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Make SROA expand assignments.

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This commit is contained in:
Camille GILLOT 2023-02-05 09:31:27 +00:00
parent 0843acbea6
commit dc4fe8e295
6 changed files with 188 additions and 32 deletions
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88
compiler/rustc_mir_transform/src/sroa.rs
View File

@ -78,10 +78,15 @@ fn escaping_locals(body: &Body<'_>) -> BitSet<Local> {
rvalue: &Rvalue<'tcx>,
location: Location,
) {
if lvalue.as_local().is_some() && let Rvalue::Aggregate(..) = rvalue {
// Aggregate assignments are expanded in run_pass.
self.visit_rvalue(rvalue, location);
return;
if lvalue.as_local().is_some() {
match rvalue {
// Aggregate assignments are expanded in run_pass.
Rvalue::Aggregate(..) | Rvalue::Use(..) => {
self.visit_rvalue(rvalue, location);
return;
}
_ => {}
}
}
self.super_assign(lvalue, rvalue, location)
}
@ -195,10 +200,9 @@ fn replace_flattened_locals<'tcx>(
return;
}
let mut fragments = IndexVec::new();
let mut fragments = IndexVec::<_, Option<Vec<_>>>::from_elem(None, &body.local_decls);
for (k, v) in &replacements.fields {
fragments.ensure_contains_elem(k.local, || Vec::new());
fragments[k.local].push((k.projection, *v));
fragments[k.local].get_or_insert_default().push((k.projection, *v));
}
debug!(?fragments);
@ -235,7 +239,7 @@ struct ReplacementVisitor<'tcx, 'll> {
all_dead_locals: BitSet<Local>,
/// Pre-computed list of all "new" locals for each "old" local. This is used to expand storage
/// and deinit statement and debuginfo.
fragments: IndexVec<Local, Vec<(&'tcx [PlaceElem<'tcx>], Local)>>,
fragments: IndexVec<Local, Option<Vec<(&'tcx [PlaceElem<'tcx>], Local)>>>,
patch: MirPatch<'tcx>,
}
@ -243,9 +247,9 @@ impl<'tcx, 'll> ReplacementVisitor<'tcx, 'll> {
fn gather_debug_info_fragments(
&self,
place: PlaceRef<'tcx>,
) -> Vec<VarDebugInfoFragment<'tcx>> {
) -> Option<Vec<VarDebugInfoFragment<'tcx>>> {
let mut fragments = Vec::new();
let parts = &self.fragments[place.local];
let Some(parts) = &self.fragments[place.local] else { return None };
for (proj, replacement_local) in parts {
if proj.starts_with(place.projection) {
fragments.push(VarDebugInfoFragment {
@ -254,7 +258,7 @@ impl<'tcx, 'll> ReplacementVisitor<'tcx, 'll> {
});
}
}
fragments
Some(fragments)
}
fn replace_place(&self, place: PlaceRef<'tcx>) -> Option<Place<'tcx>> {
@ -276,8 +280,7 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
fn visit_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) {
match statement.kind {
StatementKind::StorageLive(l) => {
if self.all_dead_locals.contains(l) {
let final_locals = &self.fragments[l];
if let Some(final_locals) = &self.fragments[l] {
for &(_, fl) in final_locals {
self.patch.add_statement(location, StatementKind::StorageLive(fl));
}
@ -286,8 +289,7 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
return;
}
StatementKind::StorageDead(l) => {
if self.all_dead_locals.contains(l) {
let final_locals = &self.fragments[l];
if let Some(final_locals) = &self.fragments[l] {
for &(_, fl) in final_locals {
self.patch.add_statement(location, StatementKind::StorageDead(fl));
}
@ -297,9 +299,8 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
}
StatementKind::Deinit(box ref place) => {
if let Some(local) = place.as_local()
&& self.all_dead_locals.contains(local)
&& let Some(final_locals) = &self.fragments[local]
{
let final_locals = &self.fragments[local];
for &(_, fl) in final_locals {
self.patch.add_statement(
location,
@ -313,9 +314,8 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
StatementKind::Assign(box (ref place, Rvalue::Aggregate(_, ref operands))) => {
if let Some(local) = place.as_local()
&& self.all_dead_locals.contains(local)
&& let Some(final_locals) = &self.fragments[local]
{
let final_locals = &self.fragments[local];
for &(projection, fl) in final_locals {
let &[PlaceElem::Field(index, _)] = projection else { bug!() };
let index = index.as_usize();
@ -330,6 +330,48 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
}
}
StatementKind::Assign(box (ref place, Rvalue::Use(Operand::Constant(_)))) => {
if let Some(local) = place.as_local()
&& let Some(final_locals) = &self.fragments[local]
{
for &(projection, fl) in final_locals {
let rvalue = Rvalue::Use(Operand::Move(place.project_deeper(projection, self.tcx)));
self.patch.add_statement(
location,
StatementKind::Assign(Box::new((fl.into(), rvalue))),
);
}
self.all_dead_locals.remove(local);
return;
}
}
StatementKind::Assign(box (ref lhs, Rvalue::Use(ref op))) => {
let (rplace, copy) = match op {
Operand::Copy(rplace) => (rplace, true),
Operand::Move(rplace) => (rplace, false),
Operand::Constant(_) => bug!(),
};
if let Some(local) = lhs.as_local()
&& let Some(final_locals) = &self.fragments[local]
{
for &(projection, fl) in final_locals {
let rplace = rplace.project_deeper(projection, self.tcx);
let rvalue = if copy {
Rvalue::Use(Operand::Copy(rplace))
} else {
Rvalue::Use(Operand::Move(rplace))
};
self.patch.add_statement(
location,
StatementKind::Assign(Box::new((fl.into(), rvalue))),
);
}
statement.make_nop();
return;
}
}
_ => {}
}
self.super_statement(statement, location)
@ -348,9 +390,8 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
VarDebugInfoContents::Place(ref mut place) => {
if let Some(repl) = self.replace_place(place.as_ref()) {
*place = repl;
} else if self.all_dead_locals.contains(place.local) {
} else if let Some(fragments) = self.gather_debug_info_fragments(place.as_ref()) {
let ty = place.ty(self.local_decls, self.tcx).ty;
let fragments = self.gather_debug_info_fragments(place.as_ref());
var_debug_info.value = VarDebugInfoContents::Composite { ty, fragments };
}
}
@ -361,8 +402,9 @@ impl<'tcx, 'll> MutVisitor<'tcx> for ReplacementVisitor<'tcx, 'll> {
if let Some(repl) = self.replace_place(fragment.contents.as_ref()) {
fragment.contents = repl;
true
} else if self.all_dead_locals.contains(fragment.contents.local) {
let frg = self.gather_debug_info_fragments(fragment.contents.as_ref());
} else if let Some(frg) =
self.gather_debug_info_fragments(fragment.contents.as_ref())
{
new_fragments.extend(frg.into_iter().map(|mut f| {
f.projection.splice(0..0, fragment.projection.iter().copied());
f

