refactor away callee::Callee and translate virtual calls through a MIR shim

These changes are in the same commit to avoid needing to adapt
meth::trans_object_shim to the new scheme.

One codegen-units test is broken because we instantiate the shims even
when they are not needed. This will be fixed in the next PR.

Author: arielb1

src/librustc_mir/lib.rs

@@ -23,6 +23,7 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![feature(associated_consts)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![cfg_attr(stage0, feature(field_init_shorthand))]
 #![feature(i128_type)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(rustc_private)]

src/librustc_mir/mir_map.rs

@@ -252,12 +252,9 @@ fn closure_self_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                              -> Ty<'tcx> {
     let closure_ty = tcx.body_tables(body_id).node_id_to_type(closure_expr_id);
 
-    // We're just hard-coding the idea that the signature will be
-    // &self or &mut self and hence will have a bound region with
-    // number 0, hokey.
     let region = ty::Region::ReFree(ty::FreeRegion {
         scope: tcx.region_maps.item_extent(body_id.node_id),
-        bound_region: ty::BoundRegion::BrAnon(0),
+        bound_region: ty::BoundRegion::BrEnv,
     });
     let region = tcx.mk_region(region);
 

src/librustc_mir/shim.rs

@@ -9,17 +9,19 @@
 // except according to those terms.
 
 use rustc::hir;
+use rustc::hir::def_id::DefId;
 use rustc::infer;
+use rustc::middle::region::ROOT_CODE_EXTENT;
 use rustc::mir::*;
 use rustc::mir::transform::MirSource;
 use rustc::ty::{self, Ty};
+use rustc::ty::subst::Subst;
 use rustc::ty::maps::Providers;
 
 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
 
 use syntax::abi::Abi;
 use syntax::ast;
-use syntax::codemap::DUMMY_SP;
 use syntax_pos::Span;
 
 use std::cell::RefCell;
@@ -35,11 +37,51 @@ fn make_shim<'a, 'tcx>(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
                        -> &'tcx RefCell<Mir<'tcx>>
 {
     debug!("make_shim({:?})", instance);
+    let did = instance.def_id();
+    let span = tcx.def_span(did);
+    let param_env =
+        tcx.construct_parameter_environment(span, did, ROOT_CODE_EXTENT);
+
     let result = match instance {
         ty::InstanceDef::Item(..) =>
             bug!("item {:?} passed to make_shim", instance),
-        ty::InstanceDef::FnPtrShim(_, ty) => {
-            build_fn_ptr_shim(tcx, ty, instance.def_ty(tcx))
+        ty::InstanceDef::FnPtrShim(def_id, ty) => {
+            let trait_ = tcx.trait_of_item(def_id).unwrap();
+            let adjustment = match tcx.lang_items.fn_trait_kind(trait_) {
+                Some(ty::ClosureKind::FnOnce) => Adjustment::Identity,
+                Some(ty::ClosureKind::FnMut) |
+                Some(ty::ClosureKind::Fn) => Adjustment::Deref,
+                None => bug!("fn pointer {:?} is not an fn", ty)
+            };
+            // HACK: we need the "real" argument types for the MIR,
+            // but because our substs are (Self, Args), where Args
+            // is a tuple, we must include the *concrete* argument
+            // types in the MIR. They will be substituted again with
+            // the param-substs, but because they are concrete, this
+            // will not do any harm.
+            let sig = tcx.erase_late_bound_regions(&ty.fn_sig());
+            let arg_tys = sig.inputs();
+
+            build_call_shim(
+                tcx,
+                &param_env,
+                def_id,
+                adjustment,
+                CallKind::Indirect,
+                Some(arg_tys)
+            )
+        }
+        ty::InstanceDef::Virtual(def_id, _) => {
+            // We are translating a call back to our def-id, which
+            // trans::mir knows to turn to an actual virtual call.
+            build_call_shim(
+                tcx,
+                &param_env,
+                def_id,
+                Adjustment::Identity,
+                CallKind::Direct(def_id),
+                None
+            )
         }
         _ => bug!("unknown shim kind")
     };
@@ -51,124 +93,135 @@ fn make_shim<'a, 'tcx>(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
     result
 }
 
