diff options
| -rw-r--r-- | src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs | 3 | ||||
| -rw-r--r-- | src/librustc_borrowck/borrowck/mir/dataflow/impls.rs | 2 | ||||
| -rw-r--r-- | src/librustc_borrowck/borrowck/mir/elaborate_drops.rs | 727 | ||||
| -rw-r--r-- | src/librustc_borrowck/borrowck/mir/mod.rs | 17 | ||||
| -rw-r--r-- | src/librustc_driver/pretty.rs | 3 | ||||
| -rw-r--r-- | src/librustc_mir/lib.rs | 4 | ||||
| -rw-r--r-- | src/librustc_mir/mir_map.rs | 6 | ||||
| -rw-r--r-- | src/librustc_mir/transform/copy_prop.rs | 2 | ||||
| -rw-r--r-- | src/librustc_mir/transform/dump_mir.rs | 4 | ||||
| -rw-r--r-- | src/librustc_mir/util/def_use.rs (renamed from src/librustc_mir/def_use.rs) | 0 | ||||
| -rw-r--r-- | src/librustc_mir/util/elaborate_drops.rs | 561 | ||||
| -rw-r--r-- | src/librustc_mir/util/graphviz.rs (renamed from src/librustc_mir/graphviz.rs) | 0 | ||||
| -rw-r--r-- | src/librustc_mir/util/mod.rs | 20 | ||||
| -rw-r--r-- | src/librustc_mir/util/patch.rs (renamed from src/librustc_borrowck/borrowck/mir/patch.rs) | 0 | ||||
| -rw-r--r-- | src/librustc_mir/util/pretty.rs (renamed from src/librustc_mir/pretty.rs) | 0 |
15 files changed, 728 insertions, 621 deletions
diff --git a/src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs b/src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs index b15c1873f9b..7f95f07f48d 100644 --- a/src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs +++ b/src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs @@ -15,6 +15,7 @@ use rustc::mir::{BasicBlock, Mir}; use rustc_data_structures::bitslice::bits_to_string; use rustc_data_structures::indexed_set::{IdxSet}; use rustc_data_structures::indexed_vec::Idx; +use rustc_mir::util as mir_util; use dot; use dot::IntoCow; @@ -219,7 +220,7 @@ impl<'a, 'tcx, MWF, P> dot::Labeller<'a> for Graph<'a, 'tcx, MWF, P> } Ok(()) } - ::rustc_mir::graphviz::write_node_label( + mir_util::write_graphviz_node_label( *n, self.mbcx.mir(), &mut v, 4, |w| { let flow = self.mbcx.flow_state(); diff --git a/src/librustc_borrowck/borrowck/mir/dataflow/impls.rs b/src/librustc_borrowck/borrowck/mir/dataflow/impls.rs index 7888a56d39d..da8aa231ccf 100644 --- a/src/librustc_borrowck/borrowck/mir/dataflow/impls.rs +++ b/src/librustc_borrowck/borrowck/mir/dataflow/impls.rs @@ -14,10 +14,10 @@ use rustc_data_structures::bitslice::BitSlice; // adds set_bit/get_bit to &[usiz use rustc_data_structures::bitslice::{BitwiseOperator}; use rustc_data_structures::indexed_set::{IdxSet}; use rustc_data_structures::indexed_vec::Idx; +use rustc_mir::util::elaborate_drops::DropFlagState; use super::super::gather_moves::{HasMoveData, MoveData, MoveOutIndex, MovePathIndex}; use super::super::MoveDataParamEnv; -use super::super::DropFlagState; use super::super::drop_flag_effects_for_function_entry; use super::super::drop_flag_effects_for_location; use super::super::on_lookup_result_bits; diff --git a/src/librustc_borrowck/borrowck/mir/elaborate_drops.rs b/src/librustc_borrowck/borrowck/mir/elaborate_drops.rs index a71d23e7e1e..88ec86cc95d 100644 --- a/src/librustc_borrowck/borrowck/mir/elaborate_drops.rs +++ b/src/librustc_borrowck/borrowck/mir/elaborate_drops.rs @@ -13,22 +13,20 @@ use super::dataflow::{MaybeInitializedLvals, MaybeUninitializedLvals}; use super::dataflow::{DataflowResults}; use super::{drop_flag_effects_for_location, on_all_children_bits}; use super::on_lookup_result_bits; -use super::{DropFlagState, MoveDataParamEnv}; -use super::patch::MirPatch; -use rustc::ty::{self, Ty, TyCtxt}; -use rustc::ty::subst::{Kind, Subst, Substs}; -use rustc::ty::util::IntTypeExt; +use super::MoveDataParamEnv; +use rustc::ty::{self, TyCtxt}; use rustc::mir::*; use rustc::mir::transform::{Pass, MirPass, MirSource}; use rustc::middle::const_val::ConstVal; -use rustc::middle::lang_items; use rustc::util::nodemap::FxHashMap; use rustc_data_structures::indexed_set::IdxSetBuf; use rustc_data_structures::indexed_vec::Idx; +use rustc_mir::util::patch::MirPatch; +use rustc_mir::util::elaborate_drops::{DropFlagState, elaborate_drop}; +use rustc_mir::util::elaborate_drops::{DropElaborator, DropStyle, DropFlagMode}; use syntax_pos::Span; use std::fmt; -use std::iter; use std::u32; pub struct ElaborateDrops; @@ -109,12 +107,116 @@ impl InitializationData { } } -impl fmt::Debug for InitializationData { +struct Elaborator<'a, 'b: 'a, 'tcx: 'b> { + init_data: &'a InitializationData, + ctxt: &'a mut ElaborateDropsCtxt<'b, 'tcx>, +} + +impl<'a, 'b, 'tcx> fmt::Debug for Elaborator<'a, 'b, 'tcx> { fn fmt(&self, _f: &mut fmt::Formatter) -> Result<(), fmt::Error> { Ok(()) } } +impl<'a, 'b, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, 'b, 'tcx> { + type Path = MovePathIndex; + + fn patch(&mut self) -> &mut MirPatch<'tcx> { + &mut self.ctxt.patch + } + + fn mir(&self) -> &'a Mir<'tcx> { + self.ctxt.mir + } + + fn tcx(&self) -> ty::TyCtxt<'a, 'tcx, 'tcx> { + self.ctxt.tcx + } + + fn param_env(&self) -> &'a ty::ParameterEnvironment<'tcx> { + self.ctxt.param_env() + } + + fn drop_style(&self, path: Self::Path, mode: DropFlagMode) -> DropStyle { + let ((maybe_live, maybe_dead), multipart) = match mode { + DropFlagMode::Shallow => (self.init_data.state(path), false), + DropFlagMode::Deep => { + let mut some_live = false; + let mut some_dead = false; + let mut children_count = 0; + on_all_children_bits( + self.tcx(), self.mir(), self.ctxt.move_data(), + path, |child| { + if self.ctxt.path_needs_drop(child) { + let (live, dead) = self.init_data.state(child); + debug!("elaborate_drop: state({:?}) = {:?