Revert "Retry: [ubsan] Reduce null checking of C++ object pointers (PR27581)"

This reverts commit r295401. It breaks the ubsan self-host. It inserts
object size checks once per C++ method which fire when the structure is
empty.

llvm-svn: 295494
diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 1c6a577..ebe0841 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -290,15 +290,10 @@
   if (CE)
     CallLoc = CE->getExprLoc();
 
-  bool SkipNullCheck = false;
-  if (const auto *CMCE = dyn_cast<CXXMemberCallExpr>(CE))
-    SkipNullCheck =
-        CanElideObjectPointerNullCheck(CMCE->getImplicitObjectArgument());
-  EmitTypeCheck(
-      isa<CXXConstructorDecl>(CalleeDecl) ? CodeGenFunction::TCK_ConstructorCall
-                                          : CodeGenFunction::TCK_MemberCall,
-      CallLoc, This.getPointer(), C.getRecordType(CalleeDecl->getParent()),
-      /*Alignment=*/CharUnits::Zero(), SkipNullCheck);
+  EmitTypeCheck(isa<CXXConstructorDecl>(CalleeDecl)
+                ? CodeGenFunction::TCK_ConstructorCall
+                : CodeGenFunction::TCK_MemberCall,
+                CallLoc, This.getPointer(), C.getRecordType(CalleeDecl->getParent()));
 
   // FIXME: Uses of 'MD' past this point need to be audited. We may need to use
   // 'CalleeDecl' instead.