From 5de9cb0703555ee6e2e0af8305be138f09545485 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 19:36:48 -0300
Subject: [PATCH 01/12] super_ty on MutVisitor is empty so avoid the call
---
src/librustc_mir/transform/erase_regions.rs | 1 -
1 file changed, 1 deletion(-)
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index 38a04ce8f3815..e9ce84a25838f 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -25,7 +25,6 @@ impl EraseRegionsVisitor<'tcx> {
impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> {
fn visit_ty(&mut self, ty: &mut Ty<'tcx>, _: TyContext) {
*ty = self.tcx.erase_regions(ty);
- self.super_ty(ty);
}
fn visit_region(&mut self, region: &mut ty::Region<'tcx>, _: Location) {
From e069e9ccacbe92de1c893be5ad77fd5d6173f937 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 16:39:20 -0300
Subject: [PATCH 02/12] Prepare promote_consts MutVisitor to have projections
interned
---
src/librustc_mir/transform/promote_consts.rs | 26 +++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index 5d241ffe1c06a..d1c79c5ae2ada 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -191,6 +191,10 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
});
}
+ fn is_temp_kind(&self, local: Local) -> bool {
+ self.source.local_kind(local) == LocalKind::Temp
+ }
+
/// Copies the initialization of this temp to the
/// promoted MIR, recursing through temps.
fn promote_temp(&mut self, temp: Local) -> Local {
@@ -396,10 +400,30 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Promoter<'a, 'tcx> {
local: &mut Local,
_: PlaceContext,
_: Location) {
- if self.source.local_kind(*local) == LocalKind::Temp {
+ if self.is_temp_kind(*local) {
*local = self.promote_temp(*local);
}
}
+
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ match elem {
+ PlaceElem::Index(local) if self.is_temp_kind(*local) => {
+ PlaceElem::Index(self.promote_temp(*local))
+ }
+ _ => elem.clone(),
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
pub fn promote_candidates<'tcx>(
From 591cc9aede4aec9b8816b8489eb98c2f2a3bfe90 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 17:58:28 -0300
Subject: [PATCH 03/12] Prepare simplify MutVisitor to have projections
interned
---
src/librustc_mir/transform/simplify.rs | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index 9ffff9a92fa53..57bc1c8fab969 100644
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -366,7 +366,27 @@ impl<'tcx> MutVisitor<'tcx> for LocalUpdater {
});
self.super_basic_block_data(block, data);
}
+
fn visit_local(&mut self, l: &mut Local, _: PlaceContext, _: Location) {
*l = self.map[*l].unwrap();
}
+
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ if let PlaceElem::Index(local) = elem {
+ PlaceElem::Index(self.map[*local].unwrap())
+ } else {
+ elem.clone()
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
From bb7d6d1c70964d1d3efd5fb448538b7de50bbe3c Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 18:15:19 -0300
Subject: [PATCH 04/12] Prepare renumber MutVisitor to have projections
interned
---
src/librustc_mir/borrow_check/nll/renumber.rs | 23 +++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/src/librustc_mir/borrow_check/nll/renumber.rs b/src/librustc_mir/borrow_check/nll/renumber.rs
index 88ad1fb129509..6eb5735cb16ba 100644
--- a/src/librustc_mir/borrow_check/nll/renumber.rs
+++ b/src/librustc_mir/borrow_check/nll/renumber.rs
@@ -1,7 +1,7 @@
use rustc::ty::subst::SubstsRef;
use rustc::ty::{self, Ty, TypeFoldable};
-use rustc::mir::{Location, Body, Promoted};
-use rustc::mir::visit::{MutVisitor, TyContext};
+use rustc::mir::{Body, Location, Place, PlaceElem, Promoted};
+use rustc::mir::visit::{MutVisitor, PlaceContext, TyContext};
use rustc::infer::{InferCtxt, NLLRegionVariableOrigin};
use rustc_index::vec::IndexVec;
@@ -62,6 +62,25 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'tcx> {
debug!("visit_ty: ty={:?}", ty);
}
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ if let PlaceElem::Field(field, ty) = elem {
+ PlaceElem::Field(*field, self.renumber_regions(ty))
+ } else {
+ elem.clone()
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
+
fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, location: Location) {
debug!("visit_substs(substs={:?}, location={:?})", substs, location);
From e3e99516730f72fa05cb964ae341156e1ca85c39 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 18:23:39 -0300
Subject: [PATCH 05/12] Prepare inline MutVisitor to have projections interned
---
src/librustc_mir/transform/inline.rs | 51 +++++++++++++++++++---------
1 file changed, 35 insertions(+), 16 deletions(-)
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index 9830ed35ffc3e..3a71d22da7873 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -647,38 +647,45 @@ impl<'a, 'tcx> Integrator<'a, 'tcx> {
debug!("updating target `{:?}`, new: `{:?}`", tgt, new);
new
}
-}
-impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
- fn visit_local(&mut self,
- local: &mut Local,
- _ctxt: PlaceContext,
- _location: Location) {
+ fn make_integrate_local(&self, local: &Local) -> Local {
if *local == RETURN_PLACE {
match self.destination {
Place {
base: PlaceBase::Local(l),
projection: box [],
} => {
- *local = l;
- return;
+ return l;
},
