1 //=-- CoverageMappingWriter.cpp - Code coverage mapping writer -------------=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing coverage mapping data for
11 // instrumentation based coverage.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/ProfileData/CoverageMappingWriter.h"
16 #include "llvm/Support/LEB128.h"
19 using namespace coverage;
21 void CoverageFilenamesSectionWriter::write(raw_ostream &OS) {
22 encodeULEB128(Filenames.size(), OS);
23 for (const auto &Filename : Filenames) {
24 encodeULEB128(Filename.size(), OS);
30 /// \brief Gather only the expressions that are used by the mapping
31 /// regions in this function.
32 class CounterExpressionsMinimizer {
33 ArrayRef<CounterExpression> Expressions;
34 llvm::SmallVector<CounterExpression, 16> UsedExpressions;
35 std::vector<unsigned> AdjustedExpressionIDs;
38 void mark(Counter C) {
39 if (!C.isExpression())
41 unsigned ID = C.getExpressionID();
42 AdjustedExpressionIDs[ID] = 1;
43 mark(Expressions[ID].LHS);
44 mark(Expressions[ID].RHS);
47 void gatherUsed(Counter C) {
48 if (!C.isExpression() || !AdjustedExpressionIDs[C.getExpressionID()])
50 AdjustedExpressionIDs[C.getExpressionID()] = UsedExpressions.size();
51 const auto &E = Expressions[C.getExpressionID()];
52 UsedExpressions.push_back(E);
57 CounterExpressionsMinimizer(ArrayRef<CounterExpression> Expressions,
58 ArrayRef<CounterMappingRegion> MappingRegions)
59 : Expressions(Expressions) {
60 AdjustedExpressionIDs.resize(Expressions.size(), 0);
61 for (const auto &I : MappingRegions)
63 for (const auto &I : MappingRegions)
67 ArrayRef<CounterExpression> getExpressions() const { return UsedExpressions; }
69 /// \brief Adjust the given counter to correctly transition from the old
70 /// expression ids to the new expression ids.
71 Counter adjust(Counter C) const {
73 C = Counter::getExpression(AdjustedExpressionIDs[C.getExpressionID()]);
79 /// \brief Encode the counter.
81 /// The encoding uses the following format:
83 /// Counter::Zero(0) - A Counter with kind Counter::Zero
84 /// Counter::CounterValueReference(1) - A counter with kind
85 /// Counter::CounterValueReference
86 /// Counter::Expression(2) + CounterExpression::Subtract(0) -
87 /// A counter with kind Counter::Expression and an expression
88 /// with kind CounterExpression::Subtract
89 /// Counter::Expression(2) + CounterExpression::Add(1) -
90 /// A counter with kind Counter::Expression and an expression
91 /// with kind CounterExpression::Add
92 /// Remaining bits - Counter/Expression ID.
93 static unsigned encodeCounter(ArrayRef<CounterExpression> Expressions,
95 unsigned Tag = unsigned(C.getKind());
97 Tag += Expressions[C.getExpressionID()].Kind;
98 unsigned ID = C.getCounterID();
100 (std::numeric_limits<unsigned>::max() >> Counter::EncodingTagBits));
101 return Tag | (ID << Counter::EncodingTagBits);
104 static void writeCounter(ArrayRef<CounterExpression> Expressions, Counter C,
106 encodeULEB128(encodeCounter(Expressions, C), OS);
109 void CoverageMappingWriter::write(raw_ostream &OS) {
110 // Sort the regions in an ascending order by the file id and the starting
112 std::sort(MappingRegions.begin(), MappingRegions.end());
114 // Write out the fileid -> filename mapping.
115 encodeULEB128(VirtualFileMapping.size(), OS);
116 for (const auto &FileID : VirtualFileMapping)
117 encodeULEB128(FileID, OS);
119 // Write out the expressions.
120 CounterExpressionsMinimizer Minimizer(Expressions, MappingRegions);
121 auto MinExpressions = Minimizer.getExpressions();
122 encodeULEB128(MinExpressions.size(), OS);
123 for (const auto &E : MinExpressions) {
124 writeCounter(MinExpressions, Minimizer.adjust(E.LHS), OS);
125 writeCounter(MinExpressions, Minimizer.adjust(E.RHS), OS);
128 // Write out the mapping regions.
129 // Split the regions into subarrays where each region in a
130 // subarray has a fileID which is the index of that subarray.
131 unsigned PrevLineStart = 0;
132 unsigned CurrentFileID = ~0U;
133 for (auto I = MappingRegions.begin(), E = MappingRegions.end(); I != E; ++I) {
134 if (I->FileID != CurrentFileID) {
135 // Ensure that all file ids have at least one mapping region.
136 assert(I->FileID == (CurrentFileID + 1));
137 // Find the number of regions with this file id.
138 unsigned RegionCount = 1;
139 for (auto J = I + 1; J != E && I->FileID == J->FileID; ++J)
141 // Start a new region sub-array.
142 encodeULEB128(RegionCount, OS);
144 CurrentFileID = I->FileID;
147 Counter Count = Minimizer.adjust(I->Count);
149 case CounterMappingRegion::CodeRegion:
150 writeCounter(MinExpressions, Count, OS);
152 case CounterMappingRegion::ExpansionRegion: {
153 assert(Count.isZero());
154 assert(I->ExpandedFileID <=
155 (std::numeric_limits<unsigned>::max() >>
156 Counter::EncodingCounterTagAndExpansionRegionTagBits));
157 // Mark an expansion region with a set bit that follows the counter tag,
158 // and pack the expanded file id into the remaining bits.
159 unsigned EncodedTagExpandedFileID =
160 (1 << Counter::EncodingTagBits) |
162 << Counter::EncodingCounterTagAndExpansionRegionTagBits);
163 encodeULEB128(EncodedTagExpandedFileID, OS);
166 case CounterMappingRegion::SkippedRegion:
167 assert(Count.isZero());
168 encodeULEB128(unsigned(I->Kind)
169 << Counter::EncodingCounterTagAndExpansionRegionTagBits,
173 assert(I->LineStart >= PrevLineStart);
174 encodeULEB128(I->LineStart - PrevLineStart, OS);
175 uint64_t CodeBeforeColumnStart =
176 uint64_t(I->HasCodeBefore) |
177 (uint64_t(I->ColumnStart)
178 << CounterMappingRegion::EncodingHasCodeBeforeBits);
179 encodeULEB128(CodeBeforeColumnStart, OS);
180 assert(I->LineEnd >= I->LineStart);
181 encodeULEB128(I->LineEnd - I->LineStart, OS);
182 encodeULEB128(I->ColumnEnd, OS);
183 PrevLineStart = I->LineStart;
185 // Ensure that all file ids have at least one mapping region.
186 assert(CurrentFileID == (VirtualFileMapping.size() - 1));