From 274c85f5c80f6a8ae800bf9054e49bb111824278 Mon Sep 17 00:00:00 2001 From: Dylan MacKenzie Date: Sun, 19 Apr 2020 10:23:57 -0700 Subject: [PATCH] Don't cache result of `in_any_value_of_ty` for locals This was needed by an early version of dataflow-based const qualification where `QualifCursor` needed to return a full `BitSet` with the current state. --- .../transform/check_consts/validation.rs | 104 +++++++++--------- 1 file changed, 51 insertions(+), 53 deletions(-) diff --git a/src/librustc_mir/transform/check_consts/validation.rs b/src/librustc_mir/transform/check_consts/validation.rs index 7b76590b7c02..5b37edd01b37 100644 --- a/src/librustc_mir/transform/check_consts/validation.rs +++ b/src/librustc_mir/transform/check_consts/validation.rs @@ -3,7 +3,6 @@ use rustc_errors::struct_span_err; use rustc_hir::lang_items; use rustc_hir::{def_id::DefId, HirId}; -use rustc_index::bit_set::BitSet; use rustc_infer::infer::TyCtxtInferExt; use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor}; use rustc_middle::mir::*; @@ -31,37 +30,22 @@ use crate::dataflow::{self, Analysis}; type IndirectlyMutableResults<'mir, 'tcx> = dataflow::ResultsCursor<'mir, 'tcx, MaybeMutBorrowedLocals<'mir, 'tcx>>; -struct QualifCursor<'a, 'mir, 'tcx, Q: Qualif> { - cursor: dataflow::ResultsCursor<'mir, 'tcx, FlowSensitiveAnalysis<'a, 'mir, 'tcx, Q>>, - in_any_value_of_ty: BitSet, -} +type QualifResults<'mir, 'tcx, Q> = + dataflow::ResultsCursor<'mir, 'tcx, FlowSensitiveAnalysis<'mir, 'mir, 'tcx, Q>>; -impl QualifCursor<'a, 'mir, 'tcx, Q> { - pub fn new(q: Q, ccx: &'a ConstCx<'mir, 'tcx>) -> Self { - let cursor = FlowSensitiveAnalysis::new(q, ccx) - .into_engine(ccx.tcx, ccx.body, ccx.def_id) - .iterate_to_fixpoint() - .into_results_cursor(ccx.body); - - let mut in_any_value_of_ty = BitSet::new_empty(ccx.body.local_decls.len()); - for (local, decl) in ccx.body.local_decls.iter_enumerated() { - if Q::in_any_value_of_ty(ccx, decl.ty) { - in_any_value_of_ty.insert(local); - } - } - - QualifCursor { cursor, in_any_value_of_ty } - } -} - -pub struct Qualifs<'a, 'mir, 'tcx> { - has_mut_interior: QualifCursor<'a, 'mir, 'tcx, HasMutInterior>, - needs_drop: QualifCursor<'a, 'mir, 'tcx, NeedsDrop>, +pub struct Qualifs<'mir, 'tcx> { + has_mut_interior: QualifResults<'mir, 'tcx, HasMutInterior>, + needs_drop: QualifResults<'mir, 'tcx, NeedsDrop>, indirectly_mutable: IndirectlyMutableResults<'mir, 'tcx>, } -impl Qualifs<'a, 'mir, 'tcx> { - fn indirectly_mutable(&mut self, local: Local, location: Location) -> bool { +impl Qualifs<'mir, 'tcx> { + fn indirectly_mutable( + &mut self, + _: &Item<'mir, 'tcx>, + local: Local, + location: Location, + ) -> bool { self.indirectly_mutable.seek_before(location); self.indirectly_mutable.get().contains(local) } @@ -69,29 +53,36 @@ impl Qualifs<'a, 'mir, 'tcx> { /// Returns `true` if `local` is `NeedsDrop` at the given `Location`. /// /// Only updates the cursor if absolutely necessary - fn needs_drop(&mut self, local: Local, location: Location) -> bool { - if !self.needs_drop.in_any_value_of_ty.contains(local) { + fn needs_drop(&mut self, item: &Item<'mir, 'tcx>, local: Local, location: Location) -> bool { + let ty = item.body.local_decls[local].ty; + if !NeedsDrop::in_any_value_of_ty(item, ty) { return false; } - self.needs_drop.cursor.seek_before(location); - self.needs_drop.cursor.get().contains(local) || self.indirectly_mutable(local, location) + self.needs_drop.seek_before(location); + self.needs_drop.get().contains(local) || self.indirectly_mutable(item, local, location) } /// Returns `true` if `local` is `HasMutInterior` at the given `Location`. /// /// Only updates the cursor if absolutely necessary. - fn has_mut_interior(&mut self, local: Local, location: Location) -> bool { - if !self.has_mut_interior.in_any_value_of_ty.contains(local) { + fn has_mut_interior( + &mut