ref place => bug!("Return place is {:?}, not local", place)
}
}
+
let idx = local.index() - 1;
if idx < self.args.len() {
- *local = self.args[idx];
- return;
+ return self.args[idx];
}
- *local = self.local_map[Local::new(idx - self.args.len())];
+
+ self.local_map[Local::new(idx - self.args.len())]
}
+}
- fn visit_place(&mut self,
- place: &mut Place<'tcx>,
- _ctxt: PlaceContext,
- _location: Location) {
+impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
+ fn visit_local(
+ &mut self,
+ local: &mut Local,
+ _ctxt: PlaceContext,
+ _location: Location,
+ ) {
+ *local = self.make_integrate_local(local);
+ }
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
match place {
Place {
base: PlaceBase::Local(RETURN_PLACE),
@@ -687,7 +694,19 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
// Return pointer; update the place itself
*place = self.destination.clone();
},
- _ => self.super_place(place, _ctxt, _location)
+ _ => {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ if let PlaceElem::Index(local) = elem {
+ PlaceElem::Index(self.make_integrate_local(local))
+ } else {
+ elem.clone()
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
}
From 0fc063f15936761024183a3bb3790684d5de3bd3 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 19:14:35 -0300
Subject: [PATCH 06/12] Prepare generator MutVisitor to have projections
interned
---
src/librustc_mir/transform/generator.rs | 52 +++++++++++++++++++++----
1 file changed, 45 insertions(+), 7 deletions(-)
diff --git a/src/librustc_mir/transform/generator.rs b/src/librustc_mir/transform/generator.rs
index 865fa012c2995..a801548efab08 100644
--- a/src/librustc_mir/transform/generator.rs
+++ b/src/librustc_mir/transform/generator.rs
@@ -88,6 +88,24 @@ impl<'tcx> MutVisitor<'tcx> for RenameLocalVisitor {
*local = self.to;
}
}
+
+ fn visit_place(&mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ match elem {
+ PlaceElem::Index(local) if *local == self.from => {
+ PlaceElem::Index(self.to)
+ }
+ _ => elem.clone(),
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
struct DerefArgVisitor;
@@ -110,7 +128,13 @@ impl<'tcx> MutVisitor<'tcx> for DerefArgVisitor {
projection: Box::new([ProjectionElem::Deref]),
});
} else {
- self.super_place(place, context, location);
+ self.visit_place_base(&mut place.base, context, location);
+
+ for elem in place.projection.iter() {
+ if let PlaceElem::Index(local) = elem {
+ assert_ne!(*local, self_arg());
+ }
+ }
}
}
}
@@ -137,7 +161,13 @@ impl<'tcx> MutVisitor<'tcx> for PinArgVisitor<'tcx> {
projection: Box::new([ProjectionElem::Field(Field::new(0), self.ref_gen_ty)]),
});
} else {
- self.super_place(place, context, location);
+ self.visit_place_base(&mut place.base, context, location);
+
+ for elem in place.projection.iter() {
+ if let PlaceElem::Index(local) = elem {
+ assert_ne!(*local, self_arg());
+ }
+ }
}
}
}
@@ -247,17 +277,25 @@ impl MutVisitor<'tcx> for TransformVisitor<'tcx> {
assert_eq!(self.remap.get(local), None);
}
- fn visit_place(&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location) {
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
if let PlaceBase::Local(l) = place.base {
// Replace an Local in the remap with a generator struct access
if let Some(&(ty, variant_index, idx)) = self.remap.get(&l) {
replace_base(place, self.make_field(variant_index, idx, ty));
}
} else {
- self.super_place(place, context, location);
+ self.visit_place_base(&mut place.base, context, location);
+
+ for elem in place.projection.iter() {
+ if let PlaceElem::Index(local) = elem {
+ assert_ne!(*local, self_arg());
+ }
+ }
}
}
From 39c9ed3ac19b3f6c79069d32a317daa763371369 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Mon, 7 Oct 2019 19:35:41 -0300
Subject: [PATCH 07/12] Prepare erase_regions MutVisitor to have projections
interned
---
src/librustc_mir/transform/erase_regions.rs | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index e9ce84a25838f..132149d5d4337 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -7,7 +7,7 @@
use rustc::ty::subst::SubstsRef;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::mir::*;
-use rustc::mir::visit::{MutVisitor, TyContext};
+use rustc::mir::visit::{MutVisitor, PlaceContext, TyContext};
use crate::transform::{MirPass, MirSource};
struct EraseRegionsVisitor<'tcx> {
@@ -38,6 +38,25 @@ impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> {
fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, _: Location) {
*substs = self.tcx.erase_regions(substs);
}
+
+ fn visit_place(
+ &mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ if let PlaceElem::Field(field, ty) = elem {
+ PlaceElem::Field(*field, self.tcx.erase_regions(ty))
+ } else {
+ elem.clone()
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
pub struct EraseRegions;
From 2b2e35bfc34618cff7b62a7726ee3a97101d3fa2 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 8 Oct 2019 00:24:18 -0300
Subject: [PATCH 08/12] Prepare def_use MutVisitor to have projections interned
---
src/librustc_mir/util/def_use.rs | 36 ++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs
index 3aea25fa8769f..d90be90bd9d49 100644
--- a/src/librustc_mir/util/def_use.rs
+++ b/src/librustc_mir/util/def_use.rs
@@ -1,6 +1,6 @@
//! Def-use analysis.