+#[derive(Copy, Clone, Debug, PartialEq)]
+enum Adjustment {
+    Identity,
+    Deref,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+enum CallKind {
+    Indirect,
+    Direct(DefId),
+}
+
+fn temp_decl(mutability: Mutability, ty: Ty) -> LocalDecl {
+    LocalDecl { mutability, ty, name: None, source_info: None }
+}
+
 fn local_decls_for_sig<'tcx>(sig: &ty::FnSig<'tcx>)
     -> IndexVec<Local, LocalDecl<'tcx>>
 {
-    iter::once(LocalDecl {
-        mutability: Mutability::Mut,
-        ty: sig.output(),
-        name: None,
-        source_info: None
-    }).chain(sig.inputs().iter().map(|ity| LocalDecl {
-        mutability: Mutability::Not,
-        ty: *ity,
-        name: None,
-        source_info: None,
-    })).collect()
+    iter::once(temp_decl(Mutability::Mut, sig.output()))
+        .chain(sig.inputs().iter().map(
+            |ity| temp_decl(Mutability::Not, ity)))
+        .collect()
 }
 
-
-fn build_fn_ptr_shim<'a, 'tcx>(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
-                               fn_ty: Ty<'tcx>,
-                               sig_ty: Ty<'tcx>)
-                               -> Mir<'tcx>
+/// Build a "call" shim for `def_id`. The shim calls the
+/// function specified by `call_kind`, first adjusting its first
+/// argument according to `rcvr_adjustment`.
+///
+/// If `untuple_args` is a vec of types, the second argument of the
+/// function will be untupled as these types.
+fn build_call_shim<'a, 'tcx>(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
+                             param_env: &ty::ParameterEnvironment<'tcx>,
+                             def_id: DefId,
+                             rcvr_adjustment: Adjustment,
+                             call_kind: CallKind,
+                             untuple_args: Option<&[Ty<'tcx>]>)
+                             -> Mir<'tcx>
 {
-    debug!("build_fn_ptr_shim(fn_ty={:?}, sig_ty={:?})", fn_ty, sig_ty);
-    let trait_sig = match sig_ty.sty {
-        ty::TyFnDef(_, _, fty) => tcx.erase_late_bound_regions(&fty),
-        _ => bug!("unexpected type for shim {:?}", sig_ty)
-    };
+    debug!("build_call_shim(def_id={:?}, rcvr_adjustment={:?}, \
+            call_kind={:?}, untuple_args={:?})",
+           def_id, rcvr_adjustment, call_kind, untuple_args);
 
-    let self_ty = match trait_sig.inputs()[0].sty {
-        ty::TyParam(..) => fn_ty,
-        ty::TyRef(r, mt) => tcx.mk_ref(r, ty::TypeAndMut {
-            ty: fn_ty,
-            mutbl: mt.mutbl
-        }),
-        _ => bug!("unexpected self_ty {:?}", trait_sig),
-    };
+    let fn_ty = tcx.item_type(def_id).subst(tcx, param_env.free_substs);
+    // Not normalizing here without a param env.
+    let sig = tcx.erase_late_bound_regions(&fn_ty.fn_sig());
+    let span = tcx.def_span(def_id);
 
-    let fn_ptr_sig = match fn_ty.sty {
-        ty::TyFnPtr(fty) |
-        ty::TyFnDef(_, _, fty) =>
-            tcx.erase_late_bound_regions_and_normalize(&fty),
-        _ => bug!("non-fn-ptr {:?} in build_fn_ptr_shim", fn_ty)
-    };
-
-    let sig = tcx.mk_fn_sig(
-        [
-            self_ty,
-            tcx.intern_tup(fn_ptr_sig.inputs(), false)
-        ].iter().cloned(),
-        fn_ptr_sig.output(),
-        false,
-        hir::Unsafety::Normal,
-        Abi::RustCall,
-    );
+    debug!("build_call_shim: sig={:?}", sig);
 