48
tests/mir-opt/sroa.copies.ScalarReplacementOfAggregates.diff Normal file
View File

@ -0,0 +1,48 @@
- // MIR for `copies` before ScalarReplacementOfAggregates
+ // MIR for `copies` after ScalarReplacementOfAggregates
fn copies(_1: Foo) -> () {
debug x => _1; // in scope 0 at $DIR/sroa.rs:+0:11: +0:12
let mut _0: (); // return place in scope 0 at $DIR/sroa.rs:+0:19: +0:19
let _2: Foo; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ let _5: u8; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ let _6: &str; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
scope 1 {
- debug y => _2; // in scope 1 at $DIR/sroa.rs:+1:9: +1:10
+ debug y => Foo{ .0 => _5, .2 => _6, }; // in scope 1 at $DIR/sroa.rs:+1:9: +1:10
let _3: u8; // in scope 1 at $DIR/sroa.rs:+2:9: +2:10
scope 2 {
debug t => _3; // in scope 2 at $DIR/sroa.rs:+2:9: +2:10
let _4: &str; // in scope 2 at $DIR/sroa.rs:+3:9: +3:10
scope 3 {
debug u => _4; // in scope 3 at $DIR/sroa.rs:+3:9: +3:10
}
}
}
bb0: {
- StorageLive(_2); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
- _2 = _1; // scope 0 at $DIR/sroa.rs:+1:13: +1:14
+ StorageLive(_5); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ StorageLive(_6); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ nop; // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ _5 = (_1.0: u8); // scope 0 at $DIR/sroa.rs:+1:13: +1:14
+ _6 = (_1.2: &str); // scope 0 at $DIR/sroa.rs:+1:13: +1:14
+ nop; // scope 0 at $DIR/sroa.rs:+1:13: +1:14
StorageLive(_3); // scope 1 at $DIR/sroa.rs:+2:9: +2:10
- _3 = (_2.0: u8); // scope 1 at $DIR/sroa.rs:+2:13: +2:16
+ _3 = _5; // scope 1 at $DIR/sroa.rs:+2:13: +2:16
StorageLive(_4); // scope 2 at $DIR/sroa.rs:+3:9: +3:10
- _4 = (_2.2: &str); // scope 2 at $DIR/sroa.rs:+3:13: +3:16
+ _4 = _6; // scope 2 at $DIR/sroa.rs:+3:13: +3:16
_0 = const (); // scope 0 at $DIR/sroa.rs:+0:19: +4:2
StorageDead(_4); // scope 2 at $DIR/sroa.rs:+4:1: +4:2
StorageDead(_3); // scope 1 at $DIR/sroa.rs:+4:1: +4:2
- StorageDead(_2); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ StorageDead(_5); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ StorageDead(_6); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ nop; // scope 0 at $DIR/sroa.rs:+4:1: +4:2
return; // scope 0 at $DIR/sroa.rs:+4:2: +4:2
}
}