-use rustc::mir::{Local, Location, Body};
+use rustc::mir::{Body, Local, Location, Place, PlaceElem};
use rustc::mir::visit::{PlaceContext, MutVisitor, Visitor};
use rustc_index::vec::IndexVec;
use std::mem;
@@ -47,13 +47,13 @@ impl DefUseAnalysis {
&self.info[local]
}
- fn mutate_defs_and_uses<F>(&self, local: Local, body: &mut Body<'_>, mut callback: F)
- where F: for<'a> FnMut(&'a mut Local,
+ fn mutate_defs_and_uses<F>(&self, local: Local, body: &mut Body<'_>, callback: F)
+ where F: for<'a> Fn(&'a Local,
PlaceContext,
- Location) {
+ Location) -> Local {
for place_use in &self.info[local].defs_and_uses {
MutateUseVisitor::new(local,
- &mut callback,
+ &callback,
body).visit_location(body, place_use.location)
}
}
@@ -63,7 +63,7 @@ impl DefUseAnalysis {
local: Local,
body: &mut Body<'_>,
new_local: Local) {
- self.mutate_defs_and_uses(local, body, |local, _, _| *local = new_local)
+ self.mutate_defs_and_uses(local, body, |_, _, _| new_local)
}
}
@@ -125,7 +125,7 @@ struct MutateUseVisitor<F> {
impl<F> MutateUseVisitor<F> {
fn new(query: Local, callback: F, _: &Body<'_>)
-> MutateUseVisitor<F>
- where F: for<'a> FnMut(&'a mut Local, PlaceContext, Location) {
+ where F: for<'a> Fn(&'a Local, PlaceContext, Location) -> Local {
MutateUseVisitor {
query,
callback,
@@ -134,13 +134,31 @@ impl<F> MutateUseVisitor<F> {
}
impl<F> MutVisitor<'_> for MutateUseVisitor<F>
- where F: for<'a> FnMut(&'a mut Local, PlaceContext, Location) {
+ where F: for<'a> Fn(&'a Local, PlaceContext, Location) -> Local {
fn visit_local(&mut self,
local: &mut Local,
context: PlaceContext,
location: Location) {
if *local == self.query {
- (self.callback)(local, context, location)
+ *local = (self.callback)(local, context, location)
}
}
+
+ fn visit_place(&mut self,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ let new_projection: Vec<_> = place.projection.iter().map(|elem|
+ match elem {
+ PlaceElem::Index(local) if *local == self.query => {
+ PlaceElem::Index((self.callback)(&local, context, location))
+ }
+ _ => elem.clone(),
+ }
+ ).collect();
+
+ place.projection = new_projection.into_boxed_slice();
+ }
}
From 4f2a11036d085227e261824a1aa76dd752c84267 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 8 Oct 2019 00:33:47 -0300
Subject: [PATCH 09/12] Remove unneeded callback and just use the new_local
value
---
src/librustc_mir/util/def_use.rs | 32 +++++++++++++-------------------
1 file changed, 13 insertions(+), 19 deletions(-)
diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs
index d90be90bd9d49..5b5f7d83f0746 100644
--- a/src/librustc_mir/util/def_use.rs
+++ b/src/librustc_mir/util/def_use.rs
@@ -47,13 +47,10 @@ impl DefUseAnalysis {
&self.info[local]
}
- fn mutate_defs_and_uses<F>(&self, local: Local, body: &mut Body<'_>, callback: F)
- where F: for<'a> Fn(&'a Local,
- PlaceContext,
- Location) -> Local {
+ fn mutate_defs_and_uses(&self, local: Local, body: &mut Body<'_>, new_local: Local) {
for place_use in &self.info[local].defs_and_uses {
MutateUseVisitor::new(local,
- &callback,
+ new_local,
body).visit_location(body, place_use.location)
}
}
@@ -63,7 +60,7 @@ impl DefUseAnalysis {
local: Local,
body: &mut Body<'_>,
new_local: Local) {
- self.mutate_defs_and_uses(local, body, |_, _, _| new_local)
+ self.mutate_defs_and_uses(local, body, new_local)
}
}
@@ -117,30 +114,27 @@ impl Info {
}
}
-struct MutateUseVisitor<F> {
+struct MutateUseVisitor {
query: Local,
- callback: F,
+ new_local: Local,
}
-impl<F> MutateUseVisitor<F> {
- fn new(query: Local, callback: F, _: &Body<'_>)
- -> MutateUseVisitor<F>
- where F: for<'a> Fn(&'a Local, PlaceContext, Location) -> Local {
+impl MutateUseVisitor {
+ fn new(query: Local, new_local: Local, _: &Body<'_>) -> MutateUseVisitor {
MutateUseVisitor {
query,
- callback,
+ new_local,
}
}
}
-impl<F> MutVisitor<'_> for MutateUseVisitor<F>
- where F: for<'a> Fn(&'a Local, PlaceContext, Location) -> Local {
+impl MutVisitor<'_> for MutateUseVisitor {
fn visit_local(&mut self,
local: &mut Local,
- context: PlaceContext,
- location: Location) {
+ _context: PlaceContext,
+ _location: Location) {
if *local == self.query {
- *local = (self.callback)(local, context, location)
