record = 1,
73 BlockEnd,
74 BlockBegin
75};
76
77llvm::ErrorOr<SerializedDiagnosticReader::Cursor>
78SerializedDiagnosticReader::skipUntilRecordOrBlock(
79 llvm::BitstreamCursor &Stream, unsigned &BlockOrRecordID) {
80 BlockOrRecordID = 0;
81
82 while (!Stream.AtEndOfStream()) {
83 unsigned Code = Stream.ReadCode();
84
85 switch ((llvm::bitc::FixedAbbrevIDs)Code) {
86 case llvm::bitc::ENTER_SUBBLOCK:
87 BlockOrRecordID = Stream.ReadSubBlockID();
88 return Cursor::BlockBegin;
89
90 case llvm::bitc::END_BLOCK:
91 if (Stream.ReadBlockEnd())
92 return SDError::InvalidDiagnostics;
93 return Cursor::BlockEnd;
94
95 case llvm::bitc::DEFINE_ABBREV:
96 Stream.ReadAbbrevRecord();
97 continue;
98
99 case llvm::bitc::UNABBREV_RECORD:
100 return SDError::UnsupportedConstruct;
101
102 default:
103 // We found a record.
104 BlockOrRecordID = Code;
105 return Cursor::Record;
106 }
107 }
108
109 return SDError::InvalidDiagnostics;
110}
111
112std::error_code
113SerializedDiagnosticReader::readMetaBlock(llvm::BitstreamCursor &Stream) {
114 if (Stream.EnterSubBlock(clang::serialized_diags::BLOCK_META))
115 return SDError::MalformedMetadataBlock;
116
117 bool VersionChecked = false;
118
119 while (true) {
120 unsigned BlockOrCode = 0;
121 llvm::ErrorOr<Cursor> Res = skipUntilRecordOrBlock(Stream, BlockOrCode);
122 if (!Res)
123 Res.getError();
124
125 switch (Res.get()) {
126 case Cursor::Record:
127 break;
128 case Cursor::BlockBegin:
129 if (Stream.SkipBlock())
130 return SDError::MalformedMetadataBlock;
131 LLVM_FALLTHROUGH[[clang::fallthrough]];
132 case Cursor::BlockEnd:
133 if (!VersionChecked)
134 return SDError::MissingVersion;
135 return std::error_code();
136 }
137
138 SmallVector<uint64_t, 1> Record;
139 unsigned RecordID = Stream.readRecord(BlockOrCode, Record);
140
141 if (RecordID == RECORD_VERSION) {
142 if (Record.size() < 1)
143 return SDError::MissingVersion;
144 if (Record[0] > VersionNumber)
145 return SDError::VersionMismatch;
146 VersionChecked = true;
147 }
148 }
149}
150
151std::error_code
152SerializedDiagnosticReader::readDiagnosticBlock(llvm::BitstreamCursor &Stream) {
153 if (Stream.EnterSubBlock(clang::serialized_diags::BLOCK_DIAG))
154 return SDError::MalformedDiagnosticBlock;
155
156 std::error_code EC;
157 if ((EC = visitStartOfDiagnostic()))
158 return EC;
159
160 SmallVector<uint64_t, 16> Record;
161 while (true) {
162 unsigned BlockOrCode = 0;
163 llvm::ErrorOr<Cursor> Res = skipUntilRecordOrBlock(Stream, BlockOrCode);
164 if (!Res)
165 Res.getError();
166
167 switch (Res.get()) {
168 case Cursor::BlockBegin:
169 // The only blocks we care about are subdiagnostics.
170 if (BlockOrCode == serialized_diags::BLOCK_DIAG) {
171 if ((EC = readDiagnosticBlock(Stream)))
172 return EC;
173 } else if (!Stream.SkipBlock())
174 return SDError::MalformedSubBlock;
175 continue;
176 case Cursor::BlockEnd:
177 if ((EC = visitEndOfDiagnostic()))
178 return EC;
179 return std::error_code();
180 case Cursor::Record:
181 break;
182 }
183
184 // Read the record.
