[asan] Rename the ABI versioning symbol to '__asan_version_mismatch_check' instead of abusing '__asan_init'

We currently version `__asan_init` and when the ABI version doesn't match, the linker gives a `undefined reference to '__asan_init_v5'` message. From this, it might not be obvious that it's actually a version mismatch error. This patch makes the error message much clearer by changing the name of the undefined symbol to be `__asan_version_mismatch_check_xxx` (followed by the version string). We obviously don't want the initializer to be named like that, so it's a separate symbol that is used only for the purpose of version checking.

Reviewed at http://reviews.llvm.org/D11004



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243003 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/ModuleUtils.cpp

@@ -107,7 +107,8 @@ Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
 
 std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
     Module &M, StringRef CtorName, StringRef InitName,
-    ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs) {
+    ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
+    StringRef VersionCheckName) {
   assert(!InitName.empty() && "Expected init function name");
   assert(InitArgTypes.size() == InitArgTypes.size() &&
          "Sanitizer's init function expects different number of arguments");
@@ -122,6 +123,13 @@ std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
           AttributeSet()));
   InitFunction->setLinkage(Function::ExternalLinkage);
   IRB.CreateCall(InitFunction, InitArgs);
+  if (!VersionCheckName.empty()) {
+    Function *VersionCheckFunction =
+        checkSanitizerInterfaceFunction(M.getOrInsertFunction(
+            VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
+            AttributeSet()));
+    IRB.CreateCall(VersionCheckFunction, {});
+  }
   return std::make_pair(Ctor, InitFunction);
 }