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Add the ability for DWARFDie objects to get the parent DWARFDie.

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In order for the llvm DWARF parser to be used in LLDB we will need to be able to get the parent of a DIE. This patch adds that functionality by changing the DWARFDebugInfoEntry class to store a depth field instead of a sibling index. Using a depth field allows us to easily calculate the sibling and the parent without increasing the size of DWARFDebugInfoEntry.

I tested llvm-dsymutil on a debug version of clang where this fully parses DWARF in over 1200 .o files to verify there was no serious regression in performance.

Added a full suite of unit tests to test this functionality.

Differential Revision: https://reviews.llvm.org/D27995

llvm-svn: 290274
This commit is contained in:
Greg Clayton 2016-12-21 21:37:06 +00:00
parent a84529a444
commit aadbc74cdf
7 changed files with 209 additions and 82 deletions
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38
include/llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h
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@ -31,13 +31,14 @@ class DWARFDebugInfoEntry {
/// Offset within the .debug_info of the start of this entry.
uint32_t Offset;
/// How many to add to "this" to get the sibling.
uint32_t SiblingIdx;
/// The integer depth of this DIE within the compile unit DIEs where the
/// compile/type unit DIE has a depth of zero.
uint32_t Depth;
const DWARFAbbreviationDeclaration *AbbrevDecl;
public:
DWARFDebugInfoEntry()
: Offset(0), SiblingIdx(0), AbbrevDecl(nullptr) {}
: Offset(0), Depth(0), AbbrevDecl(nullptr) {}
/// Extracts a debug info entry, which is a child of a given unit,
/// starting at a given offset. If DIE can't be extracted, returns false and
@ -45,33 +46,16 @@ public:
bool extractFast(const DWARFUnit &U, uint32_t *OffsetPtr);
/// High performance extraction should use this call.
bool extractFast(const DWARFUnit &U, uint32_t *OffsetPtr,
const DataExtractor &DebugInfoData, uint32_t UEndOffset);
const DataExtractor &DebugInfoData,
uint32_t UEndOffset,
uint32_t Depth);
uint32_t getOffset() const { return Offset; }
uint32_t getDepth() const { return Depth; }
dwarf::Tag getTag() const {
return AbbrevDecl ? AbbrevDecl->getTag() : dwarf::DW_TAG_null;
}
bool hasChildren() const { return AbbrevDecl && AbbrevDecl->hasChildren(); }
// We know we are kept in a vector of contiguous entries, so we know
// our sibling will be some index after "this".
const DWARFDebugInfoEntry *getSibling() const {
return SiblingIdx > 0 ? this + SiblingIdx : nullptr;
}
// We know we are kept in a vector of contiguous entries, so we know
// we don't need to store our child pointer, if we have a child it will
// be the next entry in the list...
const DWARFDebugInfoEntry *getFirstChild() const {
return hasChildren() ? this + 1 : nullptr;
}
void setSibling(const DWARFDebugInfoEntry *Sibling) {
if (Sibling) {
// We know we are kept in a vector of contiguous entries, so we know
// our sibling will be some index after "this".
SiblingIdx = Sibling - this;
} else
SiblingIdx = 0;
}
const DWARFAbbreviationDeclaration *getAbbreviationDeclarationPtr() const {
return AbbrevDecl;
}

22
include/llvm/DebugInfo/DWARF/DWARFDie.h
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@ -40,6 +40,9 @@ public:
bool isValid() const { return U && Die; }
explicit operator bool() const { return isValid(); }
bool operator ==(const DWARFDie &RHS) const {
return Die == RHS.Die && U == RHS.U;
}
const DWARFDebugInfoEntry *getDebugInfoEntry() const { return Die; }
DWARFUnit *getDwarfUnit() const { return U; }
@ -82,23 +85,26 @@ public:
/// Returns true if DIE represents a subprogram or an inlined subroutine.
bool isSubroutineDIE() const;
/// Get the silbing of this DIE object.
/// Get the parent of this DIE object.
///
/// \returns a valid DWARFDie instance if this object has a parent or an
/// invalid DWARFDie instance if it doesn't.
DWARFDie getParent() const;
/// Get the sibling of this DIE object.
///
/// \returns a valid DWARFDie instance if this object has a sibling or an
/// invalid DWARFDie instance if it doesn't.
DWARFDie getSibling() const {
assert(isValid() && "must check validity prior to calling");
return DWARFDie(U, Die->getSibling());
}
DWARFDie getSibling() const;
/// Get the first child of this DIE object.
///
/// \returns a valid DWARFDie instance if this object has children or an
/// invalid DWARFDie instance if it doesn't.
DWARFDie getFirstChild() const {
assert(isValid() && "must check validity prior to calling");
return DWARFDie(U, Die->getFirstChild());
if (isValid() && Die->hasChildren())
return DWARFDie(U, Die + 1);
return DWARFDie();
}
/// Dump the DIE and all of its attributes to the supplied stream.