}", + child, (live, dead)); + some_live |= live; + some_dead |= dead; + children_count += 1; + } + }); + ((some_live, some_dead), children_count != 1) + } + }; + match (maybe_live, maybe_dead, multipart) { + (false, _, _) => DropStyle::Dead, + (true, false, _) => DropStyle::Static, + (true, true, false) => DropStyle::Conditional, + (true, true, true) => DropStyle::Open, + } + } + + fn clear_drop_flag(&mut self, loc: Location, path: Self::Path, mode: DropFlagMode) { + match mode { + DropFlagMode::Shallow => { + self.ctxt.set_drop_flag(loc, path, DropFlagState::Absent); + } + DropFlagMode::Deep => { + on_all_children_bits( + self.tcx(), self.mir(), self.ctxt.move_data(), path, + |child| self.ctxt.set_drop_flag(loc, child, DropFlagState::Absent) + ); + } + } + } + + fn field_subpath(&self, path: Self::Path, field: Field) -> Option<Self::Path> { + super::move_path_children_matching(self.ctxt.move_data(), path, |p| { + match p { + &Projection { + elem: ProjectionElem::Field(idx, _), .. + } => idx == field, + _ => false + } + }) + } + + fn deref_subpath(&self, path: Self::Path) -> Option<Self::Path> { + super::move_path_children_matching(self.ctxt.move_data(), path, |p| { + match p { + &Projection { elem: ProjectionElem::Deref, .. } => true, + _ => false + } + }) + } + + fn downcast_subpath(&self, path: Self::Path, variant: usize) -> Option<Self::Path> { + super::move_path_children_matching(self.ctxt.move_data(), path, |p| { + match p { + &Projection { + elem: ProjectionElem::Downcast(_, idx), .. + } => idx == variant, + _ => false + } + }) + } + + fn get_drop_flag(&mut self, path: Self::Path) -> Option<Operand<'tcx>> { + self.ctxt.drop_flag(path).map(Operand::Consume) + } +} + struct ElaborateDropsCtxt<'a, 'tcx: 'a> { tcx: TyCtxt<'a, 'tcx, 'tcx>, mir: &'a Mir<'tcx>, @@ -125,19 +227,6 @@ struct ElaborateDropsCtxt<'a, 'tcx: 'a> { patch: MirPatch<'tcx>, } -#[derive(Copy, Clone, Debug)] -struct DropCtxt<'a, 'tcx: 'a> { - source_info: SourceInfo, - is_cleanup: bool, - - init_data: &'a InitializationData, - - lvalue: &'a Lvalue<'tcx>, - path: MovePathIndex, - succ: BasicBlock, - unwind: Option<BasicBlock> -} - impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> { fn move_data(&self) -> &'b MoveData<'tcx> { &self.env.move_data } fn param_env(&self) -> &'b ty::ParameterEnvironment<'tcx> { @@ -254,19 +343,22 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> { let init_data = self.initialization_data_at(loc); match self.move_data().rev_lookup.find(location) { LookupResult::Exact(path) => { - self.elaborate_drop(&DropCtxt { - source_info: terminator.source_info, - is_cleanup: data.is_cleanup, - init_data: &init_data, - lvalue: location, - path: path, - succ: target, - unwind: if data.is_cleanup { + elaborate_drop( + &mut Elaborator { + init_data: &init_data, + ctxt: self + }, + terminator.source_info, + data.is_cleanup, + location, + path, + target, + if data.is_cleanup { None } else { Some(Option::unwrap_or(unwind, resume_block)) - } - }, bb); + }, + bb) } LookupResult::Parent(..) => { span_bug!(terminator.source_info.span, @@ -343,15 +435,18 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> { debug!("elaborate_drop_and_replace({:?}) - tracked {:?}", terminator, path); let init_data = self.initialization_data_at(loc); - self.elaborate_drop(&DropCtxt { - source_info: terminator.source_info, - is_cleanup: data.is_cleanup, - init_data: &init_data, - lvalue: location, - path: path, - succ: target, - unwind: Some(unwind) - }, bb); + elaborate_drop( + &mut Elaborator { + init_data: &init_data, + ctxt: self + }, + terminator.source_info, + data.is_cleanup, + location, + path, + target, + Some(unwind), + bb); on_all_children_bits(self.tcx, self.mir, self.move_data(), path, |child| { self.set_drop_flag(Location { block: target, statement_index: 0 }, child, DropFlagState::Present); @@ -372,547 +467,6 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> { } } - /// This elaborates a single drop instruction, located at `bb`, and - /// patches over it. - /// - /// The elaborated drop checks the drop flags to only drop what - /// is initialized. - /// - /// In addition, the relevant drop flags also need to be cleared - /// to avoid double-drops. However, in the middle of a complex - /// drop, one must avoid clearing some of the flags before they - /// are read, as that would cause a memory leak. - /// - /// In particular, when dropping an ADT, multiple fields may be - /// joined together under the `rest` subpath. They are all controlled - /// by the primary drop flag, but only the last rest-field dropped - /// should clear it (and it must also not clear anything else). - /// - /// FIXME: I think we should just control the flags externally - /// and then we do not need this machinery. - fn elaborate_drop<'a>(&mut self, c: &DropCtxt<'a, 'tcx>, bb: BasicBlock) { - debug!("elaborate_drop({:?})", c); - - let mut some_live = false; - let mut some_dead = false; - let mut children_count = 0; - on_all_children_bits( - self.tcx, self.mir, self.move_data(), - c.path, |child| { - if self.path_needs_drop(child) { - let (live, dead) = c.init_data.state(child); - debug!("elaborate_drop: state({:?}) = {:?}", - child, (live, dead)); - some_live |= live; - some_dead |= dead; - children_count += 1; - } - }); - - debug!("elaborate_drop({:?}): live - {:?