rustc_codegen_llvm: add support for inlined function debuginfo.

5 files changed, 137 insertions, 64 deletions

diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
index f6b7f257f2f..6737872f203 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
@@ -3,21 +3,26 @@ use super::utils::DIB;
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext};
 use rustc_codegen_ssa::traits::*;
 
+use crate::abi::FnAbi;
 use crate::common::CodegenCx;
 use crate::llvm;
-use crate::llvm::debuginfo::DIScope;
+use crate::llvm::debuginfo::{DILocation, DIScope};
 use rustc_middle::mir::{Body, SourceScope};
+use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::{self, Instance};
 use rustc_session::config::DebugInfo;
 
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::Idx;
 
 /// Produces DIScope DIEs for each MIR Scope which has variables defined in it.
+// FIXME(eddyb) almost all of this should be in `rustc_codegen_ssa::mir::debuginfo`.
 pub fn compute_mir_scopes(
-    cx: &CodegenCx<'ll, '_>,
-    mir: &Body<'_>,
+    cx: &CodegenCx<'ll, 'tcx>,
+    instance: Instance<'tcx>,
+    mir: &Body<'tcx>,
     fn_dbg_scope: &'ll DIScope,
-    debug_context: &mut FunctionDebugContext<&'ll DIScope>,
+    debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
 ) {
     // Find all the scopes with variables defined in them.
     let mut has_variables = BitSet::new_empty(mir.source_scopes.len());
@@ -37,16 +42,17 @@ pub fn compute_mir_scopes(
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, &mir, fn_dbg_scope, &has_variables, debug_context, scope);
+        make_mir_scope(cx, instance, &mir, fn_dbg_scope, &has_variables, debug_context, scope);
     }
 }
 
 fn make_mir_scope(
-    cx: &CodegenCx<'ll, '_>,
-    mir: &Body<'_>,
+    cx: &CodegenCx<'ll, 'tcx>,
+    instance: Instance<'tcx>,
+    mir: &Body<'tcx>,
     fn_dbg_scope: &'ll DIScope,
     has_variables: &BitSet<SourceScope>,
-    debug_context: &mut FunctionDebugContext<&'ll DIScope>,
+    debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
     scope: SourceScope,
 ) {
     if debug_context.scopes[scope].dbg_scope.is_some() {
@@ -55,22 +61,23 @@ fn make_mir_scope(
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, mir, fn_dbg_scope, has_variables, debug_context, parent);
+        make_mir_scope(cx, instance, mir, fn_dbg_scope, has_variables, debug_context, parent);
         debug_context.scopes[parent]
     } else {
         // The root is the function itself.
         let loc = cx.lookup_debug_loc(mir.span.lo());
         debug_context.scopes[scope] = DebugScope {
             dbg_scope: Some(fn_dbg_scope),
+            inlined_at: None,
             file_start_pos: loc.file.start_pos,
             file_end_pos: loc.file.end_pos,
         };
         return;
     };
 
-    if !has_variables.contains(scope) {
-        // Do not create a DIScope if there are no variables
-        // defined in this MIR Scope, to avoid debuginfo bloat.
+    if !has_variables.contains(scope) && scope_data.inlined.is_none() {
+        // Do not create a DIScope if there are no variables defined in this
+        // MIR `SourceScope`, and it's not `inlined`, to avoid debuginfo bloat.
         debug_context.scopes[scope] = parent_scope;
         return;
     }
@@ -78,17 +85,39 @@ fn make_mir_scope(
     let loc = cx.lookup_debug_loc(scope_data.span.lo());
     let file_metadata = file_metadata(cx, &loc.file);
 