+ *local = self.new_local;
}
}
@@ -153,7 +147,7 @@ impl<F> MutVisitor<'_> for MutateUseVisitor<F>
let new_projection: Vec<_> = place.projection.iter().map(|elem|
match elem {
PlaceElem::Index(local) if *local == self.query => {
- PlaceElem::Index((self.callback)(&local, context, location))
+ PlaceElem::Index(self.new_local)
}
_ => elem.clone(),
}
From 7fa3425ef675b4bf4177dc2ea232078f4556b4c4 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 8 Oct 2019 12:16:26 -0300
Subject: [PATCH 10/12] Setup a different visit place set of methods for
mutable and immutable visitors
In particular, use a blank visit_place for mutable visitor to be sure,
non modified visitors are not trying to mutating place.
---
src/librustc/mir/visit.rs | 180 ++++++++++++++++++++++----------------
1 file changed, 103 insertions(+), 77 deletions(-)
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index edc7922f46eec..0fb43c7f98d16 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -158,22 +158,7 @@ macro_rules! make_mir_visitor {
self.super_place_base(base, context, location);
}
- fn visit_projection(&mut self,
- base: & $($mutability)? PlaceBase<'tcx>,
- projection: & $($mutability)? [PlaceElem<'tcx>],
- context: PlaceContext,
- location: Location) {
- self.super_projection(base, projection, context, location);
- }
-
- fn visit_projection_elem(&mut self,
- base: & $($mutability)? PlaceBase<'tcx>,
- proj_base: & $($mutability)? [PlaceElem<'tcx>],
- elem: & $($mutability)? PlaceElem<'tcx>,
- context: PlaceContext,
- location: Location) {
- self.super_projection_elem(base, proj_base, elem, context, location);
- }
+ visit_place_fns!($($mutability)?);
fn visit_constant(&mut self,
constant: & $($mutability)? Constant<'tcx>,
@@ -681,28 +666,6 @@ macro_rules! make_mir_visitor {
);
}
- fn super_place(&mut self,
- place: & $($mutability)? Place<'tcx>,
- context: PlaceContext,
- location: Location) {
- let mut context = context;
-
- if !place.projection.is_empty() {
- context = if context.is_mutating_use() {
- PlaceContext::MutatingUse(MutatingUseContext::Projection)
- } else {
- PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection)
- };
- }
-
- self.visit_place_base(& $($mutability)? place.base, context, location);
-
- self.visit_projection(& $($mutability)? place.base,
- & $($mutability)? place.projection,
- context,
- location);
- }
-
fn super_place_base(&mut self,
place_base: & $($mutability)? PlaceBase<'tcx>,
context: PlaceContext,
@@ -717,45 +680,6 @@ macro_rules! make_mir_visitor {
}
}
- fn super_projection(&mut self,
- base: & $($mutability)? PlaceBase<'tcx>,
- projection: & $($mutability)? [PlaceElem<'tcx>],
- context: PlaceContext,
- location: Location) {
- let mut cursor = projection;
- while let [proj_base @ .., elem] = cursor {
- cursor = proj_base;
- self.visit_projection_elem(base, cursor, elem, context, location);
- }
- }
-
- fn super_projection_elem(&mut self,
- _base: & $($mutability)? PlaceBase<'tcx>,
- _proj_base: & $($mutability)? [PlaceElem<'tcx>],
- elem: & $($mutability)? PlaceElem<'tcx>,
- _context: PlaceContext,
- location: Location) {
- match elem {
- ProjectionElem::Field(_field, ty) => {
- self.visit_ty(ty, TyContext::Location(location));
- }
- ProjectionElem::Index(local) => {
- self.visit_local(
- local,
- PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
- location
- );
- }
- ProjectionElem::Deref |
- ProjectionElem::Subslice { from: _, to: _ } |
- ProjectionElem::ConstantIndex { offset: _,
- min_length: _,
- from_end: _ } |
- ProjectionElem::Downcast(_, _) => {
- }
- }
- }
-
fn super_local_decl(&mut self,
local: Local,
local_decl: & $($mutability)? LocalDecl<'tcx>) {
@@ -858,6 +782,108 @@ macro_rules! make_mir_visitor {
}
}
+macro_rules! visit_place_fns {
+ (mut) => (
+ fn super_place(
+ &mut self,
+ _place: &mut Place<'tcx>,
+ _context: PlaceContext,
+ _location: Location,
+ ) {
+ }
+ );
+
+ () => (
+ fn visit_projection(
+ &mut self,
+ base: &PlaceBase<'tcx>,
+ projection: &[PlaceElem<'tcx>],
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.super_projection(base, projection, context, location);
+ }
+
+ fn visit_projection_elem(
+ &mut self,
+ base: &PlaceBase<'tcx>,
