Revert "[Sanitizers] UBSan unreachable incompatible with ASan in the presence of `noreturn` calls"

This reverts commit cea84ab93aeb079a358ab1c8aeba6d9140ef8b47.

llvm-svn: 352069
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index bebefe5..a650493 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -4401,16 +4401,12 @@
     if (UnusedReturnSizePtr)
       PopCleanupBlock();
 
-    // Replace the noreturn attribute to better diagnose unreachable UB.
+    // Strip away the noreturn attribute to better diagnose unreachable UB.
     if (SanOpts.has(SanitizerKind::Unreachable)) {
-      // Also remove from function since CS.hasFnAttr(..) also checks attributes
-      // of the called function.
       if (auto *F = CS.getCalledFunction())
         F->removeFnAttr(llvm::Attribute::NoReturn);
       CS.removeAttribute(llvm::AttributeList::FunctionIndex,
                          llvm::Attribute::NoReturn);
-      CS.addAttribute(llvm::AttributeList::FunctionIndex,
-                      llvm::Attribute::ExpectNoReturn);
     }
 
     EmitUnreachable(Loc);