23
include/llvm/DebugInfo/DWARF/DWARFUnit.h
View File

@ -140,6 +140,12 @@ class DWARFUnit {
const DWARFUnitIndex::Entry *IndexEntry;
uint32_t getDIEIndex(const DWARFDebugInfoEntry *Die) {
auto First = DieArray.data();
assert(Die >= First && Die < First + DieArray.size());
return Die - First;
}
protected:
virtual bool extractImpl(DataExtractor debug_info, uint32_t *offset_ptr);
/// Size in bytes of the unit header.
@ -251,19 +257,18 @@ public:
/// method on a DIE that isn't accessible by following
/// children/sibling links starting from this unit's getUnitDIE().
uint32_t getDIEIndex(const DWARFDie &D) {
auto DIE = D.getDebugInfoEntry();
assert(!DieArray.empty() && DIE >= &DieArray[0] &&
DIE < &DieArray[0] + DieArray.size());
return DIE - &DieArray[0];
return getDIEIndex(D.getDebugInfoEntry());
}
/// \brief Return the DIE object at the given index.
DWARFDie getDIEAtIndex(unsigned Index) {
if (Index < DieArray.size())
return DWARFDie(this, &DieArray[Index]);
return DWARFDie();
assert(Index < DieArray.size());
return DWARFDie(this, &DieArray[Index]);
}
DWARFDie getParent(const DWARFDebugInfoEntry *Die);
DWARFDie getSibling(const DWARFDebugInfoEntry *Die);
/// \brief Return the DIE object for a given offset inside the
/// unit's DIE vector.
///
@ -298,10 +303,6 @@ private:
/// extractDIEsToVector - Appends all parsed DIEs to a vector.
void extractDIEsToVector(bool AppendCUDie, bool AppendNonCUDIEs,
std::vector<DWARFDebugInfoEntry> &DIEs) const;
/// setDIERelations - We read in all of the DIE entries into our flat list
/// of DIE entries and now we need to go back through all of them and set the
/// parent, sibling and child pointers for quick DIE navigation.
void setDIERelations();
/// clearDIEs - Clear parsed DIEs to keep memory usage low.
void clearDIEs(bool KeepCUDie);

10
lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
View File

@ -26,13 +26,13 @@ bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U,
uint32_t *OffsetPtr) {
DataExtractor DebugInfoData = U.getDebugInfoExtractor();
const uint32_t UEndOffset = U.getNextUnitOffset();
return extractFast(U, OffsetPtr, DebugInfoData, UEndOffset);
return extractFast(U, OffsetPtr, DebugInfoData, UEndOffset, 0);
}
bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U,
uint32_t *OffsetPtr,
const DataExtractor &DebugInfoData,
uint32_t UEndOffset) {
bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint32_t *OffsetPtr,
const DataExtractor &DebugInfoData,
uint32_t UEndOffset, uint32_t D) {
Offset = *OffsetPtr;
Depth = D;
if (Offset >= UEndOffset || !DebugInfoData.isValidOffset(Offset))
return false;
uint64_t AbbrCode = DebugInfoData.getULEB128(OffsetPtr);

11
lib/DebugInfo/DWARF/DWARFDie.cpp
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@ -428,3 +428,14 @@ void DWARFDie::getInlinedChainForAddress(
std::reverse(InlinedChain.begin(), InlinedChain.end());
}
DWARFDie DWARFDie::getParent() const {
if (isValid())
return U->getParent(Die);
return DWARFDie();
}
DWARFDie DWARFDie::getSibling() const {
if (isValid())
return U->getSibling(Die);
return DWARFDie();
}

