Rollup merge of #138627 - EnzymeAD:autodiff-cleanups, r=oli-obk

Autodiff cleanups

Splitting out some cleanups to reduce the size of my batching PR and simplify ``@haenoe`` 's [PR](https://github.com/rust-lang/rust/pull/138314).

r? ``@oli-obk``

Tracking:

- https://github.com/rust-lang/rust/issues/124509

compiler/rustc_builtin_macros/src/autodiff.rs

@@ -26,6 +26,16 @@ mod llvm_enzyme {
 
     use crate::errors;
 
+    pub(crate) fn outer_normal_attr(
+        kind: &P<rustc_ast::NormalAttr>,
+        id: rustc_ast::AttrId,
+        span: Span,
+    ) -> rustc_ast::Attribute {
+        let style = rustc_ast::AttrStyle::Outer;
+        let kind = rustc_ast::AttrKind::Normal(kind.clone());
+        rustc_ast::Attribute { kind, id, style, span }
+    }
+
     // If we have a default `()` return type or explicitley `()` return type,
     // then we often can skip doing some work.
     fn has_ret(ty: &FnRetTy) -> bool {
@@ -224,20 +234,8 @@ mod llvm_enzyme {
             .filter(|a| **a == DiffActivity::Active || **a == DiffActivity::ActiveOnly)
             .count() as u32;
         let (d_sig, new_args, idents, errored) = gen_enzyme_decl(ecx, &sig, &x, span);
-        let new_decl_span = d_sig.span;
         let d_body = gen_enzyme_body(
-            ecx,
+            ecx, &x, n_active, &sig, &d_sig, primal, &new_args, span, sig_span, idents, errored,
-            &x,
-            n_active,
-            &sig,
-            &d_sig,
-            primal,
-            &new_args,
-            span,
-            sig_span,
-            new_decl_span,
-            idents,
-            errored,
         );
         let d_ident = first_ident(&meta_item_vec[0]);
 
@@ -270,36 +268,39 @@ mod llvm_enzyme {
         };
         let inline_never_attr = P(ast::NormalAttr { item: inline_item, tokens: None });
         let new_id = ecx.sess.psess.attr_id_generator.mk_attr_id();
-        let attr: ast::Attribute = ast::Attribute {
+        let attr = outer_normal_attr(&rustc_ad_attr, new_id, span);
-            kind: ast::AttrKind::Normal(rustc_ad_attr.clone()),
-            id: new_id,
-            style: ast::AttrStyle::Outer,
-            span,
-        };
         let new_id = ecx.sess.psess.attr_id_generator.mk_attr_id();
-        let inline_never: ast::Attribute = ast::Attribute {
+        let inline_never = outer_normal_attr(&inline_never_attr, new_id, span);
-            kind: ast::AttrKind::Normal(inline_never_attr),
+
-            id: new_id,
+        // We're avoid duplicating the attributes `#[rustc_autodiff]` and `#[inline(never)]`.
-            style: ast::AttrStyle::Outer,
+        fn same_attribute(attr: &ast::AttrKind, item: &ast::AttrKind) -> bool {
-            span,
+            match (attr, item) {
-        };
+                (ast::AttrKind::Normal(a), ast::AttrKind::Normal(b)) => {
+                    let a = &a.item.path;
+                    let b = &b.item.path;
+                    a.segments.len() == b.segments.len()
+                        && a.segments.iter().zip(b.segments.iter()).all(|(a, b)| a.ident == b.ident)
+                }
+                _ => false,
+            }
+        }
 
         // Don't add it multiple times:
         let orig_annotatable: Annotatable = match item {
             Annotatable::Item(ref mut iitem) => {
-                if !iitem.attrs.iter().any(|a| a.id == attr.id) {
+                if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     iitem.attrs.push(attr);
                 }
-                if !iitem.attrs.iter().any(|a| a.id == inline_never.id) {
+                if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
                     iitem.attrs.push(inline_never.clone());
                 }
                 Annotatable::Item(iitem.clone())
             }
             Annotatable::AssocItem(ref mut assoc_item, i @ Impl) => {
-                if !assoc_item.attrs.iter().any(|a| a.id == attr.id) {
+                if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     assoc_item.attrs.push(attr);
                 }
-                if !assoc_item.attrs.iter().any(|a| a.id == inline_never.id) {
+                if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
                     assoc_item.attrs.push(inline_never.clone());
                 }
                 Annotatable::AssocItem(assoc_item.clone(), i)
@@ -314,13 +315,7 @@ mod llvm_enzyme {
             delim: rustc_ast::token::Delimiter::Parenthesis,
             tokens: ts,
         });
-        let d_attr: ast::Attribute = ast::Attribute {
+        let d_attr = outer_normal_attr(&rustc_ad_attr, new_id, span);
-            kind: ast::AttrKind::Normal(rustc_ad_attr.clone()),
-            id: new_id,
-            style: ast::AttrStyle::Outer,
-            span,
-        };
-
         let d_annotatable = if is_impl {
             let assoc_item: AssocItemKind = ast::AssocItemKind::Fn(asdf);
             let d_fn = P(ast::AssocItem {
@@ -361,30 +356,27 @@ mod llvm_enzyme {
         ty
     }
 