185 Record.clear();
186 StringRef Blob;
187 unsigned RecID = Stream.readRecord(BlockOrCode, Record, &Blob);
188
189 if (RecID < serialized_diags::RECORD_FIRST ||
190 RecID > serialized_diags::RECORD_LAST)
191 continue;
192
193 switch ((RecordIDs)RecID) {
194 case RECORD_CATEGORY:
195 // A category has ID and name size.
196 if (Record.size() != 2)
197 return SDError::MalformedDiagnosticRecord;
198 if ((EC = visitCategoryRecord(Record[0], Blob)))
199 return EC;
200 continue;
201 case RECORD_DIAG:
202 // A diagnostic has severity, location (4), category, flag, and message
203 // size.
204 if (Record.size() != 8)
205 return SDError::MalformedDiagnosticRecord;
206 if ((EC = visitDiagnosticRecord(
207 Record[0], Location(Record[1], Record[2], Record[3], Record[4]),
208 Record[5], Record[6], Blob)))
209 return EC;
210 continue;
211 case RECORD_DIAG_FLAG:
212 // A diagnostic flag has ID and name size.
213 if (Record.size() != 2)
214 return SDError::MalformedDiagnosticRecord;
215 if ((EC = visitDiagFlagRecord(Record[0], Blob)))
216 return EC;
217 continue;
218 case RECORD_FILENAME:
219 // A filename has ID, size, timestamp, and name size. The size and
220 // timestamp are legacy fields that are always zero these days.
221 if (Record.size() != 4)
222 return SDError::MalformedDiagnosticRecord;
223 if ((EC = visitFilenameRecord(Record[0], Record[1], Record[2], Blob)))
224 return EC;
225 continue;
226 case RECORD_FIXIT:
227 // A fixit has two locations (4 each) and message size.
228 if (Record.size() != 9)
229 return SDError::MalformedDiagnosticRecord;
230 if ((EC = visitFixitRecord(
231 Location(Record[0], Record[1], Record[2], Record[3]),
232 Location(Record[4], Record[5], Record[6], Record[7]), Blob)))
233 return EC;
234 continue;
235 case RECORD_SOURCE_RANGE:
236 // A source range is two locations (4 each).
237 if (Record.size() != 8)
238 return SDError::MalformedDiagnosticRecord;
239 if ((EC = visitSourceRangeRecord(
240 Location(Record[0], Record[1], Record[2], Record[3]),
241 Location(Record[4], Record[5], Record[6], Record[7]))))
242 return EC;
243 continue;
244 case RECORD_VERSION:
245 // A version is just a number.
246 if (Record.size() != 1)
247 return SDError::MalformedDiagnosticRecord;
248 if ((EC = visitVersionRecord(Record[0])))
249 return EC;
250 continue;
251 }
252 }
253}
254
255namespace {
256class SDErrorCategoryType final : public std::error_category {
257 const char *name() const noexcept override {
258 return "clang.serialized_diags";
259 }
260 std::string message(int IE) const override {
261 SDError E = static_cast<SDError>(IE);
262 switch (E) {
263 case SDError::CouldNotLoad:
264 return "Failed to open diagnostics file";
265 case SDError::InvalidSignature:
266 return "Invalid diagnostics signature";
267 case SDError::InvalidDiagnostics:
268 return "Parse error reading diagnostics";
269 case SDError::MalformedTopLevelBlock:
270 return "Malformed block at top-level of diagnostics";
271 case SDError::MalformedSubBlock:
272 return "Malformed sub-block in a diagnostic";
273 case SDError::MalformedBlockInfoBlock:
274 return "Malformed BlockInfo block";
275 case SDError::MalformedMetadataBlock:
276 return "Malformed Metadata block";
277 case SDError::MalformedDiagnosticBlock:
278 return "Malformed Diagnostic block";
279 case SDError::MalformedDiagnosticRecord:
280 return "Malformed Diagnostic record";
281 case SDError::MissingVersion:
282 return "No version provided in diagnostics";
283 case SDError::VersionMismatch:
284 return "Unsupported diagnostics version";
285 case SDError::UnsupportedConstruct:
286 return "Bitcode constructs that are not supported in diagnostics appear";
