[ASan] Turned on callback optimization on by default.

[kstoimenov]

Summary

This will only affect projects, which use callbacks for code instrumentation.

[kstoimenov]

Removed some debug printfs.

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

 // Optimization flags. Not user visible, used mostly for testing
 // and benchmarking the tool.
 
 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
                            cl::Hidden, cl::init(true));
 
 static cl::opt<bool> ClOptimizeCallbacks("asan-optimize-callbacks",
                                          cl::desc("Optimize callbacks"),
-                                         cl::Hidden, cl::init(false));
+                                         cl::Hidden, cl::init(true));
 
 static cl::opt<bool> ClOptSameTemp(
     "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
     cl::Hidden, cl::init(true));
 
 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
                                   cl::desc("Don't instrument scalar globals"),
                                   cl::Hidden, cl::init(true));
bool ShouldInstrument =
       ClDebugMin < 0 || ClDebugMax < 0 ||
       (Instrumented >= ClDebugMin && Instrumented <= ClDebugMax);
   Instrumented++;
   return !ShouldInstrument;
 }
 
 bool AddressSanitizer::instrumentFunction(Function &F,
                                           const TargetLibraryInfo *TLI) {
+  printf("ZXCV3(%p): %s, %d\n", &F, F.getName().data(), F.getLinkage());
   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
   if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
   if (F.getName().startswith("__asan_")) return false;
 
   bool FunctionModified = false;
 
   // If needed, insert __asan_init before checking for SanitizeAddress attr.
   // This function needs to be called even if the function body is not
   // instrumented.
   if (maybeInsertAsanInitAtFunctionEntry(F))
     FunctionModified = true;
 
   // Leave if the function doesn't need instrumentation.
   if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
 
+  printf("ZXCV1(%p): %s, %d\n", &F, F.getName().data(), F.getLinkage());
+
   LLVM_DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
 
   initializeCallbacks(*F.getParent());
 
   FunctionStateRAII CleanupObj(this);
 
   FunctionModified |= maybeInsertDynamicShadowAtFunctionEntry(F);