LLVM  3.7.0
CoverageMappingWriter.cpp
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1 //=-- CoverageMappingWriter.cpp - Code coverage mapping writer -------------=//
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 file contains support for writing coverage mapping data for
11 // instrumentation based coverage.
12 //
13 //===----------------------------------------------------------------------===//
14 
16 #include "llvm/Support/LEB128.h"
17 
18 using namespace llvm;
19 using namespace coverage;
20 
22  encodeULEB128(Filenames.size(), OS);
23  for (const auto &Filename : Filenames) {
24  encodeULEB128(Filename.size(), OS);
25  OS << Filename;
26  }
27 }
28 
29 namespace {
30 /// \brief Gather only the expressions that are used by the mapping
31 /// regions in this function.
32 class CounterExpressionsMinimizer {
33  ArrayRef<CounterExpression> Expressions;
35  std::vector<unsigned> AdjustedExpressionIDs;
36 
37 public:
38  void mark(Counter C) {
39  if (!C.isExpression())
40  return;
41  unsigned ID = C.getExpressionID();
42  AdjustedExpressionIDs[ID] = 1;
43  mark(Expressions[ID].LHS);
44  mark(Expressions[ID].RHS);
45  }
46 
47  void gatherUsed(Counter C) {
48  if (!C.isExpression() || !AdjustedExpressionIDs[C.getExpressionID()])
49  return;
50  AdjustedExpressionIDs[C.getExpressionID()] = UsedExpressions.size();
51  const auto &E = Expressions[C.getExpressionID()];
52  UsedExpressions.push_back(E);
53  gatherUsed(E.LHS);
54  gatherUsed(E.RHS);
55  }
56 
57  CounterExpressionsMinimizer(ArrayRef<CounterExpression> Expressions,
58  ArrayRef<CounterMappingRegion> MappingRegions)
59  : Expressions(Expressions) {
60  AdjustedExpressionIDs.resize(Expressions.size(), 0);
61  for (const auto &I : MappingRegions)
62  mark(I.Count);
63  for (const auto &I : MappingRegions)
64  gatherUsed(I.Count);
65  }
66 
67  ArrayRef<CounterExpression> getExpressions() const { return UsedExpressions; }
68 
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 {
72  if (C.isExpression())
73  C = Counter::getExpression(AdjustedExpressionIDs[C.getExpressionID()]);
74  return C;
75  }
76 };
77 }
78 
79 /// \brief Encode the counter.
80 ///
81 /// The encoding uses the following format:
82 /// Low 2 bits - Tag:
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,
94  Counter C) {
95  unsigned Tag = unsigned(C.getKind());
96  if (C.isExpression())
97  Tag += Expressions[C.getExpressionID()].Kind;
98  unsigned ID = C.getCounterID();
99  assert(ID <=
100  (std::numeric_limits<unsigned>::max() >> Counter::EncodingTagBits));
101  return Tag | (ID << Counter::EncodingTagBits);
102 }
103 
105  raw_ostream &OS) {
106  encodeULEB128(encodeCounter(Expressions, C), OS);
107 }
108 
110  // Sort the regions in an ascending order by the file id and the starting
111  // location.
112  std::stable_sort(MappingRegions.begin(), MappingRegions.end());
113 
114  // Write out the fileid -> filename mapping.
115  encodeULEB128(VirtualFileMapping.size(), OS);
116  for (const auto &FileID : VirtualFileMapping)
117  encodeULEB128(FileID, OS);
118 
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);
126  }
127 
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)
140  ++RegionCount;
141  // Start a new region sub-array.
142  encodeULEB128(RegionCount, OS);
143 
144  CurrentFileID = I->FileID;
145  PrevLineStart = 0;
146  }
147  Counter Count = Minimizer.adjust(I->Count);
148  switch (I->Kind) {
150  writeCounter(MinExpressions, Count, OS);
151  break;
153  assert(Count.isZero());
154  assert(I->ExpandedFileID <=
155  (std::numeric_limits<unsigned>::max() >>
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) |
161  (I->ExpandedFileID
163  encodeULEB128(EncodedTagExpandedFileID, OS);
164  break;
165  }
167  assert(Count.isZero());
168  encodeULEB128(unsigned(I->Kind)
170  OS);
171  break;
172  }
173  assert(I->LineStart >= PrevLineStart);
174  encodeULEB128(I->LineStart - PrevLineStart, OS);
175  encodeULEB128(I->ColumnStart, OS);
176  assert(I->LineEnd >= I->LineStart);
177  encodeULEB128(I->LineEnd - I->LineStart, OS);
178  encodeULEB128(I->ColumnEnd, OS);
179  PrevLineStart = I->LineStart;
180  }
181  // Ensure that all file ids have at least one mapping region.
182  assert(CurrentFileID == (VirtualFileMapping.size() - 1));
183 }
void write(raw_ostream &OS)
Write encoded coverage mapping data to the given output stream.
void write(raw_ostream &OS)
Write encoded filenames to the given output stream.
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: ArrayRef.h:31
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:134
static unsigned encodeCounter(ArrayRef< CounterExpression > Expressions, Counter C)
Encode the counter.
unsigned getExpressionID() const
CounterKind getKind() const
A CodeRegion associates some code with a counter.
unsigned getCounterID() const
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
An ExpansionRegion represents a file expansion region that associates a source range with the expansi...
A SkippedRegion represents a source range with code that was skipped by a preprocessor or similar mea...
static void writeCounter(ArrayRef< CounterExpression > Expressions, Counter C, raw_ostream &OS)
static const unsigned EncodingCounterTagAndExpansionRegionTagBits
bool isExpression() const
#define I(x, y, z)
Definition: MD5.cpp:54
static const unsigned EncodingTagBits
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:38
void encodeULEB128(uint64_t Value, raw_ostream &OS, unsigned Padding=0)
Utility function to encode a ULEB128 value to an output stream.
Definition: LEB128.h:38
static Counter getExpression(unsigned ExpressionId)
Return the counter that corresponds to a specific addition counter expression.
A Counter is an abstract value that describes how to compute the execution count for a region of code...