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Inline and remove some functions.

Browse Source 
These are all functions with a single callsite, where having a separate
function does nothing to help with readability. These changes make the
code a little shorter and easier to read.
This commit is contained in:
Nicholas Nethercote 2024-08-28 10:13:17 +10:00
parent 8235af07d2
commit 48064d4498
10 changed files with 341 additions and 392 deletions
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6
compiler/rustc_mir_transform/src/add_call_guards.rs
View File

@ -32,12 +32,6 @@ pub(super) use self::AddCallGuards::*;
impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {
fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
self.add_call_guards(body);
}
}
impl AddCallGuards {
pub(super) fn add_call_guards(&self, body: &mut Body<'_>) {
let mut pred_count: IndexVec<_, _> =
body.basic_blocks.predecessors().iter().map(|ps| ps.len()).collect();
pred_count[START_BLOCK] += 1;

45
compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs
View File

@ -40,35 +40,34 @@ pub(super) struct AddMovesForPackedDrops;
impl<'tcx> crate::MirPass<'tcx> for AddMovesForPackedDrops {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
debug!("add_moves_for_packed_drops({:?} @ {:?})", body.source, body.span);
add_moves_for_packed_drops(tcx, body);
}
}
fn add_moves_for_packed_drops<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let patch = add_moves_for_packed_drops_patch(tcx, body);
patch.apply(body);
}
let def_id = body.source.def_id();
let mut patch = MirPatch::new(body);
let param_env = tcx.param_env(def_id);
fn add_moves_for_packed_drops_patch<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> MirPatch<'tcx> {
let def_id = body.source.def_id();
let mut patch = MirPatch::new(body);
let param_env = tcx.param_env(def_id);
for (bb, data) in body.basic_blocks.iter_enumerated() {
let loc = Location { block: bb, statement_index: data.statements.len() };
let terminator = data.terminator();
for (bb, data) in body.basic_blocks.iter_enumerated() {
let loc = Location { block: bb, statement_index: data.statements.len() };
let terminator = data.terminator();
match terminator.kind {
TerminatorKind::Drop { place, .. }
if util::is_disaligned(tcx, body, param_env, place) =>
{
add_move_for_packed_drop(tcx, body, &mut patch, terminator, loc, data.is_cleanup);
match terminator.kind {
TerminatorKind::Drop { place, .. }
if util::is_disaligned(tcx, body, param_env, place) =>
{
add_move_for_packed_drop(
tcx,
body,
&mut patch,
terminator,
loc,
data.is_cleanup,
);
}
_ => {}
}
_ => {}
}
}
patch
patch.apply(body);
}
}
fn add_move_for_packed_drop<'tcx>(

18
compiler/rustc_mir_transform/src/add_subtyping_projections.rs
View File

@ -51,18 +51,14 @@ impl<'a, 'tcx> MutVisitor<'tcx> for SubTypeChecker<'a, 'tcx> {
// // gets transformed to
// let temp: rval_ty = rval;
// let place: place_ty = temp as place_ty;
fn subtype_finder<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let patch = MirPatch::new(body);
let mut checker = SubTypeChecker { tcx, patcher: patch, local_decls: &body.local_decls };
for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
checker.visit_basic_block_data(bb, data);
}
checker.patcher.apply(body);
}
impl<'tcx> crate::MirPass<'tcx> for Subtyper {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
subtype_finder(tcx, body);
let patch = MirPatch::new(body);
let mut checker = SubTypeChecker { tcx, patcher: patch, local_decls: &body.local_decls };
for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
checker.visit_basic_block_data(bb, data);
}
checker.patcher.apply(body);
}
}

45
compiler/rustc_mir_transform/src/copy_prop.rs
View File

@ -27,37 +27,34 @@ impl<'tcx> crate::MirPass<'tcx> for CopyProp {
#[instrument(level = "trace", skip(self, tcx, body))]
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
debug!(def_id = ?body.source.def_id());
propagate_ssa(tcx, body);
}
}
fn propagate_ssa<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
let ssa = SsaLocals::new(tcx, body, param_env);
let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
let ssa = SsaLocals::new(tcx, body, param_env);
let fully_moved = fully_moved_locals(&ssa, body);
debug!(?fully_moved);
let fully_moved = fully_moved_locals(&ssa, body);
debug!(?fully_moved);
let mut storage_to_remove = BitSet::new_empty(fully_moved.domain_size());
for (local, &head) in ssa.copy_classes().iter_enumerated() {
if local != head {
storage_to_remove.insert(head);
let mut storage_to_remove = BitSet::new_empty(fully_moved.domain_size());
for (local, &head) in ssa.copy_classes().iter_enumerated() {
if local != head {
storage_to_remove.insert(head);
}
}
}
let any_replacement = ssa.copy_classes().iter_enumerated().any(|(l, &h)| l != h);
let any_replacement = ssa.copy_classes().iter_enumerated().any(|(l, &h)| l != h);
Replacer {
tcx,
copy_classes: ssa.copy_classes(),
fully_moved,
borrowed_locals: ssa.borrowed_locals(),
storage_to_remove,
}
.visit_body_preserves_cfg(body);
Replacer {
tcx,
copy_classes: ssa.copy_classes(),
fully_moved,
borrowed_locals: ssa.borrowed_locals(),
storage_to_remove,
}
.visit_body_preserves_cfg(body);
if any_replacement {
crate::simplify::remove_unused_definitions(body);
if any_replacement {
crate::simplify::remove_unused_definitions(body);
}
}
}