287 case SDError::HandlerFailed:
288 return "Generic error occurred while handling a record";
289 }
290 llvm_unreachable("Unknown error type!")::llvm::llvm_unreachable_internal("Unknown error type!", "/build/llvm-toolchain-snapshot-6.0~svn318693/tools/clang/lib/Frontend/SerializedDiagnosticReader.cpp"
, 290)
;
291 }
292};
293}
294
295static llvm::ManagedStatic<SDErrorCategoryType> ErrorCategory;
296const std::error_category &clang::serialized_diags::SDErrorCategory() {
297 return *ErrorCategory;
298}

/build/llvm-toolchain-snapshot-6.0~svn318693/include/llvm/Bitcode/BitstreamReader.h

1//===- BitstreamReader.h - Low-level bitstream reader interface -*- 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// This header defines the BitstreamReader class. This class can be used to
11// read an arbitrary bitstream, regardless of its contents.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_BITCODE_BITSTREAMREADER_H
16#define LLVM_BITCODE_BITSTREAMREADER_H
17
18#include "llvm/ADT/ArrayRef.h"
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/Bitcode/BitCodes.h"
21#include "llvm/Support/Endian.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;
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 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(reinterpret_cast<const uint8_t *>(BitcodeBytes.data()),
108 BitcodeBytes.size()) {}
109 explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
110 : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}
111
112 bool canSkipToPos(size_t pos) const {
113 // pos can be skipped to if it is a valid address or one byte past the end.
114 return pos <= BitcodeBytes.size();
115 }
116
117 bool AtEndOfStream() {
118 return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
119 }
120
121 /// Return the bit # of the bit we are reading.
122 uint64_t GetCurrentBitNo() const {
123 return NextChar*CHAR_BIT8 - BitsInCurWord;
124 }
125
126 // Return the byte # of the current bit.
127 uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }
128
129 ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }
130
131 /// Reset the stream to the specified bit number.
132 void JumpToBit(uint64_t BitNo) {
133 size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
134 unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
135 assert(canSkipToPos(ByteNo) && "Invalid location")(static_cast <bool> (canSkipToPos(ByteNo) && "Invalid location"
) ? void (0) : __assert_fail ("canSkipToPos(ByteNo) && \"Invalid location\""
, "/build/llvm-toolchain-snapshot-6.0~svn318693/include/llvm/Bitcode/BitstreamReader.h"
, 135, __extension__ __PRETTY_FUNCTION__))
;
136
137 // Move the cursor to the right word.
138 NextChar = ByteNo;
139 BitsInCurWord = 0;
140
141 // Skip over any bits that are already consumed.
142 if (WordBitNo)
143 Read(WordBitNo);
144 }
145
146 /// Get a pointer into the bitstream at the specified byte offset.
147 const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
148 return BitcodeBytes.data() + ByteNo;
149 }
150
151 /// Get a pointer into the bitstream at the specified bit offset.
152 ///
153 /// The bit offset must be on a byte boundary.
154 const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
155 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-6.0~svn318693/include/llvm/Bitcode/BitstreamReader.h"
, 155, __extension__ __PRETTY_FUNCTION__))
;
156 return getPointerToByte(BitNo / 8, NumBytes);
157 }
158
159 void fillCurWord() {
160 if (NextChar >= BitcodeBytes.size())
161 report_fatal_error("Unexpected end of file");
162
163 // Read the next word from the stream.
