ASan: Use `createSanitizerCtor` to create ctor, and call `__asan_init`

[ismailp]

Updated after changes in D8777;

• createSanitizerCtor renamed to createSanitizerCtorAndInitFunctions to match with changes in D8777
• Added simple check to ensure ASan's ctor is added to module ctors, and __asan_init_v5 is called from ctor

[samsonov]

LGTM

lib/Transforms/Instrumentation/AddressSanitizer.cpp

bool AddressSanitizer::doInitialization(Module &M) {
 
   GlobalsMD.init(M);
 
   C = &(M.getContext());
   LongSize = M.getDataLayout().getPointerSizeInBits();
   IntptrTy = Type::getIntNTy(*C, LongSize);
   TargetTriple = Triple(M.getTargetTriple());
 
-  AsanCtorFunction =
-      Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
-                       GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
-  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
-  // call __asan_init in the module ctor.
-  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
-  AsanInitFunction = checkSanitizerInterfaceFunction(
-      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
-  AsanInitFunction->setLinkage(Function::ExternalLinkage);
-  IRB.CreateCall(AsanInitFunction);
+  std::tie(AsanCtorFunction, AsanInitFunction) =
+      createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName,
+                                          /*InitArgTypes=*/{},
+                                          /*InitArgs=*/{});
 
   Mapping = getShadowMapping(TargetTriple, LongSize);
 
   appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
   return true;
 }
 
 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {

test/Instrumentation/AddressSanitizer/basic.ll

 ; Test basic address sanitizer instrumentation.
 ;
 ; RUN: opt < %s -asan -asan-module -S | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-unknown-linux-gnu"
+; CHECK: @llvm.global_ctors = {{.*}}@asan.module_ctor
 
 define i32 @test_load(i32* %a) sanitize_address {
 ; CHECK-LABEL: @test_load
 ; CHECK-NOT: load
 ; CHECK:   %[[LOAD_ADDR:[^ ]*]] = ptrtoint i32* %a to i64
 ; CHECK:   lshr i64 %[[LOAD_ADDR]], 3
 ; CHECK:   {{or|add}}
 ; CHECK:   %[[LOAD_SHADOW_PTR:[^ ]*]] = inttoptr

 }
 
 ; CHECK-LABEL: memintr_test
 ; CHECK: __asan_memset
 ; CHECK: __asan_memmove
 ; CHECK: __asan_memcpy
 ; CHECK: ret void
 
+; CHECK: define internal void @asan.module_ctor()
+; CHECK: call void @__asan_init_v5()
+
 ; PROF
 ; CHECK: ![[PROF]] = !{!"branch_weights", i32 1, i32 100000}