-    /// We only want this function to type-check, since we will replace the body
+    // Will generate a body of the type:
-    /// later on llvm level. Using `loop {}` does not cover all return types anymore,
+    // ```
-    /// so instead we build something that should pass. We also add a inline_asm
+    // {
-    /// line, as one more barrier for rustc to prevent inlining of this function.
+    //   unsafe {
-    /// FIXME(ZuseZ4): We still have cases of incorrect inlining across modules, see
+    //   asm!("NOP");
-    /// <https://github.com/EnzymeAD/rust/issues/173>, so this isn't sufficient.
+    //   }
-    /// It also triggers an Enzyme crash if we due to a bug ever try to differentiate
+    //   ::core::hint::black_box(primal(args));
-    /// this function (which should never happen, since it is only a placeholder).
+    //   ::core::hint::black_box((args, ret));
-    /// Finally, we also add back_box usages of all input arguments, to prevent rustc
+    //   <This part remains to be done by following function>
-    /// from optimizing any arguments away.
+    // }
-    fn gen_enzyme_body(
+    // ```
+    fn init_body_helper(
         ecx: &ExtCtxt<'_>,
-        x: &AutoDiffAttrs,
+        span: Span,
-        n_active: u32,
-        sig: &ast::FnSig,
-        d_sig: &ast::FnSig,
         primal: Ident,
         new_names: &[String],
-        span: Span,
         sig_span: Span,
         new_decl_span: Span,
-        idents: Vec<Ident>,
+        idents: &[Ident],
         errored: bool,
-    ) -> P<ast::Block> {
+    ) -> (P<ast::Block>, P<ast::Expr>, P<ast::Expr>, P<ast::Expr>) {
         let blackbox_path = ecx.std_path(&[sym::hint, sym::black_box]);
         let noop = ast::InlineAsm {
             asm_macro: ast::AsmMacro::Asm,
@@ -433,6 +425,51 @@ mod llvm_enzyme {
         }
         body.stmts.push(ecx.stmt_semi(black_box_remaining_args));
 
+        (body, primal_call, black_box_primal_call, blackbox_call_expr)
+    }
+
+    /// We only want this function to type-check, since we will replace the body
+    /// later on llvm level. Using `loop {}` does not cover all return types anymore,
+    /// so instead we manually build something that should pass the type checker.
+    /// We also add a inline_asm line, as one more barrier for rustc to prevent inlining
+    /// or const propagation. inline_asm will also triggers an Enzyme crash if due to another
+    /// bug would ever try to accidentially differentiate this placeholder function body.
+    /// Finally, we also add back_box usages of all input arguments, to prevent rustc
+    /// from optimizing any arguments away.
+    fn gen_enzyme_body(
+        ecx: &ExtCtxt<'_>,
+        x: &AutoDiffAttrs,
+        n_active: u32,
+        sig: &ast::FnSig,
+        d_sig: &ast::FnSig,
+        primal: Ident,
+        new_names: &[String],
+        span: Span,
+        sig_span: Span,
+        idents: Vec<Ident>,
+        errored: bool,
+    ) -> P<ast::Block> {
+        let new_decl_span = d_sig.span;
+
+        // Just adding some default inline-asm and black_box usages to prevent early inlining
+        // and optimizations which alter the function signature.
+        //
+        // The bb_primal_call is the black_box call of the primal function. We keep it around,
+        // since it has the convenient property of returning the type of the primal function,
+        // Remember, we only care to match types here.
+        // No matter which return we pick, we always wrap it into a std::hint::black_box call,
+        // to prevent rustc from propagating it into the caller.
+        let (mut body, primal_call, bb_primal_call, bb_call_expr) = init_body_helper(
+            ecx,
+            span,
+            primal,
+            new_names,
+            sig_span,
+            new_decl_span,
+            &idents,
+            errored,
+        );
+
         if !has_ret(&d_sig.decl.output) {
             // there is no return type that we have to match, () works fine.
             return body;
@@ -444,7 +481,7 @@ mod llvm_enzyme {
 
