Auto merge of #70755 - wesleywiser:simplify_locals_2_electric_boogaloo, r=oli-obk

[mir-opt] Run SimplifyLocals to a fixedpoint and handle most rvalues

Follow up to review feedback left on #70595.
This commit is contained in:
bors 2020-04-16 14:26:43 +00:00
commit 7fb5187d04
7 changed files with 324 additions and 159 deletions

View File

@ -306,49 +306,82 @@ pub fn remove_dead_blocks(body: &mut BodyAndCache<'_>) {
impl<'tcx> MirPass<'tcx> for SimplifyLocals {
fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut BodyAndCache<'tcx>) {
trace!("running SimplifyLocals on {:?}", source);
let locals = {
let read_only_cache = read_only!(body);
let mut marker = DeclMarker { locals: BitSet::new_empty(body.local_decls.len()), body };
marker.visit_body(&read_only_cache);
// Return pointer and arguments are always live
marker.locals.insert(RETURN_PLACE);
for arg in body.args_iter() {
marker.locals.insert(arg);
}
marker.locals
// First, we're going to get a count of *actual* uses for every `Local`.
// Take a look at `DeclMarker::visit_local()` to see exactly what is ignored.
let mut used_locals = {
let read_only_cache = read_only!(body);
let mut marker = DeclMarker::new(body);
marker.visit_body(&read_only_cache);
marker.local_counts
};
let map = make_local_map(&mut body.local_decls, locals);
// Update references to all vars and tmps now
LocalUpdater { map, tcx }.visit_body(body);
body.local_decls.shrink_to_fit();
let arg_count = body.arg_count;
// Next, we're going to remove any `Local` with zero actual uses. When we remove those
// `Locals`, we're also going to subtract any uses of other `Locals` from the `used_locals`
// count. For example, if we removed `_2 = discriminant(_1)`, then we'll subtract one from
// `use_counts[_1]`. That in turn might make `_1` unused, so we loop until we hit a
// fixedpoint where there are no more unused locals.
loop {
let mut remove_statements = RemoveStatements::new(&mut used_locals, arg_count, tcx);
remove_statements.visit_body(body);
if !remove_statements.modified {
break;
}
}
// Finally, we'll actually do the work of shrinking `body.local_decls` and remapping the `Local`s.
let map = make_local_map(&mut body.local_decls, used_locals, arg_count);
// Only bother running the `LocalUpdater` if we actually found locals to remove.
if map.iter().any(Option::is_none) {
// Update references to all vars and tmps now
let mut updater = LocalUpdater { map, tcx };
updater.visit_body(body);
body.local_decls.shrink_to_fit();
}
}
}
/// Construct the mapping while swapping out unused stuff out from the `vec`.
fn make_local_map<V>(
vec: &mut IndexVec<Local, V>,
mask: BitSet<Local>,
local_decls: &mut IndexVec<Local, V>,
used_locals: IndexVec<Local, usize>,
arg_count: usize,
) -> IndexVec<Local, Option<Local>> {
let mut map: IndexVec<Local, Option<Local>> = IndexVec::from_elem(None, &*vec);
let mut map: IndexVec<Local, Option<Local>> = IndexVec::from_elem(None, &*local_decls);
let mut used = Local::new(0);
for alive_index in mask.iter() {
for (alive_index, count) in used_locals.iter_enumerated() {
// The `RETURN_PLACE` and arguments are always live.
if alive_index.as_usize() > arg_count && *count == 0 {
continue;
}
map[alive_index] = Some(used);
if alive_index != used {
vec.swap(alive_index, used);
local_decls.swap(alive_index, used);
}
used.increment_by(1);
}
vec.truncate(used.index());
local_decls.truncate(used.index());
map
}
struct DeclMarker<'a, 'tcx> {
pub locals: BitSet<Local>,
pub local_counts: IndexVec<Local, usize>,
pub body: &'a Body<'tcx>,
}
impl<'a, 'tcx> DeclMarker<'a, 'tcx> {
pub fn new(body: &'a Body<'tcx>) -> Self {
Self { local_counts: IndexVec::from_elem(0, &body.local_decls), body }
}
}
impl<'a, 'tcx> Visitor<'tcx> for DeclMarker<'a, 'tcx> {
fn visit_local(&mut self, local: &Local, ctx: PlaceContext, location: Location) {
// Ignore storage markers altogether, they get removed along with their otherwise unused
@ -368,21 +401,39 @@ fn visit_local(&mut self, local: &Local, ctx: PlaceContext, location: Location)
if location.statement_index != block.statements.len() {
let stmt = &block.statements[location.statement_index];
fn can_skip_constant(c: &ty::Const<'tcx>) -> bool {