+ proj_base: &[PlaceElem<'tcx>],
+ elem: &PlaceElem<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ self.super_projection_elem(base, proj_base, elem, context, location);
+ }
+
+ fn super_place(
+ &mut self,
+ place: &Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
+ ) {
+ let mut context = context;
+
+ if !place.projection.is_empty() {
+ context = if context.is_mutating_use() {
+ PlaceContext::MutatingUse(MutatingUseContext::Projection)
+ } else {
+ PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection)
+ };
+ }
+
+ self.visit_place_base(&place.base, context, location);
+
+ self.visit_projection(&place.base,
+ &place.projection,
+ context,
+ location);
+ }
+
+ fn super_projection(
+ &mut self,
+ base: &PlaceBase<'tcx>,
+ projection: &[PlaceElem<'tcx>],
+ context: PlaceContext,
+ location: Location,
+ ) {
+ let mut cursor = projection;
+ while let [proj_base @ .., elem] = cursor {
+ cursor = proj_base;
+ self.visit_projection_elem(base, cursor, elem, context, location);
+ }
+ }
+
+ fn super_projection_elem(
+ &mut self,
+ _base: &PlaceBase<'tcx>,
+ _proj_base: &[PlaceElem<'tcx>],
+ elem: &PlaceElem<'tcx>,
+ _context: PlaceContext,
+ location: Location,
+ ) {
+ match elem {
+ ProjectionElem::Field(_field, ty) => {
+ self.visit_ty(ty, TyContext::Location(location));
+ }
+ ProjectionElem::Index(local) => {
+ self.visit_local(
+ local,
+ PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
+ location
+ );
+ }
+ ProjectionElem::Deref |
+ ProjectionElem::Subslice { from: _, to: _ } |
+ ProjectionElem::ConstantIndex { offset: _,
+ min_length: _,
+ from_end: _ } |
+ ProjectionElem::Downcast(_, _) => {
+ }
+ }
+ }
+ );
+}
+
make_mir_visitor!(Visitor,);
make_mir_visitor!(MutVisitor,mut);
From d53fc9cae5b17c138be09383dea8b8f10d3df3a1 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 8 Oct 2019 15:33:19 -0300
Subject: [PATCH 11/12] Add process_* place hooks to improve code reutilization
---
src/librustc/mir/visit.rs | 28 +++++++++++++++++--
src/librustc_mir/borrow_check/nll/renumber.rs | 28 +++++++------------
src/librustc_mir/transform/erase_regions.rs | 26 ++++++-----------
src/librustc_mir/transform/inline.rs | 23 +++++++--------
src/librustc_mir/transform/promote_consts.rs | 24 ++++++----------
src/librustc_mir/transform/simplify.rs | 24 ++++++----------
src/librustc_mir/util/def_use.rs | 26 +++++++----------
7 files changed, 82 insertions(+), 97 deletions(-)
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index 0fb43c7f98d16..c8a6367899ba9 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -786,10 +786,32 @@ macro_rules! visit_place_fns {
(mut) => (
fn super_place(
&mut self,
- _place: &mut Place<'tcx>,
- _context: PlaceContext,
- _location: Location,
+ place: &mut Place<'tcx>,
+ context: PlaceContext,
+ location: Location,
) {
+ self.visit_place_base(&mut place.base, context, location);
+
+ place.projection = self.process_projection(&place.projection);
+ }
+
+ fn process_projection(
+ &mut self,
+ projection: &Box<[PlaceElem<'tcx>]>,
+ ) -> Box<[PlaceElem<'tcx>]> {
+ let new_projection: Vec<_> = projection.iter().map(|elem|
+ self.process_projection_elem(elem)
+ ).collect();
+
+ new_projection.into_boxed_slice()
+ }
+
+ fn process_projection_elem(
+ &mut self,
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ // FIXME: avoid cloning here
+ elem.clone()
}
);
diff --git a/src/librustc_mir/borrow_check/nll/renumber.rs b/src/librustc_mir/borrow_check/nll/renumber.rs
index 6eb5735cb16ba..c4a19ce5128b5 100644
--- a/src/librustc_mir/borrow_check/nll/renumber.rs
+++ b/src/librustc_mir/borrow_check/nll/renumber.rs
@@ -1,7 +1,7 @@
use rustc::ty::subst::SubstsRef;
use rustc::ty::{self, Ty, TypeFoldable};
-use rustc::mir::{Body, Location, Place, PlaceElem, Promoted};
-use rustc::mir::visit::{MutVisitor, PlaceContext, TyContext};
+use rustc::mir::{Body, Location, PlaceElem, Promoted};
+use rustc::mir::visit::{MutVisitor, TyContext};
use rustc::infer::{InferCtxt, NLLRegionVariableOrigin};
use rustc_index::vec::IndexVec;
@@ -62,23 +62,15 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'tcx> {
debug!("visit_ty: ty={:?}", ty);
}
- fn visit_place(
+ fn process_projection_elem(
