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[ELF] SymbolTable: change some vector<Symbol *> to SmallVector 

The generated assembly for Symbol::insert is much shorter (std::vector resize is
inefficient) and enables some inlining.
This commit is contained in:
Fangrui Song 2021-12-23 16:49:38 -08:00
parent 71b3bfde9c
commit 417cd2e5c5
2 changed files with 16 additions and 15 deletions
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14
lld/ELF/SymbolTable.cpp
View File

@ -133,7 +133,7 @@ static bool canBeVersioned(const Symbol &sym) {
// other than trying to match a pattern against all demangled symbols.
// So, if "extern C++" feature is used, we need to demangle all known
// symbols.
StringMap<std::vector<Symbol *>> &SymbolTable::getDemangledSyms() {
StringMap<SmallVector<Symbol *, 0>> &SymbolTable::getDemangledSyms() {
if (!demangledSyms) {
demangledSyms.emplace();
std::string demangled;
@ -154,7 +154,7 @@ StringMap<std::vector<Symbol *>> &SymbolTable::getDemangledSyms() {
return *demangledSyms;
}
std::vector<Symbol *> SymbolTable::findByVersion(SymbolVersion ver) {
SmallVector<Symbol *, 0> SymbolTable::findByVersion(SymbolVersion ver) {
if (ver.isExternCpp)
return getDemangledSyms().lookup(ver.name);
if (Symbol *sym = find(ver.name))
@ -163,9 +163,9 @@ std::vector<Symbol *> SymbolTable::findByVersion(SymbolVersion ver) {
return {};
}
std::vector<Symbol *> SymbolTable::findAllByVersion(SymbolVersion ver,
bool includeNonDefault) {
std::vector<Symbol *> res;
SmallVector<Symbol *, 0> SymbolTable::findAllByVersion(SymbolVersion ver,
bool includeNonDefault) {
SmallVector<Symbol *, 0> res;
SingleStringMatcher m(ver.name);
auto check = [&](StringRef name) {
size_t pos = name.find('@');
@ -191,8 +191,8 @@ std::vector<Symbol *> SymbolTable::findAllByVersion(SymbolVersion ver,
}
void SymbolTable::handleDynamicList() {
SmallVector<Symbol *, 0> syms;
for (SymbolVersion &ver : config->dynamicList) {
std::vector<Symbol *> syms;
if (ver.hasWildcard)
syms = findAllByVersion(ver, /*includeNonDefault=*/true);
else
@ -209,7 +209,7 @@ bool SymbolTable::assignExactVersion(SymbolVersion ver, uint16_t versionId,
StringRef versionName,
bool includeNonDefault) {
// Get a list of symbols which we need to assign the version to.
std::vector<Symbol *> syms = findByVersion(ver);
SmallVector<Symbol *, 0> syms = findByVersion(ver);
auto getName = [](uint16_t ver) -> std::string {
if (ver == VER_NDX_LOCAL)

17
lld/ELF/SymbolTable.h
View File

@ -35,8 +35,9 @@ class SymbolTable {
struct FilterOutPlaceholder {
bool operator()(Symbol *S) const { return !S->isPlaceholder(); }
};
using iterator = llvm::filter_iterator<std::vector<Symbol *>::const_iterator,
FilterOutPlaceholder>;
using iterator =
llvm::filter_iterator<SmallVector<Symbol *, 0>::const_iterator,
FilterOutPlaceholder>;
public:
llvm::iterator_range<iterator> symbols() const {
@ -64,11 +65,11 @@ public:
llvm::DenseMap<llvm::CachedHashStringRef, const InputFile *> comdatGroups;
private:
std::vector<Symbol *> findByVersion(SymbolVersion ver);
std::vector<Symbol *> findAllByVersion(SymbolVersion ver,
bool includeNonDefault);
SmallVector<Symbol *, 0> findByVersion(SymbolVersion ver);
SmallVector<Symbol *, 0> findAllByVersion(SymbolVersion ver,
bool includeNonDefault);
llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
llvm::StringMap<SmallVector<Symbol *, 0>> &getDemangledSyms();
bool assignExactVersion(SymbolVersion ver, uint16_t versionId,
StringRef versionName, bool includeNonDefault);
void assignWildcardVersion(SymbolVersion ver, uint16_t versionId,
@ -82,13 +83,13 @@ private:
// FIXME: Experiment with passing in a custom hashing or sorting the symbols
// once symbol resolution is finished.
llvm::DenseMap<llvm::CachedHashStringRef, int> symMap;
std::vector<Symbol *> symVector;
SmallVector<Symbol *, 0> symVector;
// A map from demangled symbol names to their symbol objects.
// This mapping is 1:N because two symbols with different versions
// can have the same name. We use this map to handle "extern C++ {}"
// directive in version scripts.
llvm::Optional<llvm::StringMap<std::vector<Symbol *>>> demangledSyms;
llvm::Optional<llvm::StringMap<SmallVector<Symbol *, 0>>> demangledSyms;
};
extern std::unique_ptr<SymbolTable> symtab;