79
compiler/rustc_mir_transform/src/gvn.rs
View File

@ -119,53 +119,50 @@ impl<'tcx> crate::MirPass<'tcx> for GVN {
#[instrument(level = "trace", skip(self, tcx, body))]
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
debug!(def_id = ?body.source.def_id());
propagate_ssa(tcx, body);
}
}
fn propagate_ssa<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
let ssa = SsaLocals::new(tcx, body, param_env);
// Clone dominators as we need them while mutating the body.
let dominators = body.basic_blocks.dominators().clone();
let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
let ssa = SsaLocals::new(tcx, body, param_env);
// Clone dominators as we need them while mutating the body.
let dominators = body.basic_blocks.dominators().clone();
let mut state = VnState::new(tcx, body, param_env, &ssa, &dominators, &body.local_decls);
ssa.for_each_assignment_mut(
body.basic_blocks.as_mut_preserves_cfg(),
|local, value, location| {
let value = match value {
// We do not know anything of this assigned value.
AssignedValue::Arg | AssignedValue::Terminator => None,
// Try to get some insight.
AssignedValue::Rvalue(rvalue) => {
let value = state.simplify_rvalue(rvalue, location);
// FIXME(#112651) `rvalue` may have a subtype to `local`. We can only mark
// `local` as reusable if we have an exact type match.
if state.local_decls[local].ty != rvalue.ty(state.local_decls, tcx) {
return;
let mut state = VnState::new(tcx, body, param_env, &ssa, &dominators, &body.local_decls);
ssa.for_each_assignment_mut(
body.basic_blocks.as_mut_preserves_cfg(),
|local, value, location| {
let value = match value {
// We do not know anything of this assigned value.
AssignedValue::Arg | AssignedValue::Terminator => None,
// Try to get some insight.
AssignedValue::Rvalue(rvalue) => {
let value = state.simplify_rvalue(rvalue, location);
// FIXME(#112651) `rvalue` may have a subtype to `local`. We can only mark
// `local` as reusable if we have an exact type match.
if state.local_decls[local].ty != rvalue.ty(state.local_decls, tcx) {
return;
}
value
}
value
}
};
// `next_opaque` is `Some`, so `new_opaque` must return `Some`.
let value = value.or_else(|| state.new_opaque()).unwrap();
state.assign(local, value);
},
);
};
// `next_opaque` is `Some`, so `new_opaque` must return `Some`.
let value = value.or_else(|| state.new_opaque()).unwrap();
state.assign(local, value);
},
);
// Stop creating opaques during replacement as it is useless.
state.next_opaque = None;
// Stop creating opaques during replacement as it is useless.
state.next_opaque = None;
let reverse_postorder = body.basic_blocks.reverse_postorder().to_vec();
for bb in reverse_postorder {
let data = &mut body.basic_blocks.as_mut_preserves_cfg()[bb];
state.visit_basic_block_data(bb, data);
let reverse_postorder = body.basic_blocks.reverse_postorder().to_vec();
for bb in reverse_postorder {
let data = &mut body.basic_blocks.as_mut_preserves_cfg()[bb];
state.visit_basic_block_data(bb, data);
}
// For each local that is reused (`y` above), we remove its storage statements do avoid any
// difficulty. Those locals are SSA, so should be easy to optimize by LLVM without storage
// statements.
StorageRemover { tcx, reused_locals: state.reused_locals }.visit_body_preserves_cfg(body);
}
// For each local that is reused (`y` above), we remove its storage statements do avoid any
// difficulty. Those locals are SSA, so should be easy to optimize by LLVM without storage
// statements.
StorageRemover { tcx, reused_locals: state.reused_locals }.visit_body_preserves_cfg(body);
}
newtype_index! {