     let local_decls = local_decls_for_sig(&sig);
-    let source_info = SourceInfo {
-        span: DUMMY_SP,
-        scope: ARGUMENT_VISIBILITY_SCOPE
+    let source_info = SourceInfo { span, scope: ARGUMENT_VISIBILITY_SCOPE };
+
+    let rcvr_l = Lvalue::Local(Local::new(1+0));
+
+    let return_block_id = BasicBlock::new(1);
+
+    let rcvr = match rcvr_adjustment {
+        Adjustment::Identity => Operand::Consume(rcvr_l),
+        Adjustment::Deref => Operand::Consume(Lvalue::Projection(
+            box Projection { base: rcvr_l, elem: ProjectionElem::Deref }
+        ))
     };
 
-    let fn_ptr = Lvalue::Local(Local::new(1+0));
-    let fn_ptr = match trait_sig.inputs()[0].sty {
-        ty::TyParam(..) => fn_ptr,
-        ty::TyRef(..) => Lvalue::Projection(box Projection {
-            base: fn_ptr, elem: ProjectionElem::Deref
-        }),
-        _ => bug!("unexpected self_ty {:?}", trait_sig),
+    let (callee, mut args) = match call_kind {
+        CallKind::Indirect => (rcvr, vec![]),
+        CallKind::Direct(def_id) => (
+            Operand::Constant(Constant {
+                span: span,
+                ty: tcx.item_type(def_id).subst(tcx, param_env.free_substs),
+                literal: Literal::Item { def_id, substs: param_env.free_substs },
+            }),
+            vec![rcvr]
+        )
     };
-    let fn_args = Local::new(1+1);
 
-    let return_block_id = BasicBlock::new(1);
+    if let Some(untuple_args) = untuple_args {
+        args.extend(untuple_args.iter().enumerate().map(|(i, ity)| {
+            let arg_lv = Lvalue::Local(Local::new(1+1));
+            Operand::Consume(Lvalue::Projection(box Projection {
+                base: arg_lv,
+                elem: ProjectionElem::Field(Field::new(i), *ity)
+            }))
+        }));
+    } else {
+        args.extend((1..sig.inputs().len()).map(|i| {
+            Operand::Consume(Lvalue::Local(Local::new(1+i)))
+        }));
+    }
 
-    // return = ADT(arg0, arg1, ...); return
-    let start_block = BasicBlockData {
+    let mut blocks = IndexVec::new();
+    blocks.push(BasicBlockData {
         statements: vec![],
         terminator: Some(Terminator {
             source_info: source_info,
             kind: TerminatorKind::Call {
-                func: Operand::Consume(fn_ptr),
-                args: fn_ptr_sig.inputs().iter().enumerate().map(|(i, ity)| {
-                    Operand::Consume(Lvalue::Projection(box Projection {
-                        base: Lvalue::Local(fn_args),
-                        elem: ProjectionElem::Field(
-                            Field::new(i), *ity
-                        )
-                    }))
-                }).collect(),
-                // FIXME: can we pass a Some destination for an uninhabited ty?
+                func: callee,
+                args: args,
                 destination: Some((Lvalue::Local(RETURN_POINTER),
                                    return_block_id)),
                 cleanup: None
             }
         }),
         is_cleanup: false
-    };
-    let return_block = BasicBlockData {
+    });
+    blocks.push(BasicBlockData {
         statements: vec![],
         terminator: Some(Terminator {
             source_info: source_info,
             kind: TerminatorKind::Return
         }),
         is_cleanup: false
-    };
+    });
 
     let mut mir = Mir::new(
-        vec![start_block, return_block].into_iter().collect(),
+        blocks,
         IndexVec::from_elem_n(
-            VisibilityScopeData { span: DUMMY_SP, parent_scope: None }, 1
+            VisibilityScopeData { span: span, parent_scope: None }, 1
         ),
         IndexVec::new(),
         sig.output(),
         local_decls,
         sig.inputs().len(),
         vec![],
-        DUMMY_SP
+        span
     );
-    mir.spread_arg = Some(fn_args);
+    if let Abi::RustCall = sig.abi {
+        mir.spread_arg = Some(Local::new(sig.inputs().len()));
+    }
     mir
 }
 

