rustc_monomorphize/partitioning/
autodiff.rs

1use rustc_ast::expand::autodiff_attrs::{AutoDiffItem, DiffActivity};
2use rustc_hir::def_id::LOCAL_CRATE;
3use rustc_middle::bug;
4use rustc_middle::mir::mono::MonoItem;
5use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
6use rustc_symbol_mangling::symbol_name_for_instance_in_crate;
7use tracing::{debug, trace};
8
9use crate::partitioning::UsageMap;
10
11fn adjust_activity_to_abi<'tcx>(tcx: TyCtxt<'tcx>, fn_ty: Ty<'tcx>, da: &mut Vec<DiffActivity>) {
12    if !matches!(fn_ty.kind(), ty::FnDef(..)) {
13        bug!("expected fn def for autodiff, got {:?}", fn_ty);
14    }
15
16    // We don't actually pass the types back into the type system.
17    // All we do is decide how to handle the arguments.
18    let sig = fn_ty.fn_sig(tcx).skip_binder();
19
20    let mut new_activities = vec![];
21    let mut new_positions = vec![];
22    for (i, ty) in sig.inputs().iter().enumerate() {
23        if let Some(inner_ty) = ty.builtin_deref(true) {
24            if inner_ty.is_slice() {
25                // We know that the length will be passed as extra arg.
26                if !da.is_empty() {
27                    // We are looking at a slice. The length of that slice will become an
28                    // extra integer on llvm level. Integers are always const.
29                    // However, if the slice get's duplicated, we want to know to later check the
30                    // size. So we mark the new size argument as FakeActivitySize.
31                    let activity = match da[i] {
32                        DiffActivity::DualOnly
33                        | DiffActivity::Dual
34                        | DiffActivity::DuplicatedOnly
35                        | DiffActivity::Duplicated => DiffActivity::FakeActivitySize,
36                        DiffActivity::Const => DiffActivity::Const,
37                        _ => bug!("unexpected activity for ptr/ref"),
38                    };
39                    new_activities.push(activity);
40                    new_positions.push(i + 1);
41                }
42                continue;
43            }
44        }
45    }
46    // now add the extra activities coming from slices
47    // Reverse order to not invalidate the indices
48    for _ in 0..new_activities.len() {
49        let pos = new_positions.pop().unwrap();
50        let activity = new_activities.pop().unwrap();
51        da.insert(pos, activity);
52    }
53}
54
55pub(crate) fn find_autodiff_source_functions<'tcx>(
56    tcx: TyCtxt<'tcx>,
57    usage_map: &UsageMap<'tcx>,
58    autodiff_mono_items: Vec<(&MonoItem<'tcx>, &Instance<'tcx>)>,
59) -> Vec<AutoDiffItem> {
60    let mut autodiff_items: Vec<AutoDiffItem> = vec![];
61    for (item, instance) in autodiff_mono_items {
62        let target_id = instance.def_id();
63        let cg_fn_attr = &tcx.codegen_fn_attrs(target_id).autodiff_item;
64        let Some(target_attrs) = cg_fn_attr else {
65            continue;
66        };
67        let mut input_activities: Vec<DiffActivity> = target_attrs.input_activity.clone();
68        if target_attrs.is_source() {
69            trace!("source found: {:?}", target_id);
70        }
71        if !target_attrs.apply_autodiff() {
72            continue;
73        }
74
75        let target_symbol = symbol_name_for_instance_in_crate(tcx, instance.clone(), LOCAL_CRATE);
76
77        let source =
78            usage_map.used_map.get(&item).unwrap().into_iter().find_map(|item| match *item {
79                MonoItem::Fn(ref instance_s) => {
80                    let source_id = instance_s.def_id();
81                    if let Some(ad) = &tcx.codegen_fn_attrs(source_id).autodiff_item
82                        && ad.is_active()
83                    {
84                        return Some(instance_s);
85                    }
86                    None
87                }
88                _ => None,
89            });
90        let inst = match source {
91            Some(source) => source,
92            None => continue,
93        };
94
95        debug!("source_id: {:?}", inst.def_id());
96        let fn_ty = inst.ty(tcx, ty::TypingEnv::fully_monomorphized());
97        assert!(fn_ty.is_fn());
98        adjust_activity_to_abi(tcx, fn_ty, &mut input_activities);
99        let symb = symbol_name_for_instance_in_crate(tcx, inst.clone(), LOCAL_CRATE);
100
101        let mut new_target_attrs = target_attrs.clone();
102        new_target_attrs.input_activity = input_activities;
103        let itm = new_target_attrs.into_item(symb, target_symbol);
104        autodiff_items.push(itm);
105    }
106
107    if !autodiff_items.is_empty() {
108        trace!("AUTODIFF ITEMS EXIST");
109        for item in &mut *autodiff_items {
110            trace!("{}", &item);
111        }
112    }
113
114    autodiff_items
115}
rustc_monomorphize/partitioning/autodiff.rs

rustc_monomorphize/partitioning/
autodiff.rs