}", c, - (some_live, some_dead)); - match (some_live, some_dead) { - (false, false) | (false, true) => { - // dead drop - patch it out - self.patch.patch_terminator(bb, TerminatorKind::Goto { - target: c.succ - }); - } - (true, false) => { - // static drop - just set the flag - self.patch.patch_terminator(bb, TerminatorKind::Drop { - location: c.lvalue.clone(), - target: c.succ, - unwind: c.unwind - }); - self.drop_flags_for_drop(c, bb); - } - (true, true) => { - // dynamic drop - let drop_bb = if children_count == 1 || self.must_complete_drop(c) { - self.conditional_drop(c) - } else { - self.open_drop(c) - }; - self.patch.patch_terminator(bb, TerminatorKind::Goto { - target: drop_bb - }); - } - } - } - - /// Return the lvalue and move path for each field of `variant`, - /// (the move path is `None` if the field is a rest field). - fn move_paths_for_fields(&self, - base_lv: &Lvalue<'tcx>, - variant_path: MovePathIndex, - variant: &'tcx ty::VariantDef, - substs: &'tcx Substs<'tcx>) - -> Vec<(Lvalue<'tcx>, Option<MovePathIndex>)> - { - variant.fields.iter().enumerate().map(|(i, f)| { - let subpath = - super::move_path_children_matching(self.move_data(), variant_path, |p| { - match p { - &Projection { - elem: ProjectionElem::Field(idx, _), .. - } => idx.index() == i, - _ => false - } - }); - - let field_ty = - self.tcx.normalize_associated_type_in_env( - &f.ty(self.tcx, substs), - self.param_env() - ); - (base_lv.clone().field(Field::new(i), field_ty), subpath) - }).collect() - } - - /// Create one-half of the drop ladder for a list of fields, and return - /// the list of steps in it in reverse order. - /// - /// `unwind_ladder` is such a list of steps in reverse order, - /// which is called instead of the next step if the drop unwinds - /// (the first field is never reached). If it is `None`, all - /// unwind targets are left blank. - fn drop_halfladder<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - unwind_ladder: Option<Vec<BasicBlock>>, - succ: BasicBlock, - fields: &[(Lvalue<'tcx>, Option<MovePathIndex>)], - is_cleanup: bool) - -> Vec<BasicBlock> - { - let mut unwind_succ = if is_cleanup { - None - } else { - c.unwind - }; - - let mut succ = self.new_block( - c, c.is_cleanup, TerminatorKind::Goto { target: succ } - ); - - // Always clear the "master" drop flag at the bottom of the - // ladder. This is needed because the "master" drop flag - // protects the ADT's discriminant, which is invalidated - // after the ADT is dropped. - self.set_drop_flag( - Location { block: succ, statement_index: 0 }, - c.path, - DropFlagState::Absent - ); - - fields.iter().rev().enumerate().map(|(i, &(ref lv, path))| { - succ = if let Some(path) = path { - debug!("drop_ladder: for std field {} ({:?})", i, lv); - - self.elaborated_drop_block(&DropCtxt { - source_info: c.source_info, - is_cleanup: is_cleanup, - init_data: c.init_data, - lvalue: lv, - path: path, - succ: succ, - unwind: unwind_succ, - }) - } else { - debug!("drop_ladder: for rest field {} ({:?})", i, lv); - - self.complete_drop(&DropCtxt { - source_info: c.source_info, - is_cleanup: is_cleanup, - init_data: c.init_data, - lvalue: lv, - path: c.path, - succ: succ, - unwind: unwind_succ, - }, false) - }; - - unwind_succ = unwind_ladder.as_ref().map(|p| p[i]); - succ - }).collect() - } - - /// Create a full drop ladder, consisting of 2 connected half-drop-ladders - /// - /// For example, with 3 fields, the drop ladder is - /// - /// .d0: - /// ELAB(drop location.0 [target=.d1, unwind=.c1]) - /// .d1: - /// ELAB(drop location.1 [target=.d2, unwind=.c2]) - /// .d2: - /// ELAB(drop location.2 [target=`c.succ`, unwind=`c.unwind`]) - /// .c1: - /// ELAB(drop location.1 [target=.c2]) - /// .c2: - /// ELAB(drop location.2 [target=`c.unwind]) - fn drop_ladder<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - fields: Vec<(Lvalue<'tcx>, Option<MovePathIndex>)>) - -> BasicBlock - { - debug!("drop_ladder({:?}, {:?})", c, fields); - - let mut fields = fields; - fields.retain(|&(ref lvalue, _)| { - let ty = lvalue.ty(self.mir, self.tcx).to_ty(self.tcx); - self.tcx.type_needs_drop_given_env(ty, self.param_env()) - }); - - debug!("drop_ladder - fields needing drop: {:?}", fields); - - let unwind_ladder = if c.is_cleanup { - None - } else { - Some(self.drop_halfladder(c, None, c.unwind.unwrap(), &fields, true)) - }; - - self.drop_halfladder(c, unwind_ladder, c.succ, &fields, c.is_cleanup) - .last().cloned().unwrap_or(c.succ) - } - - fn open_drop_for_tuple<'a>(&mut self, c: &DropCtxt<'a, 'tcx>, tys: &[Ty<'tcx>]) - -> BasicBlock - { - debug!("open_drop_for_tuple({:?}, {:?})", c, tys); - - let fields = tys.iter().enumerate().map(|(i, &ty)| { - (c.lvalue.clone().field(Field::new(i), ty), - super::move_path_children_matching( - self.move_data(), c.path, |proj| match proj { - &Projection { - elem: ProjectionElem::Field(f, _), .. - } => f.index() == i, - _ => false - } - )) - }).collect(); - - self.drop_ladder(c, fields) - } - - fn open_drop_for_box<'a>(&mut self, c: &DropCtxt<'a, 'tcx>, ty: Ty<'tcx>) - -> BasicBlock - { - debug!("open_drop_for_box({:?}, {:?})", c, ty); - - let interior_path = super::move_path_children_matching( - self.move_data(), c.path, |proj| match proj { - &Projection { elem: ProjectionElem::Deref, .. } => true, - _ => false - }).unwrap(); - - let interior = c.lvalue.clone().deref(); - let inner_c = DropCtxt { - lvalue: &interior, - unwind: c.unwind.map(|u| { - self.box_free_block(c, ty, u, true) - }), - succ: self.box_free_block(c, ty, c.succ, c.is_cleanup), - path: interior_path, - ..*c - }; - - self.elaborated_drop_block(&inner_c) - } - - fn open_drop_for_adt<'a>(&mut self, c: &DropCtxt<'a, 'tcx>, - adt: &'tcx ty::AdtDef, substs: &'tcx Substs<'tcx>) - -> BasicBlock { - debug!("open_drop_for_adt({:?}, {:?}, {:?