[asan] Delay creation of asan ctor.

Create the constructor in the module pass.
This in needed for the GC-friendly globals change, where the constructor can be
put in a comdat  in some cases, but we don't know about that in the function
pass.

This is a rebase of r298731 which was reverted due to a false alarm.

llvm-svn: 299695

include/llvm/Transforms/Utils/ModuleUtils.h

@@ -46,6 +46,9 @@ void appendToGlobalDtors(Module &M, Function *F, int Priority,
 // getOrInsertFunction returns a bitcast.
 Function *checkSanitizerInterfaceFunction(Constant *FuncOrBitcast);
 
+Function *declareSanitizerInitFunction(Module &M, StringRef InitName,
+                                       ArrayRef<Type *> InitArgTypes);
+
 /// \brief Creates sanitizer constructor function, and calls sanitizer's init
 /// function from it.
 /// \return Returns pair of pointers to constructor, and init functions

lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -576,8 +576,6 @@ struct AddressSanitizer : public FunctionPass {
   Type *IntptrTy;
   ShadowMapping Mapping;
   DominatorTree *DT;
-  Function *AsanCtorFunction = nullptr;
-  Function *AsanInitFunction = nullptr;
   Function *AsanHandleNoReturnFunc;
   Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
   // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
@@ -1936,13 +1934,19 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
   Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
   initializeCallbacks(M);
 
-  bool Changed = false;
+  if (CompileKernel)
+    return false;
 
+  Function *AsanCtorFunction;
+  std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
+      M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
+      /*InitArgs=*/{}, kAsanVersionCheckName);
+  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
+
+  bool Changed = false;
   // TODO(glider): temporarily disabled globals instrumentation for KASan.
-  if (ClGlobals && !CompileKernel) {
-    Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
-    assert(CtorFunc);
-    IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
+  if (ClGlobals) {
+    IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
     Changed |= InstrumentGlobals(IRB, M);
   }
 
@@ -2011,7 +2015,6 @@ void AddressSanitizer::initializeCallbacks(Module &M) {
 // virtual
 bool AddressSanitizer::doInitialization(Module &M) {
   // Initialize the private fields. No one has accessed them before.
-
   GlobalsMD.init(M);
 
   C = &(M.getContext());
@@ -2019,13 +2022,6 @@ bool AddressSanitizer::doInitialization(Module &M) {
   IntptrTy = Type::getIntNTy(*C, LongSize);
   TargetTriple = Triple(M.getTargetTriple());
 
-  if (!CompileKernel) {
-    std::tie(AsanCtorFunction, AsanInitFunction) =
-        createSanitizerCtorAndInitFunctions(
-            M, kAsanModuleCtorName, kAsanInitName,
-            /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
-    appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
-  }
   Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
   return true;
 }
@@ -2044,6 +2040,8 @@ bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
   // We cannot just ignore these methods, because they may call other
   // instrumented functions.
   if (F.getName().find(" load]") != std::string::npos) {
+    Function *AsanInitFunction =
+        declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
     IRBuilder<> IRB(&F.front(), F.front().begin());
     IRB.CreateCall(AsanInitFunction, {});
     return true;
@@ -2091,7 +2089,6 @@ void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
 }
 
 bool AddressSanitizer::runOnFunction(Function &F) {
-  if (&F == AsanCtorFunction) return false;
   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
   if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
   if (F.getName().startswith("__asan_")) return false;

lib/Transforms/Utils/ModuleUtils.cpp

@@ -138,6 +138,17 @@ Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
   report_fatal_error(Err);
 }
 
+Function *llvm::declareSanitizerInitFunction(Module &M, StringRef InitName,
+                                             ArrayRef<Type *> InitArgTypes) {
+  assert(!InitName.empty() && "Expected init function name");
+  Function *F = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
+      InitName,
+      FunctionType::get(Type::getVoidTy(M.getContext()), InitArgTypes, false),
+      AttributeList()));
+  F->setLinkage(Function::ExternalLinkage);
+  return F;
+}
+
 std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
     Module &M, StringRef CtorName, StringRef InitName,
     ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
@@ -145,16 +156,13 @@ std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
   assert(!InitName.empty() && "Expected init function name");
   assert(InitArgs.size() == InitArgTypes.size() &&
          "Sanitizer's init function expects different number of arguments");
+  Function *InitFunction =
+      declareSanitizerInitFunction(M, InitName, InitArgTypes);
   Function *Ctor = Function::Create(
       FunctionType::get(Type::getVoidTy(M.getContext()), false),
       GlobalValue::InternalLinkage, CtorName, &M);
   BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
   IRBuilder<> IRB(ReturnInst::Create(M.getContext(), CtorBB));
-  Function *InitFunction =
-      checkSanitizerInterfaceFunction(M.getOrInsertFunction(
-          InitName, FunctionType::get(IRB.getVoidTy(), InitArgTypes, false),
-          AttributeList()));
-  InitFunction->setLinkage(Function::ExternalLinkage);
   IRB.CreateCall(InitFunction, InitArgs);
   if (!VersionCheckName.empty()) {
     Function *VersionCheckFunction =

test/Instrumentation/AddressSanitizer/instrument_load_then_store.ll

@@ -16,10 +16,10 @@ entry:
 ; OPT1: IncrementMe
 ; OPT1: __asan_report_
 ; OPT1-NOT: __asan_report_
-; OPT1: asan.module_ctor
+; OPT1: ret void
 
 ; Without optimizations we should see two calls to __asan_report_*
 ; OPT0: IncrementMe
 ; OPT0: __asan_report_
 ; OPT0: __asan_report_
-; OPT0: asan.module_ctor
+; OPT0: ret void