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 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 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: 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 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 } 99 100 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 } 109 110 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. 114 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. 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 } 147 148 static void writeCounter(ArrayRef<CounterExpression> Expressions, Counter C, 149 raw_ostream &OS) { 150 encodeULEB128(encodeCounter(Expressions, C), OS); 151 } 152 153 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