feat: add gradient and adjoints wrt inputs (#45)

* added sens function to llvm and updating interface

* add tests for sgrad and srgrad

* tests for sgrad and srgrad seem to work

* add mass_rgrad

* fix some interface sigs, check for reserved names

* fix llvm intrinsic bug

* cranelift grad impl dupnoneed

* cargo fmt

src/discretise/discrete_model.rs

@@ -101,6 +101,27 @@ impl<'s> DiscreteModel<'s> {
 
     fn build_array(array: &ast::Tensor<'s>, env: &mut Env) -> Option<Tensor<'s>> {
         let rank = array.indices().len();
+        let reserved_names = [
+            "u0",
+            "t",
+            "data",
+            "root",
+            "thread_id",
+            "thread_dim",
+            "rr",
+            "states",
+            "inputs",
+            "outputs",
+            "hass_mass",
+        ];
+        if reserved_names.contains(&array.name()) {
+            let span = env.current_span().to_owned();
+            env.errs_mut().push(ValidationError::new(
+                format!("{} is a reserved name", array.name()),
+                span,
+            ));
+            return None;
+        }
         let mut elmts = Vec::new();
         let mut start = Index::zeros(rank);
         let nerrs = env.errs().len();
@@ -148,6 +169,16 @@ impl<'s> DiscreteModel<'s> {
                             i64::try_from(elmt_layout.shape()[0]).unwrap()
                         };
 
+                        if reserved_names
+                            .contains(&name.as_ref().unwrap_or(&"".to_string()).as_str())
+                        {
+                            let span = env.current_span().to_owned();
+                            env.errs_mut().push(ValidationError::new(
+                                format!("{} is a reserved name", name.as_ref().unwrap()),
+                                span,
+                            ));
+                        }
+
                         elmts.push(TensorBlock::new(
                             name,
                             start.clone(),
@@ -446,7 +477,7 @@ impl<'s> DiscreteModel<'s> {
                     None,
                 )],
             );
-            ret.out = Self::build_array(&out_tensor, &mut env).unwrap();
+            ret.out = Self::build_array(&out_tensor, &mut env).unwrap_or(Tensor::new_empty("out"));
         }
         if let Some(span) = span_f {
             Self::check_match(&ret.rhs, &ret.state, span, &mut env);