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Resolver: optimize fallback atoms. 

Atoms with fallback atoms are never be added to the symbol table.
However, we added such atoms to _undefines array. We had to call
isCoalescedAway to identify and skip them. We should just stop
adding them in the first place.

This seems to make the linker ~1% faster in my test case.

llvm-svn: 231552
This commit is contained in:
Rui Ueyama 2015-03-07 04:23:46 +00:00
parent abd39f0549
commit 9b21ded6c8
1 changed files with 4 additions and 5 deletions
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9
lld/lib/Core/Resolver.cpp
View File

@ -54,8 +54,7 @@ void Resolver::forEachUndefines(File &file, bool searchForOverrides,
StringRef undefName = _undefines[i];
if (undefName.empty())
continue;
const Atom *atom = _symbolTable.findByName(undefName);
if (!isa<UndefinedAtom>(atom) || _symbolTable.isCoalescedAway(atom)) {
if (_symbolTable.isDefined(undefName)) {
// The symbol was resolved by some other file. Cache the result.
_undefines[i] = "";
continue;
@ -119,18 +118,18 @@ bool Resolver::doUndefinedAtom(const UndefinedAtom &atom) {
// tell symbol table
bool newUndefAdded = _symbolTable.add(atom);
if (newUndefAdded)
_undefines.push_back(atom.name());
// If the undefined symbol has an alternative name, try to resolve the
// symbol with the name to give it a second chance. This feature is used
// for COFF "weak external" symbol.
if (newUndefAdded || !_symbolTable.isDefined(atom.name())) {
if (const UndefinedAtom *fallbackAtom = atom.fallback()) {
doUndefinedAtom(*fallbackAtom);
_symbolTable.addReplacement(&atom, fallbackAtom);
return doUndefinedAtom(*fallbackAtom);
}
}
if (newUndefAdded)
_undefines.push_back(atom.name());
return newUndefAdded;
}