})", c, adt, substs); - - match adt.variants.len() { - 1 => { - let fields = self.move_paths_for_fields( - c.lvalue, - c.path, - &adt.variants[0], - substs - ); - self.drop_ladder(c, fields) - } - _ => { - let mut values = Vec::with_capacity(adt.variants.len()); - let mut blocks = Vec::with_capacity(adt.variants.len()); - let mut otherwise = None; - for (variant_index, discr) in adt.discriminants(self.tcx).enumerate() { - let subpath = super::move_path_children_matching( - self.move_data(), c.path, |proj| match proj { - &Projection { - elem: ProjectionElem::Downcast(_, idx), .. - } => idx == variant_index, - _ => false - }); - if let Some(variant_path) = subpath { - let base_lv = c.lvalue.clone().elem( - ProjectionElem::Downcast(adt, variant_index) - ); - let fields = self.move_paths_for_fields( - &base_lv, - variant_path, - &adt.variants[variant_index], - substs); - values.push(discr); - blocks.push(self.drop_ladder(c, fields)); - } else { - // variant not found - drop the entire enum - if let None = otherwise { - otherwise = Some(self.complete_drop(c, true)); - } - } - } - if let Some(block) = otherwise { - blocks.push(block); - } else { - values.pop(); - } - // If there are multiple variants, then if something - // is present within the enum the discriminant, tracked - // by the rest path, must be initialized. - // - // Additionally, we do not want to switch on the - // discriminant after it is free-ed, because that - // way lies only trouble. - let discr_ty = adt.repr.discr_type().to_ty(self.tcx); - let discr = Lvalue::Local(self.patch.new_temp(discr_ty)); - let switch_block = self.patch.new_block(BasicBlockData { - statements: vec![ - Statement { - source_info: c.source_info, - kind: StatementKind::Assign(discr.clone(), - Rvalue::Discriminant(c.lvalue.clone())) - } - ], - terminator: Some(Terminator { - source_info: c.source_info, - kind: TerminatorKind::SwitchInt { - discr: Operand::Consume(discr), - switch_ty: discr_ty, - values: From::from(values), - targets: blocks, - } - }), - is_cleanup: c.is_cleanup, - }); - self.drop_flag_test_block(c, switch_block) - } - } - } - - /// The slow-path - create an "open", elaborated drop for a type - /// which is moved-out-of only partially, and patch `bb` to a jump - /// to it. This must not be called on ADTs with a destructor, - /// as these can't be moved-out-of, except for `Box<T>`, which is - /// special-cased. - /// - /// This creates a "drop ladder" that drops the needed fields of the - /// ADT, both in the success case or if one of the destructors fail. - fn open_drop<'a>(&mut self, c: &DropCtxt<'a, 'tcx>) -> BasicBlock { - let ty = c.lvalue.ty(self.mir, self.tcx).to_ty(self.tcx); - match ty.sty { - ty::TyClosure(def_id, substs) => { - let tys : Vec<_> = substs.upvar_tys(def_id, self.tcx).collect(); - self.open_drop_for_tuple(c, &tys) - } - ty::TyTuple(tys, _) => { - self.open_drop_for_tuple(c, tys) - } - ty::TyAdt(def, _) if def.is_box() => { - self.open_drop_for_box(c, ty.boxed_ty()) - } - ty::TyAdt(def, substs) => { - self.open_drop_for_adt(c, def, substs) - } - _ => bug!("open drop from non-ADT `{:?}`", ty) - } - } - - /// Return a basic block that drop an lvalue using the context - /// and path in `c`. If `update_drop_flag` is true, also - /// clear `c`. - /// - /// if FLAG(c.path) - /// if(update_drop_flag) FLAG(c.path) = false - /// drop(c.lv) - fn complete_drop<'a>( - &mut self, - c: &DropCtxt<'a, 'tcx>, - update_drop_flag: bool) - -> BasicBlock - { - debug!("complete_drop({:?},{:?})", c, update_drop_flag); - - let drop_block = self.drop_block(c); - if update_drop_flag { - self.set_drop_flag( - Location { block: drop_block, statement_index: 0 }, - c.path, - DropFlagState::Absent - ); - } - - self.drop_flag_test_block(c, drop_block) - } - - /// Create a simple conditional drop. - /// - /// if FLAG(c.lv) - /// FLAGS(c.lv) = false - /// drop(c.lv) - fn conditional_drop<'a>(&mut self, c: &DropCtxt<'a, 'tcx>) - -> BasicBlock - { - debug!("conditional_drop({:?})", c); - let drop_bb = self.drop_block(c); - self.drop_flags_for_drop(c, drop_bb); - - self.drop_flag_test_block(c, drop_bb) - } - - fn new_block<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - is_cleanup: bool, - k: TerminatorKind<'tcx>) - -> BasicBlock - { - self.patch.new_block(BasicBlockData { - statements: vec![], - terminator: Some(Terminator { - source_info: c.source_info, kind: k - }), - is_cleanup: is_cleanup - }) - } - - fn elaborated_drop_block<'a>(&mut self, c: &DropCtxt<'a, 'tcx>) -> BasicBlock { - debug!("elaborated_drop_block({:?})", c); - let blk = self.drop_block(c); - self.elaborate_drop(c, blk); - blk - } - - fn drop_flag_test_block<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - on_set: BasicBlock) - -> BasicBlock { - self.drop_flag_test_block_with_succ(c, c.is_cleanup, on_set, c.succ) - } - - fn drop_flag_test_block_with_succ<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - is_cleanup: bool, - on_set: BasicBlock, - on_unset: BasicBlock) - -> BasicBlock - { - let (maybe_live, maybe_dead) = c.init_data.state(c.path); - debug!("drop_flag_test_block({:?},{:?},{:?}) - {:?}", - c, is_cleanup, on_set, (maybe_live, maybe_dead)); - - match (maybe_live, maybe_dead) { - (false, _) => on_unset, - (true, false) => on_set, - (true, true) => { - let flag = self.drop_flag(c.path).unwrap(); - let term = TerminatorKind::if_(self.tcx, Operand::Consume(flag), on_set, on_unset); - self.new_block(c, is_cleanup, term) - } - } - } - - fn drop_block<'a>(&mut self, c: &DropCtxt<'a, 'tcx>) -> BasicBlock { - self.new_block(c, c.is_cleanup, TerminatorKind::Drop { - location: c.lvalue.clone(), - target: c.succ, - unwind: c.unwind - }) - } - - fn box_free_block<'a>( - &mut self, - c: &DropCtxt<'a, 'tcx>, - ty: Ty<'tcx>, - target: BasicBlock, - is_cleanup: bool - ) -> BasicBlock { - let block = self.unelaborated_free_block(c, ty, target, is_cleanup); - self.drop_flag_test_block_with_succ(c, is_cleanup, block, target) - } - - fn unelaborated_free_block<'a>( - &mut self, - c: &DropCtxt<'a, 'tcx>, - ty: Ty<'tcx>, - target: BasicBlock, - is_cleanup: bool - ) -> BasicBlock { - let mut statements = vec![]; - if let Some(&flag) = self.drop_flags.get(&c.path) { - statements.push(Statement { - source_info: c.source_info, - kind: StatementKind::Assign( - Lvalue::Local(flag), - self.constant_bool(c.source_info.span, false) - ) - }); - } - - let tcx = self.tcx; - let unit_temp = Lvalue::Local(self.patch.new_temp(tcx.mk_nil())); - let free_func = tcx.require_lang_item(lang_items::BoxFreeFnLangItem); - let substs = tcx.mk_substs(iter::once(Kind::from(ty))); - let fty = tcx.item_type(free_func).subst(tcx, substs); - - self.patch.new_block(BasicBlockData { - statements: statements, - terminator: Some(Terminator { - source_info: c.source_info, kind: TerminatorKind::Call { - func: Operand::Constant(Constant { - span: c.source_info.span, - ty: fty, - literal: Literal::Item { - def_id: free_func, - substs: substs - } - }), - args: vec![Operand::Consume(c.lvalue.clone())], - destination: Some((unit_temp, target)), - cleanup: None - } - }), - is_cleanup: is_cleanup - }) - } - - fn must_complete_drop<'a>(&self, c: &DropCtxt<'a, 'tcx>) -> bool { - // if we have a destuctor, we must *not* split the drop. - - // dataflow can create unneeded children in some cases - // - be sure to ignore them. - - let ty = c.lvalue.ty(self.mir, self.tcx).to_ty(self.tcx); - - match ty.sty { - ty::TyAdt(def, _) => { - if def.has_dtor(self.tcx) && !def.is_box() { - self.tcx.sess.span_warn( - c.source_info.span, - &format!