// Keep assignments from unevaluated constants around, since the
// evaluation may report errors, even if the use of the constant
// is dead code.
!matches!(c.val, ty::ConstKind::Unevaluated(..))
}
fn can_skip_operand(o: &Operand<'_>) -> bool {
match o {
Operand::Copy(_) | Operand::Move(_) => true,
Operand::Constant(c) => can_skip_constant(c.literal),
}
}
if let StatementKind::Assign(box (dest, rvalue)) = &stmt.kind {
if !dest.is_indirect() && dest.local == *local {
if let Rvalue::Use(Operand::Constant(c)) = rvalue {
match c.literal.val {
// Keep assignments from unevaluated constants around, since the
// evaluation may report errors, even if the use of the constant
// is dead code.
ty::ConstKind::Unevaluated(..) => {}
_ => {
trace!("skipping store of const value {:?} to {:?}", c, dest);
return;
}
let can_skip = match rvalue {
Rvalue::Use(op) => can_skip_operand(op),
Rvalue::Discriminant(_) => true,
Rvalue::BinaryOp(_, l, r) | Rvalue::CheckedBinaryOp(_, l, r) => {
can_skip_operand(l) && can_skip_operand(r)
}
} else if let Rvalue::Discriminant(d) = rvalue {
trace!("skipping store of discriminant value {:?} to {:?}", d, dest);
Rvalue::Repeat(op, c) => can_skip_operand(op) && can_skip_constant(c),
Rvalue::AddressOf(_, _) => true,
Rvalue::Len(_) => true,
Rvalue::UnaryOp(_, op) => can_skip_operand(op),
Rvalue::Aggregate(_, operands) => operands.iter().all(can_skip_operand),
_ => false,
};
if can_skip {
trace!("skipping store of {:?} to {:?}", rvalue, dest);
return;
}
}
@ -390,7 +441,94 @@ fn visit_local(&mut self, local: &Local, ctx: PlaceContext, location: Location)
}
}
self.locals.insert(*local);
self.local_counts[*local] += 1;
}
}
struct StatementDeclMarker<'a, 'tcx> {
used_locals: &'a mut IndexVec<Local, usize>,
statement: &'a Statement<'tcx>,
}
impl<'a, 'tcx> StatementDeclMarker<'a, 'tcx> {
pub fn new(
used_locals: &'a mut IndexVec<Local, usize>,
statement: &'a Statement<'tcx>,
) -> Self {
Self { used_locals, statement }
}
}
impl<'a, 'tcx> Visitor<'tcx> for StatementDeclMarker<'a, 'tcx> {
fn visit_local(&mut self, local: &Local, context: PlaceContext, _location: Location) {
// Skip the lvalue for assignments
if let StatementKind::Assign(box (p, _)) = self.statement.kind {
if p.local == *local && context.is_place_assignment() {
return;
}
}
let use_count = &mut self.used_locals[*local];
// If this is the local we're removing...
if *use_count != 0 {
*use_count -= 1;
}
}
}
struct RemoveStatements<'a, 'tcx> {
used_locals: &'a mut IndexVec<Local, usize>,
arg_count: usize,
tcx: TyCtxt<'tcx>,
modified: bool,
}
impl<'a, 'tcx> RemoveStatements<'a, 'tcx> {
fn new(
used_locals: &'a mut IndexVec<Local, usize>,
arg_count: usize,
tcx: TyCtxt<'tcx>,
) -> Self {
Self { used_locals, arg_count, tcx, modified: false }
}
fn keep_local(&self, l: Local) -> bool {
trace!("keep_local({:?}): count: {:?}", l, self.used_locals[l]);
l.as_usize() <= self.arg_count || self.used_locals[l] != 0
}
}
impl<'a, 'tcx> MutVisitor<'tcx> for RemoveStatements<'a, 'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
// Remove unnecessary StorageLive and StorageDead annotations.
let mut i = 0usize;
data.statements.retain(|stmt| {
let keep = match &stmt.kind {
StatementKind::StorageLive(l) | StatementKind::StorageDead(l) => {
self.keep_local(*l)
}
StatementKind::Assign(box (place, _)) => self.keep_local(place.local),
_ => true,
};
if !keep {
trace!("removing statement {:?}", stmt);
self.modified = true;
let mut visitor = StatementDeclMarker::new(self.used_locals, stmt);
visitor.visit_statement(stmt, Location { block, statement_index: i });
}
i += 1;
keep
});
self.super_basic_block_data(block, data);
}
}
@ -404,16 +542,6 @@ fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
// Remove unnecessary StorageLive and StorageDead annotations.
data.statements.retain(|stmt| match &stmt.kind {
StatementKind::StorageLive(l) | StatementKind::StorageDead(l) => self.map[*l].is_some(),
StatementKind::Assign(box (place, _)) => self.map[place.local].is_some(),
_ => true,
});
self.super_basic_block_data(block, data);
}
fn visit_local(&mut self, l: &mut Local, _: PlaceContext, _: Location) {
*l = self.map[*l].unwrap();
}