         if primal_ret && n_active == 0 && x.mode.is_rev() {
             // We only have the primal ret.
-            body.stmts.push(ecx.stmt_expr(black_box_primal_call));
+            body.stmts.push(ecx.stmt_expr(bb_primal_call));
             return body;
         }
 
@@ -536,11 +573,11 @@ mod llvm_enzyme {
                 return body;
             }
             [arg] => {
-                ret = ecx.expr_call(new_decl_span, blackbox_call_expr, thin_vec![arg.clone()]);
+                ret = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![arg.clone()]);
             }
             args => {
                 let ret_tuple: P<ast::Expr> = ecx.expr_tuple(span, args.into());
-                ret = ecx.expr_call(new_decl_span, blackbox_call_expr, thin_vec![ret_tuple]);
+                ret = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![ret_tuple]);
             }
         }
         assert!(has_ret(&d_sig.decl.output));
@@ -553,7 +590,7 @@ mod llvm_enzyme {
         ecx: &ExtCtxt<'_>,
         span: Span,
         primal: Ident,
-        idents: Vec<Ident>,
+        idents: &[Ident],
     ) -> P<ast::Expr> {
         let has_self = idents.len() > 0 && idents[0].name == kw::SelfLower;
         if has_self {

compiler/rustc_codegen_llvm/src/builder/autodiff.rs

@@ -28,6 +28,113 @@ fn get_params(fnc: &Value) -> Vec<&Value> {
     }
 }
 
+fn match_args_from_caller_to_enzyme<'ll>(
+    cx: &SimpleCx<'ll>,
+    args: &mut Vec<&'ll llvm::Value>,
+    inputs: &[DiffActivity],
+    outer_args: &[&'ll llvm::Value],
+) {
+    debug!("matching autodiff arguments");
+    // We now handle the issue that Rust level arguments not always match the llvm-ir level
+    // arguments. A slice, `&[f32]`, for example, is represented as a pointer and a length on
+    // llvm-ir level. The number of activities matches the number of Rust level arguments, so we
+    // need to match those.
+    // FIXME(ZuseZ4): This logic is a bit more complicated than it should be, can we simplify it
+    // using iterators and peek()?
+    let mut outer_pos: usize = 0;
+    let mut activity_pos = 0;
+
+    let enzyme_const = cx.create_metadata("enzyme_const".to_string()).unwrap();
+    let enzyme_out = cx.create_metadata("enzyme_out".to_string()).unwrap();
+    let enzyme_dup = cx.create_metadata("enzyme_dup".to_string()).unwrap();
+    let enzyme_dupnoneed = cx.create_metadata("enzyme_dupnoneed".to_string()).unwrap();
+
+    while activity_pos < inputs.len() {
+        let diff_activity = inputs[activity_pos as usize];
+        // Duplicated arguments received a shadow argument, into which enzyme will write the
+        // gradient.
+        let (activity, duplicated): (&Metadata, bool) = match diff_activity {
+            DiffActivity::None => panic!("not a valid input activity"),
+            DiffActivity::Const => (enzyme_const, false),
+            DiffActivity::Active => (enzyme_out, false),
+            DiffActivity::ActiveOnly => (enzyme_out, false),
+            DiffActivity::Dual => (enzyme_dup, true),
+            DiffActivity::DualOnly => (enzyme_dupnoneed, true),
+            DiffActivity::Duplicated => (enzyme_dup, true),
+            DiffActivity::DuplicatedOnly => (enzyme_dupnoneed, true),
+            DiffActivity::FakeActivitySize => (enzyme_const, false),
+        };
+        let outer_arg = outer_args[outer_pos];
+        args.push(cx.get_metadata_value(activity));
+        args.push(outer_arg);
+        if duplicated {
+            // We know that duplicated args by construction have a following argument,
+            // so this can not be out of bounds.
+            let next_outer_arg = outer_args[outer_pos + 1];
+            let next_outer_ty = cx.val_ty(next_outer_arg);
+            // FIXME(ZuseZ4): We should add support for Vec here too, but it's less urgent since
+            // vectors behind references (&Vec<T>) are already supported. Users can not pass a
+            // Vec by value for reverse mode, so this would only help forward mode autodiff.
+            let slice = {
+                if activity_pos + 1 >= inputs.len() {
+                    // If there is no arg following our ptr, it also can't be a slice,
+                    // since that would lead to a ptr, int pair.
+                    false
+                } else {
+                    let next_activity = inputs[activity_pos + 1];