("dataflow bug??? moving out of type with dtor {:?}", - c)); - true - } else { - false - } - } - _ => false - } - } - fn constant_bool(&self, span: Span, val: bool) -> Rvalue<'tcx> { Rvalue::Use(Operand::Constant(Constant { span: span, @@ -1023,15 +577,4 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> { } } } - - fn drop_flags_for_drop<'a>(&mut self, - c: &DropCtxt<'a, 'tcx>, - bb: BasicBlock) - { - let loc = self.patch.terminator_loc(self.mir, bb); - on_all_children_bits( - self.tcx, self.mir, self.move_data(), c.path, - |child| self.set_drop_flag(loc, child, DropFlagState::Absent) - ); - } } diff --git a/src/librustc_borrowck/borrowck/mir/mod.rs b/src/librustc_borrowck/borrowck/mir/mod.rs index 1c9ee335699..9237bb31f6b 100644 --- a/src/librustc_borrowck/borrowck/mir/mod.rs +++ b/src/librustc_borrowck/borrowck/mir/mod.rs @@ -16,12 +16,12 @@ use syntax_pos::DUMMY_SP; use rustc::mir::{self, BasicBlock, BasicBlockData, Mir, Statement, Terminator, Location}; use rustc::session::Session; use rustc::ty::{self, TyCtxt}; +use rustc_mir::util::elaborate_drops::DropFlagState; mod abs_domain; pub mod elaborate_drops; mod dataflow; mod gather_moves; -mod patch; // mod graphviz; use self::dataflow::{BitDenotation}; @@ -183,21 +183,6 @@ impl<'b, 'a: 'b, 'tcx: 'a> MirBorrowckCtxt<'b, 'a, 'tcx> { } } -#[derive(Debug, PartialEq, Eq, Copy, Clone)] -enum DropFlagState { - Present, // i.e. initialized - Absent, // i.e. deinitialized or "moved" -} - -impl DropFlagState { - fn value(self) -> bool { - match self { - DropFlagState::Present => true, - DropFlagState::Absent => false - } - } -} - fn move_path_children_matching<'tcx, F>(move_data: &MoveData<'tcx>, path: MovePathIndex, mut cond: F) diff --git a/src/librustc_driver/pretty.rs b/src/librustc_driver/pretty.rs index b6978478085..6cd97e95598 100644 --- a/src/librustc_driver/pretty.rs +++ b/src/librustc_driver/pretty.rs @@ -26,8 +26,7 @@ use rustc::session::config::Input; use rustc_borrowck as borrowck; use rustc_borrowck::graphviz as borrowck_dot; -use rustc_mir::pretty::write_mir_pretty; -use rustc_mir::graphviz::write_mir_graphviz; +use rustc_mir::util::{write_mir_pretty, write_mir_graphviz}; use syntax::ast::{self, BlockCheckMode}; use syntax::fold::{self, Folder}; diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs index 2718a0204a1..590c6a430b9 100644 --- a/src/librustc_mir/lib.rs +++ b/src/librustc_mir/lib.rs @@ -49,13 +49,11 @@ pub mod diagnostics; pub mod build; pub mod callgraph; -pub mod def_use; -pub mod graphviz; mod hair; mod shim; pub mod mir_map; -pub mod pretty; pub mod transform; +pub mod util; use rustc::ty::maps::Providers; diff --git a/src/librustc_mir/mir_map.rs b/src/librustc_mir/mir_map.rs index 2d2b90235ca..8c138d779c1 100644 --- a/src/librustc_mir/mir_map.rs +++ b/src/librustc_mir/mir_map.rs @@ -23,8 +23,8 @@ use rustc::mir::Mir; use rustc::mir::transform::MirSource; use rustc::mir::visit::MutVisitor; use shim; -use pretty; use hair::cx::Cx; +use util as mir_util; use rustc::traits::Reveal; use rustc::ty::{self, Ty, TyCtxt}; @@ -175,7 +175,7 @@ fn build_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) mem::transmute::<Mir, Mir<'tcx>>(mir) }; - pretty::dump_mir(tcx, "mir_map", &0, src, &mir); + mir_util::dump_mir(tcx, "mir_map", &0, src, &mir); tcx.alloc_mir(mir) }) @@ -234,7 +234,7 @@ fn create_constructor_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, mem::transmute::<Mir, Mir<'tcx>>(mir) }; - pretty::dump_mir(tcx, "mir_map", &0, src, &mir); + mir_util::dump_mir(tcx, "mir_map", &0, src, &mir); tcx.alloc_mir(mir) }) diff --git a/src/librustc_mir/transform/copy_prop.rs b/src/librustc_mir/transform/copy_prop.rs index 2194c20c2f4..5d127a5aed4 100644 --- a/src/librustc_mir/transform/copy_prop.rs +++ b/src/librustc_mir/transform/copy_prop.rs @@ -29,11 +29,11 @@ //! (non-mutating) use of `SRC`. These restrictions are conservative and may be relaxed in the //! future. -use def_use::DefUseAnalysis; use rustc::mir::{Constant, Local, LocalKind, Location, Lvalue, Mir, Operand, Rvalue, StatementKind}; use rustc::mir::transform::{MirPass, MirSource, Pass}; use rustc::mir::visit::MutVisitor; use rustc::ty::TyCtxt; +use util::def_use::DefUseAnalysis; use transform::qualify_consts; pub struct CopyPropagation; diff --git a/src/librustc_mir/transform/dump_mir.rs b/src/librustc_mir/transform/dump_mir.rs index 035f33de91a..f22a71636a9 100644 --- a/src/librustc_mir/transform/dump_mir.rs +++ b/src/librustc_mir/transform/dump_mir.rs @@ -15,7 +15,7 @@ use std::fmt; use rustc::ty::TyCtxt; use rustc::mir::*; use rustc::mir::transform::{Pass, MirPass, MirPassHook, MirSource}; -use pretty; +use util as mir_util; pub struct Marker<'a>(pub &'a str); @@ -56,7 +56,7 @@ impl<'tcx> MirPassHook<'tcx> for DumpMir { pass: &Pass, is_after: bool) { - pretty::dump_mir( + mir_util::dump_mir( tcx, &*pass.name(), &Disambiguator { diff --git a/src/librustc_mir/def_use.rs b/src/librustc_mir/util/def_use.rs index