View File

@ -30,30 +30,30 @@ fn main() -> () {
}
alloc0 (static: FOO, size: 4, align: 4) {
╾alloc10+0╼ │ ╾──╼
╾alloc9+0─╼ │ ╾──╼
}
alloc10 (size: 168, align: 1) {
alloc9 (size: 168, align: 1) {
0x00 │ ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab │ ................
0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾alloc5+0─╼ │ ............╾──╼
0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾alloc4+0─╼ │ ............╾──╼
0x20 │ 01 ef cd ab 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x30 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x40 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x50 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x60 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x70 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x80 │ 00 00 00 00 00 00 00 00 00 00 ╾alloc7+0─╼ 00 00 │ ..........╾──╼..
0x90 │ ╾alloc8+99╼ 00 00 00 00 00 00 00 00 00 00 00 00 │ ╾──╼............
0x80 │ 00 00 00 00 00 00 00 00 00 00 ╾alloc6+0─╼ 00 00 │ ..........╾──╼..
0x90 │ ╾alloc7+99╼ 00 00 00 00 00 00 00 00 00 00 00 00 │ ╾──╼............
0xa0 │ 00 00 00 00 00 00 00 00 │ ........
}
alloc5 (size: 4, align: 4) {
alloc4 (size: 4, align: 4) {
2a 00 00 00 │ *...
}
alloc7 (fn: main)
alloc6 (fn: main)
alloc8 (size: 100, align: 1) {
alloc7 (size: 100, align: 1) {
0x00 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x10 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x20 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................

View File

@ -30,12 +30,12 @@ fn main() -> () {
}
alloc0 (static: FOO, size: 8, align: 8) {
╾──────alloc10+0──────╼ │ ╾──────╼
╾──────alloc9+0───────╼ │ ╾──────╼
}
alloc10 (size: 180, align: 1) {
alloc9 (size: 180, align: 1) {
0x00 │ ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab │ ................
0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾─alloc5+0─ │ ............╾───
0x10 │ ab ab ab ab ab ab ab ab ab ab ab ab ╾─alloc4+0─ │ ............╾───
0x20 │ ──────────╼ 01 ef cd ab 00 00 00 00 00 00 00 00 │ ───╼............
0x30 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x40 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
@ -43,18 +43,18 @@ alloc10 (size: 180, align: 1) {
0x60 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x70 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x80 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ╾──── │ ..............╾─
0x90 │ ────alloc7+0────╼ 00 00 ╾──────alloc8+99──────╼ │ ─────╼..╾──────╼
0x90 │ ────alloc6+0────╼ 00 00 ╾──────alloc7+99──────╼ │ ─────╼..╾──────╼
0xa0 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0xb0 │ 00 00 00 00 │ ....
}
alloc5 (size: 4, align: 4) {
alloc4 (size: 4, align: 4) {
2a 00 00 00 │ *...
}
alloc7 (fn: main)
alloc6 (fn: main)
alloc8 (size: 100, align: 1) {
alloc7 (size: 100, align: 1) {
0x00 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x10 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................
0x20 │ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 │ ................

