attr: add a pre-codegen #[spirv(...)] attribute checking pass.

crates/rustc_codegen_spirv/src/attr.rs

@@ -0,0 +1,312 @@
+//! `#[spirv(...)]` attribute support.
+//!
+//! The attribute-checking parts of this try to follow `rustc_passes::check_attr`.
+
+use crate::symbols::{SpirvAttribute, Symbols};
+use rustc_ast::Attribute;
+use rustc_hir as hir;
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
+use rustc_hir::{HirId, MethodKind, Target, CRATE_HIR_ID};
+use rustc_middle::hir::map::Map;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::TyCtxt;
+use std::fmt;
+use std::rc::Rc;
+
+// FIXME(eddyb) make this reusable from somewhere in `rustc`.
+pub(crate) fn target_from_impl_item<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    impl_item: &hir::ImplItem<'_>,
+) -> Target {
+    match impl_item.kind {
+        hir::ImplItemKind::Const(..) => Target::AssocConst,
+        hir::ImplItemKind::Fn(..) => {
+            let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id);
+            let containing_item = tcx.hir().expect_item(parent_hir_id);
+            let containing_impl_is_for_trait = match &containing_item.kind {
+                hir::ItemKind::Impl { of_trait, .. } => of_trait.is_some(),
+                _ => unreachable!("parent of an ImplItem must be an Impl"),
+            };
+            if containing_impl_is_for_trait {
+                Target::Method(MethodKind::Trait { body: true })
+            } else {
+                Target::Method(MethodKind::Inherent)
+            }
+        }
+        hir::ImplItemKind::TyAlias(..) => Target::AssocTy,
+    }
+}
+
+// HACK(eddyb) current `Target` (after rust-lang/rust#80641 + rust-lang/rust#80920),
+// emulated before we can rustup to that point and use the new variants directly.
+enum TargetNew {
+    Old(Target),
+
+    // Added by rust-lang/rust#80641.
+    Field,
+    Arm,
+    MacroDef,
+
+    // Added by rust-lang/rust#80920.
+    Param,
+}
+
+impl From<Target> for TargetNew {
+    fn from(target: Target) -> Self {
+        Self::Old(target)
+    }
+}
+
+impl fmt::Display for TargetNew {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let description = match self {
+            Self::Old(target) => return write!(f, "{}", target),
+
+            Self::Field => "struct field",
+            Self::Arm => "match arm",
+            Self::MacroDef => "macro def",
+
+            Self::Param => "function param",
+        };
+        f.write_str(description)
+    }
+}
+
+struct CheckSpirvAttrVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    sym: Rc<Symbols>,
+}
+
+impl CheckSpirvAttrVisitor<'_> {
+    fn check_spirv_attributes(
+        &self,
+        hir_id: HirId,
+        attrs: &[Attribute],
+        target: impl Into<TargetNew>,
+    ) {
+        let parse_attrs = |attrs| crate::symbols::parse_attrs_for_checking(&self.sym, attrs);
+
+        let target = target.into();
+        for parse_attr_result in parse_attrs(attrs) {
+            let (span, attr) = match parse_attr_result {
+                Ok(span_and_attr) => span_and_attr,
+                Err((span, msg)) => {
+                    self.tcx.sess.span_err(span, &msg);
+                    continue;
+                }
+            };
+
+            /// Error newtype marker used below for readability.
+            struct Expected<T>(T);
+
+            let valid_target = match attr {
+                SpirvAttribute::Builtin(_)
+                | SpirvAttribute::DescriptorSet(_)
+                | SpirvAttribute::Binding(_)
+                | SpirvAttribute::Flat => match target {
+                    TargetNew::Param => {
+                        let parent_hir_id = self.tcx.hir().get_parent_node(hir_id);
+                        let parent_is_entry_point =
+                            parse_attrs(self.tcx.hir().attrs(parent_hir_id))
+                                .filter_map(|r| r.ok())