+                    // We analyze the MIR types and add this dummy activity if we visit a slice.
+                    next_activity == DiffActivity::FakeActivitySize
+                }
+            };
+            if slice {
+                // A duplicated slice will have the following two outer_fn arguments:
+                // (..., ptr1, int1, ptr2, int2, ...). We add the following llvm-ir to our __enzyme call:
+                // (..., metadata! enzyme_dup, ptr, ptr, int1, ...).
+                // FIXME(ZuseZ4): We will upstream a safety check later which asserts that
+                // int2 >= int1, which means the shadow vector is large enough to store the gradient.
+                assert!(unsafe {
+                    llvm::LLVMRustGetTypeKind(next_outer_ty) == llvm::TypeKind::Integer
+                });
+                let next_outer_arg2 = outer_args[outer_pos + 2];
+                let next_outer_ty2 = cx.val_ty(next_outer_arg2);
+                assert!(unsafe {
+                    llvm::LLVMRustGetTypeKind(next_outer_ty2) == llvm::TypeKind::Pointer
+                });
+                let next_outer_arg3 = outer_args[outer_pos + 3];
+                let next_outer_ty3 = cx.val_ty(next_outer_arg3);
+                assert!(unsafe {
+                    llvm::LLVMRustGetTypeKind(next_outer_ty3) == llvm::TypeKind::Integer
+                });
+                args.push(next_outer_arg2);
+                args.push(cx.get_metadata_value(enzyme_const));
+                args.push(next_outer_arg);
+                outer_pos += 4;
+                activity_pos += 2;
+            } else {
+                // A duplicated pointer will have the following two outer_fn arguments:
+                // (..., ptr, ptr, ...). We add the following llvm-ir to our __enzyme call:
+                // (..., metadata! enzyme_dup, ptr, ptr, ...).
+                if matches!(diff_activity, DiffActivity::Duplicated | DiffActivity::DuplicatedOnly)
+                {
+                    assert!(
+                        unsafe { llvm::LLVMRustGetTypeKind(next_outer_ty) }
+                            == llvm::TypeKind::Pointer
+                    );
+                }
+                // In the case of Dual we don't have assumptions, e.g. f32 would be valid.
+                args.push(next_outer_arg);
+                outer_pos += 2;
+                activity_pos += 1;
+            }
+        } else {
+            // We do not differentiate with resprect to this argument.
+            // We already added the metadata and argument above, so just increase the counters.
+            outer_pos += 1;
+            activity_pos += 1;
+        }
+    }
+}
+
 /// When differentiating `fn_to_diff`, take a `outer_fn` and generate another
 /// function with expected naming and calling conventions[^1] which will be
 /// discovered by the enzyme LLVM pass and its body populated with the differentiated
@@ -43,9 +150,6 @@ fn generate_enzyme_call<'ll>(
     outer_fn: &'ll Value,
     attrs: AutoDiffAttrs,
 ) {
-    let inputs = attrs.input_activity;
-    let output = attrs.ret_activity;
-
     // We have to pick the name depending on whether we want forward or reverse mode autodiff.
     let mut ad_name: String = match attrs.mode {
         DiffMode::Forward => "__enzyme_fwddiff",
@@ -132,111 +236,13 @@ fn generate_enzyme_call<'ll>(
         let mut args = Vec::with_capacity(num_args as usize + 1);
         args.push(fn_to_diff);
 
-        let enzyme_const = cx.create_metadata("enzyme_const".to_string()).unwrap();
-        let enzyme_out = cx.create_metadata("enzyme_out".to_string()).unwrap();
-        let enzyme_dup = cx.create_metadata("enzyme_dup".to_string()).unwrap();
-        let enzyme_dupnoneed = cx.create_metadata("enzyme_dupnoneed".to_string()).unwrap();
         let enzyme_primal_ret = cx.create_metadata("enzyme_primal_return".to_string()).unwrap();
-
+        if matches!(attrs.ret_activity, DiffActivity::Dual | DiffActivity::Active) {
-        match output {
+            args.push(cx.get_metadata_value(enzyme_primal_ret));
-            DiffActivity::Dual => {
-                args.push(cx.get_metadata_value(enzyme_primal_ret));
-            }
-            DiffActivity::Active => {
-                args.push(cx.get_metadata_value(enzyme_primal_ret));
-            }
-            _ => {}
         }
 
