Remove a std::map and std::set that show up in LLD profiles

rnk · rnk · commit 5883989e5144 · 2017-11-13T18:38:53.000Z
For GC roots, add a bit to SymbolBody to ensure that we don't add the same root twice, and switch to a vector. In addition to being faster, this may also fix some latent non-determinism. We iterate the GCRoot list later and it the order should be deterministic. For fixupExports, we can just use DenseMap. This is a simple string uniquing task, and we don't iterate the map. Reviewers: ruiu Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D39609 llvm-svn: 318072
diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
@@ -94,7 +94,7 @@ struct Configuration {
   std::vector<llvm::StringRef> Argv;
 
   // Symbols in this set are considered as live by the garbage collector.
-  std::set<Symbol *> GCRoot;
+  std::vector<Symbol *> GCRoot;
 
   std::set<StringRef> NoDefaultLibs;
   bool NoDefaultLibAll = false;
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
@@ -355,7 +355,10 @@ void LinkerDriver::addLibSearchPaths() {
 
 Symbol *LinkerDriver::addUndefined(StringRef Name) {
   Symbol *B = Symtab->addUndefined(Name);
-  Config->GCRoot.insert(B);
+  if (!B->IsGCRoot) {
+    B->IsGCRoot = true;
+    Config->GCRoot.push_back(B);
+  }
   return B;
 }
 
diff --git a/lld/COFF/Symbols.h b/lld/COFF/Symbols.h
@@ -77,7 +77,8 @@ class Symbol {
   friend SymbolTable;
   explicit Symbol(Kind K, StringRef N = "")
       : SymbolKind(K), IsExternal(true), IsCOMDAT(false),
-        WrittenToSymtab(false), Name(N) {}
+        WrittenToSymtab(false), PendingArchiveLoad(false), IsGCRoot(false),
+        Name(N) {}
 
   const unsigned SymbolKind : 8;
   unsigned IsExternal : 1;
@@ -98,6 +99,9 @@ class Symbol {
   // not load any more archive members to resolve the same symbol.
   unsigned PendingArchiveLoad : 1;
 
+  /// True if we've already added this symbol to the list of GC roots.
+  unsigned IsGCRoot : 1;
+
 protected:
   StringRef Name;
 };