src/librustc_trans/abi.rs

@@ -11,7 +11,7 @@
 use llvm::{self, ValueRef, Integer, Pointer, Float, Double, Struct, Array, Vector, AttributePlace};
 use base;
 use builder::Builder;
-use common::{type_is_fat_ptr, C_uint};
+use common::{self, type_is_fat_ptr, C_uint};
 use context::CrateContext;
 use cabi_x86;
 use cabi_x86_64;
@@ -334,9 +334,30 @@ impl FnType {
         fn_ty
     }
 
-    pub fn unadjusted<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
+    pub fn new_vtable<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
                                 sig: ty::FnSig<'tcx>,
                                 extra_args: &[Ty<'tcx>]) -> FnType {
+        let mut fn_ty = FnType::unadjusted(ccx, sig, extra_args);
+        // Don't pass the vtable, it's not an argument of the virtual fn.
+        fn_ty.args[1].ignore();
+        fn_ty.adjust_for_abi(ccx, sig);
+        fn_ty
+    }
+
+    pub fn from_instance<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
+                                   instance: &ty::Instance<'tcx>,
+                                   extra_args: &[Ty<'tcx>]) -> FnType
+    {
+        let ity = common::instance_ty(ccx.shared(), instance);
+        let sig = common::ty_fn_sig(ccx, ity);
+        let sig = ccx.tcx().erase_late_bound_regions_and_normalize(&sig);
+
+        Self::new(ccx, sig, extra_args)
+    }
+
+    fn unadjusted<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
+                            sig: ty::FnSig<'tcx>,
+                            extra_args: &[Ty<'tcx>]) -> FnType {
         use self::Abi::*;
         let cconv = match ccx.sess().target.target.adjust_abi(sig.abi) {
             RustIntrinsic | PlatformIntrinsic |
@@ -532,9 +553,9 @@ impl FnType {
         }
     }
 
-    pub fn adjust_for_abi<'a, 'tcx>(&mut self,
-                                    ccx: &CrateContext<'a, 'tcx>,
-                                    sig: ty::FnSig<'tcx>) {
+    fn adjust_for_abi<'a, 'tcx>(&mut self,
+                                ccx: &CrateContext<'a, 'tcx>,
+                                sig: ty::FnSig<'tcx>) {
         let abi = sig.abi;
         if abi == Abi::Unadjusted { return }
 

src/librustc_trans/base.rs

@@ -47,7 +47,7 @@ use abi;
 use mir::lvalue::LvalueRef;
 use attributes;
 use builder::Builder;
-use callee::{Callee};
+use callee;
 use common::{C_bool, C_bytes_in_context, C_i32, C_uint};
 use collector::{self, TransItemCollectionMode};
 use common::{C_struct_in_context, C_u64, C_undef};
@@ -654,7 +654,7 @@ pub fn maybe_create_entry_wrapper(ccx: &CrateContext) {
         return;
     }
 
-    let main_llfn = Callee::def(ccx, main_def_id, instance.substs).reify(ccx);
+    let main_llfn = callee::get_fn(ccx, instance);
 
     let et = ccx.sess().entry_type.get().unwrap();
     match et {
@@ -688,8 +688,8 @@ pub fn maybe_create_entry_wrapper(ccx: &CrateContext) {
 
         let (start_fn, args) = if use_start_lang_item {
             let start_def_id = ccx.tcx().require_lang_item(StartFnLangItem);
-            let empty_substs = ccx.tcx().intern_substs(&[]);
-            let start_fn = Callee::def(ccx, start_def_id, empty_substs).reify(ccx);
+            let start_instance = Instance::mono(ccx.tcx(), start_def_id);
+            let start_fn = callee::get_fn(ccx, start_instance);
             (start_fn, vec![bld.pointercast(rust_main, Type::i8p(ccx).ptr_to()), get_param(llfn, 0),
                 get_param(llfn, 1)])
         } else {