8
compiler/rustc_mir_transform/src/instsimplify.rs
View File

@ -18,19 +18,13 @@ pub(super) enum InstSimplify {
AfterSimplifyCfg,
}
impl InstSimplify {
impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
fn name(&self) -> &'static str {
match self {
InstSimplify::BeforeInline => "InstSimplify-before-inline",
InstSimplify::AfterSimplifyCfg => "InstSimplify-after-simplifycfg",
}
}
}
impl<'tcx> crate::MirPass<'tcx> for InstSimplify {
fn name(&self) -> &'static str {
self.name()
}
fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
sess.mir_opt_level() > 0

345
compiler/rustc_mir_transform/src/large_enums.rs
View File

@ -37,7 +37,169 @@ impl<'tcx> crate::MirPass<'tcx> for EnumSizeOpt {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
// NOTE: This pass may produce different MIR based on the alignment of the target
// platform, but it will still be valid.
self.optim(tcx, body);
let mut alloc_cache = FxHashMap::default();
let body_did = body.source.def_id();
let param_env = tcx.param_env_reveal_all_normalized(body_did);
let blocks = body.basic_blocks.as_mut();
let local_decls = &mut body.local_decls;
for bb in blocks {
bb.expand_statements(|st| {
let StatementKind::Assign(box (
lhs,
Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)),
)) = &st.kind
else {
return None;
};
let ty = lhs.ty(local_decls, tcx).ty;
let (adt_def, num_variants, alloc_id) =
self.candidate(tcx, param_env, ty, &mut alloc_cache)?;
let source_info = st.source_info;
let span = source_info.span;
let tmp_ty = Ty::new_array(tcx, tcx.types.usize, num_variants as u64);
let size_array_local = local_decls.push(LocalDecl::new(tmp_ty, span));
let store_live =
Statement { source_info, kind: StatementKind::StorageLive(size_array_local) };
let place = Place::from(size_array_local);
let constant_vals = ConstOperand {
span,
user_ty: None,
const_: Const::Val(
ConstValue::Indirect { alloc_id, offset: Size::ZERO },
tmp_ty,
),
};
let rval = Rvalue::Use(Operand::Constant(Box::new(constant_vals)));
let const_assign =
Statement { source_info, kind: StatementKind::Assign(Box::new((place, rval))) };
let discr_place = Place::from(
local_decls.push(LocalDecl::new(adt_def.repr().discr_type().to_ty(tcx), span)),
);
let store_discr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
discr_place,
Rvalue::Discriminant(*rhs),
))),
};
let discr_cast_place =
Place::from(local_decls.push(LocalDecl::new(tcx.types.usize, span)));
let cast_discr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
discr_cast_place,
Rvalue::Cast(
CastKind::IntToInt,
Operand::Copy(discr_place),
tcx.types.usize,
),
))),
};
let size_place =
Place::from(local_decls.push(LocalDecl::new(tcx.types.usize, span)));
let store_size = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
size_place,
Rvalue::Use(Operand::Copy(Place {
local: size_array_local,
projection: tcx
.mk_place_elems(&[PlaceElem::Index(discr_cast_place.local)]),
})),
))),
};
let dst =
Place::from(local_decls.push(LocalDecl::new(Ty::new_mut_ptr(tcx, ty), span)));
let dst_ptr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
dst,
Rvalue::RawPtr(Mutability::Mut, *lhs),
))),
};
let dst_cast_ty = Ty::new_mut_ptr(tcx, tcx.types.u8);
let dst_cast_place =
Place::from(local_decls.push(LocalDecl::new(dst_cast_ty, span)));
let dst_cast = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
dst_cast_place,
Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(dst), dst_cast_ty),
))),
};
let src =
Place::from(local_decls.push(LocalDecl::new(Ty::new_imm_ptr(tcx, ty), span)));
let src_ptr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
src,
Rvalue::RawPtr(Mutability::Not, *rhs),
))),
};
let src_cast_ty = Ty::new_imm_ptr(tcx, tcx.types.u8);
let src_cast_place =
Place::from(local_decls.push(LocalDecl::new(src_cast_ty, span)));
let src_cast = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
src_cast_place,
Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(src), src_cast_ty),
))),
};
let deinit_old =
Statement { source_info, kind: StatementKind::Deinit(Box::new(dst)) };
let copy_bytes = Statement {
source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::CopyNonOverlapping(CopyNonOverlapping {
src: Operand::Copy(src_cast_place),
dst: Operand::Copy(dst_cast_place),
count: Operand::Copy(size_place),
