From 42c4df01a8b498c56bf762c2307fb4a3c55293fe Mon Sep 17 00:00:00 2001 From: Gurinder Singh Date: Tue, 20 Feb 2024 07:41:48 +0530 Subject: [PATCH] Rename `ConstPropLint` to `KnownPanicsLint` It is a clearer name because it communicates what the lint does instead of the underlying mechanism it uses (const propagation). --- ...onst_prop_lint.rs => known_panics_lint.rs} | 32 ++++++++++--------- compiler/rustc_mir_transform/src/lib.rs | 4 +-- 2 files changed, 19 insertions(+), 17 deletions(-) rename compiler/rustc_mir_transform/src/{const_prop_lint.rs => known_panics_lint.rs} (97%) diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/known_panics_lint.rs similarity index 97% rename from compiler/rustc_mir_transform/src/const_prop_lint.rs rename to compiler/rustc_mir_transform/src/known_panics_lint.rs index 6f2ef8f9a4fdf..a9cd688c31551 100644 --- a/compiler/rustc_mir_transform/src/const_prop_lint.rs +++ b/compiler/rustc_mir_transform/src/known_panics_lint.rs @@ -1,5 +1,8 @@ -//! Propagates constants for early reporting of statically known -//! assertion failures +//! A lint that checks for known panics like +//! overflows, division by zero, +//! out-of-bound access etc. +//! Uses const propagation to determine the +//! values of operands during checks. use std::fmt::Debug; @@ -21,9 +24,9 @@ use crate::dataflow_const_prop::DummyMachine; use crate::errors::{AssertLint, AssertLintKind}; use crate::MirLint; -pub struct ConstPropLint; +pub struct KnownPanicsLint; -impl<'tcx> MirLint<'tcx> for ConstPropLint { +impl<'tcx> MirLint<'tcx> for KnownPanicsLint { fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) { if body.tainted_by_errors.is_some() { return; @@ -37,31 +40,28 @@ impl<'tcx> MirLint<'tcx> for ConstPropLint { // Only run const prop on functions, methods, closures and associated constants if !is_fn_like && !is_assoc_const { // skip anon_const/statics/consts because they'll be evaluated by miri anyway - trace!("ConstPropLint skipped for {:?}", def_id); + trace!("KnownPanicsLint skipped for {:?}", def_id); return; } // FIXME(welseywiser) const prop doesn't work on coroutines because of query cycles // computing their layout. if tcx.is_coroutine(def_id.to_def_id()) { - trace!("ConstPropLint skipped for coroutine {:?}", def_id); + trace!("KnownPanicsLint skipped for coroutine {:?}", def_id); return; } - trace!("ConstPropLint starting for {:?}", def_id); + trace!("KnownPanicsLint starting for {:?}", def_id); - // FIXME(oli-obk, eddyb) Optimize locals (or even local paths) to hold - // constants, instead of just checking for const-folding succeeding. - // That would require a uniform one-def no-mutation analysis - // and RPO (or recursing when needing the value of a local). let mut linter = ConstPropagator::new(body, tcx); linter.visit_body(body); - trace!("ConstPropLint done for {:?}", def_id); + trace!("KnownPanicsLint done for {:?}", def_id); } } -/// Finds optimization opportunities on the MIR. +/// Visits MIR nodes, performs const propagation +/// and runs lint checks as it goes struct ConstPropagator<'mir, 'tcx> { ecx: InterpCx<'mir, 'tcx, DummyMachine>, tcx: TyCtxt<'tcx>, @@ -238,7 +238,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { // dedicated error variants should be introduced instead. assert!( !error.kind().formatted_string(), - "const-prop encountered formatting error: {}", + "known panics lint encountered formatting error: {}", format_interp_error(self.ecx.tcx.dcx(), error), ); None @@ -253,7 +253,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { return None; } - // Normalization needed b/c const prop lint runs in + // Normalization needed b/c known panics lint runs in // `mir_drops_elaborated_and_const_checked`, which happens before // optimized MIR. Only after optimizing the MIR can we guarantee // that the `RevealAll` pass has happened and that the body's consts @@ -864,6 +864,8 @@ pub enum ConstPropMode { NoPropagation, } +/// A visitor that determines locals in a MIR body +/// that can be const propagated pub struct CanConstProp { can_const_prop: IndexVec, // False at the beginning. Once set, no more assignments are allowed to that local. diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 74b36eb5ee89e..945c3c662a604 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -59,7 +59,6 @@ mod remove_place_mention; mod add_subtyping_projections; pub mod cleanup_post_borrowck; mod const_debuginfo; -mod const_prop_lint; mod copy_prop; mod coroutine; mod cost_checker; @@ -83,6 +82,7 @@ mod gvn; pub mod inline; mod instsimplify; mod jump_threading; +mod known_panics_lint; mod large_enums; mod lint; mod lower_intrinsics; @@ -533,7 +533,7 @@ fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { &elaborate_box_derefs::ElaborateBoxDerefs, &coroutine::StateTransform, &add_retag::AddRetag, - &Lint(const_prop_lint::ConstPropLint), + &Lint(known_panics_lint::KnownPanicsLint), ]; pm::run_passes_no_validate(tcx, body, passes, Some(MirPhase::Runtime(RuntimePhase::Initial))); }