-    let dbg_scope = unsafe {
-        Some(llvm::LLVMRustDIBuilderCreateLexicalBlock(
-            DIB(cx),
-            parent_scope.dbg_scope.unwrap(),
-            file_metadata,
-            loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
-            loc.col.unwrap_or(UNKNOWN_COLUMN_NUMBER),
-        ))
+    let dbg_scope = match scope_data.inlined {
+        Some((callee, _)) => {
+            // FIXME(eddyb) this would be `self.monomorphize(&callee)`
+            // if this is moved to `rustc_codegen_ssa::mir::debuginfo`.
+            let callee = cx.tcx.subst_and_normalize_erasing_regions(
+                instance.substs,
+                ty::ParamEnv::reveal_all(),
+                &callee,
+            );
+            let callee_fn_abi = FnAbi::of_instance(cx, callee, &[]);
+            cx.dbg_scope_fn(callee, &callee_fn_abi, None)
+        }
+        None => unsafe {
+            llvm::LLVMRustDIBuilderCreateLexicalBlock(
+                DIB(cx),
+                parent_scope.dbg_scope.unwrap(),
+                file_metadata,
+                loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
+                loc.col.unwrap_or(UNKNOWN_COLUMN_NUMBER),
+            )
+        },
     };
+
+    let inlined_at = scope_data.inlined.map(|(_, callsite_span)| {
+        // FIXME(eddyb) this doesn't account for the macro-related
+        // `Span` fixups that `rustc_codegen_ssa::mir::debuginfo` does.
+        let callsite_scope = parent_scope.adjust_dbg_scope_for_span(cx, callsite_span);
+        cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span)
+    });
+
     debug_context.scopes[scope] = DebugScope {
-        dbg_scope,
+        dbg_scope: Some(dbg_scope),
+        inlined_at: inlined_at.or(parent_scope.inlined_at),
         file_start_pos: loc.file.start_pos,
         file_end_pos: loc.file.end_pos,
     };
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index 7b416f1f6ad..beaea49874e 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -265,22 +265,27 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         instance: Instance<'tcx>,
         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
         llfn: &'ll Value,
-        mir: &mir::Body<'_>,
-    ) -> Option<FunctionDebugContext<&'ll DIScope>> {
+        mir: &mir::Body<'tcx>,
+    ) -> Option<FunctionDebugContext<&'ll DIScope, &'ll DILocation>> {
         if self.sess().opts.debuginfo == DebugInfo::None {
             return None;
         }
 
         // Initialize fn debug context (including scopes).
         // FIXME(eddyb) figure out a way to not need `Option` for `dbg_scope`.
-        let empty_scope =
-            DebugScope { dbg_scope: None, file_start_pos: BytePos(0), file_end_pos: BytePos(0) };
+        let empty_scope = DebugScope {
+            dbg_scope: None,
+            inlined_at: None,
+            file_start_pos: BytePos(0),
+            file_end_pos: BytePos(0),
+        };
         let mut fn_debug_context =
             FunctionDebugContext { scopes: IndexVec::from_elem(empty_scope, &mir.source_scopes) };
 
         // Fill in all the scopes, with the information from the MIR body.
         compute_mir_scopes(
             self,
+            instance,
             mir,
             self.dbg_scope_fn(instance, fn_abi, Some(llfn)),
             &mut fn_debug_context,
@@ -537,7 +542,12 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         }
     }
 
-    fn dbg_loc(&self, scope: &'ll DIScope, span: Span) -> &'ll DILocation {
+    fn dbg_loc(
+        &self,
+        scope: &'ll DIScope,
+        inlined_at: Option<&'ll DILocation>,
+        span: Span,
+    ) -> &'ll DILocation {
         let DebugLoc { line, col, .. } = self.lookup_debug_loc(span.lo());
 
         unsafe {
@@ -546,7 +556,7 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                 line.unwrap_or(UNKNOWN_LINE_NUMBER),
                 col.unwrap_or(UNKNOWN_COLUMN_NUMBER),
                 scope,
-                None,
+                inlined_at,
             )
         }
     }
diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
index ddb9372cf8f..e93830397c9 100644
--- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
@@ -12,8 +12,8 @@ use super::operand::OperandValue;
 use super::place::PlaceRef;
 use super::{FunctionCx, LocalRef};
 
-pub struct FunctionDebugContext<D> {
-    pub scopes: IndexVec<mir::SourceScope, DebugScope<D>>,
+pub struct FunctionDebugContext<S, L> {
+    pub scopes: IndexVec<mir::SourceScope, DebugScope<S, L>>,
 }
 
 #[derive(Copy, Clone)]
@@ -36,15 +36,42 @@ pub struct PerLocalVarDebugInfo<'tcx, D> {
 }
 