71
lib/DebugInfo/DWARF/DWARFUnit.cpp
View File

@ -158,35 +158,6 @@ Optional<uint64_t> DWARFUnit::getDWOId() {
return getUnitDIE().getAttributeValueAsUnsignedConstant(DW_AT_GNU_dwo_id);
}
void DWARFUnit::setDIERelations() {
if (DieArray.size() <= 1)
return;
std::vector<DWARFDebugInfoEntry *> ParentChain;
DWARFDebugInfoEntry *SiblingChain = nullptr;
for (auto &DIE : DieArray) {
if (SiblingChain) {
SiblingChain->setSibling(&DIE);
}
if (const DWARFAbbreviationDeclaration *AbbrDecl =
DIE.getAbbreviationDeclarationPtr()) {
// Normal DIE.
if (AbbrDecl->hasChildren()) {
ParentChain.push_back(&DIE);
SiblingChain = nullptr;
} else {
SiblingChain = &DIE;
}
} else {
// NULL entry terminates the sibling chain.
SiblingChain = ParentChain.back();
ParentChain.pop_back();
}
}
assert(SiblingChain == nullptr || SiblingChain == &DieArray[0]);
assert(ParentChain.empty());
}
void DWARFUnit::extractDIEsToVector(
bool AppendCUDie, bool AppendNonCUDies,
std::vector<DWARFDebugInfoEntry> &Dies) const {
@ -202,7 +173,8 @@ void DWARFUnit::extractDIEsToVector(
uint32_t Depth = 0;
bool IsCUDie = true;
while (DIE.extractFast(*this, &DIEOffset, DebugInfoData, NextCUOffset)) {
while (DIE.extractFast(*this, &DIEOffset, DebugInfoData, NextCUOffset,
Depth)) {
if (IsCUDie) {
if (AppendCUDie)
Dies.push_back(DIE);
@ -266,7 +238,6 @@ size_t DWARFUnit::extractDIEsIfNeeded(bool CUDieOnly) {
// skeleton CU DIE, so that DWARF users not aware of it are not broken.
}
setDIERelations();
return DieArray.size();
}
@ -409,4 +380,42 @@ const DWARFUnitIndex &getDWARFUnitIndex(DWARFContext &Context,
return Context.getTUIndex();
}
DWARFDie DWARFUnit::getParent(const DWARFDebugInfoEntry *Die) {
if (!Die)
return DWARFDie();
const uint32_t Depth = Die->getDepth();
// Unit DIEs always have a depth of zero and never have parents.
if (Depth == 0)
return DWARFDie();
// Depth of 1 always means parent is the compile/type unit.
if (Depth == 1)
return getUnitDIE();
// Look for previous DIE with a depth that is one less than the Die's depth.
const uint32_t ParentDepth = Depth - 1;
for (uint32_t I = getDIEIndex(Die) - 1; I > 0; --I) {
if (DieArray[I].getDepth() == ParentDepth)
return DWARFDie(this, &DieArray[I]);
}
return DWARFDie();
}
DWARFDie DWARFUnit::getSibling(const DWARFDebugInfoEntry *Die) {
if (!Die)
return DWARFDie();
uint32_t Depth = Die->getDepth();
// Unit DIEs always have a depth of zero and never have siblings.
if (Depth == 0)
return DWARFDie();
// NULL DIEs don't have siblings.
if (Die->getAbbreviationDeclarationPtr() == nullptr)
return DWARFDie();
// Find the next DIE whose depth is the same as the Die's depth.
for (size_t I=getDIEIndex(Die)+1, EndIdx = DieArray.size(); I<EndIdx; ++I) {
if (DieArray[I].getDepth() == Depth)
return DWARFDie(this, &DieArray[I]);
}
return DWARFDie();
}
} // end namespace llvm