&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location,
- ) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- if let PlaceElem::Field(field, ty) = elem {
- PlaceElem::Field(*field, self.renumber_regions(ty))
- } else {
- elem.clone()
- }
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ if let PlaceElem::Field(field, ty) = elem {
+ PlaceElem::Field(*field, self.renumber_regions(ty))
+ } else {
+ elem.clone()
+ }
}
fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, location: Location) {
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index 132149d5d4337..725a8de8fe7d1 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -7,7 +7,7 @@
use rustc::ty::subst::SubstsRef;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::mir::*;
-use rustc::mir::visit::{MutVisitor, PlaceContext, TyContext};
+use rustc::mir::visit::{MutVisitor, TyContext};
use crate::transform::{MirPass, MirSource};
struct EraseRegionsVisitor<'tcx> {
@@ -39,23 +39,15 @@ impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> {
*substs = self.tcx.erase_regions(substs);
}
- fn visit_place(
+ fn process_projection_elem(
&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location,
- ) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- if let PlaceElem::Field(field, ty) = elem {
- PlaceElem::Field(*field, self.tcx.erase_regions(ty))
- } else {
- elem.clone()
- }
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ if let PlaceElem::Field(field, ty) = elem {
+ PlaceElem::Field(*field, self.tcx.erase_regions(ty))
+ } else {
+ elem.clone()
+ }
}
}
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index 3a71d22da7873..dd13d0c96557d 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -695,21 +695,22 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
*place = self.destination.clone();
},
_ => {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- if let PlaceElem::Index(local) = elem {
- PlaceElem::Index(self.make_integrate_local(local))
- } else {
- elem.clone()
- }
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ self.super_place(place, context, location);
}
}
}
+ fn process_projection_elem(
+ &mut self,
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ if let PlaceElem::Index(local) = elem {
+ PlaceElem::Index(self.make_integrate_local(local))
+ } else {
+ elem.clone()
+ }
+ }
+
fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
self.in_cleanup_block = data.is_cleanup;
self.super_basic_block_data(block, data);
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index d1c79c5ae2ada..565f260546bc7 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -405,24 +405,16 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Promoter<'a, 'tcx> {
}
}
- fn visit_place(
+ fn process_projection_elem(
&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location,
- ) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- match elem {
- PlaceElem::Index(local) if self.is_temp_kind(*local) => {
- PlaceElem::Index(self.promote_temp(*local))
- }
- _ => elem.clone(),
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ match elem {
+ PlaceElem::Index(local) if self.is_temp_kind(*local) => {
+ PlaceElem::Index(self.promote_temp(*local))
}
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ _ => elem.clone(),
+ }
}
}
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index 57bc1c8fab969..7dca3e357cc94 100644
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -371,22 +371,14 @@ impl<'tcx> MutVisitor<'tcx> for LocalUpdater {
*l = self.map[*l].unwrap();
}
- fn visit_place(
+ fn process_projection_elem(
&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location,
- ) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- if let PlaceElem::Index(local) = elem {
- PlaceElem::Index(self.map[*local].unwrap())
- } else {
- elem.clone()
- }
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ if let PlaceElem::Index(local) = elem {
+ PlaceElem::Index(self.map[*local].unwrap())
+ } else {
+ elem.clone()
+ }
}
}
diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs
index 5b5f7d83f0746..25930df020aa9 100644
--- a/src/librustc_mir/util/def_use.rs
+++ b/src/librustc_mir/util/def_use.rs
@@ -1,6 +1,6 @@
//! Def-use analysis.
