[Clang] Add noalias to this pointer in C++ constructors

Author: guy-david

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -1552,6 +1552,9 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
   // Emit the standard function prologue.
   StartFunction(GD, ResTy, Fn, FnInfo, Args, Loc, BodyRange.getBegin());
 
+  if (isa<CXXConstructorDecl>(FD))
+    Fn->addParamAttr(0, llvm::Attribute::NoAlias);
+
   // Save parameters for coroutine function.
   if (Body && isa_and_nonnull<CoroutineBodyStmt>(Body))
     llvm::append_range(FnArgs, FD->parameters());