diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/lib.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/lower_slice_len.rs | 24 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/normalize_array_len.rs | 103 |
3 files changed, 8 insertions, 123 deletions
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 87dd9cc11eb..fe195f0112f 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -88,7 +88,6 @@ mod lower_slice_len; mod match_branches; mod mentioned_items; mod multiple_return_terminators; -mod normalize_array_len; mod nrvo; mod prettify; mod promote_consts; @@ -581,9 +580,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { &o1(simplify::SimplifyCfg::AfterUnreachableEnumBranching), // Inlining may have introduced a lot of redundant code and a large move pattern. // Now, we need to shrink the generated MIR. - - // Has to run after `slice::len` lowering - &normalize_array_len::NormalizeArrayLen, &ref_prop::ReferencePropagation, &sroa::ScalarReplacementOfAggregates, &match_branches::MatchBranchSimplification, diff --git a/compiler/rustc_mir_transform/src/lower_slice_len.rs b/compiler/rustc_mir_transform/src/lower_slice_len.rs index 2267a621a83..77a7f4f47dd 100644 --- a/compiler/rustc_mir_transform/src/lower_slice_len.rs +++ b/compiler/rustc_mir_transform/src/lower_slice_len.rs @@ -1,10 +1,9 @@ -//! This pass lowers calls to core::slice::len to just Len op. +//! This pass lowers calls to core::slice::len to just PtrMetadata op. //! It should run before inlining! use rustc_hir::def_id::DefId; -use rustc_index::IndexSlice; use rustc_middle::mir::*; -use rustc_middle::ty::{self, TyCtxt}; +use rustc_middle::ty::TyCtxt; pub struct LowerSliceLenCalls; @@ -29,16 +28,11 @@ pub fn lower_slice_len_calls<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { let basic_blocks = body.basic_blocks.as_mut_preserves_cfg(); for block in basic_blocks { // lower `<[_]>::len` calls - lower_slice_len_call(tcx, block, &body.local_decls, slice_len_fn_item_def_id); + lower_slice_len_call(block, slice_len_fn_item_def_id); } } -fn lower_slice_len_call<'tcx>( - tcx: TyCtxt<'tcx>, - block: &mut BasicBlockData<'tcx>, - local_decls: &IndexSlice<Local, LocalDecl<'tcx>>, - slice_len_fn_item_def_id: DefId, -) { +fn lower_slice_len_call<'tcx>(block: &mut BasicBlockData<'tcx>, slice_len_fn_item_def_id: DefId) { let terminator = block.terminator(); if let TerminatorKind::Call { func, @@ -50,19 +44,17 @@ fn lower_slice_len_call<'tcx>( } = &terminator.kind // some heuristics for fast rejection && let [arg] = &args[..] - && let Some(arg) = arg.node.place() - && let ty::FnDef(fn_def_id, _) = func.ty(local_decls, tcx).kind() - && *fn_def_id == slice_len_fn_item_def_id + && let Some((fn_def_id, _)) = func.const_fn_def() + && fn_def_id == slice_len_fn_item_def_id { // perform modifications from something like: // _5 = core::slice::<impl [u8]>::len(move _6) -> bb1 // into: - // _5 = Len(*_6) + // _5 = PtrMetadata(move _6) // goto bb1 // make new RValue for Len - let deref_arg = tcx.mk_place_deref(arg); - let r_value = Rvalue::Len(deref_arg); + let r_value = Rvalue::UnaryOp(UnOp::PtrMetadata, arg.node.clone()); let len_statement_kind = StatementKind::Assign(Box::new((*destination, r_value))); let add_statement = Statement { kind: len_statement_kind, source_info: terminator.source_info }; diff --git a/compiler/rustc_mir_transform/src/normalize_array_len.rs b/compiler/rustc_mir_transform/src/normalize_array_len.rs deleted file mode 100644 index d5e72706661..00000000000 --- a/compiler/rustc_mir_transform/src/normalize_array_len.rs +++ /dev/null @@ -1,103 +0,0 @@ -//! This pass eliminates casting of arrays into slices when their length -//! is taken using `.len()` method. Handy to preserve information in MIR for const prop - -use crate::ssa::SsaLocals; -use rustc_index::IndexVec; -use rustc_middle::mir::visit::*; -use rustc_middle::mir::*; -use rustc_middle::ty::{self, TyCtxt}; - -pub struct NormalizeArrayLen; - -impl<'tcx> MirPass<'tcx> for NormalizeArrayLen { - fn is_enabled(&self, sess: &rustc_session::Session) -> bool { - sess.mir_opt_level() >= 3 - } - - #[instrument(level = "trace", skip(self, tcx, body))] - fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { - debug!(def_id = ?body.source.def_id()); - normalize_array_len_calls(tcx, body) - } -} - -fn normalize_array_len_calls<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { - let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id()); - let ssa = SsaLocals::new(tcx, body, param_env); - - let slice_lengths = compute_slice_length(tcx, &ssa, body); - debug!(?slice_lengths); - - Replacer { tcx, slice_lengths }.visit_body_preserves_cfg(body); -} - -fn compute_slice_length<'tcx>( - tcx: TyCtxt<'tcx>, - ssa: &SsaLocals, - body: &Body<'tcx>, -) -> IndexVec<Local, Option<ty::Const<'tcx>>> { - let mut slice_lengths = IndexVec::from_elem(None, &body.local_decls); - - for (local, rvalue, _) in ssa.assignments(body) { - match rvalue { - Rvalue::Cast( - CastKind::PointerCoercion(ty::adjustment::PointerCoercion::Unsize), - operand, - cast_ty, - ) => { - let operand_ty = operand.ty(body, tcx); - debug!(?operand_ty); - if let Some(operand_ty) = operand_ty.builtin_deref(true) - && let ty::Array(_, len) = operand_ty.kind() - && let Some(cast_ty) = cast_ty.builtin_deref(true) - && let ty::Slice(..) = cast_ty.kind() - { - slice_lengths[local] = Some(*len); - } - } - // The length information is stored in the fat pointer, so we treat `operand` as a value. - Rvalue::Use(operand) => { - if let Some(rhs) = operand.place() - && let Some(rhs) = rhs.as_local() - { - slice_lengths[local] = slice_lengths[rhs]; - } - } - // The length information is stored in the fat pointer. - // Reborrowing copies length information from one pointer to the other. - Rvalue::Ref(_, _, rhs) | Rvalue::AddressOf(_, rhs) => { - if let [PlaceElem::Deref] = rhs.projection[..] { - slice_lengths[local] = slice_lengths[rhs.local]; - } - } - _ => {} - } - } - - slice_lengths -} - -struct Replacer<'tcx> { - tcx: TyCtxt<'tcx>, - slice_lengths: IndexVec<Local, Option<ty::Const<'tcx>>>, -} - -impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> { - fn tcx(&self) -> TyCtxt<'tcx> { - self.tcx - } - - fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, loc: Location) { - if let Rvalue::Len(place) = rvalue - && let [PlaceElem::Deref] = &place.projection[..] - && let Some(len) = self.slice_lengths[place.local] - { - *rvalue = Rvalue::Use(Operand::Constant(Box::new(ConstOperand { - span: rustc_span::DUMMY_SP, - user_ty: None, - const_: Const::from_ty_const(len, self.tcx.types.usize, self.tcx), - }))); - } - self.super_rvalue(rvalue, loc); - } -} |