-        debug!("matching autodiff arguments");
-        // We now handle the issue that Rust level arguments not always match the llvm-ir level
-        // arguments. A slice, `&[f32]`, for example, is represented as a pointer and a length on
-        // llvm-ir level. The number of activities matches the number of Rust level arguments, so we
-        // need to match those.
-        // FIXME(ZuseZ4): This logic is a bit more complicated than it should be, can we simplify it
-        // using iterators and peek()?
-        let mut outer_pos: usize = 0;
-        let mut activity_pos = 0;
         let outer_args: Vec<&llvm::Value> = get_params(outer_fn);
-        while activity_pos < inputs.len() {
+        match_args_from_caller_to_enzyme(&cx, &mut args, &attrs.input_activity, &outer_args);
-            let diff_activity = inputs[activity_pos as usize];
-            // Duplicated arguments received a shadow argument, into which enzyme will write the
-            // gradient.
-            let (activity, duplicated): (&Metadata, bool) = match diff_activity {
-                DiffActivity::None => panic!("not a valid input activity"),
-                DiffActivity::Const => (enzyme_const, false),
-                DiffActivity::Active => (enzyme_out, false),
-                DiffActivity::ActiveOnly => (enzyme_out, false),
-                DiffActivity::Dual => (enzyme_dup, true),
-                DiffActivity::DualOnly => (enzyme_dupnoneed, true),
-                DiffActivity::Duplicated => (enzyme_dup, true),
-                DiffActivity::DuplicatedOnly => (enzyme_dupnoneed, true),
-                DiffActivity::FakeActivitySize => (enzyme_const, false),
-            };
-            let outer_arg = outer_args[outer_pos];
-            args.push(cx.get_metadata_value(activity));
-            args.push(outer_arg);
-            if duplicated {
-                // We know that duplicated args by construction have a following argument,
-                // so this can not be out of bounds.
-                let next_outer_arg = outer_args[outer_pos + 1];
-                let next_outer_ty = cx.val_ty(next_outer_arg);
-                // FIXME(ZuseZ4): We should add support for Vec here too, but it's less urgent since
-                // vectors behind references (&Vec<T>) are already supported. Users can not pass a
-                // Vec by value for reverse mode, so this would only help forward mode autodiff.
-                let slice = {
-                    if activity_pos + 1 >= inputs.len() {
-                        // If there is no arg following our ptr, it also can't be a slice,
-                        // since that would lead to a ptr, int pair.
-                        false
-                    } else {
-                        let next_activity = inputs[activity_pos + 1];
-                        // We analyze the MIR types and add this dummy activity if we visit a slice.
-                        next_activity == DiffActivity::FakeActivitySize
-                    }
-                };
-                if slice {
-                    // A duplicated slice will have the following two outer_fn arguments:
-                    // (..., ptr1, int1, ptr2, int2, ...). We add the following llvm-ir to our __enzyme call:
-                    // (..., metadata! enzyme_dup, ptr, ptr, int1, ...).
-                    // FIXME(ZuseZ4): We will upstream a safety check later which asserts that
-                    // int2 >= int1, which means the shadow vector is large enough to store the gradient.
-                    assert!(llvm::LLVMRustGetTypeKind(next_outer_ty) == llvm::TypeKind::Integer);
-                    let next_outer_arg2 = outer_args[outer_pos + 2];
-                    let next_outer_ty2 = cx.val_ty(next_outer_arg2);
-                    assert!(llvm::LLVMRustGetTypeKind(next_outer_ty2) == llvm::TypeKind::Pointer);
-                    let next_outer_arg3 = outer_args[outer_pos + 3];
-                    let next_outer_ty3 = cx.val_ty(next_outer_arg3);
-                    assert!(llvm::LLVMRustGetTypeKind(next_outer_ty3) == llvm::TypeKind::Integer);
-                    args.push(next_outer_arg2);
-                    args.push(cx.get_metadata_value(enzyme_const));
-                    args.push(next_outer_arg);
-                    outer_pos += 4;
-                    activity_pos += 2;
-                } else {
-                    // A duplicated pointer will have the following two outer_fn arguments:
-                    // (..., ptr, ptr, ...). We add the following llvm-ir to our __enzyme call:
-                    // (..., metadata! enzyme_dup, ptr, ptr, ...).
-                    if matches!(
-                        diff_activity,
-                        DiffActivity::Duplicated | DiffActivity::DuplicatedOnly
-                    ) {
-                        assert!(
-                            llvm::LLVMRustGetTypeKind(next_outer_ty) == llvm::TypeKind::Pointer
-                        );
-                    }
-                    // In the case of Dual we don't have assumptions, e.g. f32 would be valid.
-                    args.push(next_outer_arg);
-                    outer_pos += 2;
-                    activity_pos += 1;
-                }
-            } else {
-                // We do not differentiate with resprect to this argument.
-                // We already added the metadata and argument above, so just increase the counters.
-                outer_pos += 1;
-                activity_pos += 1;
-            }
-        }
 