View File

@ -3,15 +3,14 @@
fn main() -> () {
let mut _0: (); // return place in scope 0 at $DIR/optimizes_into_variable.rs:11:11: 11:11
let _1: i32; // in scope 0 at $DIR/optimizes_into_variable.rs:12:9: 12:10
let mut _3: [i32; 6]; // in scope 0 at $DIR/optimizes_into_variable.rs:13:13: 13:31
scope 1 {
debug x => _1; // in scope 1 at $DIR/optimizes_into_variable.rs:12:9: 12:10
let _2: i32; // in scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
scope 2 {
debug y => _2; // in scope 2 at $DIR/optimizes_into_variable.rs:13:9: 13:10
let _4: u32; // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
let _3: u32; // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
scope 3 {
debug z => _4; // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
debug z => _3; // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
}
}
}
@ -26,70 +25,31 @@ fn main() -> () {
// + span: $DIR/optimizes_into_variable.rs:12:13: 12:18
// + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
StorageLive(_2); // bb0[2]: scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
StorageLive(_3); // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
_3 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32]; // bb0[4]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000000))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:14: 13:15
// + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000001))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:17: 13:18
// + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000002))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:20: 13:21
// + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000003))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:23: 13:24
// + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000004))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:26: 13:27
// + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000005))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:29: 13:30
// + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) }
_2 = const 3i32; // bb0[5]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
_2 = const 3i32; // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000003))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:13: 13:34
// + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
StorageDead(_3); // bb0[6]: scope 1 at $DIR/optimizes_into_variable.rs:13:34: 13:35
StorageLive(_4); // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
_4 = const 42u32; // bb0[8]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
StorageLive(_3); // bb0[4]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
_3 = const 42u32; // bb0[5]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
// ty::Const
// + ty: u32
// + val: Value(Scalar(0x0000002a))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:14:13: 14:38
// + literal: Const { ty: u32, val: Value(Scalar(0x0000002a)) }
_0 = const (); // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
_0 = const (); // bb0[6]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:11:11: 15:2
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
StorageDead(_4); // bb0[10]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_2); // bb0[11]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_1); // bb0[12]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
return; // bb0[13]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
StorageDead(_3); // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_2); // bb0[8]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_1); // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
return; // bb0[10]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
}
}

View File

@ -3,15 +3,14 @@
fn main() -> () {
let mut _0: (); // return place in scope 0 at $DIR/optimizes_into_variable.rs:11:11: 11:11
let _1: i32; // in scope 0 at $DIR/optimizes_into_variable.rs:12:9: 12:10
let mut _3: [i32; 6]; // in scope 0 at $DIR/optimizes_into_variable.rs:13:13: 13:31
scope 1 {
debug x => _1; // in scope 1 at $DIR/optimizes_into_variable.rs:12:9: 12:10
let _2: i32; // in scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
scope 2 {
debug y => _2; // in scope 2 at $DIR/optimizes_into_variable.rs:13:9: 13:10
let _4: u32; // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
let _3: u32; // in scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
scope 3 {
debug z => _4; // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
debug z => _3; // in scope 3 at $DIR/optimizes_into_variable.rs:14:9: 14:10
}
}
}
@ -26,70 +25,31 @@ fn main() -> () {
// + span: $DIR/optimizes_into_variable.rs:12:13: 12:18
// + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
StorageLive(_2); // bb0[2]: scope 1 at $DIR/optimizes_into_variable.rs:13:9: 13:10
StorageLive(_3); // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
_3 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32]; // bb0[4]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:31
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000000))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:14: 13:15
// + literal: Const { ty: i32, val: Value(Scalar(0x00000000)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000001))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:17: 13:18
// + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000002))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:20: 13:21
// + literal: Const { ty: i32, val: Value(Scalar(0x00000002)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000003))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:23: 13:24
// + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000004))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:26: 13:27
// + literal: Const { ty: i32, val: Value(Scalar(0x00000004)) }
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000005))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:29: 13:30
// + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) }
_2 = const 3i32; // bb0[5]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
_2 = const 3i32; // bb0[3]: scope 1 at $DIR/optimizes_into_variable.rs:13:13: 13:34
// ty::Const
// + ty: i32
// + val: Value(Scalar(0x00000003))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:13:13: 13:34
// + literal: Const { ty: i32, val: Value(Scalar(0x00000003)) }
StorageDead(_3); // bb0[6]: scope 1 at $DIR/optimizes_into_variable.rs:13:34: 13:35
StorageLive(_4); // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
_4 = const 42u32; // bb0[8]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
StorageLive(_3); // bb0[4]: scope 2 at $DIR/optimizes_into_variable.rs:14:9: 14:10
_3 = const 42u32; // bb0[5]: scope 2 at $DIR/optimizes_into_variable.rs:14:13: 14:38
// ty::Const
// + ty: u32
// + val: Value(Scalar(0x0000002a))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:14:13: 14:38
// + literal: Const { ty: u32, val: Value(Scalar(0x0000002a)) }
_0 = const (); // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
_0 = const (); // bb0[6]: scope 0 at $DIR/optimizes_into_variable.rs:11:11: 15:2
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/optimizes_into_variable.rs:11:11: 15:2
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
StorageDead(_4); // bb0[10]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_2); // bb0[11]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_1); // bb0[12]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
return; // bb0[13]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
StorageDead(_3); // bb0[7]: scope 2 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_2); // bb0[8]: scope 1 at $DIR/optimizes_into_variable.rs:15:1: 15:2
StorageDead(_1); // bb0[9]: scope 0 at $DIR/optimizes_into_variable.rs:15:1: 15:2
return; // bb0[10]: scope 0 at $DIR/optimizes_into_variable.rs:15:2: 15:2
}
}