 #[derive(Clone, Copy, Debug)]
-pub struct DebugScope<D> {
+pub struct DebugScope<S, L> {
     // FIXME(eddyb) this should never be `None`, after initialization.
-    pub dbg_scope: Option<D>,
+    pub dbg_scope: Option<S>,
+
+    /// Call site location, if this scope was inlined from another function.
+    pub inlined_at: Option<L>,
+
     // Start and end offsets of the file to which this DIScope belongs.
     // These are used to quickly determine whether some span refers to the same file.
     pub file_start_pos: BytePos,
     pub file_end_pos: BytePos,
 }
 
+impl<'tcx, S: Copy, L: Copy> DebugScope<S, L> {
+    /// DILocations inherit source file name from the parent DIScope.  Due to macro expansions
+    /// it may so happen that the current span belongs to a different file than the DIScope
+    /// corresponding to span's containing source scope.  If so, we need to create a DIScope
+    /// "extension" into that file.
+    pub fn adjust_dbg_scope_for_span<Cx: CodegenMethods<'tcx, DIScope = S, DILocation = L>>(
+        &self,
+        cx: &Cx,
+        span: Span,
+    ) -> S {
+        // FIXME(eddyb) this should never be `None`.
+        let dbg_scope = self.dbg_scope.unwrap();
+
+        let pos = span.lo();
+        if pos < self.file_start_pos || pos >= self.file_end_pos {
+            let sm = cx.sess().source_map();
+            cx.extend_scope_to_file(dbg_scope, &sm.lookup_char_pos(pos).file)
+        } else {
+            dbg_scope
+        }
+    }
+}
+
 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     pub fn set_debug_loc(&self, bx: &mut Bx, source_info: mir::SourceInfo) {
         bx.set_span(source_info.span);
@@ -54,19 +81,21 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     }
 
     fn dbg_loc(&self, source_info: mir::SourceInfo) -> Option<Bx::DILocation> {
-        let (scope, span) = self.dbg_scope_and_span(source_info)?;
-        Some(self.cx.dbg_loc(scope, span))
+        let span = self.adjust_span_for_debugging(source_info.span);
+        let scope = &self.debug_context.as_ref()?.scopes[source_info.scope];
+        let dbg_scope = scope.adjust_dbg_scope_for_span(self.cx, span);
+        Some(self.cx.dbg_loc(dbg_scope, scope.inlined_at, span))
     }
 
-    fn dbg_scope_and_span(&self, source_info: mir::SourceInfo) -> Option<(Bx::DIScope, Span)> {
+    /// In order to have a good line stepping behavior in debugger, we overwrite debug
+    /// locations of macro expansions with that of the outermost expansion site
+    /// (unless the crate is being compiled with `-Z debug-macros`).
+    fn adjust_span_for_debugging(&self, mut span: Span) -> Span {
         // Bail out if debug info emission is not enabled.
-        let debug_context = self.debug_context.as_ref()?;
-        let scope = &debug_context.scopes[source_info.scope];
+        if self.debug_context.is_none() {
+            return span;
+        }
 
-        // In order to have a good line stepping behavior in debugger, we overwrite debug
-        // locations of macro expansions with that of the outermost expansion site
-        // (unless the crate is being compiled with `-Z debug-macros`).
-        let mut span = source_info.span;
         if span.from_expansion() && !self.cx.sess().opts.debugging_opts.debug_macros {
             // Walk up the macro expansion chain until we reach a non-expanded span.
             // We also stop at the function body level because no line stepping can occur
@@ -75,20 +104,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             span = rustc_span::hygiene::walk_chain(span, self.mir.span.ctxt());
         }
 
-        // FIXME(eddyb) this should never be `None`.
-        let mut dbg_scope = scope.dbg_scope?;
-
-        // DILocations inherit source file name from the parent DIScope.  Due to macro expansions
-        // it may so happen that the current span belongs to a different file than the DIScope
-        // corresponding to span's containing source scope.  If so, we need to create a DIScope
-        // "extension" into that file.
-        let pos = span.lo();
-        if pos < scope.file_start_pos || pos >= scope.file_end_pos {
-            let sm = self.cx.sess().source_map();
-            dbg_scope = self.cx.extend_scope_to_file(dbg_scope, &sm.lookup_char_pos(pos).file);
-        }
-
-        Some((dbg_scope, span))
+        span
     }
 