164 const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
165 unsigned BytesRead;
166 if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
167 BytesRead = sizeof(word_t);
168 CurWord =
169 support::endian::read<word_t, support::little, support::unaligned>(
170 NextCharPtr);
171 } else {
172 // Short read.
173 BytesRead = BitcodeBytes.size() - NextChar;
174 CurWord = 0;
175 for (unsigned B = 0; B != BytesRead; ++B)
176 CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
177 }
178 NextChar += BytesRead;
179 BitsInCurWord = BytesRead * 8;
180 }
181
182 word_t Read(unsigned NumBits) {
183 static const unsigned BitsInWord = MaxChunkSize;
184
185 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-6.0~svn318693/include/llvm/Bitcode/BitstreamReader.h"
, 186, __extension__ __PRETTY_FUNCTION__))
186 "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-6.0~svn318693/include/llvm/Bitcode/BitstreamReader.h"
, 186, __extension__ __PRETTY_FUNCTION__))
;
187
188 static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
4
'?' condition is true
189
190 // If the field is fully contained by CurWord, return it quickly.
191 if (BitsInCurWord >= NumBits) {
5
Assuming the condition is false
6
Taking false branch
192 word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
193
194 // Use a mask to avoid undefined behavior.
195 CurWord >>= (NumBits & Mask);
196
197 BitsInCurWord -= NumBits;
198 return R;
199 }
200
201 word_t R = BitsInCurWord ? CurWord : 0;
7
'?' condition is true
202 unsigned BitsLeft = NumBits - BitsInCurWord;
203
204 fillCurWord();
205
206 // If we run out of data, abort.
207 if (BitsLeft > BitsInCurWord)
8
Assuming the condition is false
9
Taking false branch
208 report_fatal_error("Unexpected end of file");
209
210 word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
10
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'
211
212 // Use a mask to avoid undefined behavior.
213 CurWord >>= (BitsLeft & Mask);
214
215 BitsInCurWord -= BitsLeft;
216
217 R |= R2 << (NumBits - BitsLeft);
218
219 return R;
220 }
221
222 uint32_t ReadVBR(unsigned NumBits) {
223 uint32_t Piece = Read(NumBits);
224 if ((Piece & (1U << (NumBits-1))) == 0)
225 return Piece;
226
227 uint32_t Result = 0;
228 unsigned NextBit = 0;
229 while (true) {
230 Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
231
232 if ((Piece & (1U << (NumBits-1))) == 0)
233 return Result;
234
235 NextBit += NumBits-1;
236 Piece = Read(NumBits);
237 }
238 }
239
240 // Read a VBR that may have a value up to 64-bits in size. The chunk size of
241 // the VBR must still be <= 32 bits though.
242 uint64_t ReadVBR64(unsigned NumBits) {
243 uint32_t Piece = Read(NumBits);
244 if ((Piece & (1U << (NumBits-1))) == 0)
245 return uint64_t(Piece);
246
247 uint64_t Result = 0;
248 unsigned NextBit = 0;
249 while (true) {
250 Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;
251
252 if ((Piece & (1U << (NumBits-1))) == 0)
253 return Result;
254
255 NextBit += NumBits-1;
256 Piece = Read(NumBits);
257 }
258 }
259
260 void SkipToFourByteBoundary() {
261 // If word_t is 64-bits and if we've read less than 32 bits, just dump
262 // the bits we have up to the next 32-bit boundary.
263 if (sizeof(word_t) > 4 &&
264 BitsInCurWord >= 32) {
265 CurWord >>= BitsInCurWord-32;
266 BitsInCurWord = 32;
267 return;
268 }
269
270 BitsInCurWord = 0;
271 }
272
273 /// Skip to the end of the file.
274 void skipToEnd() { NextChar = BitcodeBytes.size(); }
275};
276
277/// When advancing through a bitstream cursor, each advance can discover a few
278/// different kinds of entries:
279struct BitstreamEntry {
280 enum {
281 Error, // Malformed bitcode was found.
282 EndBlock, // We've reached the end of the current block, (or the end of the
283 // file, which is treated like a series of EndBlock records.