View File

@ -0,0 +1,15 @@
// compile-flags: -Zmir-opt-level=1
fn foo<T>() {
if let (Some(a), None) = (Option::<u8>::None, Option::<T>::None) {
if a > 42u8 {
}
}
}
fn main() {
foo::<()>();
}
// EMIT_MIR rustc.foo.SimplifyLocals.diff

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@ -0,0 +1,102 @@
- // MIR for `foo` before SimplifyLocals
+ // MIR for `foo` after SimplifyLocals
fn foo() -> () {
let mut _0: (); // return place in scope 0 at $DIR/simplify-locals-fixedpoint.rs:3:13: 3:13
let mut _1: (std::option::Option<u8>, std::option::Option<T>); // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:30: 4:69
let mut _2: std::option::Option<u8>; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:31: 4:49
let mut _3: std::option::Option<T>; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:51: 4:68
let mut _4: isize; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
let mut _5: isize; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
let _6: u8; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
let mut _7: bool; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
let mut _8: u8; // in scope 0 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
scope 1 {
debug a => _6; // in scope 1 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
}
bb0: {
StorageLive(_1); // bb0[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:30: 4:69
StorageLive(_2); // bb0[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:31: 4:49
discriminant(_2) = 0; // bb0[2]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:31: 4:49
StorageLive(_3); // bb0[3]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:51: 4:68
discriminant(_3) = 0; // bb0[4]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:51: 4:68
(_1.0: std::option::Option<u8>) = move _2; // bb0[5]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:30: 4:69
(_1.1: std::option::Option<T>) = move _3; // bb0[6]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:30: 4:69
StorageDead(_3); // bb0[7]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:68: 4:69
StorageDead(_2); // bb0[8]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:68: 4:69
_5 = discriminant((_1.0: std::option::Option<u8>)); // bb0[9]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
switchInt(move _5) -> [1isize: bb2, otherwise: bb1]; // bb0[10]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:13: 4:20
}
bb1: {
_0 = const (); // bb1[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
goto -> bb7; // bb1[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
}
bb2: {
_4 = discriminant((_1.1: std::option::Option<T>)); // bb2[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
switchInt(move _4) -> [0isize: bb3, otherwise: bb1]; // bb2[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:22: 4:26
}
bb3: {
StorageLive(_6); // bb3[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
_6 = (((_1.0: std::option::Option<u8>) as Some).0: u8); // bb3[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:18: 4:19
StorageLive(_7); // bb3[2]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
StorageLive(_8); // bb3[3]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
_8 = _6; // bb3[4]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:13
_7 = Gt(move _8, const 42u8); // bb3[5]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:12: 5:20
// ty::Const
// + ty: u8
// + val: Value(Scalar(0x2a))
// mir::Constant
// + span: $DIR/simplify-locals-fixedpoint.rs:5:16: 5:20
// + literal: Const { ty: u8, val: Value(Scalar(0x2a)) }
StorageDead(_8); // bb3[6]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:19: 5:20
switchInt(_7) -> [false: bb4, otherwise: bb5]; // bb3[7]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
}
bb4: {
_0 = const (); // bb4[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
goto -> bb6; // bb4[1]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
}
bb5: {
_0 = const (); // bb5[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/simplify-locals-fixedpoint.rs:5:21: 7:10
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
goto -> bb6; // bb5[1]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:5:9: 7:10
}
bb6: {
StorageDead(_7); // bb6[0]: scope 1 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
StorageDead(_6); // bb6[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:8:5: 8:6
goto -> bb7; // bb6[2]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:4:5: 8:6
}
bb7: {
drop(_1) -> bb8; // bb7[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
}
bb8: {
StorageDead(_1); // bb8[0]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:1: 9:2
return; // bb8[1]: scope 0 at $DIR/simplify-locals-fixedpoint.rs:9:2: 9:2
}
}