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//===- CoverageMappingWriter.cpp - Code coverage mapping writer -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing coverage mapping data for
// instrumentation based coverage.
//
//===----------------------------------------------------------------------===//
#include "llvm/ProfileData/Coverage/CoverageMappingWriter.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <limits>
#include <vector>
using namespace llvm;
using namespace coverage;
void CoverageFilenamesSectionWriter::write(raw_ostream &OS) {
encodeULEB128(Filenames.size(), OS);
for (const auto &Filename : Filenames) {
encodeULEB128(Filename.size(), OS);
OS << Filename;
}
}
namespace {
/// Gather only the expressions that are used by the mapping
/// regions in this function.
class CounterExpressionsMinimizer {
ArrayRef<CounterExpression> Expressions;
SmallVector<CounterExpression, 16> UsedExpressions;
std::vector<unsigned> AdjustedExpressionIDs;
public:
CounterExpressionsMinimizer(ArrayRef<CounterExpression> Expressions,
ArrayRef<CounterMappingRegion> MappingRegions)
: Expressions(Expressions) {
AdjustedExpressionIDs.resize(Expressions.size(), 0);
for (const auto &I : MappingRegions)
mark(I.Count);
for (const auto &I : MappingRegions)
gatherUsed(I.Count);
}
void mark(Counter C) {
if (!C.isExpression())
return;
unsigned ID = C.getExpressionID();
AdjustedExpressionIDs[ID] = 1;
mark(Expressions[ID].LHS);
mark(Expressions[ID].RHS);
}
void gatherUsed(Counter C) {
if (!C.isExpression() || !AdjustedExpressionIDs[C.getExpressionID()])
return;
AdjustedExpressionIDs[C.getExpressionID()] = UsedExpressions.size();
const auto &E = Expressions[C.getExpressionID()];
UsedExpressions.push_back(E);
gatherUsed(E.LHS);
gatherUsed(E.RHS);
}
ArrayRef<CounterExpression> getExpressions() const { return UsedExpressions; }
/// Adjust the given counter to correctly transition from the old
/// expression ids to the new expression ids.
Counter adjust(Counter C) const {
if (C.isExpression())
C = Counter::getExpression(AdjustedExpressionIDs[C.getExpressionID()]);
return C;
}
};
} // end anonymous namespace
/// Encode the counter.
///
/// The encoding uses the following format:
/// Low 2 bits - Tag:
/// Counter::Zero(0) - A Counter with kind Counter::Zero
/// Counter::CounterValueReference(1) - A counter with kind
/// Counter::CounterValueReference
/// Counter::Expression(2) + CounterExpression::Subtract(0) -
/// A counter with kind Counter::Expression and an expression
/// with kind CounterExpression::Subtract
/// Counter::Expression(2) + CounterExpression::Add(1) -
/// A counter with kind Counter::Expression and an expression
/// with kind CounterExpression::Add
/// Remaining bits - Counter/Expression ID.
static unsigned encodeCounter(ArrayRef<CounterExpression> Expressions,
Counter C) {
unsigned Tag = unsigned(C.getKind());
if (C.isExpression())
Tag += Expressions[C.getExpressionID()].Kind;
unsigned ID = C.getCounterID();
assert(ID <=
(std::numeric_limits<unsigned>::max() >> Counter::EncodingTagBits));
return Tag | (ID << Counter::EncodingTagBits);
}
static void writeCounter(ArrayRef<CounterExpression> Expressions, Counter C,
raw_ostream &OS) {
encodeULEB128(encodeCounter(Expressions, C), OS);
}
void CoverageMappingWriter::write(raw_ostream &OS) {
// Check that we don't have any bogus regions.
assert(all_of(MappingRegions,
[](const CounterMappingRegion &CMR) {
return CMR.startLoc() <= CMR.endLoc();
}) &&
"Source region does not begin before it ends");
// Sort the regions in an ascending order by the file id and the starting
// location. Sort by region kinds to ensure stable order for tests.
llvm::stable_sort(MappingRegions, [](const CounterMappingRegion &LHS,
const CounterMappingRegion &RHS) {
if (LHS.FileID != RHS.FileID)
return LHS.FileID < RHS.FileID;
if (LHS.startLoc() != RHS.startLoc())
return LHS.startLoc() < RHS.startLoc();
return LHS.Kind < RHS.Kind;
});
// Write out the fileid -> filename mapping.
encodeULEB128(VirtualFileMapping.size(), OS);
for (const auto &FileID : VirtualFileMapping)
encodeULEB128(FileID, OS);
// Write out the expressions.
CounterExpressionsMinimizer Minimizer(Expressions, MappingRegions);
auto MinExpressions = Minimizer.getExpressions();
encodeULEB128(MinExpressions.size(), OS);
for (const auto &E : MinExpressions) {
writeCounter(MinExpressions, Minimizer.adjust(E.LHS), OS);
writeCounter(MinExpressions, Minimizer.adjust(E.RHS), OS);
}
// Write out the mapping regions.
// Split the regions into subarrays where each region in a
// subarray has a fileID which is the index of that subarray.
unsigned PrevLineStart = 0;
unsigned CurrentFileID = ~0U;
for (auto I = MappingRegions.begin(), E = MappingRegions.end(); I != E; ++I) {
if (I->FileID != CurrentFileID) {
// Ensure that all file ids have at least one mapping region.
assert(I->FileID == (CurrentFileID + 1));
// Find the number of regions with this file id.
unsigned RegionCount = 1;
for (auto J = I + 1; J != E && I->FileID == J->FileID; ++J)
++RegionCount;
// Start a new region sub-array.
encodeULEB128(RegionCount, OS);
CurrentFileID = I->FileID;
PrevLineStart = 0;
}
Counter Count = Minimizer.adjust(I->Count);
switch (I->Kind) {
case CounterMappingRegion::CodeRegion:
case CounterMappingRegion::GapRegion:
writeCounter(MinExpressions, Count, OS);
break;
case CounterMappingRegion::ExpansionRegion: {
assert(Count.isZero());
assert(I->ExpandedFileID <=
(std::numeric_limits<unsigned>::max() >>
Counter::EncodingCounterTagAndExpansionRegionTagBits));
// Mark an expansion region with a set bit that follows the counter tag,
// and pack the expanded file id into the remaining bits.
unsigned EncodedTagExpandedFileID =
(1 << Counter::EncodingTagBits) |
(I->ExpandedFileID
<< Counter::EncodingCounterTagAndExpansionRegionTagBits);
encodeULEB128(EncodedTagExpandedFileID, OS);
break;
}
case CounterMappingRegion::SkippedRegion:
assert(Count.isZero());
encodeULEB128(unsigned(I->Kind)
<< Counter::EncodingCounterTagAndExpansionRegionTagBits,
OS);
break;
}
assert(I->LineStart >= PrevLineStart);
encodeULEB128(I->LineStart - PrevLineStart, OS);
encodeULEB128(I->ColumnStart, OS);
assert(I->LineEnd >= I->LineStart);
encodeULEB128(I->LineEnd - I->LineStart, OS);
encodeULEB128(I->ColumnEnd, OS);
PrevLineStart = I->LineStart;
}
// Ensure that all file ids have at least one mapping region.
assert(CurrentFileID == (VirtualFileMapping.size() - 1));
}
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