     /// Apply debuginfo and/or name, after creating the `alloca` for a local,
@@ -130,11 +146,17 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let name = kw::Invalid;
                 let decl = &self.mir.local_decls[local];
                 let dbg_var = if full_debug_info {
-                    self.dbg_scope_and_span(decl.source_info).map(|(scope, span)| {
+                    self.debug_context.as_ref().map(|debug_context| {
                         // FIXME(eddyb) is this `+ 1` needed at all?
                         let kind = VariableKind::ArgumentVariable(arg_index + 1);
 
-                        self.cx.create_dbg_var(name, self.monomorphize(&decl.ty), scope, kind, span)
+                        let arg_ty = self.monomorphize(&decl.ty);
+
+                        let span = self.adjust_span_for_debugging(decl.source_info.span);
+                        let scope = &debug_context.scopes[decl.source_info.scope];
+                        let dbg_scope = scope.adjust_dbg_scope_for_span(self.cx, span);
+
+                        self.cx.create_dbg_var(name, arg_ty, dbg_scope, kind, span)
                     })
                 } else {
                     None
@@ -288,9 +310,16 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
         let mut per_local = IndexVec::from_elem(vec![], &self.mir.local_decls);
         for var in &self.mir.var_debug_info {
-            let scope_and_span =
-                if full_debug_info { self.dbg_scope_and_span(var.source_info) } else { None };
-            let dbg_var = scope_and_span.map(|(scope, span)| {
+            let dbg_scope_and_span = if full_debug_info {
+                self.debug_context.as_ref().map(|debug_context| {
+                    let span = self.adjust_span_for_debugging(var.source_info.span);
+                    let scope = &debug_context.scopes[var.source_info.scope];
+                    (scope.adjust_dbg_scope_for_span(self.cx, span), span)
+                })
+            } else {
+                None
+            };
+            let dbg_var = dbg_scope_and_span.map(|(dbg_scope, span)| {
                 let place = var.place;
                 let var_ty = self.monomorphized_place_ty(place.as_ref());
                 let var_kind = if self.mir.local_kind(place.local) == mir::LocalKind::Arg
@@ -306,7 +335,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 } else {
                     VariableKind::LocalVariable
                 };
-                self.cx.create_dbg_var(var.name, var_ty, scope, var_kind, span)
+                self.cx.create_dbg_var(var.name, var_ty, dbg_scope, var_kind, span)
             });
 
             per_local[var.place.local].push(PerLocalVarDebugInfo {
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index bff263567bf..84e82e88e8e 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -26,7 +26,7 @@ pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
 
     mir: &'tcx mir::Body<'tcx>,
 
-    debug_context: Option<FunctionDebugContext<Bx::DIScope>>,
+    debug_context: Option<FunctionDebugContext<Bx::DIScope, Bx::DILocation>>,
 
     llfn: Bx::Function,
 
diff --git a/compiler/rustc_codegen_ssa/src/traits/debuginfo.rs b/compiler/rustc_codegen_ssa/src/traits/debuginfo.rs
index a7588eb4d14..3e66d711d2e 100644
--- a/compiler/rustc_codegen_ssa/src/traits/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/debuginfo.rs
@@ -18,8 +18,8 @@ pub trait DebugInfoMethods<'tcx>: BackendTypes {
         instance: Instance<'tcx>,
         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
         llfn: Self::Function,
-        mir: &mir::Body<'_>,
-    ) -> Option<FunctionDebugContext<Self::DIScope>>;
+        mir: &mir::Body<'tcx>,
+    ) -> Option<FunctionDebugContext<Self::DIScope, Self::DILocation>>;
 
     // FIXME(eddyb) find a common convention for all of the debuginfo-related
     // names (choose between `dbg`, `debug`, `debuginfo`, `debug_info` etc.).
@@ -30,7 +30,12 @@ pub trait DebugInfoMethods<'tcx>: BackendTypes {
         maybe_definition_llfn: Option<Self::Function>,
     ) -> Self::DIScope;
 
-    fn dbg_loc(&self, scope: Self::DIScope, span: Span) -> Self::DILocation;
+    fn dbg_loc(
+        &self,
+        scope: Self::DIScope,
+        inlined_at: Option<Self::DILocation>,
+        span: Span,
+    ) -> Self::DILocation;
 
     fn extend_scope_to_file(
         &self,