Add UWTable attr to functions with a personality function

Adding a personality function forces LLVM to generate unwinding info that might be incorrect.
To solve it, always apply the UWTable attribute when setting a personality function.

Fixes rust-lang#123733

compiler/rustc_codegen_llvm/src/builder.rs

@@ -1029,6 +1029,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn set_personality_fn(&mut self, personality: &'ll Value) {
+        // Work around for https://github.com/rust-lang/rust/issues/123733
+        // add the UWTable attribute to every function with a personality function.
+        let uwtable = llvm::AttributeKind::UWTable.create_attr(self.llcx);
+        attributes::apply_to_llfn(self.llfn(), llvm::AttributePlace::Function, &[uwtable]);
+
         unsafe {
             llvm::LLVMSetPersonalityFn(self.llfn(), personality);
         }