[lld] r318072 - Remove a std::map and std::set that show up in LLD profiles

[Reid Kleckner via llvm-commits]

Author: rnk
Date: Mon Nov 13 10:38:53 2017
New Revision: 318072

URL: http://llvm.org/viewvc/llvm-project?rev=318072&view=rev
Log:
Remove a std::map and std::set that show up in LLD profiles

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

Modified:
    lld/trunk/COFF/Config.h
    lld/trunk/COFF/Driver.cpp
    lld/trunk/COFF/Symbols.h

Modified: lld/trunk/COFF/Config.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Config.h?rev=318072&r1=318071&r2=318072&view=diff
==============================================================================
--- lld/trunk/COFF/Config.h (original)
+++ lld/trunk/COFF/Config.h Mon Nov 13 10:38:53 2017
@@ -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;

Modified: lld/trunk/COFF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=318072&r1=318071&r2=318072&view=diff
==============================================================================
--- lld/trunk/COFF/Driver.cpp (original)
+++ lld/trunk/COFF/Driver.cpp Mon Nov 13 10:38:53 2017
@@ -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;
 }
 

Modified: lld/trunk/COFF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Symbols.h?rev=318072&r1=318071&r2=318072&view=diff
==============================================================================
--- lld/trunk/COFF/Symbols.h (original)
+++ lld/trunk/COFF/Symbols.h Mon Nov 13 10:38:53 2017
@@ -77,7 +77,8 @@ protected:
   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 @@ public:
   // 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;
 };