-use rustc::mir::{Body, Local, Location, Place, PlaceElem};
+use rustc::mir::{Body, Local, Location, PlaceElem};
use rustc::mir::visit::{PlaceContext, MutVisitor, Visitor};
use rustc_index::vec::IndexVec;
use std::mem;
@@ -138,21 +138,15 @@ impl MutVisitor<'_> for MutateUseVisitor {
}
}
- fn visit_place(&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- match elem {
- PlaceElem::Index(local) if *local == self.query => {
- PlaceElem::Index(self.new_local)
- }
- _ => elem.clone(),
+ fn process_projection_elem(
+ &mut self,
+ elem: &PlaceElem<'tcx>,
+ ) -> PlaceElem<'tcx> {
+ match elem {
+ PlaceElem::Index(local) if *local == self.query => {
+ PlaceElem::Index(self.new_local)
}
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ _ => elem.clone(),
+ }
}
}
From 48349960e68a9d19b17ac54cd12e939a9a46ea7d Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Tue, 8 Oct 2019 23:46:14 -0300
Subject: [PATCH 12/12] Use Cow to handle modifications of projection in
preparation for interning
---
src/librustc/mir/visit.rs | 33 ++++++++++++-------
src/librustc_mir/borrow_check/nll/renumber.rs | 12 ++++---
src/librustc_mir/transform/erase_regions.rs | 12 ++++---
src/librustc_mir/transform/generator.rs | 24 +++++---------
src/librustc_mir/transform/inline.rs | 12 ++++---
src/librustc_mir/transform/promote_consts.rs | 6 ++--
src/librustc_mir/transform/simplify.rs | 11 ++++---
src/librustc_mir/util/def_use.rs | 6 ++--
8 files changed, 67 insertions(+), 49 deletions(-)
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index c8a6367899ba9..fef406e898783 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -792,26 +792,37 @@ macro_rules! visit_place_fns {
) {
self.visit_place_base(&mut place.base, context, location);
- place.projection = self.process_projection(&place.projection);
+ if let Some(new_projection) = self.process_projection(&place.projection) {
+ place.projection = new_projection;
+ }
}
fn process_projection(
&mut self,
- projection: &Box<[PlaceElem<'tcx>]>,
- ) -> Box<[PlaceElem<'tcx>]> {
- let new_projection: Vec<_> = projection.iter().map(|elem|
- self.process_projection_elem(elem)
- ).collect();
+ projection: &'a [PlaceElem<'tcx>],
+ ) -> Option<Box<[PlaceElem<'tcx>]>> {
+ let mut projection = Cow::Borrowed(projection);
+
+ for i in 0..projection.len() {
+ if let Some(elem) = projection.get(i) {
+ if let Some(elem) = self.process_projection_elem(elem) {
+ let vec = projection.to_mut();
+ vec[i] = elem;
+ }
+ }
+ }
- new_projection.into_boxed_slice()
+ match projection {
+ Cow::Borrowed(_) => None,
+ Cow::Owned(vec) => Some(vec.into_boxed_slice()),
+ }
}
fn process_projection_elem(
&mut self,
- elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
- // FIXME: avoid cloning here
- elem.clone()
+ _elem: &PlaceElem<'tcx>,
+ ) -> Option<PlaceElem<'tcx>> {
+ None
}
);
diff --git a/src/librustc_mir/borrow_check/nll/renumber.rs b/src/librustc_mir/borrow_check/nll/renumber.rs
index c4a19ce5128b5..9ecd6f837750e 100644
--- a/src/librustc_mir/borrow_check/nll/renumber.rs
+++ b/src/librustc_mir/borrow_check/nll/renumber.rs
@@ -65,12 +65,16 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'tcx> {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
+ ) -> Option<PlaceElem<'tcx>> {
if let PlaceElem::Field(field, ty) = elem {
- PlaceElem::Field(*field, self.renumber_regions(ty))
- } else {
- elem.clone()
+ let new_ty = self.renumber_regions(ty);
+
+ if new_ty != *ty {
+ return Some(PlaceElem::Field(*field, new_ty));
+ }
}
+
+ None
}
fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, location: Location) {
diff --git a/src/librustc_mir/transform/erase_regions.rs b/src/librustc_mir/transform/erase_regions.rs
index 725a8de8fe7d1..439cae2093ae5 100644
