Implement drop support (fixes rust-lang#11)

Author: bjorn3

examples/mini_core.rs

@@ -197,6 +197,11 @@ unsafe fn allocate(size: usize, _align: usize) -> *mut u8 {
     &mut MY_TINY_HEAP as *mut [u8; 16] as *mut u8
 }
 
+#[lang = "drop"]
+pub trait Drop {
+    fn drop(&mut self);
+}
+
 pub mod intrinsics {
     extern "rust-intrinsic" {
         pub fn abort() -> !;

examples/mini_core_hello_world.rs

@@ -49,6 +49,29 @@ impl SomeTrait for &'static str {
     }
 }
 
+struct NoisyDrop {
+    text: &'static str,
+    inner: NoisyDropInner,
+}
+
+struct NoisyDropInner;
+
+impl Drop for NoisyDrop {
+    fn drop(&mut self) {
+        unsafe {
+            puts(self.text as *const str as *const u8);
+        }
+    }
+}
+
+impl Drop for NoisyDropInner {
+    fn drop(&mut self) {
+        unsafe {
+            puts("Inner got dropped!\0" as *const str as *const u8);
+        }
+    }
+}
+
 #[lang = "start"]
 fn start<T: Termination + 'static>(
     main: fn() -> T,
@@ -91,4 +114,9 @@ fn main() {
             panic(&("", "", 0, 0));
         }
     }
+
+    let _ = NoisyDrop {
+        text: "Outer got dropped!\0",
+        inner: NoisyDropInner,
+    };
 }

src/abi.rs

@@ -433,7 +433,7 @@ pub fn codegen_fn_prelude<'a, 'tcx: 'a>(
         .jump(*fx.ebb_map.get(&START_BLOCK).unwrap(), &[]);
 }
 
-pub fn codegen_call<'a, 'tcx: 'a>(
+pub fn codegen_terminator_call<'a, 'tcx: 'a>(
     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
     func: &Operand<'tcx>,
     args: &[Operand<'tcx>],
@@ -466,19 +466,42 @@ pub fn codegen_call<'a, 'tcx: 'a>(
 
     let destination = destination
         .as_ref()
-        .map(|(place, bb)| (trans_place(fx, place), *bb));
-
-    if codegen_intrinsic_call(fx, fn_ty, sig, &args, destination) {
-        return;
+        .map(|&(ref place, bb)| (trans_place(fx, place), bb));
+
+    if !codegen_intrinsic_call(fx, fn_ty, &args, destination) {
+        codegen_call_inner(
+            fx,
+            Some(func),
+            fn_ty,
+            args,
+            destination.map(|(place, _)| place),
+        );
+
+        if let Some((_, dest)) = destination {
+            let ret_ebb = fx.get_ebb(dest);
+            fx.bcx.ins().jump(ret_ebb, &[]);
+        } else {
+            fx.bcx.ins().trap(TrapCode::User(!0));
+        }
     }
+}
+
+pub fn codegen_call_inner<'a, 'tcx: 'a>(
+    fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
+    func: Option<&Operand<'tcx>>,
+    fn_ty: Ty<'tcx>,
+    args: Vec<CValue<'tcx>>,
+    ret_place: Option<CPlace<'tcx>>,
+) {
+    let sig = ty_fn_sig(fx.tcx, fn_ty);
 
     let ret_layout = fx.layout_of(sig.output());
 
     let output_pass_mode = get_pass_mode(fx.tcx, sig.abi, sig.output(), true);
     let return_ptr = match output_pass_mode {
         PassMode::NoPass => None,
-        PassMode::ByRef => match destination {
-            Some((place, _)) => Some(place.expect_addr()),
+        PassMode::ByRef => match ret_place {
+            Some(ret_place) => Some(ret_place.expect_addr()),
             None => Some(fx.bcx.ins().iconst(fx.module.pointer_type(), 0)),
         },
         PassMode::ByVal(_) => None,
@@ -504,7 +527,7 @@ pub fn codegen_call<'a, 'tcx: 'a>(
             Some(ptr)
         } else {
             func_ref = if instance.is_none() {
-                let func = trans_operand(fx, func);
+                let func = trans_operand(fx, func.expect("indirect call without func Operand"));
                 Some(func.load_value(fx))
             } else {
                 None
@@ -534,19 +557,13 @@ pub fn codegen_call<'a, 'tcx: 'a>(
     match output_pass_mode {
         PassMode::NoPass => {}
         PassMode::ByVal(_) => {
-            if let Some((ret_place, _)) = destination {
+            if let Some(ret_place) = ret_place {
                 let results = fx.bcx.inst_results(call_inst);
                 ret_place.write_cvalue(fx, CValue::ByVal(results[0], ret_layout));
             }
         }
         PassMode::ByRef => {}
     }
-    if let Some((_, dest)) = destination {
-        let ret_ebb = fx.get_ebb(dest);
-        fx.bcx.ins().jump(ret_ebb, &[]);
-    } else {
-        fx.bcx.ins().trap(TrapCode::User(!0));
-    }
 }
 