4
tests/mir-opt/sroa.escaping.ScalarReplacementOfAggregates.diff
View File

@ -17,7 +17,7 @@
StorageLive(_5); // scope 0 at $DIR/sroa.rs:+2:34: +2:37
_5 = g() -> bb1; // scope 0 at $DIR/sroa.rs:+2:34: +2:37
// mir::Constant
// + span: $DIR/sroa.rs:78:34: 78:35
// + span: $DIR/sroa.rs:73:34: 73:35
// + literal: Const { ty: fn() -> u32 {g}, val: Value(<ZST>) }
}
@ -28,7 +28,7 @@
_2 = &raw const (*_3); // scope 0 at $DIR/sroa.rs:+2:7: +2:41
_1 = f(move _2) -> bb2; // scope 0 at $DIR/sroa.rs:+2:5: +2:42
// mir::Constant
// + span: $DIR/sroa.rs:78:5: 78:6
// + span: $DIR/sroa.rs:73:5: 73:6
// + literal: Const { ty: fn(*const u32) {f}, val: Value(<ZST>) }
}

2
tests/mir-opt/sroa.flat.ScalarReplacementOfAggregates.diff
View File

@ -45,7 +45,7 @@
+ _9 = move _6; // scope 0 at $DIR/sroa.rs:+1:30: +1:70
+ _10 = const "a"; // scope 0 at $DIR/sroa.rs:+1:30: +1:70
// mir::Constant
// + span: $DIR/sroa.rs:57:52: 57:55
// + span: $DIR/sroa.rs:53:52: 53:55
// + literal: Const { ty: &str, val: Value(Slice(..)) }
+ _11 = move _7; // scope 0 at $DIR/sroa.rs:+1:30: +1:70
+ nop; // scope 0 at $DIR/sroa.rs:+1:30: +1:70

48
tests/mir-opt/sroa.ref_copies.ScalarReplacementOfAggregates.diff Normal file
View File

