rustc_codegen_ssa: move local variable debuginfo to mir::debuginfo.

Author: eddyb

src/librustc_codegen_ssa/mir/analyze.rs

@@ -7,6 +7,7 @@ use rustc_index::vec::{Idx, IndexVec};
 use rustc::mir::{self, Location, TerminatorKind};
 use rustc::mir::visit::{Visitor, PlaceContext, MutatingUseContext, NonMutatingUseContext};
 use rustc::mir::traversal;
+use rustc::session::config::DebugInfo;
 use rustc::ty;
 use rustc::ty::layout::{LayoutOf, HasTyCtxt};
 use syntax_pos::DUMMY_SP;
@@ -21,13 +22,20 @@ pub fn non_ssa_locals<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
     analyzer.visit_body(mir);
 
-    for (index, (ty, span)) in mir.local_decls.iter()
-        .map(|l| (l.ty, l.source_info.span))
-        .enumerate()
+    for (local, decl) in mir.local_decls.iter_enumerated()
     {
-        let ty = fx.monomorphize(&ty);
-        debug!("local {} has type {:?}", index, ty);
-        let layout = fx.cx.spanned_layout_of(ty, span);
+        // FIXME(eddyb): We should figure out how to use llvm.dbg.value instead
+        // of putting everything in allocas just so we can use llvm.dbg.declare.
+        if fx.cx.sess().opts.debuginfo == DebugInfo::Full {
+            if mir.local_kind(local) == mir::LocalKind::Arg || decl.name.is_some() {
+                analyzer.not_ssa(local);
+                continue;
+            }
+        }
+
+        let ty = fx.monomorphize(&decl.ty);
+        debug!("local {:?} has type `{}`", local, ty);
+        let layout = fx.cx.spanned_layout_of(ty, decl.source_info.span);
         if fx.cx.is_backend_immediate(layout) {
             // These sorts of types are immediates that we can store
             // in an Value without an alloca.
@@ -40,7 +48,7 @@ pub fn non_ssa_locals<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             // (e.g., structs) into an alloca unconditionally, just so
             // that we don't have to deal with having two pathways
             // (gep vs extractvalue etc).
-            analyzer.not_ssa(mir::Local::new(index));
+            analyzer.not_ssa(local);
         }
     }
 

src/librustc_codegen_ssa/mir/debuginfo.rs

@@ -1,10 +1,16 @@
+use rustc_index::vec::Idx;
 use rustc::hir::def_id::CrateNum;
 use rustc::mir;
+use rustc::session::config::DebugInfo;
+use rustc::ty::{self, UpvarSubsts};
+use rustc::ty::layout::HasTyCtxt;
+use rustc_target::abi::{Variants, VariantIdx};
 use crate::traits::*;
 
 use syntax_pos::{DUMMY_SP, BytePos, Span};
+use syntax::symbol::kw;
 
-use super::FunctionCx;
+use super::{FunctionCx, LocalRef};
 