}),
)),
};
let store_dead =
Statement { source_info, kind: StatementKind::StorageDead(size_array_local) };
let iter = [
store_live,
const_assign,
store_discr,
cast_discr,
store_size,
dst_ptr,
dst_cast,
src_ptr,
src_cast,
deinit_old,
copy_bytes,
store_dead,
]
.into_iter();
st.make_nop();
Some(iter)
});
}
}
}
@ -116,185 +278,4 @@ impl EnumSizeOpt {
let alloc = tcx.reserve_and_set_memory_alloc(tcx.mk_const_alloc(alloc));
Some((*adt_def, num_discrs, *alloc_cache.entry(ty).or_insert(alloc)))
}
fn optim<'tcx>(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let mut alloc_cache = FxHashMap::default();
let body_did = body.source.def_id();
let param_env = tcx.param_env_reveal_all_normalized(body_did);
let blocks = body.basic_blocks.as_mut();
let local_decls = &mut body.local_decls;
for bb in blocks {
bb.expand_statements(|st| {
if let StatementKind::Assign(box (
lhs,
Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)),
)) = &st.kind
{
let ty = lhs.ty(local_decls, tcx).ty;
let source_info = st.source_info;
let span = source_info.span;
let (adt_def, num_variants, alloc_id) =
self.candidate(tcx, param_env, ty, &mut alloc_cache)?;
let tmp_ty = Ty::new_array(tcx, tcx.types.usize, num_variants as u64);
let size_array_local = local_decls.push(LocalDecl::new(tmp_ty, span));
let store_live = Statement {
source_info,
kind: StatementKind::StorageLive(size_array_local),
};
let place = Place::from(size_array_local);
let constant_vals = ConstOperand {
span,
user_ty: None,
const_: Const::Val(
ConstValue::Indirect { alloc_id, offset: Size::ZERO },
tmp_ty,
),
};
let rval = Rvalue::Use(Operand::Constant(Box::new(constant_vals)));
let const_assign = Statement {
source_info,
kind: StatementKind::Assign(Box::new((place, rval))),
};
let discr_place = Place::from(
local_decls
.push(LocalDecl::new(adt_def.repr().discr_type().to_ty(tcx), span)),
);
let store_discr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
discr_place,
Rvalue::Discriminant(*rhs),
))),
};
let discr_cast_place =
Place::from(local_decls.push(LocalDecl::new(tcx.types.usize, span)));
let cast_discr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
discr_cast_place,
Rvalue::Cast(
CastKind::IntToInt,
Operand::Copy(discr_place),
tcx.types.usize,
),
))),
};
let size_place =
Place::from(local_decls.push(LocalDecl::new(tcx.types.usize, span)));
let store_size = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
size_place,
Rvalue::Use(Operand::Copy(Place {
local: size_array_local,
projection: tcx
.mk_place_elems(&[PlaceElem::Index(discr_cast_place.local)]),
})),
))),
};
let dst = Place::from(
local_decls.push(LocalDecl::new(Ty::new_mut_ptr(tcx, ty), span)),
);
let dst_ptr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
dst,
Rvalue::RawPtr(Mutability::Mut, *lhs),
))),
};
let dst_cast_ty = Ty::new_mut_ptr(tcx, tcx.types.u8);
let dst_cast_place =
Place::from(local_decls.push(LocalDecl::new(dst_cast_ty, span)));
let dst_cast = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
dst_cast_place,
Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(dst), dst_cast_ty),
))),
};
let src = Place::from(
local_decls.push(LocalDecl::new(Ty::new_imm_ptr(tcx, ty), span)),
);
let src_ptr = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
src,
Rvalue::RawPtr(Mutability::Not, *rhs),
))),
};
let src_cast_ty = Ty::new_imm_ptr(tcx, tcx.types.u8);
let src_cast_place =
Place::from(local_decls.push(LocalDecl::new(src_cast_ty, span)));
let src_cast = Statement {
source_info,
kind: StatementKind::Assign(Box::new((
src_cast_place,
Rvalue::Cast(CastKind::PtrToPtr, Operand::Copy(src), src_cast_ty),
))),
};
let deinit_old =
Statement { source_info, kind: StatementKind::Deinit(Box::new(dst)) };
let copy_bytes = Statement {
source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::CopyNonOverlapping(CopyNonOverlapping {
src: Operand::Copy(src_cast_place),
dst: Operand::Copy(dst_cast_place),
count: Operand::Copy(size_place),
}),
)),
};
let store_dead = Statement {
source_info,
kind: StatementKind::StorageDead(size_array_local),
};
let iter = [
store_live,
const_assign,
store_discr,
cast_discr,
store_size,
dst_ptr,
dst_cast,
src_ptr,
src_cast,
deinit_old,
copy_bytes,
store_dead,
]
.into_iter();
st.make_nop();
Some(iter)
} else {
None
}
});
}
}
}

