Rollup merge of #138345 - oli-obk:autodiff-cleanup, r=compiler-errors

Some autodiff cleanups

cc ````@ZuseZ4````

just some things I noticed
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Matthias Krüger 2025-03-12 17:59:09 +01:00 committed by GitHub
commit de7e5e96be
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@ -12,21 +12,15 @@ fn adjust_activity_to_abi<'tcx>(tcx: TyCtxt<'tcx>, fn_ty: Ty<'tcx>, da: &mut Vec
if !matches!(fn_ty.kind(), ty::FnDef(..)) {
bug!("expected fn def for autodiff, got {:?}", fn_ty);
}
let fnc_binder: ty::Binder<'_, ty::FnSig<'_>> = fn_ty.fn_sig(tcx);
// If rustc compiles the unmodified primal, we know that this copy of the function
// also has correct lifetimes. We know that Enzyme won't free the shadow too early
// (or actually at all), so let's strip lifetimes when computing the layout.
let x = tcx.instantiate_bound_regions_with_erased(fnc_binder);
// We don't actually pass the types back into the type system.
// All we do is decide how to handle the arguments.
let sig = fn_ty.fn_sig(tcx).skip_binder();
let mut new_activities = vec![];
let mut new_positions = vec![];
for (i, ty) in x.inputs().iter().enumerate() {
for (i, ty) in sig.inputs().iter().enumerate() {
if let Some(inner_ty) = ty.builtin_deref(true) {
if ty.is_fn_ptr() {
// FIXME(ZuseZ4): add a nicer error, or just figure out how to support them,
// since Enzyme itself can handle them.
tcx.dcx().err("function pointers are currently not supported in autodiff");
}
if inner_ty.is_slice() {
// We know that the length will be passed as extra arg.
if !da.is_empty() {