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[DWARF parser] Compress DIEMinimal even further, simplify building DIE tree.

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DIE doesn't need to store a pointer to its parent: we can traverse the DIE tree
only with functions getFirstChild() and getSibling(). Parents must be known
only when we construct the tree. Rewrite setDIERelations() procedure in a more
straightforward way, and get rid of lots of now unused DIEMinimal methods.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207563 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexey Samsonov 2014-04-29 17:12:42 +00:00
parent f38f17c463
commit b58db2293d
2 changed files with 28 additions and 61 deletions
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36
lib/DebugInfo/DWARFDebugInfoEntry.h
View File

@ -29,17 +29,13 @@ class DWARFDebugInfoEntryMinimal {
/// Offset within the .debug_info of the start of this entry.
uint32_t Offset;
/// How many to subtract from "this" to get the parent.
/// If zero this die has no parent.
uint32_t ParentIdx;
/// How many to add to "this" to get the sibling.
uint32_t SiblingIdx;
const DWARFAbbreviationDeclaration *AbbrevDecl;
public:
DWARFDebugInfoEntryMinimal()
: Offset(0), ParentIdx(0), SiblingIdx(0), AbbrevDecl(nullptr) {}
: Offset(0), SiblingIdx(0), AbbrevDecl(nullptr) {}
void dump(raw_ostream &OS, const DWARFUnit *u, unsigned recurseDepth,
unsigned indent = 0) const;
@ -63,46 +59,24 @@ public:
uint32_t getOffset() const { return Offset; }
bool hasChildren() const { return !isNULL() && AbbrevDecl->hasChildren(); }
// We know we are kept in a vector of contiguous entries, so we know
// our parent will be some index behind "this".
DWARFDebugInfoEntryMinimal *getParent() {
return ParentIdx > 0 ? this - ParentIdx : nullptr;
}
const DWARFDebugInfoEntryMinimal *getParent() const {
return ParentIdx > 0 ? this - ParentIdx : nullptr;
}
// We know we are kept in a vector of contiguous entries, so we know
// our sibling will be some index after "this".
DWARFDebugInfoEntryMinimal *getSibling() {
return SiblingIdx > 0 ? this + SiblingIdx : nullptr;
}
const DWARFDebugInfoEntryMinimal *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...
DWARFDebugInfoEntryMinimal *getFirstChild() {
return hasChildren() ? this + 1 : nullptr;
}
const DWARFDebugInfoEntryMinimal *getFirstChild() const {
return hasChildren() ? this + 1 : nullptr;
}
void setParent(DWARFDebugInfoEntryMinimal *parent) {
if (parent) {
// We know we are kept in a vector of contiguous entries, so we know
// our parent will be some index behind "this".
ParentIdx = this - parent;
} else
ParentIdx = 0;
}
void setSibling(DWARFDebugInfoEntryMinimal *sibling) {
if (sibling) {
void setSibling(const DWARFDebugInfoEntryMinimal *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;
sibling->setParent(getParent());
SiblingIdx = Sibling - this;
} else
SiblingIdx = 0;
}

53
lib/DebugInfo/DWARFUnit.cpp
View File

@ -126,38 +126,32 @@ uint64_t DWARFUnit::getDWOId() {
}
void DWARFUnit::setDIERelations() {
if (DieArray.empty())
if (DieArray.size() <= 1)
return;
DWARFDebugInfoEntryMinimal *die_array_begin = &DieArray.front();
DWARFDebugInfoEntryMinimal *die_array_end = &DieArray.back();
DWARFDebugInfoEntryMinimal *curr_die;
// We purposely are skipping the last element in the array in the loop below
// so that we can always have a valid next item
for (curr_die = die_array_begin; curr_die < die_array_end; ++curr_die) {
// Since our loop doesn't include the last element, we can always
// safely access the next die in the array.
DWARFDebugInfoEntryMinimal *next_die = curr_die + 1;
const DWARFAbbreviationDeclaration *curr_die_abbrev =
curr_die->getAbbreviationDeclarationPtr();
if (curr_die_abbrev) {
// Normal DIE
if (curr_die_abbrev->hasChildren())
next_die->setParent(curr_die);
else
curr_die->setSibling(next_die);
std::vector<DWARFDebugInfoEntryMinimal *> ParentChain;
DWARFDebugInfoEntryMinimal *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 DIE that terminates a sibling chain
DWARFDebugInfoEntryMinimal *parent = curr_die->getParent();
if (parent)
parent->setSibling(next_die);
// NULL entry terminates the sibling chain.
SiblingChain = ParentChain.back();
ParentChain.pop_back();
}
}
// Since we skipped the last element, we need to fix it up!
if (die_array_begin < die_array_end)
curr_die->setParent(die_array_begin);
assert(SiblingChain == nullptr || SiblingChain == &DieArray[0]);
assert(ParentChain.empty());
}
void DWARFUnit::extractDIEsToVector(
@ -189,9 +183,8 @@ void DWARFUnit::extractDIEsToVector(
Dies.push_back(DIE);
}
const DWARFAbbreviationDeclaration *AbbrDecl =
DIE.getAbbreviationDeclarationPtr();
if (AbbrDecl) {
if (const DWARFAbbreviationDeclaration *AbbrDecl =
DIE.getAbbreviationDeclarationPtr()) {
// Normal DIE
if (AbbrDecl->hasChildren())
++Depth;