+                                .any(|(_, attr)| matches!(attr, SpirvAttribute::Entry(_)));
+                        if !parent_is_entry_point {
+                            self.tcx.sess.span_err(
+                                span,
+                                "attribute is only valid on a parameter of an entry-point function",
+                            );
+                        }
+                        Ok(())
+                    }
+
+                    _ => Err(Expected("function parameter")),
+                },
+
+                SpirvAttribute::Entry(_) => match target {
+                    TargetNew::Old(Target::Fn)
+                    | TargetNew::Old(Target::Method(MethodKind::Trait { body: true }))
+                    | TargetNew::Old(Target::Method(MethodKind::Inherent)) => {
+                        // FIXME(eddyb) further check entry-point attribute validity,
+                        // e.g. signature, shouldn't have `#[inline]` or generics, etc.
+                        Ok(())
+                    }
+
+                    _ => Err(Expected("function")),
+                },
+
+                SpirvAttribute::UnrollLoops => match target {
+                    TargetNew::Old(Target::Fn)
+                    | TargetNew::Old(Target::Closure)
+                    | TargetNew::Old(Target::Method(MethodKind::Trait { body: true }))
+                    | TargetNew::Old(Target::Method(MethodKind::Inherent)) => Ok(()),
+
+                    _ => Err(Expected("function or closure")),
+                },
+
+                SpirvAttribute::StorageClass(_)
+                | SpirvAttribute::ImageType { .. }
+                | SpirvAttribute::Sampler
+                | SpirvAttribute::SampledImage
+                | SpirvAttribute::Block => match target {
+                    TargetNew::Old(Target::Struct) => {
+                        // FIXME(eddyb) further check type attribute validity,
+                        // e.g. layout, generics, other attributes, etc.
+                        Ok(())
+                    }
+
+                    _ => Err(Expected("struct")),
+                },
+            };
+            match valid_target {
+                Ok(()) => {}
+                Err(Expected(expected_target)) => self.tcx.sess.span_err(
+                    span,
+                    &format!(
+                        "attribute is only valid on a {}, not on a {}",
+                        expected_target, target
+                    ),
+                ),
+            }
+        }
+    }
+}
+
+// FIXME(eddyb) DRY this somehow and make it reusable from somewhere in `rustc`.
+impl<'tcx> Visitor<'tcx> for CheckSpirvAttrVisitor<'tcx> {
+    type Map = Map<'tcx>;
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::OnlyBodies(self.tcx.hir())
+    }
+
+    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+        let target = Target::from_item(item);
+        self.check_spirv_attributes(item.hir_id, item.attrs, target);
+        intravisit::walk_item(self, item)
+    }
+
+    fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
+        let target = Target::from_generic_param(generic_param);
+        self.check_spirv_attributes(generic_param.hir_id, generic_param.attrs, target);
+        intravisit::walk_generic_param(self, generic_param)
+    }
+
+    fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
+        let target = Target::from_trait_item(trait_item);
+        self.check_spirv_attributes(trait_item.hir_id, trait_item.attrs, target);
+        intravisit::walk_trait_item(self, trait_item)
+    }
+
+    fn visit_struct_field(&mut self, struct_field: &'tcx hir::StructField<'tcx>) {
+        self.check_spirv_attributes(struct_field.hir_id, struct_field.attrs, TargetNew::Field);
+        intravisit::walk_struct_field(self, struct_field);
+    }
+
+    fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
