diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/const_goto.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/const_prop.rs | 54 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/const_prop_lint.rs | 6 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/errors.rs | 11 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/lib.rs | 5 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/required_consts.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/separate_const_switch.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/sroa.rs | 50 |
8 files changed, 103 insertions, 31 deletions
diff --git a/compiler/rustc_mir_transform/src/const_goto.rs b/compiler/rustc_mir_transform/src/const_goto.rs index da101ca7ad2..024bea62098 100644 --- a/compiler/rustc_mir_transform/src/const_goto.rs +++ b/compiler/rustc_mir_transform/src/const_goto.rs @@ -28,7 +28,7 @@ pub struct ConstGoto; impl<'tcx> MirPass<'tcx> for ConstGoto { fn is_enabled(&self, sess: &rustc_session::Session) -> bool { - sess.mir_opt_level() >= 4 + sess.mir_opt_level() >= 2 } fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs index 1ba1951afde..1d43dbda0aa 100644 --- a/compiler/rustc_mir_transform/src/const_prop.rs +++ b/compiler/rustc_mir_transform/src/const_prop.rs @@ -4,6 +4,7 @@ use either::Right; use rustc_const_eval::const_eval::CheckAlignment; +use rustc_const_eval::ReportErrorExt; use rustc_data_structures::fx::FxHashSet; use rustc_hir::def::DefKind; use rustc_index::bit_set::BitSet; @@ -37,6 +38,7 @@ macro_rules! throw_machine_stop_str { ($($tt:tt)*) => {{ // We make a new local type for it. The type itself does not carry any information, // but its vtable (for the `MachineStopType` trait) does. + #[derive(Debug)] struct Zst; // Printing this type shows the desired string. impl std::fmt::Display for Zst { @@ -44,7 +46,17 @@ macro_rules! throw_machine_stop_str { write!(f, $($tt)*) } } - impl rustc_middle::mir::interpret::MachineStopType for Zst {} + + impl rustc_middle::mir::interpret::MachineStopType for Zst { + fn diagnostic_message(&self) -> rustc_errors::DiagnosticMessage { + self.to_string().into() + } + + fn add_args( + self: Box<Self>, + _: &mut dyn FnMut(std::borrow::Cow<'static, str>, rustc_errors::DiagnosticArgValue<'static>), + ) {} + } throw_machine_stop!(Zst) }}; } @@ -103,7 +115,14 @@ impl<'tcx> MirPass<'tcx> for ConstProp { // That would require a uniform one-def no-mutation analysis // and RPO (or recursing when needing the value of a local). let mut optimization_finder = ConstPropagator::new(body, dummy_body, tcx); - optimization_finder.visit_body(body); + + // Traverse the body in reverse post-order, to ensure that `FullConstProp` locals are + // assigned before being read. + let postorder = body.basic_blocks.postorder().to_vec(); + for bb in postorder.into_iter().rev() { + let data = &mut body.basic_blocks.as_mut_preserves_cfg()[bb]; + optimization_finder.visit_basic_block_data(bb, data); + } trace!("ConstProp done for {:?}", def_id); } @@ -367,7 +386,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { op } Err(e) => { - trace!("get_const failed: {}", e); + trace!("get_const failed: {:?}", e.into_kind().debug()); return None; } }; @@ -789,12 +808,6 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> { self.tcx } - fn visit_body(&mut self, body: &mut Body<'tcx>) { - for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() { - self.visit_basic_block_data(bb, data); - } - } - fn visit_operand(&mut self, operand: &mut Operand<'tcx>, location: Location) { self.super_operand(operand, location); @@ -885,14 +898,23 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> { } } StatementKind::StorageLive(local) => { - let frame = self.ecx.frame_mut(); - frame.locals[local].value = - LocalValue::Live(interpret::Operand::Immediate(interpret::Immediate::Uninit)); - } - StatementKind::StorageDead(local) => { - let frame = self.ecx.frame_mut(); - frame.locals[local].value = LocalValue::Dead; + Self::remove_const(&mut self.ecx, local); } + // We do not need to mark dead locals as such. For `FullConstProp` locals, + // this allows to propagate the single assigned value in this case: + // ``` + // let x = SOME_CONST; + // if a { + // f(copy x); + // StorageDead(x); + // } else { + // g(copy x); + // StorageDead(x); + // } + // ``` + // + // This may propagate a constant where the local would be uninit or dead. + // In both cases, this does not matter, as those reads would be UB anyway. _ => {} } } diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs index 0fe49b8a1bb..759650fe4db 100644 --- a/compiler/rustc_mir_transform/src/const_prop_lint.rs +++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs @@ -9,6 +9,7 @@ use rustc_const_eval::interpret::Immediate; use rustc_const_eval::interpret::{ self, InterpCx, InterpResult, LocalValue, MemoryKind, OpTy, Scalar, StackPopCleanup, }; +use rustc_const_eval::ReportErrorExt; use rustc_hir::def::DefKind; use rustc_hir::HirId; use rustc_index::bit_set::BitSet; @@ -232,7 +233,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { op } Err(e) => { - trace!("get_const failed: {}", e); + trace!("get_const failed: {:?}", e.into_kind().debug()); return None; } }; @@ -272,8 +273,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { // dedicated error variants should be introduced instead. assert!( !error.kind().formatted_string(), - "const-prop encountered formatting error: {}", - error + "const-prop encountered formatting error: {error:?}", ); None } diff --git a/compiler/rustc_mir_transform/src/errors.rs b/compiler/rustc_mir_transform/src/errors.rs index 602e40d5131..22f71bb0851 100644 --- a/compiler/rustc_mir_transform/src/errors.rs +++ b/compiler/rustc_mir_transform/src/errors.rs @@ -163,7 +163,14 @@ impl<'a, P: std::fmt::Debug> DecorateLint<'a, ()> for AssertLint<P> { self, diag: &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()> { - diag.span_label(self.span(), format!("{:?}", self.panic())); + let span = self.span(); + let assert_kind = self.panic(); + let message = assert_kind.diagnostic_message(); + assert_kind.add_args(&mut |name, value| { + diag.set_arg(name, value); + }); + diag.span_label(span, message); + diag } @@ -191,7 +198,7 @@ impl<P> AssertLint<P> { AssertLint::ArithmeticOverflow(sp, _) | AssertLint::UnconditionalPanic(sp, _) => *sp, } } - pub fn panic(&self) -> &AssertKind<P> { + pub fn panic(self) -> AssertKind<P> { match self { AssertLint::ArithmeticOverflow(_, p) | AssertLint::UnconditionalPanic(_, p) => p, } diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 54c138b6fbd..7d9f6c38e36 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -559,10 +559,13 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { // inst combine is after MatchBranchSimplification to clean up Ne(_1, false) &multiple_return_terminators::MultipleReturnTerminators, &instsimplify::InstSimplify, - &separate_const_switch::SeparateConstSwitch, &simplify::SimplifyLocals::BeforeConstProp, ©_prop::CopyProp, &ref_prop::ReferencePropagation, + // Perform `SeparateConstSwitch` after SSA-based analyses, as cloning blocks may + // destroy the SSA property. It should still happen before const-propagation, so the + // latter pass will leverage the created opportunities. + &separate_const_switch::SeparateConstSwitch, &const_prop::ConstProp, &dataflow_const_prop::DataflowConstProp, // diff --git a/compiler/rustc_mir_transform/src/required_consts.rs b/compiler/rustc_mir_transform/src/required_consts.rs index 0ea8f2ba93f..243cb463560 100644 --- a/compiler/rustc_mir_transform/src/required_consts.rs +++ b/compiler/rustc_mir_transform/src/required_consts.rs @@ -17,8 +17,8 @@ impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'_, 'tcx> { let literal = constant.literal; match literal { ConstantKind::Ty(c) => match c.kind() { - ConstKind::Param(_) | ConstKind::Error(_) => {} - _ => bug!("only ConstKind::Param should be encountered here, got {:#?