rustc_mir: track inlined callees in SourceScopeData.

Author: eddyb

src/librustc/mir/mod.rs

@@ -112,7 +112,7 @@ pub struct Body<'tcx> {
 
     /// A list of source scopes; these are referenced by statements
     /// and used for debuginfo. Indexed by a `SourceScope`.
-    pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
+    pub source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
 
     /// The yield type of the function, if it is a generator.
     pub yield_ty: Option<Ty<'tcx>>,
@@ -179,7 +179,7 @@ pub struct Body<'tcx> {
 impl<'tcx> Body<'tcx> {
     pub fn new(
         basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
-        source_scopes: IndexVec<SourceScope, SourceScopeData>,
+        source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
         local_decls: LocalDecls<'tcx>,
         user_type_annotations: CanonicalUserTypeAnnotations<'tcx>,
         arg_count: usize,
@@ -1916,11 +1916,16 @@ rustc_index::newtype_index! {
     }
 }
 
-#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
-pub struct SourceScopeData {
+#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
+pub struct SourceScopeData<'tcx> {
     pub span: Span,
     pub parent_scope: Option<SourceScope>,
 
+    /// Whether this scope is the root of a scope tree of another body,
+    /// inlined into this body by the MIR inliner.
+    /// `ty::Instance` is the callee, and the `Span` is the call site.
+    pub inlined: Option<(ty::Instance<'tcx>, Span)>,
+
     /// Crate-local information for this source scope, that can't (and
     /// needn't) be tracked across crates.
     pub local_data: ClearCrossCrate<SourceScopeLocalData>,
@@ -2621,7 +2626,6 @@ CloneTypeFoldableAndLiftImpls! {
     FakeReadCause,
     RetagKind,
     SourceScope,
-    SourceScopeData,
     SourceScopeLocalData,
     UserTypeAnnotationIndex,
 }

src/librustc/mir/visit.rs

@@ -94,7 +94,7 @@ macro_rules! make_mir_visitor {
             }
 
             fn visit_source_scope_data(&mut self,
-                                           scope_data: & $($mutability)? SourceScopeData) {
+                                           scope_data: & $($mutability)? SourceScopeData<'tcx>) {
                 self.super_source_scope_data(scope_data);
             }
 
@@ -329,17 +329,45 @@ macro_rules! make_mir_visitor {
                 }
             }
 
-            fn super_source_scope_data(&mut self, scope_data: & $($mutability)? SourceScopeData) {
+            fn super_source_scope_data(
+                &mut self,
+                scope_data: & $($mutability)? SourceScopeData<'tcx>,
+            ) {
                 let SourceScopeData {
                     span,
                     parent_scope,
+                    inlined,
                     local_data: _,
                 } = scope_data;
 
                 self.visit_span(span);
                 if let Some(parent_scope) = parent_scope {
                     self.visit_source_scope(parent_scope);
                 }
+                if let Some((callee, callsite_span)) = inlined {
+                    let location = START_BLOCK.start_location();
+
+                    self.visit_span(callsite_span);
+
+                    let ty::Instance { def: callee_def, substs: callee_substs } = callee;
+                    match callee_def {
+                        ty::InstanceDef::Item(_def_id) |
+                        ty::InstanceDef::Intrinsic(_def_id) |
+                        ty::InstanceDef::VtableShim(_def_id) |
+                        ty::InstanceDef::ReifyShim(_def_id) |
+                        ty::InstanceDef::Virtual(_def_id, _) |
+                        ty::InstanceDef::ClosureOnceShim { call_once: _def_id } |
+                        ty::InstanceDef::DropGlue(_def_id, None) => {}
+
+                        ty::InstanceDef::FnPtrShim(_def_id, ty) |
+                        ty::InstanceDef::DropGlue(_def_id, Some(ty)) |
+                        ty::InstanceDef::CloneShim(_def_id, ty) => {
+                            // FIXME(eddyb) use a better `TyContext` here.
+                            self.visit_ty(ty, TyContext::Location(location));
+                        }
+                    }
+                    self.visit_substs(callee_substs, location);
+                }
             }
 
             fn super_statement(&mut self,

src/librustc_mir/shim.rs

@@ -243,7 +243,12 @@ fn new_body<'tcx>(
     Body::new(
         basic_blocks,
         IndexVec::from_elem_n(
-            SourceScopeData { span, parent_scope: None, local_data: ClearCrossCrate::Clear },
+            SourceScopeData {
+                span,
+                parent_scope: None,
+                inlined: None,
+                local_data: ClearCrossCrate::Clear,
+            },
             1,
         ),
         local_decls,