@ -0,0 +1,48 @@
- // MIR for `ref_copies` before ScalarReplacementOfAggregates
+ // MIR for `ref_copies` after ScalarReplacementOfAggregates
fn ref_copies(_1: &Foo) -> () {
debug x => _1; // in scope 0 at $DIR/sroa.rs:+0:15: +0:16
let mut _0: (); // return place in scope 0 at $DIR/sroa.rs:+0:24: +0:24
let _2: Foo; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ let _5: u8; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ let _6: &str; // in scope 0 at $DIR/sroa.rs:+1:9: +1:10
scope 1 {
- debug y => _2; // in scope 1 at $DIR/sroa.rs:+1:9: +1:10
+ debug y => Foo{ .0 => _5, .2 => _6, }; // in scope 1 at $DIR/sroa.rs:+1:9: +1:10
let _3: u8; // in scope 1 at $DIR/sroa.rs:+2:9: +2:10
scope 2 {
debug t => _3; // in scope 2 at $DIR/sroa.rs:+2:9: +2:10
let _4: &str; // in scope 2 at $DIR/sroa.rs:+3:9: +3:10
scope 3 {
debug u => _4; // in scope 3 at $DIR/sroa.rs:+3:9: +3:10
}
}
}
bb0: {
- StorageLive(_2); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
- _2 = (*_1); // scope 0 at $DIR/sroa.rs:+1:13: +1:15
+ StorageLive(_5); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ StorageLive(_6); // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ nop; // scope 0 at $DIR/sroa.rs:+1:9: +1:10
+ _5 = ((*_1).0: u8); // scope 0 at $DIR/sroa.rs:+1:13: +1:15
+ _6 = ((*_1).2: &str); // scope 0 at $DIR/sroa.rs:+1:13: +1:15
+ nop; // scope 0 at $DIR/sroa.rs:+1:13: +1:15
StorageLive(_3); // scope 1 at $DIR/sroa.rs:+2:9: +2:10
- _3 = (_2.0: u8); // scope 1 at $DIR/sroa.rs:+2:13: +2:16
+ _3 = _5; // scope 1 at $DIR/sroa.rs:+2:13: +2:16
StorageLive(_4); // scope 2 at $DIR/sroa.rs:+3:9: +3:10
- _4 = (_2.2: &str); // scope 2 at $DIR/sroa.rs:+3:13: +3:16
+ _4 = _6; // scope 2 at $DIR/sroa.rs:+3:13: +3:16
_0 = const (); // scope 0 at $DIR/sroa.rs:+0:24: +4:2
StorageDead(_4); // scope 2 at $DIR/sroa.rs:+4:1: +4:2
StorageDead(_3); // scope 1 at $DIR/sroa.rs:+4:1: +4:2
- StorageDead(_2); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ StorageDead(_5); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ StorageDead(_6); // scope 0 at $DIR/sroa.rs:+4:1: +4:2
+ nop; // scope 0 at $DIR/sroa.rs:+4:1: +4:2
return; // scope 0 at $DIR/sroa.rs:+4:2: +4:2
}
}

30
tests/mir-opt/sroa.rs
View File

@ -12,17 +12,14 @@ impl Drop for Tag {
fn drop(&mut self) {}
}
// EMIT_MIR sroa.dropping.ScalarReplacementOfAggregates.diff
pub fn dropping() {
S(Tag(0), Tag(1), Tag(2)).1;
}
// EMIT_MIR sroa.enums.ScalarReplacementOfAggregates.diff
pub fn enums(a: usize) -> usize {
if let Some(a) = Some(a) { a } else { 0 }
}
// EMIT_MIR sroa.structs.ScalarReplacementOfAggregates.diff
pub fn structs(a: f32) -> f32 {
struct U {
_foo: usize,
@ -32,7 +29,6 @@ pub fn structs(a: f32) -> f32 {
U { _foo: 0, a }.a
}
// EMIT_MIR sroa.unions.ScalarReplacementOfAggregates.diff
pub fn unions(a: f32) -> u32 {
union Repr {
f: f32,
@ -41,6 +37,7 @@ pub fn unions(a: f32) -> u32 {
unsafe { Repr { f: a }.u }
}
#[derive(Copy, Clone)]
struct Foo {
a: u8,
b: (),
@ -52,7 +49,6 @@ fn g() -> u32 {
3
}
// EMIT_MIR sroa.flat.ScalarReplacementOfAggregates.diff
pub fn flat() {
let Foo { a, b, c, d } = Foo { a: 5, b: (), c: "a", d: Some(-4) };
let _ = a;
@ -72,12 +68,23 @@ fn f(a: *const u32) {
println!("{}", unsafe { *a.add(2) });
}
// EMIT_MIR sroa.escaping.ScalarReplacementOfAggregates.diff
pub fn escaping() {
// Verify this struct is not flattened.
f(&Escaping { a: 1, b: 2, c: g() }.a);
}
fn copies(x: Foo) {
let y = x;
let t = y.a;
let u = y.c;
}
fn ref_copies(x: &Foo) {
let y = *x;
let t = y.a;
let u = y.c;
}
fn main() {
dropping();
enums(5);
@ -85,4 +92,15 @@ fn main() {
unions(5.);
flat();
escaping();
copies(Foo { a: 5, b: (), c: "a", d: Some(-4) });
ref_copies(&Foo { a: 5, b: (), c: "a", d: Some(-4) });
}
// EMIT_MIR sroa.dropping.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.enums.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.structs.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.unions.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.flat.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.escaping.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.copies.ScalarReplacementOfAggregates.diff
// EMIT_MIR sroa.ref_copies.ScalarReplacementOfAggregates.diff