d20d50c5611..d20d50c5611 100644 --- a/src/librustc_mir/def_use.rs +++ b/src/librustc_mir/util/def_use.rs diff --git a/src/librustc_mir/util/elaborate_drops.rs b/src/librustc_mir/util/elaborate_drops.rs new file mode 100644 index 00000000000..ce6debab9a4 --- /dev/null +++ b/src/librustc_mir/util/elaborate_drops.rs @@ -0,0 +1,561 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use std::fmt; +use rustc::mir::*; +use rustc::middle::lang_items; +use rustc::ty::{self, Ty}; +use rustc::ty::subst::{Kind, Subst, Substs}; +use rustc::ty::util::IntTypeExt; +use rustc_data_structures::indexed_vec::Idx; +use util::patch::MirPatch; + +use std::iter; + +#[derive(Debug, PartialEq, Eq, Copy, Clone)] +pub enum DropFlagState { + Present, // i.e. initialized + Absent, // i.e. deinitialized or "moved" +} + +impl DropFlagState { + pub fn value(self) -> bool { + match self { + DropFlagState::Present => true, + DropFlagState::Absent => false + } + } +} + +#[derive(Debug)] +pub enum DropStyle { + Dead, + Static, + Conditional, + Open, +} + +#[derive(Debug)] +pub enum DropFlagMode { + Shallow, + Deep +} + +pub trait DropElaborator<'a, 'tcx: 'a> : fmt::Debug { + type Path : Copy + fmt::Debug; + + fn patch(&mut self) -> &mut MirPatch<'tcx>; + fn mir(&self) -> &'a Mir<'tcx>; + fn tcx(&self) -> ty::TyCtxt<'a, 'tcx, 'tcx>; + fn param_env(&self) -> &'a ty::ParameterEnvironment<'tcx>; + + fn drop_style(&self, path: Self::Path, mode: DropFlagMode) -> DropStyle; + fn get_drop_flag(&mut self, path: Self::Path) -> Option<Operand<'tcx>>; + fn clear_drop_flag(&mut self, location: Location, path: Self::Path, mode: DropFlagMode); + + + fn field_subpath(&self, path: Self::Path, field: Field) -> Option<Self::Path>; + fn deref_subpath(&self, path: Self::Path) -> Option<Self::Path>; + fn downcast_subpath(&self, path: Self::Path, variant: usize) -> Option<Self::Path>; +} + +#[derive(Debug)] +struct DropCtxt<'l, 'b: 'l, 'tcx: 'b, D> + where D : DropElaborator<'b, 'tcx> + 'l +{ + elaborator: &'l mut D, + + source_info: SourceInfo, + is_cleanup: bool, + + lvalue: &'l Lvalue<'tcx>, + path: D::Path, + succ: BasicBlock, + unwind: Option<BasicBlock>, +} + +pub fn elaborate_drop<'b, 'tcx, D>( + elaborator: &mut D, + source_info: SourceInfo, + is_cleanup: bool, + lvalue: &Lvalue<'tcx>, + path: D::Path, + succ: BasicBlock, + unwind: Option<BasicBlock>, + bb: BasicBlock) + where D: DropElaborator<'b, 'tcx> +{ + DropCtxt { + elaborator, source_info, is_cleanup, lvalue, path, succ, unwind + }.elaborate_drop(bb) +} + +impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D> + where D: DropElaborator<'b, 'tcx> +{ + fn lvalue_ty(&self, lvalue: &Lvalue<'tcx>) -> Ty<'tcx> { + lvalue.ty(self.elaborator.mir(), self.tcx()).to_ty(self.tcx()) + } + + fn tcx(&self) -> ty::TyCtxt<'b, 'tcx, 'tcx> { + self.elaborator.tcx() + } + + /// This elaborates a single drop instruction, located at `bb`, and + /// patches over it. + /// + /// The elaborated drop checks the drop flags to only drop what + /// is initialized. + /// + /// In addition, the relevant drop flags also need to be cleared + /// to avoid double-drops. However, in the middle of a complex + /// drop, one must avoid clearing some of the flags before they + /// are read, as that would cause a memory leak. + /// + /// In particular, when dropping an ADT, multiple fields may be + /// joined together under the `rest` subpath. They are all controlled + /// by the primary drop flag, but only the last rest-field dropped + /// should clear it (and it must also not clear anything else). + /// + /// FIXME: I think we should just control the flags externally + /// and then we do not need this machinery. + pub fn elaborate_drop<'a>(&mut self, bb: BasicBlock) { + debug!("elaborate_drop({:?})", self); + let style = self.elaborator.drop_style(self.path, DropFlagMode::Deep); + debug!("elaborate_drop({:?}): live - {:?}", self, style); + match style { + DropStyle::Dead => { + self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto { + target: self.succ + }); + } + DropStyle::Static => { + let loc = self.terminator_loc(bb); + self.elaborator.clear_drop_flag(loc, self.path, DropFlagMode::Deep); + self.elaborator.patch().patch_terminator(bb, TerminatorKind::Drop { + location: self.lvalue.clone(), + target: self.succ, + unwind: self.unwind + }); + } + DropStyle::Conditional => { + let drop_bb = self.complete_drop(Some(DropFlagMode::Deep)); + self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto { + target: drop_bb + }); + } + DropStyle::Open => { + let drop_bb = self.open_drop(); + self.elaborator.patch().patch_terminator(bb, TerminatorKind::Goto { + target: drop_bb + }); + } + } + } + + /// Return the lvalue and move path for each field of `variant`, + /// (the move path is `None` if the field is a rest field). + fn move_paths_for_fields(&self, + base_lv: &Lvalue<'tcx>, + variant_path: D::Path, + variant: &'tcx ty::VariantDef, + substs: &'tcx Substs<'tcx>) + -> Vec<(Lvalue<'tcx>, Option<D::Path>)> + { + variant.fields.iter().enumerate().map(|(i, f)| { + let field = Field::new(i); + let subpath = self.elaborator.field_subpath(variant_path, field); + + let field_ty = + self.tcx().normalize_associated_type_in_env( + &f.ty(self.tcx(), substs), + self.elaborator.param_env() + ); + (base_lv.clone().field(field, field_ty), subpath) + }).collect() + } + + fn drop_subpath(&mut self, + is_cleanup: bool, + lvalue: &Lvalue<'tcx>, + path: Option<D::Path>, + succ: BasicBlock, + unwind: Option<BasicBlock>) + -> BasicBlock + { + if let Some(path) = path { + debug!("drop_subpath: for std field {:?}", lvalue); + + DropCtxt { + elaborator: self.elaborator, + source_info: self.source_info, + path, lvalue, succ, unwind, is_cleanup + }.elaborated_drop_block() + } else { + debug!("drop_subpath: for rest field {:?