1 //===- CoverageMappingWriter.cpp - Code coverage mapping writer -----------===//
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 file contains support for writing coverage mapping data for
10 // instrumentation based coverage.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/ProfileData/InstrProf.h"
15 #include "llvm/ProfileData/Coverage/CoverageMappingWriter.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Support/Compression.h"
19 #include "llvm/Support/LEB128.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <algorithm>
22 #include <cassert>
23 #include <limits>
24 #include <vector>
25
26 using namespace llvm;
27 using namespace coverage;
28
CoverageFilenamesSectionWriter(ArrayRef<std::string> Filenames)29 CoverageFilenamesSectionWriter::CoverageFilenamesSectionWriter(
30 ArrayRef<std::string> Filenames)
31 : Filenames(Filenames) {
32 #ifndef NDEBUG
33 StringSet<> NameSet;
34 for (StringRef Name : Filenames)
35 assert(NameSet.insert(Name).second && "Duplicate filename");
36 #endif
37 }
38
write(raw_ostream & OS,bool Compress)39 void CoverageFilenamesSectionWriter::write(raw_ostream &OS, bool Compress) {
40 std::string FilenamesStr;
41 {
42 raw_string_ostream FilenamesOS{FilenamesStr};
43 for (const auto &Filename : Filenames) {
44 encodeULEB128(Filename.size(), FilenamesOS);
45 FilenamesOS << Filename;
46 }
47 }
48
49 SmallVector<uint8_t, 128> CompressedStr;
50 bool doCompression = Compress && compression::zlib::isAvailable() &&
51 DoInstrProfNameCompression;
52 if (doCompression)
53 compression::zlib::compress(arrayRefFromStringRef(FilenamesStr),
54 CompressedStr,
55 compression::zlib::BestSizeCompression);
56
57 // ::= <num-filenames>
58 // <uncompressed-len>
59 // <compressed-len-or-zero>
60 // (<compressed-filenames> | <uncompressed-filenames>)
61 encodeULEB128(Filenames.size(), OS);
62 encodeULEB128(FilenamesStr.size(), OS);
63 encodeULEB128(doCompression ? CompressedStr.size() : 0U, OS);
64 OS << (doCompression ? toStringRef(CompressedStr) : StringRef(FilenamesStr));
65 }
66
67 namespace {
68
69 /// Gather only the expressions that are used by the mapping
70 /// regions in this function.
71 class CounterExpressionsMinimizer {
72 ArrayRef<CounterExpression> Expressions;
73 SmallVector<CounterExpression, 16> UsedExpressions;
74 std::vector<unsigned> AdjustedExpressionIDs;
75
76 public:
CounterExpressionsMinimizer(ArrayRef<CounterExpression> Expressions,ArrayRef<CounterMappingRegion> MappingRegions)77 CounterExpressionsMinimizer(ArrayRef<CounterExpression> Expressions,
78 ArrayRef<CounterMappingRegion> MappingRegions)
79 : Expressions(Expressions) {
80 AdjustedExpressionIDs.resize(Expressions.size(), 0);
81 for (const auto &I : MappingRegions) {
82 mark(I.Count);
83 mark(I.FalseCount);
84 }
85 for (const auto &I : MappingRegions) {
86 gatherUsed(I.Count);
87 gatherUsed(I.FalseCount);
88 }
89 }
90
mark(Counter C)91 void mark(Counter C) {
92 if (!C.isExpression())
93 return;
94 unsigned ID = C.getExpressionID();
95 AdjustedExpressionIDs[ID] = 1;
96 mark(Expressions[ID].LHS);
97 mark(Expressions[ID].RHS);
98 }
99
gatherUsed(Counter C)100 void gatherUsed(Counter C) {
101 if (!C.isExpression() || !AdjustedExpressionIDs[C.getExpressionID()])
102 return;
103 AdjustedExpressionIDs[C.getExpressionID()] = UsedExpressions.size();
104 const auto &E = Expressions[C.getExpressionID()];
105 UsedExpressions.push_back(E);
106 gatherUsed(E.LHS);
107 gatherUsed(E.RHS);
108 }
109
getExpressions() const110 ArrayRef<CounterExpression> getExpressions() const { return UsedExpressions; }
111
112 /// Adjust the given counter to correctly transition from the old
113 /// expression ids to the new expression ids.
adjust(Counter C) const114 Counter adjust(Counter C) const {
115 if (C.isExpression())
116 C = Counter::getExpression(AdjustedExpressionIDs[C.getExpressionID()]);
117 return C;
118 }
119 };
120
121 } // end anonymous namespace
122
123 /// Encode the counter.
124 ///
125 /// The encoding uses the following format:
126 /// Low 2 bits - Tag:
127 /// Counter::Zero(0) - A Counter with kind Counter::Zero
128 /// Counter::CounterValueReference(1) - A counter with kind
129 /// Counter::CounterValueReference
130 /// Counter::Expression(2) + CounterExpression::Subtract(0) -
131 /// A counter with kind Counter::Expression and an expression
132 /// with kind CounterExpression::Subtract
133 /// Counter::Expression(2) + CounterExpression::Add(1) -
134 /// A counter with kind Counter::Expression and an expression
135 /// with kind CounterExpression::Add
136 /// Remaining bits - Counter/Expression ID.