284 SubBlock, // This is the start of a new subblock of a specific ID.
285 Record // This is a record with a specific AbbrevID.
286 } Kind;
287
288 unsigned ID;
289
290 static BitstreamEntry getError() {
291 BitstreamEntry E; E.Kind = Error; return E;
292 }
293
294 static BitstreamEntry getEndBlock() {
295 BitstreamEntry E; E.Kind = EndBlock; return E;
296 }
297
298 static BitstreamEntry getSubBlock(unsigned ID) {
299 BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
300 }
301
302 static BitstreamEntry getRecord(unsigned AbbrevID) {
303 BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
304 }
305};
306
307/// This represents a position within a bitcode file, implemented on top of a
308/// SimpleBitstreamCursor.
309///
310/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
311/// be passed by value.
312class BitstreamCursor : SimpleBitstreamCursor {
313 // This is the declared size of code values used for the current block, in
314 // bits.
315 unsigned CurCodeSize = 2;
316
317 /// Abbrevs installed at in this block.
318 std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
319
320 struct Block {
321 unsigned PrevCodeSize;
322 std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
323
324 explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
325 };
326
327 /// This tracks the codesize of parent blocks.
328 SmallVector<Block, 8> BlockScope;
329
330 BitstreamBlockInfo *BlockInfo = nullptr;
331
332public:
333 static const size_t MaxChunkSize = sizeof(word_t) * 8;
334
335 BitstreamCursor() = default;
336 explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
337 : SimpleBitstreamCursor(BitcodeBytes) {}
338 explicit BitstreamCursor(StringRef BitcodeBytes)
339 : SimpleBitstreamCursor(BitcodeBytes) {}
340 explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
341 : SimpleBitstreamCursor(BitcodeBytes) {}
342
343 using SimpleBitstreamCursor::canSkipToPos;
344 using SimpleBitstreamCursor::AtEndOfStream;
345 using SimpleBitstreamCursor::getBitcodeBytes;
346 using SimpleBitstreamCursor::GetCurrentBitNo;
347 using SimpleBitstreamCursor::getCurrentByteNo;
348 using SimpleBitstreamCursor::getPointerToByte;
349 using SimpleBitstreamCursor::JumpToBit;
350 using SimpleBitstreamCursor::fillCurWord;
351 using SimpleBitstreamCursor::Read;
352 using SimpleBitstreamCursor::ReadVBR;
353 using SimpleBitstreamCursor::ReadVBR64;
354
355 /// Return the number of bits used to encode an abbrev #.
356 unsigned getAbbrevIDWidth() const { return CurCodeSize; }
357
358 /// Flags that modify the behavior of advance().
359 enum {
360 /// If this flag is used, the advance() method does not automatically pop
361 /// the block scope when the end of a block is reached.
362 AF_DontPopBlockAtEnd = 1,
363
364 /// If this flag is used, abbrev entries are returned just like normal
365 /// records.
366 AF_DontAutoprocessAbbrevs = 2
367 };
368
369 /// Advance the current bitstream, returning the next entry in the stream.
370 BitstreamEntry advance(unsigned Flags = 0) {
371 while (true) {
372 if (AtEndOfStream())
373 return BitstreamEntry::getError();
374
375 unsigned Code = ReadCode();
376 if (Code == bitc::END_BLOCK) {
377 // Pop the end of the block unless Flags tells us not to.
378 if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
379 return BitstreamEntry::getError();
380 return BitstreamEntry::getEndBlock();
381 }
382
383 if (Code == bitc::ENTER_SUBBLOCK)
384 return BitstreamEntry::getSubBlock(ReadSubBlockID());
385
386 if (Code == bitc::DEFINE_ABBREV &&
387 !(Flags & AF_DontAutoprocessAbbrevs)) {
388 // We read and accumulate abbrev's, the client can't do anything with
389 // them anyway.