self, + item: &Item<'mir, 'tcx>, + local: Local, + location: Location, + ) -> bool { + let ty = ccx.body.local_decls[local].ty; + if !HasMutInterior::in_any_value_of_ty(ccx, ty) { return false; } - self.has_mut_interior.cursor.seek_before(location); - self.has_mut_interior.cursor.get().contains(local) - || self.indirectly_mutable(local, location) + self.has_mut_interior.seek_before(location); + self.has_mut_interior.get().contains(local) + || self.indirectly_mutable(item, local, location) } - fn in_return_place(&mut self, ccx: &ConstCx<'_, 'tcx>) -> ConstQualifs { + fn in_return_place(&mut self, item: &Item<'mir, 'tcx>) -> ConstQualifs { // Find the `Return` terminator if one exists. // // If no `Return` terminator exists, this MIR is divergent. Just return the conservative @@ -114,21 +105,21 @@ impl Qualifs<'a, 'mir, 'tcx> { let return_loc = ccx.body.terminator_loc(return_block); ConstQualifs { - needs_drop: self.needs_drop(RETURN_PLACE, return_loc), - has_mut_interior: self.has_mut_interior(RETURN_PLACE, return_loc), + needs_drop: self.needs_drop(ccx, RETURN_PLACE, return_loc), + has_mut_interior: self.has_mut_interior(ccx, RETURN_PLACE, return_loc), } } } -pub struct Validator<'a, 'mir, 'tcx> { - ccx: &'a ConstCx<'mir, 'tcx>, - qualifs: Qualifs<'a, 'mir, 'tcx>, +pub struct Validator<'mir, 'tcx> { + ccx: &'mir ConstCx<'mir, 'tcx>, + qualifs: Qualifs<'mir, 'tcx>, /// The span of the current statement. span: Span, } -impl Deref for Validator<'_, 'mir, 'tcx> { +impl Deref for Validator<'mir, 'tcx> { type Target = ConstCx<'mir, 'tcx>; fn deref(&self) -> &Self::Target { @@ -136,12 +127,9 @@ impl Deref for Validator<'_, 'mir, 'tcx> { } } -impl Validator<'a, 'mir, 'tcx> { - pub fn new(ccx: &'a ConstCx<'mir, 'tcx>) -> Self { - let ConstCx { tcx, body, def_id, param_env, .. } = *ccx; - - let needs_drop = QualifCursor::new(NeedsDrop, ccx); - let has_mut_interior = QualifCursor::new(HasMutInterior, ccx); +impl Validator<'mir, 'tcx> { + pub fn new(item: &'mir Item<'mir, 'tcx>) -> Self { + let Item { tcx, body, def_id, param_env, .. } = *item; // We can use `unsound_ignore_borrow_on_drop` here because custom drop impls are not // allowed in a const. @@ -154,6 +142,16 @@ impl Validator<'a, 'mir, 'tcx> { .iterate_to_fixpoint() .into_results_cursor(body); + let needs_drop = FlowSensitiveAnalysis::new(NeedsDrop, item) + .into_engine(item.tcx, &item.body, item.def_id) + .iterate_to_fixpoint() + .into_results_cursor(*item.body); + + let has_mut_interior = FlowSensitiveAnalysis::new(HasMutInterior, item) + .into_engine(item.tcx, &item.body, item.def_id) + .iterate_to_fixpoint() + .into_results_cursor(*item.body); + let qualifs = Qualifs { needs_drop, has_mut_interior, indirectly_mutable }; Validator { span: ccx.body.span, ccx, qualifs } @@ -239,7 +237,7 @@ impl Validator<'a, 'mir, 'tcx> { } } -impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { +impl Visitor<'tcx> for Validator<'mir, 'tcx> { fn visit_basic_block_data(&mut self, bb: BasicBlock, block: &BasicBlockData<'tcx>) { trace!("visit_basic_block_data: bb={:?} is_cleanup={:?}", bb, block.is_cleanup); @@ -345,7 +343,7 @@ impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { | Rvalue::AddressOf(Mutability::Not, ref place) => { let borrowed_place_has_mut_interior = qualifs::in_place::( &self.ccx, - &mut |local| self.qualifs.has_mut_interior(local, location), + &mut |local| self.qualifs.has_mut_interior(self.ccx, local, location), place.as_ref(), ); @@ -571,7 +569,7 @@ impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { let needs_drop = if let Some(local) = dropped_place.as_local() { // Use the span where the local was declared as the span of the drop error. err_span = self.body.local_decls[local].source_info.span; - self.qualifs.needs_drop(local, location) + self.qualifs.needs_drop(self.ccx, local, location) } else { true };