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Preserve DebugInfo in DeadStoreElimination.

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This commit is contained in:
Camille GILLOT 2023-01-12 20:04:42 +00:00
parent 1bc0463b18
commit 27d6a57e58
30 changed files with 773 additions and 807 deletions
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22
compiler/rustc_mir_transform/src/dead_store_elimination.rs
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@ -13,10 +13,10 @@
//!
use crate::util::is_within_packed;
use rustc_index::bit_set::BitSet;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
use rustc_mir_dataflow::debuginfo::debuginfo_locals;
use rustc_mir_dataflow::impls::{
borrowed_locals, LivenessTransferFunction, MaybeTransitiveLiveLocals,
};
@ -26,8 +26,15 @@ use rustc_mir_dataflow::Analysis;
///
/// The `borrowed` set must be a `BitSet` of all the locals that are ever borrowed in this body. It
/// can be generated via the [`borrowed_locals`] function.
pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitSet<Local>) {
let mut live = MaybeTransitiveLiveLocals::new(borrowed)
pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let borrowed_locals = borrowed_locals(body);
// If the user requests complete debuginfo, mark the locals that appear in it as live, so
// we don't remove assignements to them.
let mut always_live = debuginfo_locals(body);
always_live.union(&borrowed_locals);
let mut live = MaybeTransitiveLiveLocals::new(&always_live)
.into_engine(tcx, body)
.iterate_to_fixpoint()
.into_results_cursor(body);
@ -48,7 +55,9 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
for (index, arg) in args.iter().enumerate().rev() {
if let Operand::Copy(place) = *arg
&& !place.is_indirect()
&& !borrowed.contains(place.local)
// Do not skip the transformation if the local is in debuginfo, as we do
// not really lose any information for this purpose.
&& !borrowed_locals.contains(place.local)
&& !state.contains(place.local)
// If `place` is a projection of a disaligned field in a packed ADT,
// the move may be codegened as a pointer to that field.
@ -75,7 +84,7 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS
StatementKind::Assign(box (place, _))
| StatementKind::SetDiscriminant { place: box place, .. }
| StatementKind::Deinit(box place) => {
if !place.is_indirect() && !borrowed.contains(place.local) {
if !place.is_indirect() && !always_live.contains(place.local) {
live.seek_before_primary_effect(loc);
if !live.get().contains(place.local) {
patch.push(loc);
@ -126,7 +135,6 @@ impl<'tcx> MirPass<'tcx> for DeadStoreElimination {
}
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let borrowed = borrowed_locals(body);
eliminate(tcx, body, &borrowed);
eliminate(tcx, body);
}
}