encodeCounter(ArrayRef<CounterExpression> Expressions,Counter C)137 static unsigned encodeCounter(ArrayRef<CounterExpression> Expressions,
138 Counter C) {
139 unsigned Tag = unsigned(C.getKind());
140 if (C.isExpression())
141 Tag += Expressions[C.getExpressionID()].Kind;
142 unsigned ID = C.getCounterID();
143 assert(ID <=
144 (std::numeric_limits<unsigned>::max() >> Counter::EncodingTagBits));
145 return Tag | (ID << Counter::EncodingTagBits);
146 }
147
writeCounter(ArrayRef<CounterExpression> Expressions,Counter C,raw_ostream & OS)148 static void writeCounter(ArrayRef<CounterExpression> Expressions, Counter C,
149 raw_ostream &OS) {
150 encodeULEB128(encodeCounter(Expressions, C), OS);
151 }
152
write(raw_ostream & OS)153 void CoverageMappingWriter::write(raw_ostream &OS) {
154 // Check that we don't have any bogus regions.
155 assert(all_of(MappingRegions,
156 [](const CounterMappingRegion &CMR) {
157 return CMR.startLoc() <= CMR.endLoc();
158 }) &&
159 "Source region does not begin before it ends");
160
161 // Sort the regions in an ascending order by the file id and the starting
162 // location. Sort by region kinds to ensure stable order for tests.
163 llvm::stable_sort(MappingRegions, [](const CounterMappingRegion &LHS,
164 const CounterMappingRegion &RHS) {
165 if (LHS.FileID != RHS.FileID)
166 return LHS.FileID < RHS.FileID;
167 if (LHS.startLoc() != RHS.startLoc())
168 return LHS.startLoc() < RHS.startLoc();
169 return LHS.Kind < RHS.Kind;
170 });
171
172 // Write out the fileid -> filename mapping.
173 encodeULEB128(VirtualFileMapping.size(), OS);
174 for (const auto &FileID : VirtualFileMapping)
175 encodeULEB128(FileID, OS);
176
177 // Write out the expressions.
178 CounterExpressionsMinimizer Minimizer(Expressions, MappingRegions);
179 auto MinExpressions = Minimizer.getExpressions();
180 encodeULEB128(MinExpressions.size(), OS);
181 for (const auto &E : MinExpressions) {
182 writeCounter(MinExpressions, Minimizer.adjust(E.LHS), OS);
183 writeCounter(MinExpressions, Minimizer.adjust(E.RHS), OS);
184 }
185
186 // Write out the mapping regions.
187 // Split the regions into subarrays where each region in a
188 // subarray has a fileID which is the index of that subarray.
189 unsigned PrevLineStart = 0;
190 unsigned CurrentFileID = ~0U;
191 for (auto I = MappingRegions.begin(), E = MappingRegions.end(); I != E; ++I) {
192 if (I->FileID != CurrentFileID) {
193 // Ensure that all file ids have at least one mapping region.
194 assert(I->FileID == (CurrentFileID + 1));
195 // Find the number of regions with this file id.
196 unsigned RegionCount = 1;
197 for (auto J = I + 1; J != E && I->FileID == J->FileID; ++J)
198 ++RegionCount;
199 // Start a new region sub-array.
200 encodeULEB128(RegionCount, OS);
201
202 CurrentFileID = I->FileID;
203 PrevLineStart = 0;
204 }
205 Counter Count = Minimizer.adjust(I->Count);
206 Counter FalseCount = Minimizer.adjust(I->FalseCount);
207 switch (I->Kind) {
208 case CounterMappingRegion::CodeRegion:
209 case CounterMappingRegion::GapRegion:
210 writeCounter(MinExpressions, Count, OS);
211 break;
212 case CounterMappingRegion::ExpansionRegion: {
213 assert(Count.isZero());
214 assert(I->ExpandedFileID <=
215 (std::numeric_limits<unsigned>::max() >>
216 Counter::EncodingCounterTagAndExpansionRegionTagBits));
217 // Mark an expansion region with a set bit that follows the counter tag,
218 // and pack the expanded file id into the remaining bits.
219 unsigned EncodedTagExpandedFileID =
220 (1 << Counter::EncodingTagBits) |
221 (I->ExpandedFileID
222 << Counter::EncodingCounterTagAndExpansionRegionTagBits);
223 encodeULEB128(EncodedTagExpandedFileID, OS);
224 break;
225 }
226 case CounterMappingRegion::SkippedRegion:
227 assert(Count.isZero());
228 encodeULEB128(unsigned(I->Kind)
229 << Counter::EncodingCounterTagAndExpansionRegionTagBits,
230 OS);
231 break;
232 case CounterMappingRegion::BranchRegion:
233 encodeULEB128(unsigned(I->Kind)
234 << Counter::EncodingCounterTagAndExpansionRegionTagBits,
235 OS);
236 writeCounter(MinExpressions, Count, OS);
237 writeCounter(MinExpressions, FalseCount, OS);
238 break;
239 }
240 assert(I->LineStart >= PrevLineStart);
241 encodeULEB128(I->LineStart - PrevLineStart, OS);
242 encodeULEB128(I->ColumnStart, OS);
243 assert(I->LineEnd >= I->LineStart);
244 encodeULEB128(I->LineEnd - I->LineStart, OS);
245 encodeULEB128(I->ColumnEnd, OS);
246 PrevLineStart = I->LineStart;
247 }
248 // Ensure that all file ids have at least one mapping region.
249 assert(CurrentFileID == (VirtualFileMapping.size() - 1));
250 }
251