+        self.check_spirv_attributes(arm.hir_id, arm.attrs, TargetNew::Arm);
+        intravisit::walk_arm(self, arm);
+    }
+
+    fn visit_foreign_item(&mut self, f_item: &'tcx hir::ForeignItem<'tcx>) {
+        let target = Target::from_foreign_item(f_item);
+        self.check_spirv_attributes(f_item.hir_id, f_item.attrs, target);
+        intravisit::walk_foreign_item(self, f_item)
+    }
+
+    fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
+        let target = target_from_impl_item(self.tcx, impl_item);
+        self.check_spirv_attributes(impl_item.hir_id, impl_item.attrs, target);
+        intravisit::walk_impl_item(self, impl_item)
+    }
+
+    fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
+        // When checking statements ignore expressions, they will be checked later.
+        if let hir::StmtKind::Local(l) = stmt.kind {
+            self.check_spirv_attributes(l.hir_id, &l.attrs, Target::Statement);
+        }
+        intravisit::walk_stmt(self, stmt)
+    }
+
+    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+        let target = match expr.kind {
+            hir::ExprKind::Closure(..) => Target::Closure,
+            _ => Target::Expression,
+        };
+
+        self.check_spirv_attributes(expr.hir_id, &expr.attrs, target);
+        intravisit::walk_expr(self, expr)
+    }
+
+    fn visit_variant(
+        &mut self,
+        variant: &'tcx hir::Variant<'tcx>,
+        generics: &'tcx hir::Generics<'tcx>,
+        item_id: HirId,
+    ) {
+        self.check_spirv_attributes(variant.id, variant.attrs, Target::Variant);
+        intravisit::walk_variant(self, variant, generics, item_id)
+    }
+
+    fn visit_macro_def(&mut self, macro_def: &'tcx hir::MacroDef<'tcx>) {
+        self.check_spirv_attributes(macro_def.hir_id, macro_def.attrs, TargetNew::MacroDef);
+        intravisit::walk_macro_def(self, macro_def);
+    }
+
+    fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
+        self.check_spirv_attributes(param.hir_id, param.attrs, TargetNew::Param);
+
+        intravisit::walk_param(self, param);
+    }
+}
+
+fn check_invalid_macro_level_spirv_attr(tcx: TyCtxt<'_>, sym: &Symbols, attrs: &[Attribute]) {
+    for attr in attrs {
+        if tcx.sess.check_name(attr, sym.spirv) {
+            tcx.sess
+                .span_err(attr.span, "#[spirv(..)] cannot be applied to a macro");
+        }
+    }
+}
+
+// FIXME(eddyb) DRY this somehow and make it reusable from somewhere in `rustc`.
+fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
+    let check_spirv_attr_visitor = &mut CheckSpirvAttrVisitor {
+        tcx,
+        sym: Symbols::get(),
+    };
+    tcx.hir().visit_item_likes_in_module(
+        module_def_id,
+        &mut check_spirv_attr_visitor.as_deep_visitor(),
+    );
+    // FIXME(eddyb) use `tcx.hir().visit_exported_macros_in_krate(...)` after rustup.
+    for id in tcx.hir().krate().exported_macros {
+        check_spirv_attr_visitor.visit_macro_def(match tcx.hir().find(id.hir_id) {
+            Some(hir::Node::MacroDef(macro_def)) => macro_def,
+            _ => unreachable!(),
+        });
+    }
+    check_invalid_macro_level_spirv_attr(
+        tcx,
+        &check_spirv_attr_visitor.sym,
+        tcx.hir().krate().non_exported_macro_attrs,
+    );
+    if module_def_id.is_top_level_module() {
+        check_spirv_attr_visitor.check_spirv_attributes(
+            CRATE_HIR_ID,
+            tcx.hir().krate_attrs(),
+            Target::Mod,
+        );
+    }
+}
+
+pub(crate) fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        check_mod_attrs: |tcx, def_id| {
+            // Run both the default checks, and our `#[spirv(...)]` ones.
+            (rustc_interface::DEFAULT_QUERY_PROVIDERS.check_mod_attrs)(tcx, def_id);
+            check_mod_attrs(tcx, def_id)
+        },
+        ..*providers
+    };
+}