390 ReadAbbrevRecord();
391 continue;
392 }
393
394 return BitstreamEntry::getRecord(Code);
395 }
396 }
397
398 /// This is a convenience function for clients that don't expect any
399 /// subblocks. This just skips over them automatically.
400 BitstreamEntry advanceSkippingSubblocks(unsigned Flags = 0) {
401 while (true) {
402 // If we found a normal entry, return it.
403 BitstreamEntry Entry = advance(Flags);
404 if (Entry.Kind != BitstreamEntry::SubBlock)
405 return Entry;
406
407 // If we found a sub-block, just skip over it and check the next entry.
408 if (SkipBlock())
409 return BitstreamEntry::getError();
410 }
411 }
412
413 unsigned ReadCode() {
414 return Read(CurCodeSize);
415 }
416
417 // Block header:
418 // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
419
420 /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
421 unsigned ReadSubBlockID() {
422 return ReadVBR(bitc::BlockIDWidth);
423 }
424
425 /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
426 /// of this block. If the block record is malformed, return true.
427 bool SkipBlock() {
428 // Read and ignore the codelen value. Since we are skipping this block, we
429 // don't care what code widths are used inside of it.
430 ReadVBR(bitc::CodeLenWidth);
431 SkipToFourByteBoundary();
432 unsigned NumFourBytes = Read(bitc::BlockSizeWidth);
433
434 // Check that the block wasn't partially defined, and that the offset isn't
435 // bogus.
436 size_t SkipTo = GetCurrentBitNo() + NumFourBytes*4*8;
437 if (AtEndOfStream() || !canSkipToPos(SkipTo/8))
438 return true;
439
440 JumpToBit(SkipTo);
441 return false;
442 }
443
444 /// Having read the ENTER_SUBBLOCK abbrevid, enter the block, and return true
445 /// if the block has an error.
446 bool EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);
447
448 bool ReadBlockEnd() {
449 if (BlockScope.empty()) return true;
450
451 // Block tail:
452 // [END_BLOCK, <align4bytes>]
453 SkipToFourByteBoundary();
454
455 popBlockScope();
456 return false;
457 }
458
459private:
460 void popBlockScope() {
461 CurCodeSize = BlockScope.back().PrevCodeSize;
462
463 CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
464 BlockScope.pop_back();
465 }
466
467 //===--------------------------------------------------------------------===//
468 // Record Processing
469 //===--------------------------------------------------------------------===//
470
471public:
472 /// Return the abbreviation for the specified AbbrevId.
473 const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
474 unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
475 if (AbbrevNo >= CurAbbrevs.size())
476 report_fatal_error("Invalid abbrev number");
477 return CurAbbrevs[AbbrevNo].get();
478 }
479
480 /// Read the current record and discard it, returning the code for the record.
481 unsigned skipRecord(unsigned AbbrevID);
482
483 unsigned readRecord(unsigned AbbrevID, SmallVectorImpl<uint64_t> &Vals,
484 StringRef *Blob = nullptr);
485
486 //===--------------------------------------------------------------------===//
487 // Abbrev Processing
488 //===--------------------------------------------------------------------===//
489 void ReadAbbrevRecord();
490
491 /// Read and return a block info block from the bitstream. If an error was
492 /// encountered, return None.
493 ///
494 /// \param ReadBlockInfoNames Whether to read block/record name information in
495 /// the BlockInfo block. Only llvm-bcanalyzer uses this.
496 Optional<BitstreamBlockInfo>
497 ReadBlockInfoBlock(bool ReadBlockInfoNames = false);
498
499 /// Set the block info to be used by this BitstreamCursor to interpret
500 /// abbreviated records.
501 void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
502};
503
504} // end llvm namespace
505
506#endif // LLVM_BITCODE_BITSTREAMREADER_H