src/librustc_mir/transform/const_prop.rs

@@ -297,7 +297,7 @@ struct ConstPropagator<'mir, 'tcx> {
     param_env: ParamEnv<'tcx>,
     // FIXME(eddyb) avoid cloning these two fields more than once,
     // by accessing them through `ecx` instead.
-    source_scopes: IndexVec<SourceScope, SourceScopeData>,
+    source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
     local_decls: IndexVec<Local, LocalDecl<'tcx>>,
     ret: Option<OpTy<'tcx, ()>>,
     // Because we have `MutVisitor` we can't obtain the `SourceInfo` from a `Location`. So we store

src/librustc_mir/transform/inline.rs

@@ -109,7 +109,7 @@ impl Inliner<'tcx> {
                 let callee_node_id = self.tcx.hir().as_local_node_id(callsite.callee.def_id());
 
                 let callee_body = if let Some(callee_node_id) = callee_node_id {
-                    // Avoid a cycle here by only using `optimized_mir` only if we have
+                    // Avoid a cycle here by only using `instance_mir` only if we have
                     // a lower node id than the callee. This ensures that the callee will
                     // not inline us. This trick only works without incremental compilation.
                     // So don't do it if that is enabled.
@@ -416,15 +416,11 @@ impl Inliner<'tcx> {
                 for mut scope in callee_body.source_scopes.iter().cloned() {
                     if scope.parent_scope.is_none() {
                         scope.parent_scope = Some(callsite.source_info.scope);
-                        // FIXME(eddyb) is this really needed?
-                        // (also note that it's always overwritten below)
-                        scope.span = callee_body.span;
-                    }
 
-                    // FIXME(eddyb) this doesn't seem right at all.
-                    // The inlined source scopes should probably be annotated as
-                    // such, but also contain all of the original information.
-                    scope.span = callsite.source_info.span;
+                        // Mark the outermost callee scope as an inlined one.
+                        assert_eq!(scope.inlined, None);
+                        scope.inlined = Some((callsite.callee, callsite.source_info.span));
+                    }
 
                     let idx = caller_body.source_scopes.push(scope);
                     scope_map.push(idx);

src/librustc_mir/util/pretty.rs

@@ -495,8 +495,23 @@ fn write_scope_tree(
     };
 
     for &child in children {
-        assert_eq!(body.source_scopes[child].parent_scope, Some(parent));
-        writeln!(w, "{0:1$}scope {2} {{", "", indent, child.index())?;
+        let child_data = &body.source_scopes[child];
+        assert_eq!(child_data.parent_scope, Some(parent));
+
+        if let Some((callee, callsite_span)) = child_data.inlined {
+            let indented_header =
+                format!("{0:1$}scope {2} (inlined {3}) {{", "", indent, child.index(), callee);
+            writeln!(
+                w,
+                "{0:1$} // at {2}",
+                indented_header,
+                ALIGN,
+                tcx.sess.source_map().span_to_string(callsite_span),
+            )?;
+        } else {
+            writeln!(w, "{0:1$}scope {2} {{", "", indent, child.index())?;
+        }
+
         write_scope_tree(tcx, body, scope_tree, w, child, depth + 1)?;
         writeln!(w, "{0:1$}}}", "", depth * INDENT.len())?;
     }

src/librustc_mir_build/build/mod.rs

@@ -298,7 +298,7 @@ struct Builder<'a, 'tcx> {
 
     /// The vector of all scopes that we have created thus far;
     /// we track this for debuginfo later.
-    source_scopes: IndexVec<SourceScope, SourceScopeData>,
+    source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,
     source_scope: SourceScope,
 
     /// The guard-context: each time we build the guard expression for

src/librustc_mir_build/build/scope.rs

@@ -684,6 +684,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.source_scopes.push(SourceScopeData {
             span,
             parent_scope: Some(parent),
+            inlined: None,
             local_data: ClearCrossCrate::Set(scope_local_data),
         })
     }

src/test/mir-opt/inline/inline-closure-borrows-arg.rs

@@ -30,7 +30,7 @@ fn foo<T: Copy>(_t: T, q: &i32) -> i32 {
 //     let mut _9: &i32;
 //     scope 1 {
 //         debug x => _3;
-//         scope 2 {
+//         scope 2 (inlined foo::<T>::{{closure}}#0) {
 //             debug r => _8;
 //             debug _s => _9;
 //         }

src/test/mir-opt/inline/inline-closure-captures.rs

@@ -26,7 +26,7 @@ fn foo<T: Copy>(t: T, q: i32) -> (i32, T) {
 //     let mut _11: i32;
 //     scope 1 {
 //         debug x => _3;
-//         scope 2 {
+//         scope 2 (inlined foo::<T>::{{closure}}#0) {
 //             debug _q => _11;
 //             debug q => (*((*_6).0: &i32));
 //             debug t => (*((*_6).1: &T));