         let call = builder.call(enzyme_ty, ad_fn, &args, None);
 

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -790,16 +790,10 @@ fn autodiff_attrs(tcx: TyCtxt<'_>, id: DefId) -> Option<AutoDiffAttrs> {
 
     // check for exactly one autodiff attribute on placeholder functions.
     // There should only be one, since we generate a new placeholder per ad macro.
-    // FIXME(ZuseZ4): re-enable this check. Currently we add multiple, which doesn't cause harm but
-    // looks strange e.g. under cargo-expand.
     let attr = match &attrs[..] {
         [] => return None,
         [attr] => attr,
-        // These two attributes are the same and unfortunately duplicated due to a previous bug.
-        [attr, _attr2] => attr,
         _ => {
-            //FIXME(ZuseZ4): Once we fixed our parser, we should also prohibit the two-attribute
-            //branch above.
             span_bug!(attrs[1].span(), "cg_ssa: rustc_autodiff should only exist once per source");
         }
     };

tests/pretty/autodiff_forward.pp

@@ -53,7 +53,7 @@ pub fn df2(x: &[f64], bx: &[f64], y: f64) -> f64 {
 pub fn f3(x: &[f64], y: f64) -> f64 {
     ::core::panicking::panic("not implemented")
 }
-#[rustc_autodiff(ForwardFirst, Dual, Const, Const,)]
+#[rustc_autodiff(Forward, Dual, Const, Const,)]
 #[inline(never)]
 pub fn df3(x: &[f64], bx: &[f64], y: f64) -> f64 {
     unsafe { asm!("NOP", options(pure, nomem)); };
@@ -73,10 +73,6 @@ pub fn df4() {
 }
 #[rustc_autodiff]
 #[inline(never)]
-#[rustc_autodiff]
-#[inline(never)]
-#[rustc_autodiff]
-#[inline(never)]
 pub fn f5(x: &[f64], y: f64) -> f64 {
     ::core::panicking::panic("not implemented")
 }

tests/pretty/autodiff_forward.rs

@@ -19,7 +19,7 @@ pub fn f2(x: &[f64], y: f64) -> f64 {
     unimplemented!()
 }
 
-#[autodiff(df3, ForwardFirst, Dual, Const, Const)]
+#[autodiff(df3, Forward, Dual, Const, Const)]
 pub fn f3(x: &[f64], y: f64) -> f64 {
     unimplemented!()
 }

tests/pretty/autodiff_reverse.pp

@@ -51,7 +51,7 @@ pub fn df2() {
 pub fn f3(x: &[f64], y: f64) -> f64 {
     ::core::panicking::panic("not implemented")
 }
-#[rustc_autodiff(ReverseFirst, Duplicated, Const, Active,)]
+#[rustc_autodiff(Reverse, Duplicated, Const, Active,)]
 #[inline(never)]
 pub fn df3(x: &[f64], dx: &mut [f64], y: f64, dret: f64) -> f64 {
     unsafe { asm!("NOP", options(pure, nomem)); };

tests/pretty/autodiff_reverse.rs

@@ -18,7 +18,7 @@ pub fn f1(x: &[f64], y: f64) -> f64 {
 #[autodiff(df2, Reverse)]
 pub fn f2() {}
 
-#[autodiff(df3, ReverseFirst, Duplicated, Const, Active)]
+#[autodiff(df3, Reverse, Duplicated, Const, Active)]
 pub fn f3(x: &[f64], y: f64) -> f64 {
     unimplemented!()
 }