[llvm] r177178 - [ADT] Fix StringSet::insert() to not allocate on every lookup.
Daniel Dunbar
daniel at zuster.org
Fri Mar 15 13:16:59 PDT 2013
Author: ddunbar
Date: Fri Mar 15 15:16:59 2013
New Revision: 177178
URL: http://llvm.org/viewvc/llvm-project?rev=177178&view=rev
Log:
[ADT] Fix StringSet::insert() to not allocate on every lookup.
- The previous implementation always constructed the StringMap entry, even if
the key was present in the set.
Modified:
llvm/trunk/include/llvm/ADT/StringSet.h
Modified: llvm/trunk/include/llvm/ADT/StringSet.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/StringSet.h?rev=177178&r1=177177&r2=177178&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/StringSet.h (original)
+++ llvm/trunk/include/llvm/ADT/StringSet.h Fri Mar 15 15:16:59 2013
@@ -18,23 +18,25 @@
namespace llvm {
- /// StringSet - A wrapper for StringMap that provides set-like
- /// functionality. Only insert() and count() methods are used by my
- /// code.
+ /// StringSet - A wrapper for StringMap that provides set-like functionality.
template <class AllocatorTy = llvm::MallocAllocator>
class StringSet : public llvm::StringMap<char, AllocatorTy> {
typedef llvm::StringMap<char, AllocatorTy> base;
public:
- bool insert(StringRef InLang) {
- assert(!InLang.empty());
- const char *KeyStart = InLang.data();
- const char *KeyEnd = KeyStart + InLang.size();
- llvm::StringMapEntry<char> *Entry = llvm::StringMapEntry<char>::
- Create(KeyStart, KeyEnd, base::getAllocator(), '+');
- if (!base::insert(Entry)) {
- Entry->Destroy(base::getAllocator());
+
+ /// insert - Insert the specified key into the set. If the key already
+ /// exists in the set, return false and ignore the request, otherwise insert
+ /// it and return true.
+ bool insert(StringRef Key) {
+ // Get or create the map entry for the key; if it doesn't exist the value
+ // type will be default constructed which we use to detect insert.
+ //
+ // We use '+' as the sentinel value in the map.
+ assert(!Key.empty());
+ StringMapEntry<char> &Entry = this->GetOrCreateValue(Key);
+ if (Entry.getValue() == '+')
return false;
- }
+ Entry.setValue('+');
return true;
}
};
More information about the llvm-commits
mailing list