116
unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
View File

@ -967,5 +967,121 @@ TEST(DWARFDebugInfo, TestDWARF32Version4Addr8Addresses) {
TestAddresses<4, AddrType>();
}
TEST(DWARFDebugInfo, TestRelations) {
// Test the DWARF APIs related to accessing the DW_AT_low_pc and
// DW_AT_high_pc.
uint16_t Version = 4;
const uint8_t AddrSize = sizeof(void *);
initLLVMIfNeeded();
Triple Triple = getHostTripleForAddrSize(AddrSize);
auto ExpectedDG = dwarfgen::Generator::create(Triple, Version);
if (HandleExpectedError(ExpectedDG))
return;
dwarfgen::Generator *DG = ExpectedDG.get().get();
dwarfgen::CompileUnit &CU = DG->addCompileUnit();
enum class Tag: uint16_t {
A = dwarf::DW_TAG_lo_user,
B,
B1,
B2,
C,
C1
};
// Scope to allow us to re-use the same DIE names
{
// Create DWARF tree that looks like:
//
// CU
// A
// B
// B1
// B2
// C
// C1
dwarfgen::DIE CUDie = CU.getUnitDIE();
CUDie.addChild((dwarf::Tag)Tag::A);
dwarfgen::DIE B = CUDie.addChild((dwarf::Tag)Tag::B);
dwarfgen::DIE C = CUDie.addChild((dwarf::Tag)Tag::C);
B.addChild((dwarf::Tag)Tag::B1);
B.addChild((dwarf::Tag)Tag::B2);
C.addChild((dwarf::Tag)Tag::C1);
}
MemoryBufferRef FileBuffer(DG->generate(), "dwarf");
auto Obj = object::ObjectFile::createObjectFile(FileBuffer);
EXPECT_TRUE((bool)Obj);
DWARFContextInMemory DwarfContext(*Obj.get());
// Verify the number of compile units is correct.
uint32_t NumCUs = DwarfContext.getNumCompileUnits();
EXPECT_EQ(NumCUs, 1u);
DWARFCompileUnit *U = DwarfContext.getCompileUnitAtIndex(0);
// Get the compile unit DIE is valid.
auto CUDie = U->getUnitDIE(false);
EXPECT_TRUE(CUDie.isValid());
// DieDG.dump(llvm::outs(), U, UINT32_MAX);
// The compile unit doesn't have a parent or a sibling.
auto ParentDie = CUDie.getParent();
EXPECT_FALSE(ParentDie.isValid());
auto SiblingDie = CUDie.getSibling();
EXPECT_FALSE(SiblingDie.isValid());
// Get the children of the compile unit
auto A = CUDie.getFirstChild();
auto B = A.getSibling();
auto C = B.getSibling();
auto Null = C.getSibling();
// Verify NULL Die is NULL and has no children or siblings
EXPECT_TRUE(Null.isNULL());
EXPECT_FALSE(Null.getSibling().isValid());
EXPECT_FALSE(Null.getFirstChild().isValid());
// Verify all children of the compile unit DIE are correct.
EXPECT_EQ(A.getTag(), (dwarf::Tag)Tag::A);
EXPECT_EQ(B.getTag(), (dwarf::Tag)Tag::B);
EXPECT_EQ(C.getTag(), (dwarf::Tag)Tag::C);
// Verify who has children
EXPECT_FALSE(A.hasChildren());
EXPECT_TRUE(B.hasChildren());
// Make sure the parent of all the children of the compile unit are the
// compile unit.
EXPECT_EQ(A.getParent(), CUDie);
EXPECT_EQ(B.getParent(), CUDie);
EXPECT_EQ(Null.getParent(), CUDie);
EXPECT_FALSE(A.getFirstChild().isValid());
// Verify the children of the B DIE
auto B1 = B.getFirstChild();
auto B2 = B1.getSibling();
EXPECT_TRUE(B2.getSibling().isNULL());
// Verify all children of the B DIE correctly valid or invalid.
EXPECT_EQ(B1.getTag(), (dwarf::Tag)Tag::B1);
EXPECT_EQ(B2.getTag(), (dwarf::Tag)Tag::B2);
// Make sure the parent of all the children of the B are the B.
EXPECT_EQ(B1.getParent(), B);
EXPECT_EQ(B2.getParent(), B);
}
TEST(DWARFDebugInfo, TestDWARFDie) {
// Make sure a default constructed DWARFDie doesn't have any parent, sibling
// or child;
DWARFDie DefaultDie;
EXPECT_FALSE(DefaultDie.getParent().isValid());
EXPECT_FALSE(DefaultDie.getFirstChild().isValid());
EXPECT_FALSE(DefaultDie.getSibling().isValid());
}
} // end anonymous namespace