}", lvalue); + + DropCtxt { + elaborator: self.elaborator, + source_info: self.source_info, + lvalue, succ, unwind, is_cleanup, + // Using `self.path` here to condition the drop on + // our own drop flag. + path: self.path + }.complete_drop(None) + } + } + + /// Create one-half of the drop ladder for a list of fields, and return + /// the list of steps in it in reverse order. + /// + /// `unwind_ladder` is such a list of steps in reverse order, + /// which is called instead of the next step if the drop unwinds + /// (the first field is never reached). If it is `None`, all + /// unwind targets are left blank. + fn drop_halfladder<'a>(&mut self, + unwind_ladder: Option<Vec<BasicBlock>>, + succ: BasicBlock, + fields: &[(Lvalue<'tcx>, Option<D::Path>)], + is_cleanup: bool) + -> Vec<BasicBlock> + { + let mut unwind_succ = if is_cleanup { + None + } else { + self.unwind + }; + + let goto = TerminatorKind::Goto { target: succ }; + let mut succ = self.new_block(is_cleanup, goto); + + // Always clear the "master" drop flag at the bottom of the + // ladder. This is needed because the "master" drop flag + // protects the ADT's discriminant, which is invalidated + // after the ADT is dropped. + let succ_loc = Location { block: succ, statement_index: 0 }; + self.elaborator.clear_drop_flag(succ_loc, self.path, DropFlagMode::Shallow); + + fields.iter().rev().enumerate().map(|(i, &(ref lv, path))| { + succ = self.drop_subpath(is_cleanup, lv, path, succ, unwind_succ); + unwind_succ = unwind_ladder.as_ref().map(|p| p[i]); + succ + }).collect() + } + + /// Create a full drop ladder, consisting of 2 connected half-drop-ladders + /// + /// For example, with 3 fields, the drop ladder is + /// + /// .d0: + /// ELAB(drop location.0 [target=.d1, unwind=.c1]) + /// .d1: + /// ELAB(drop location.1 [target=.d2, unwind=.c2]) + /// .d2: + /// ELAB(drop location.2 [target=`self.succ`, unwind=`self.unwind`]) + /// .c1: + /// ELAB(drop location.1 [target=.c2]) + /// .c2: + /// ELAB(drop location.2 [target=`self.unwind]) + fn drop_ladder<'a>(&mut self, + fields: Vec<(Lvalue<'tcx>, Option<D::Path>)>) + -> BasicBlock + { + debug!("drop_ladder({:?}, {:?})", self, fields); + + let mut fields = fields; + fields.retain(|&(ref lvalue, _)| { + self.tcx().type_needs_drop_given_env( + self.lvalue_ty(lvalue), self.elaborator.param_env()) + }); + + debug!("drop_ladder - fields needing drop: {:?}", fields); + + let unwind_ladder = if self.is_cleanup { + None + } else { + let unwind = self.unwind.unwrap(); // FIXME(#6393) + Some(self.drop_halfladder(None, unwind, &fields, true)) + }; + + let succ = self.succ; // FIXME(#6393) + let is_cleanup = self.is_cleanup; + self.drop_halfladder(unwind_ladder, succ, &fields, is_cleanup) + .last().cloned().unwrap_or(succ) + } + + fn open_drop_for_tuple<'a>(&mut self, tys: &[Ty<'tcx>]) + -> BasicBlock + { + debug!("open_drop_for_tuple({:?}, {:?})", self, tys); + + let fields = tys.iter().enumerate().map(|(i, &ty)| { + (self.lvalue.clone().field(Field::new(i), ty), + self.elaborator.field_subpath(self.path, Field::new(i))) + }).collect(); + + self.drop_ladder(fields) + } + + fn open_drop_for_box<'a>(&mut self, ty: Ty<'tcx>) -> BasicBlock + { + debug!("open_drop_for_box({:?}, {:?})", self, ty); + + let interior = self.lvalue.clone().deref(); + let interior_path = self.elaborator.deref_subpath(self.path); + + let succ = self.succ; // FIXME(#6393) + let is_cleanup = self.is_cleanup; + let succ = self.box_free_block(ty, succ, is_cleanup); + let unwind_succ = self.unwind.map(|u| { + self.box_free_block(ty, u, true) + }); + + self.drop_subpath(is_cleanup, &interior, interior_path, succ, unwind_succ) + } + + fn open_drop_for_adt<'a>(&mut self, adt: &'tcx ty::AdtDef, substs: &'tcx Substs<'tcx>) + -> BasicBlock { + debug!("open_drop_for_adt({:?}, {:?}, {:?})", self, adt, substs); + + match adt.variants.len() { + 1 => { + let fields = self.move_paths_for_fields( + self.lvalue, + self.path, + &adt.variants[0], + substs + ); + self.drop_ladder(fields) + } + _ => { + let mut values = Vec::with_capacity(adt.variants.len()); + let mut blocks = Vec::with_capacity(adt.variants.len()); + let mut otherwise = None; + for (variant_index, discr) in adt.discriminants(self.tcx()).enumerate() { + let subpath = self.elaborator.downcast_subpath( + self.path, variant_index); + if let Some(variant_path) = subpath { + let base_lv = self.lvalue.clone().elem( + ProjectionElem::Downcast(adt, variant_index) + ); + let fields = self.move_paths_for_fields( + &base_lv, + variant_path, + &adt.variants[variant_index], + substs); + values.push(discr); + blocks.push(self.drop_ladder(fields)); + } else { + // variant not found - drop the entire enum + if let None = otherwise { + otherwise = + Some(self.complete_drop(Some(DropFlagMode::Shallow))); + } + } + } + if let Some(block) = otherwise { + blocks.push(block); + } else { + values.pop(); + } + // If there are multiple variants, then if something + // is present within the enum the discriminant, tracked + // by the rest path, must be initialized. + // + // Additionally, we do not want to switch on the + // discriminant after it is free-ed, because that + // way lies only trouble. + let discr_ty = adt.repr.discr_type().to_ty(self.tcx()); + let discr = Lvalue::Local(self.new_temp(discr_ty)); + let discr_rv = Rvalue::Discriminant(self.lvalue.clone()); + let switch_block = self.elaborator.patch().new_block(BasicBlockData { + statements: vec![ + Statement { + source_info: self.source_info, + kind: StatementKind::Assign(discr.clone(), discr_rv), + } + ], + terminator: Some(Terminator { + source_info: self.source_info, + kind: TerminatorKind::SwitchInt { + discr: Operand::Consume(discr), + switch_ty: discr_ty, + values: From::from(values), + targets: blocks, + } + }), + is_cleanup: self.is_cleanup, + }); + self.drop_flag_test_block(switch_block) + } + } + } + + /// The slow-path - create an "open", elaborated drop for a type + /// which is moved-out-of only partially, and patch `bb` to a jump + /// to it. This must not be called on ADTs with a destructor, + /// as these can't be moved-out-of, except for `Box<T>`, which is + /// special-cased. + /// + /// This creates a "drop ladder" that drops the needed fields of the + /// ADT, both in the success case or if one of the destructors fail. + fn open_drop<'a>(&mut self) -> BasicBlock { + let ty = self.lvalue_ty(self.lvalue); + match ty.sty { + ty::TyClosure(def_id, substs) => { + let tys : Vec<_> = substs.upvar_tys(def_id, self.tcx()).collect(); + self.open_drop_for_tuple(&tys) + } + ty::TyTuple(tys, _) => { + self.open_drop_for_tuple(tys) + } + ty::TyAdt(def, _) if def.is_box() => { + self.open_drop_for_box(ty.boxed_ty()) + } + ty::TyAdt(def, substs) => { + self.open_drop_for_adt(def, substs) + } + _ => bug!("open drop from non-ADT `{:?}`", ty) + } + } + + /// Return a basic block that drop an lvalue using the context + /// and path in `c`. If `mode` is something, also clear `c` + /// according to it. + /// + /// if FLAG(self.path) + /// if let Some(mode) = mode: FLAG(self.path)[mode] = false + /// drop(self.lv) + fn complete_drop<'a>(&mut self, drop_mode: Option<DropFlagMode>) -> BasicBlock + { + debug!("complete_drop({:?},{:?})", self, drop_mode); + + let drop_block = self.drop_block(); + if let Some(mode) = drop_mode { + let block_start = Location { block: drop_block, statement_index: 0 }; + self.elaborator.clear_drop_flag(block_start, self.path, mode); + } + + self.drop_flag_test_block(drop_block) + } + + fn elaborated_drop_block<'a>(&mut self) -> BasicBlock { + debug!("elaborated_drop_block({:?})", self); + let blk = self.drop_block(); + self.elaborate_drop(blk); + blk + } + + fn box_free_block<'a>( + &mut self, + ty: Ty<'tcx>, + target: BasicBlock, + is_cleanup: bool + ) -> BasicBlock { + let block = self.unelaborated_free_block(ty, target, is_cleanup); + self.drop_flag_test_block_with_succ(is_cleanup, block, target) + } + + fn unelaborated_free_block<'a>( + &mut self, + ty: Ty<'tcx>, + target: BasicBlock, + is_cleanup: bool + ) -> BasicBlock { + let tcx = self.tcx(); + let unit_temp = Lvalue::Local(self.new_temp(tcx.mk_nil())); + let free_func = tcx.require_lang_item(lang_items::BoxFreeFnLangItem); + let substs = tcx.mk_substs(iter::once(Kind::from(ty))); + let fty = tcx.item_type(free_func).subst(tcx, substs); + + let free_block = self.elaborator.patch().new_block(BasicBlockData { + statements: vec![], + terminator: Some(Terminator { + source_info: self.source_info, kind: TerminatorKind::Call { + func: Operand::Constant(Constant { + span: self.source_info.span, + ty: fty, + literal: Literal::Item { + def_id: free_func, + substs: substs + } + }), + args: vec![Operand::Consume(self.lvalue.clone())], + destination: Some((unit_temp, target)), + cleanup: None + } + }), + is_cleanup: is_cleanup + }); + let block_start = Location { block: free_block, statement_index: 0 }; + self.elaborator.clear_drop_flag(block_start, self.path, DropFlagMode::Shallow); + free_block + } + + fn drop_block<'a>(&mut self) -> BasicBlock { + let block = TerminatorKind::Drop { + location: self.lvalue.clone(), + target: self.succ, + unwind: self.unwind + }; + let is_cleanup = self.is_cleanup; // FIXME(#6393) + self.new_block(is_cleanup, block) + } + + fn drop_flag_test_block<'a>(&mut self, on_set: BasicBlock) -> BasicBlock { + let is_cleanup = self.is_cleanup; + let succ = self.succ; // FIXME(#6393) + self.drop_flag_test_block_with_succ(is_cleanup, on_set, succ) + } + + fn drop_flag_test_block_with_succ<'a>(&mut self, + is_cleanup: bool, + on_set: BasicBlock, + on_unset: BasicBlock) + -> BasicBlock + { + let style = self.elaborator.drop_style(self.path, DropFlagMode::Shallow); + debug!("drop_flag_test_block({:?},{:?},{:?}) - {:?}", + self, is_cleanup, on_set, style); + + match style { + DropStyle::Dead => on_unset, + DropStyle::Static => on_set, + DropStyle::Conditional | DropStyle::Open => { + let flag = self.elaborator.get_drop_flag(self.path).unwrap(); + let term = TerminatorKind::if_(self.tcx(), flag, on_set, on_unset); + self.new_block(is_cleanup, term) + } + } + } + + fn new_block<'a>(&mut self, + is_cleanup: bool, + k: TerminatorKind<'tcx>) + -> BasicBlock + { + self.elaborator.patch().new_block(BasicBlockData { + statements: vec![], + terminator: Some(Terminator { + source_info: self.source_info, kind: k + }), + is_cleanup: is_cleanup + }) + } + + fn new_temp(&mut self, ty: Ty<'tcx>) -> Local { + self.elaborator.patch().new_temp(ty) + } + + fn terminator_loc(&mut self, bb: BasicBlock) -> Location { + let mir = self.elaborator.mir(); + self.elaborator.patch().terminator_loc(mir, bb) + } +} diff --git a/src/librustc_mir/graphviz.rs b/src/librustc_mir/util/graphviz.rs index 91600b947c6..91600b947c6 100644 --- a/src/librustc_mir/graphviz.rs +++ b/src/librustc_mir/util/graphviz.rs diff --git a/src/librustc_mir/util/mod.rs b/src/librustc_mir/util/mod.rs new file mode 100644 index 00000000000..cafc5bca76a --- /dev/null +++ b/src/librustc_mir/util/mod.rs @@ -0,0 +1,20 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +pub mod elaborate_drops; +pub mod def_use; +pub mod patch; + +mod graphviz; +mod pretty; + +pub use self::pretty::{dump_mir, write_mir_pretty}; +pub use self::graphviz::{write_mir_graphviz}; +pub use self::graphviz::write_node_label as write_graphviz_node_label; diff --git a/src/librustc_borrowck/borrowck/mir/patch.rs b/src/librustc_mir/util/patch.rs index 19f240da730..19f240da730 100644 --- a/src/librustc_borrowck/borrowck/mir/patch.rs +++ b/src/librustc_mir/util/patch.rs diff --git a/src/librustc_mir/pretty.rs b/src/librustc_mir/util/pretty.rs index 35734dcce2b..35734dcce2b 100644 --- a/src/librustc_mir/pretty.rs +++ b/src/librustc_mir/util/pretty.rs |