 pub enum FunctionDebugContext<D> {
     RegularContext(FunctionDebugContextData<D>),
@@ -142,4 +148,175 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             scope_metadata
         }
     }
+
+    pub fn debug_declare_locals(&self, bx: &mut Bx) {
+        let tcx = self.cx.tcx();
+        let upvar_debuginfo = &self.mir.__upvar_debuginfo_codegen_only_do_not_use;
+
+        if bx.sess().opts.debuginfo != DebugInfo::Full {
+            return;
+        }
+
+        for (local, local_ref) in self.locals.iter_enumerated() {
+            if local == mir::RETURN_PLACE {
+                continue;
+            }
+
+            // FIXME(eddyb) add debuginfo for unsized places too.
+            let place = match local_ref {
+                LocalRef::Place(place) => place,
+                _ => continue,
+            };
+
+            let decl = &self.mir.local_decls[local];
+            let (name, kind) = if self.mir.local_kind(local) == mir::LocalKind::Arg {
+                let arg_index = local.index() - 1;
+
+                // Add debuginfo even to unnamed arguments.
+                // FIXME(eddyb) is this really needed?
+                let name = if arg_index == 0 && !upvar_debuginfo.is_empty() {
+                    // Hide closure environments from debuginfo.
+                    // FIXME(eddyb) shouldn't `ArgumentVariable` indices
+                    // be offset to account for the hidden environment?
+                    None
+                } else {
+                    Some(decl.name.unwrap_or(kw::Invalid))
+                };
+                (name, VariableKind::ArgumentVariable(arg_index + 1))
+            } else {
+                (decl.name, VariableKind::LocalVariable)
+            };
+            if let Some(name) = name {
+                let (scope, span) = self.debug_loc(mir::SourceInfo {
+                    span: decl.source_info.span,
+                    scope: decl.visibility_scope,
+                });
+                if let Some(scope) = scope {
+                    bx.declare_local(&self.debug_context, name, place.layout.ty, scope,
+                        VariableAccess::DirectVariable { alloca: place.llval },
+                        kind, span);
+                }
+            }
+        }
+
+        // Declare closure captures as if they were local variables.
+        // FIXME(eddyb) generalize this to `name => place` mappings.
+        let upvar_scope = if !upvar_debuginfo.is_empty() {
+            self.scopes[mir::OUTERMOST_SOURCE_SCOPE].scope_metadata
+        } else {
+            None
+        };
+        if let Some(scope) = upvar_scope {
+            let place = match self.locals[mir::Local::new(1)] {
+                LocalRef::Place(place) => place,
+                _ => bug!(),
+            };
+
+            let pin_did = tcx.lang_items().pin_type();
+            let (closure_layout, env_ref) = match place.layout.ty.kind {
+                ty::RawPtr(ty::TypeAndMut { ty, .. }) |
+                ty::Ref(_, ty, _)  => (bx.layout_of(ty), true),
+                ty::Adt(def, substs) if Some(def.did) == pin_did => {
+                    match substs.type_at(0).kind {
+                        ty::Ref(_, ty, _)  => (bx.layout_of(ty), true),
+                        _ => (place.layout, false),
+                    }
+                }
+                _ => (place.layout, false)
+            };
+
+            let (def_id, upvar_substs) = match closure_layout.ty.kind {
+                ty::Closure(def_id, substs) => (def_id, UpvarSubsts::Closure(substs)),
+                ty::Generator(def_id, substs, _) => (def_id, UpvarSubsts::Generator(substs)),
+                _ => bug!("upvar debuginfo with non-closure arg0 type `{}`", closure_layout.ty)
+            };
+            let upvar_tys = upvar_substs.upvar_tys(def_id, tcx);
+
+            let extra_locals = {
+                let upvars = upvar_debuginfo
+                    .iter()
+                    .zip(upvar_tys)
+                    .enumerate()
+                    .map(|(i, (upvar, ty))| {
+                        (None, i, upvar.debug_name, upvar.by_ref, ty, scope, DUMMY_SP)
+                    });
+
+                let generator_fields = self.mir.generator_layout.as_ref().map(|generator_layout| {
+                    let (def_id, gen_substs) = match closure_layout.ty.kind {
+                        ty::Generator(def_id, substs, _) => (def_id, substs),
+                        _ => bug!("generator layout without generator substs"),
+                    };
+                    let state_tys = gen_substs.as_generator().state_tys(def_id, tcx);
+
+                    generator_layout.variant_fields.iter()
+                        .zip(state_tys)
+                        .enumerate()
+                        .flat_map(move |(variant_idx, (fields, tys))| {
+                            let variant_idx = Some(VariantIdx::from(variant_idx));
+                            fields.iter()
+                                .zip(tys)
+                                .enumerate()
+                                .filter_map(move |(i, (field, ty))| {
+                                    let decl = &generator_layout.
+                                        __local_debuginfo_codegen_only_do_not_use[*field];
+                                    if let Some(name) = decl.name {
+                                        let ty = self.monomorphize(&ty);
+                                        let (var_scope, var_span) = self.debug_loc(mir::SourceInfo {
+                                            span: decl.source_info.span,
+                                            scope: decl.visibility_scope,
+                                        });
+                                        let var_scope = var_scope.unwrap_or(scope);
+                                        Some((variant_idx, i, name, false, ty, var_scope, var_span))
+                                    } else {
+                                        None
+                                    }
+                            })
+                        })
+                }).into_iter().flatten();
+
+                upvars.chain(generator_fields)
+            };
+
+            for (variant_idx, field, name, by_ref, ty, var_scope, var_span) in extra_locals {
+                let fields = match variant_idx {
+                    Some(variant_idx) => {
+                        match &closure_layout.variants {
+                            Variants::Multiple { variants, .. } => {
+                                &variants[variant_idx].fields
+                            },
+                            _ => bug!("variant index on univariant layout"),
+                        }
+                    }
+                    None => &closure_layout.fields,
+                };
+                let byte_offset_of_var_in_env = fields.offset(field).bytes();
+
+                let ops = bx.debuginfo_upvar_ops_sequence(byte_offset_of_var_in_env);
+
+                // The environment and the capture can each be indirect.
+                let mut ops = if env_ref { &ops[..] } else { &ops[1..] };
+
+                let ty = if let (true, &ty::Ref(_, ty, _)) = (by_ref, &ty.kind) {
+                    ty
+                } else {
+                    ops = &ops[..ops.len() - 1];
+                    ty
+                };
+
+                let variable_access = VariableAccess::IndirectVariable {
+                    alloca: place.llval,
+                    address_operations: &ops
+                };
+                bx.declare_local(
+                    &self.debug_context,
+                    name,
+                    ty,
+                    var_scope,
+                    variable_access,
+                    VariableKind::LocalVariable,
+                    var_span
+                );
+            }
+        }
+    }
 }