 pub fn codegen_return(fx: &mut FunctionCx<impl Backend>) {
@@ -565,11 +582,12 @@ pub fn codegen_return(fx: &mut FunctionCx<impl Backend>) {
 fn codegen_intrinsic_call<'a, 'tcx: 'a>(
     fx: &mut FunctionCx<'a, 'tcx, impl Backend>,
     fn_ty: Ty<'tcx>,
-    sig: FnSig<'tcx>,
     args: &[CValue<'tcx>],
     destination: Option<(CPlace<'tcx>, BasicBlock)>,
 ) -> bool {
     if let ty::FnDef(def_id, substs) = fn_ty.sty {
+        let sig = ty_fn_sig(fx.tcx, fn_ty);
+
         if sig.abi == Abi::RustIntrinsic {
             let intrinsic = fx.tcx.item_name(def_id).as_str();
             let intrinsic = &intrinsic[..];

src/base.rs

@@ -224,19 +224,90 @@ fn codegen_fn_content<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx, impl Backend>)
                 destination,
                 cleanup: _,
             } => {
-                crate::abi::codegen_call(fx, func, args, destination);
+                crate::abi::codegen_terminator_call(fx, func, args, destination);
             }
             TerminatorKind::Resume | TerminatorKind::Abort | TerminatorKind::Unreachable => {
                 fx.bcx.ins().trap(TrapCode::User(!0));
             }
             TerminatorKind::Yield { .. }
             | TerminatorKind::FalseEdges { .. }
-            | TerminatorKind::FalseUnwind { .. } => {
+            | TerminatorKind::FalseUnwind { .. }
+            | TerminatorKind::DropAndReplace { .. } => {
                 bug!("shouldn't exist at trans {:?}", bb_data.terminator());
             }
-            TerminatorKind::Drop { target, .. } | TerminatorKind::DropAndReplace { target, .. } => {
-                // TODO call drop impl
-                // unimplemented!("terminator {:?}", bb_data.terminator());
+            TerminatorKind::Drop {
+                location,
+                target,
+                unwind: _,
+            } => {
+                let ty = location.ty(fx.mir, fx.tcx).to_ty(fx.tcx);
+                let ty = fx.monomorphize(&ty);
+                let drop_fn = ::rustc_mir::monomorphize::resolve_drop_in_place(fx.tcx, ty);
+
+                if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
+                    // we don't actually need to drop anything
+                } else {
+                    let drop_place = trans_place(fx, location);
+                    let arg_place = CPlace::temp(
+                        fx,
+                        fx.tcx.mk_ref(
+                            &ty::RegionKind::ReErased,
+                            TypeAndMut {
+                                ty,
+                                mutbl: ::rustc::hir::Mutability::MutMutable,
+                            },
+                        ),
+                    );
+                    drop_place.write_place_ref(fx, arg_place);
+                    match ty.sty {
+                        ty::Dynamic(..) => {
+                            unimplemented!("Drop for trait object");
+                        }
+                        _ => {
+                            let drop_fn_ty = drop_fn.ty(fx.tcx);
+                            let arg_value = arg_place.to_cvalue(fx);
+                            crate::abi::codegen_call_inner(
+                                fx,
+                                None,
+                                drop_fn_ty,
+                                vec![arg_value],
+                                None,
+                            );
+                        }
+                    }
+                    /*
+                    let (args1, args2);
+                    /*let mut args = if let Some(llextra) = place.llextra {
+                        args2 = [place.llval, llextra];
+                        &args2[..]
+                    } else {
+                        args1 = [place.llval];
+                        &args1[..]
+                    };*/
+                    let (drop_fn, fn_ty) = match ty.sty {
+                        ty::Dynamic(..) => {
+                            let fn_ty = drop_fn.ty(bx.cx.tcx);
+                            let sig = common::ty_fn_sig(bx.cx, fn_ty);
+                            let sig = bx.tcx().normalize_erasing_late_bound_regions(
+                                ty::ParamEnv::reveal_all(),
+                                &sig,
+                            );
+                            let fn_ty = FnType::new_vtable(bx.cx, sig, &[]);
+                            let vtable = args[1];
+                            args = &args[..1];
+                            (meth::DESTRUCTOR.get_fn(&bx, vtable, &fn_ty), fn_ty)
+                        }
+                        _ => {
+                            let value = place.to_cvalue(fx);
+                            (callee::get_fn(bx.cx, drop_fn),
+                            FnType::of_instance(bx.cx, &drop_fn))
+                        }
+                    };
+                    do_call(self, bx, fn_ty, drop_fn, args,
+                            Some((ReturnDest::Nothing, target)),
+                            unwind);*/
+                }
+
                 let target_ebb = fx.get_ebb(*target);
                 fx.bcx.ins().jump(target_ebb, &[]);
             }