--- a/src/librustc_mir/transform/erase_regions.rs
+++ b/src/librustc_mir/transform/erase_regions.rs
@@ -42,12 +42,16 @@ impl MutVisitor<'tcx> for EraseRegionsVisitor<'tcx> {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
+ ) -> Option<PlaceElem<'tcx>> {
if let PlaceElem::Field(field, ty) = elem {
- PlaceElem::Field(*field, self.tcx.erase_regions(ty))
- } else {
- elem.clone()
+ let new_ty = self.tcx.erase_regions(ty);
+
+ if new_ty != *ty {
+ return Some(PlaceElem::Field(*field, new_ty));
+ }
}
+
+ None
}
}
diff --git a/src/librustc_mir/transform/generator.rs b/src/librustc_mir/transform/generator.rs
index a801548efab08..6533e3c5ba81f 100644
--- a/src/librustc_mir/transform/generator.rs
+++ b/src/librustc_mir/transform/generator.rs
@@ -89,22 +89,16 @@ impl<'tcx> MutVisitor<'tcx> for RenameLocalVisitor {
}
}
- fn visit_place(&mut self,
- place: &mut Place<'tcx>,
- context: PlaceContext,
- location: Location) {
- self.visit_place_base(&mut place.base, context, location);
-
- let new_projection: Vec<_> = place.projection.iter().map(|elem|
- match elem {
- PlaceElem::Index(local) if *local == self.from => {
- PlaceElem::Index(self.to)
- }
- _ => elem.clone(),
+ fn process_projection_elem(
+ &mut self,
+ elem: &PlaceElem<'tcx>,
+ ) -> Option<PlaceElem<'tcx>> {
+ match elem {
+ PlaceElem::Index(local) if *local == self.from => {
+ Some(PlaceElem::Index(self.to))
}
- ).collect();
-
- place.projection = new_projection.into_boxed_slice();
+ _ => None,
+ }
}
}
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index dd13d0c96557d..0cbdcedff4780 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -703,12 +703,16 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
+ ) -> Option<PlaceElem<'tcx>> {
if let PlaceElem::Index(local) = elem {
- PlaceElem::Index(self.make_integrate_local(local))
- } else {
- elem.clone()
+ let new_local = self.make_integrate_local(local);
+
+ if new_local != *local {
+ return Some(PlaceElem::Index(new_local))
+ }
}
+
+ None
}
fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs
index 565f260546bc7..ad1785417cd93 100644
--- a/src/librustc_mir/transform/promote_consts.rs
+++ b/src/librustc_mir/transform/promote_consts.rs
@@ -408,12 +408,12 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Promoter<'a, 'tcx> {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
+ ) -> Option<PlaceElem<'tcx>> {
match elem {
PlaceElem::Index(local) if self.is_temp_kind(*local) => {
- PlaceElem::Index(self.promote_temp(*local))
+ Some(PlaceElem::Index(self.promote_temp(*local)))
}
- _ => elem.clone(),
+ _ => None,
}
}
}
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index 7dca3e357cc94..606c1a3a1cc09 100644
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -374,11 +374,12 @@ impl<'tcx> MutVisitor<'tcx> for LocalUpdater {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
- if let PlaceElem::Index(local) = elem {
- PlaceElem::Index(self.map[*local].unwrap())
- } else {
- elem.clone()
+ ) -> Option<PlaceElem<'tcx>> {
+ match elem {
+ PlaceElem::Index(local) => {
+ Some(PlaceElem::Index(self.map[*local].unwrap()))
+ }
+ _ => None
}
}
}
diff --git a/src/librustc_mir/util/def_use.rs b/src/librustc_mir/util/def_use.rs
index 25930df020aa9..cdd07ad4b8ff4 100644
--- a/src/librustc_mir/util/def_use.rs
+++ b/src/librustc_mir/util/def_use.rs
@@ -141,12 +141,12 @@ impl MutVisitor<'_> for MutateUseVisitor {
fn process_projection_elem(
&mut self,
elem: &PlaceElem<'tcx>,
- ) -> PlaceElem<'tcx> {
+ ) -> Option<PlaceElem<'tcx>> {
match elem {
PlaceElem::Index(local) if *local == self.query => {
- PlaceElem::Index(self.new_local)
+ Some(PlaceElem::Index(self.new_local))
}
- _ => elem.clone(),
+ _ => None,
}
}
}