crates/rustc_codegen_spirv/src/lib.rs

@@ -81,6 +81,7 @@ macro_rules! assert_ty_eq {
 }
 
 mod abi;
+mod attr;
 mod builder;
 mod builder_spirv;
 mod codegen_cx;
@@ -299,6 +300,9 @@ impl CodegenBackend for SpirvCodegenBackend {
                 inner
             })
         };
+
+        // Extra hooks provided by other parts of `rustc_codegen_spirv`.
+        crate::attr::provide(providers);
     }
 
     fn provide_extern(&self, providers: &mut query::Providers) {

crates/rustc_codegen_spirv/src/symbols.rs

@@ -448,6 +448,7 @@ impl From<ExecutionModel> for Entry {
     }
 }
 
+// FIXME(eddyb) maybe move this to `attr`?
 #[derive(Debug, Clone)]
 pub enum SpirvAttribute {
     Builtin(BuiltIn),
@@ -471,28 +472,32 @@ pub enum SpirvAttribute {
     UnrollLoops,
 }
 
-// Note that we could mark the attr as used via cx.tcx.sess.mark_attr_used(attr), but unused
-// reporting already happens even before we get here :(
+// FIXME(eddyb) maybe move this to `attr`?
 /// Returns only the spirv attributes that could successfully parsed.
-/// For any malformed ones, an error is reported.
+/// For any malformed ones, an error is reported prior to codegen, by a check pass.
 pub fn parse_attrs<'a, 'tcx>(
     cx: &'a CodegenCx<'tcx>,
     attrs: &'tcx [Attribute],
 ) -> impl Iterator<Item = SpirvAttribute> + Captures<'tcx> + 'a {
-    parse_attrs_with_errors(&cx.sym, attrs).filter_map(move |parse_attr_result| {
-        parse_attr_result
-            .map_err(|(span, msg)| cx.tcx.sess.span_err(span, &msg))
-            .ok()
-    })
+    parse_attrs_for_checking(&cx.sym, attrs)
+        .filter_map(move |parse_attr_result| {
+            // NOTE(eddyb) `delay_span_bug` ensures that if attribute checking fails
+            // to see an attribute error, it will cause an ICE instead.
+            parse_attr_result
+                .map_err(|(span, msg)| cx.tcx.sess.delay_span_bug(span, &msg))
+                .ok()
+        })
+        .map(|(_span, parsed_attr)| parsed_attr)
 }
 
 // FIXME(eddyb) find something nicer for the error type.
 type ParseAttrError = (Span, String);
 
-fn parse_attrs_with_errors<'a>(
+// FIXME(eddyb) maybe move this to `attr`?
+pub(crate) fn parse_attrs_for_checking<'a>(
     sym: &'a Symbols,
     attrs: &'a [Attribute],
-) -> impl Iterator<Item = Result<SpirvAttribute, ParseAttrError>> + 'a {
+) -> impl Iterator<Item = Result<(Span, SpirvAttribute), ParseAttrError>> + 'a {
     attrs.iter().flat_map(move |attr| {
         let is_spirv = match attr.kind {
             AttrKind::Normal(ref item, _) => {
@@ -519,18 +524,19 @@ fn parse_attrs_with_errors<'a>(
         whole_attr_error
             .into_iter()
             .chain(args.into_iter().map(move |ref arg| {
-                if arg.has_name(sym.image_type) {
-                    parse_image_type(sym, arg)
+                let span = arg.span();
+                let parsed_attr = if arg.has_name(sym.image_type) {
+                    parse_image_type(sym, arg)?
                 } else if arg.has_name(sym.descriptor_set) {
-                    Ok(SpirvAttribute::DescriptorSet(parse_attr_int_value(arg)?))
+                    SpirvAttribute::DescriptorSet(parse_attr_int_value(arg)?)
                 } else if arg.has_name(sym.binding) {
-                    Ok(SpirvAttribute::Binding(parse_attr_int_value(arg)?))
+                    SpirvAttribute::Binding(parse_attr_int_value(arg)?)
                 } else {
                     let name = match arg.ident() {
                         Some(i) => i,
                         None => {
                             return Err((
-                                arg.span(),
+                                span,
                                 "#[spirv(..)] attribute argument must be single identifier"
                                     .to_string(),
                             ));
@@ -548,8 +554,9 @@ fn parse_attrs_with_errors<'a>(
                         })
                         .unwrap_or_else(|| {
                             Err((name.span, "unknown argument to spirv attribute".to_string()))
-                        })
-                }
+                        })?
+                };
+                Ok((span, parsed_attr))
             }))
     })
 }