}", c), + ConstKind::Param(_) | ConstKind::Error(_) | ConstKind::Value(_) => {} + _ => bug!("only ConstKind::Param/Value should be encountered here, got {:#?}", c), }, ConstantKind::Unevaluated(..) => self.required_consts.push(*constant), ConstantKind::Val(..) => {} diff --git a/compiler/rustc_mir_transform/src/separate_const_switch.rs b/compiler/rustc_mir_transform/src/separate_const_switch.rs index 2479856b727..f35a5fb4276 100644 --- a/compiler/rustc_mir_transform/src/separate_const_switch.rs +++ b/compiler/rustc_mir_transform/src/separate_const_switch.rs @@ -46,7 +46,7 @@ pub struct SeparateConstSwitch; impl<'tcx> MirPass<'tcx> for SeparateConstSwitch { fn is_enabled(&self, sess: &rustc_session::Session) -> bool { - sess.mir_opt_level() >= 4 + sess.mir_opt_level() >= 2 } fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { diff --git a/compiler/rustc_mir_transform/src/sroa.rs b/compiler/rustc_mir_transform/src/sroa.rs index 2d77291293d..e4b3b8b9262 100644 --- a/compiler/rustc_mir_transform/src/sroa.rs +++ b/compiler/rustc_mir_transform/src/sroa.rs @@ -6,23 +6,29 @@ use rustc_middle::mir::visit::*; use rustc_middle::mir::*; use rustc_middle::ty::{self, Ty, TyCtxt}; use rustc_mir_dataflow::value_analysis::{excluded_locals, iter_fields}; -use rustc_target::abi::FieldIdx; +use rustc_target::abi::{FieldIdx, ReprFlags, FIRST_VARIANT}; pub struct ScalarReplacementOfAggregates; impl<'tcx> MirPass<'tcx> for ScalarReplacementOfAggregates { fn is_enabled(&self, sess: &rustc_session::Session) -> bool { - sess.mir_opt_level() >= 3 + sess.mir_opt_level() >= 2 } #[instrument(level = "debug", skip(self, tcx, body))] fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { debug!(def_id = ?body.source.def_id()); + + // Avoid query cycles (generators require optimized MIR for layout). + if tcx.type_of(body.source.def_id()).subst_identity().is_generator() { + return; + } + let mut excluded = excluded_locals(body); let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id()); loop { debug!(?excluded); - let escaping = escaping_locals(&excluded, body); + let escaping = escaping_locals(tcx, param_env, &excluded, body); debug!(?escaping); let replacements = compute_flattening(tcx, param_env, body, escaping); debug!(?replacements); @@ -48,11 +54,45 @@ impl<'tcx> MirPass<'tcx> for ScalarReplacementOfAggregates { /// - the locals is a union or an enum; /// - the local's address is taken, and thus the relative addresses of the fields are observable to /// client code. -fn escaping_locals(excluded: &BitSet<Local>, body: &Body<'_>) -> BitSet<Local> { +fn escaping_locals<'tcx>( + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + excluded: &BitSet<Local>, + body: &Body<'tcx>, +) -> BitSet<Local> { + let is_excluded_ty = |ty: Ty<'tcx>| { + if ty.is_union() || ty.is_enum() { + return true; + } + if let ty::Adt(def, _substs) = ty.kind() { + if def.repr().flags.contains(ReprFlags::IS_SIMD) { + // Exclude #[repr(simd)] types so that they are not de-optimized into an array + return true; + } + // We already excluded unions and enums, so this ADT must have one variant + let variant = def.variant(FIRST_VARIANT); + if variant.fields.len() > 1 { + // If this has more than one field, it cannot be a wrapper that only provides a + // niche, so we do not want to automatically exclude it. + return false; + } + let Ok(layout) = tcx.layout_of(param_env.and(ty)) else { + // We can't get the layout + return true; + }; + if layout.layout.largest_niche().is_some() { + // This type has a niche + return true; + } + } + // Default for non-ADTs + false + }; + let mut set = BitSet::new_empty(body.local_decls.len()); set.insert_range(RETURN_PLACE..=Local::from_usize(body.arg_count)); for (local, decl) in body.local_decls().iter_enumerated() { - if decl.ty.is_union() || decl.ty.is_enum() || excluded.contains(local) { + if excluded.contains(local) || is_excluded_ty(decl.ty) { set.insert(local); } } |