Enable dead function removal for internal function in whole-module compilation.

This is controlled by a new isWholeModule() attribute in SILModule.

It gives about 9% code size reduction on the benchmark executables.
For test-suite reasons it is currently not done for the stdlib.



Swift SVN r22491

lib/SIL/SILModule.cpp

@@ -18,6 +18,7 @@
 #include "swift/Serialization/SerializedSILLoader.h"
 #include "swift/SIL/SILValue.h"
 #include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/Debug.h"
@@ -91,10 +92,11 @@ class SILModule::SerializationCallback : public SerializedSILLoader::Callback {
   }
 };
 
-SILModule::SILModule(Module *SwiftModule, const DeclContext *associatedDC)
+SILModule::SILModule(Module *SwiftModule, const DeclContext *associatedDC,
+                     bool wholeModule)
   : TheSwiftModule(SwiftModule), AssociatedDeclContext(associatedDC),
     Stage(SILStage::Raw), Callback(new SILModule::SerializationCallback()),
-    Types(*this) {
+    wholeModule(wholeModule), Types(*this) {
   TypeListUniquing = new SILTypeListUniquingType();
 }
 
@@ -663,6 +665,12 @@ private:
 
 } // end anonymous namespace.
 
+SILFunction *SILModule::lookUpFunction(SILDeclRef fnRef) {
+  llvm::SmallString<32> name;
+  fnRef.mangle(name);
+  return lookUpFunction(name);
+}
+
 bool SILModule::linkFunction(SILFunction *Fun, SILModule::LinkingMode Mode) {
   return SILLinkerVisitor(*this, getSILLoader(), Mode,
                           ExternalSource).processFunction(Fun);