26
compiler/rustc_mir_transform/src/lower_slice_len.rs
View File

@ -13,22 +13,18 @@ impl<'tcx> crate::MirPass<'tcx> for LowerSliceLenCalls {
}
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
lower_slice_len_calls(tcx, body)
}
}
let language_items = tcx.lang_items();
let Some(slice_len_fn_item_def_id) = language_items.slice_len_fn() else {
// there is no lang item to compare to :)
return;
};
fn lower_slice_len_calls<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let language_items = tcx.lang_items();
let Some(slice_len_fn_item_def_id) = language_items.slice_len_fn() else {
// there is no lang item to compare to :)
return;
};
// The one successor remains unchanged, so no need to invalidate
let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
for block in basic_blocks {
// lower `<[_]>::len` calls
lower_slice_len_call(block, slice_len_fn_item_def_id);
// The one successor remains unchanged, so no need to invalidate
let basic_blocks = body.basic_blocks.as_mut_preserves_cfg();
for block in basic_blocks {
// lower `<[_]>::len` calls
lower_slice_len_call(block, slice_len_fn_item_def_id);
}
}
}

113
compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs
View File

@ -18,7 +18,61 @@ impl<'tcx> crate::MirPass<'tcx> for RemoveNoopLandingPads {
fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let def_id = body.source.def_id();
debug!(?def_id);
self.remove_nop_landing_pads(body)
// Skip the pass if there are no blocks with a resume terminator.
let has_resume = body
.basic_blocks
.iter_enumerated()
.any(|(_bb, block)| matches!(block.terminator().kind, TerminatorKind::UnwindResume));
if !has_resume {
debug!("remove_noop_landing_pads: no resume block in MIR");
return;
}
// make sure there's a resume block without any statements
let resume_block = {
let mut patch = MirPatch::new(body);
let resume_block = patch.resume_block();
patch.apply(body);
resume_block
};
debug!("remove_noop_landing_pads: resume block is {:?}", resume_block);
let mut jumps_folded = 0;
let mut landing_pads_removed = 0;
let mut nop_landing_pads = BitSet::new_empty(body.basic_blocks.len());
// This is a post-order traversal, so that if A post-dominates B
// then A will be visited before B.
let postorder: Vec<_> = traversal::postorder(body).map(|(bb, _)| bb).collect();
for bb in postorder {
debug!(" processing {:?}", bb);
if let Some(unwind) = body[bb].terminator_mut().unwind_mut() {
if let UnwindAction::Cleanup(unwind_bb) = *unwind {
if nop_landing_pads.contains(unwind_bb) {
debug!(" removing noop landing pad");
landing_pads_removed += 1;
*unwind = UnwindAction::Continue;
}
}
}
for target in body[bb].terminator_mut().successors_mut() {
if *target != resume_block && nop_landing_pads.contains(*target) {
debug!(" folding noop jump to {:?} to resume block", target);
*target = resume_block;
jumps_folded += 1;
}
}
let is_nop_landing_pad = self.is_nop_landing_pad(bb, body, &nop_landing_pads);
if is_nop_landing_pad {
nop_landing_pads.insert(bb);
}
debug!(" is_nop_landing_pad({:?}) = {}", bb, is_nop_landing_pad);
}
debug!("removed {:?} jumps and {:?} landing pads", jumps_folded, landing_pads_removed);
}
}
@ -82,61 +136,4 @@ impl RemoveNoopLandingPads {
| TerminatorKind::InlineAsm { .. } => false,
}
}
fn remove_nop_landing_pads(&self, body: &mut Body<'_>) {
// Skip the pass if there are no blocks with a resume terminator.
let has_resume = body
.basic_blocks
.iter_enumerated()
.any(|(_bb, block)| matches!(block.terminator().kind, TerminatorKind::UnwindResume));
if !has_resume {
debug!("remove_noop_landing_pads: no resume block in MIR");
return;
}
// make sure there's a resume block without any statements
let resume_block = {
let mut patch = MirPatch::new(body);
let resume_block = patch.resume_block();
patch.apply(body);
resume_block
};
debug!("remove_noop_landing_pads: resume block is {:?}", resume_block);
let mut jumps_folded = 0;
let mut landing_pads_removed = 0;
let mut nop_landing_pads = BitSet::new_empty(body.basic_blocks.len());
// This is a post-order traversal, so that if A post-dominates B
// then A will be visited before B.
let postorder: Vec<_> = traversal::postorder(body).map(|(bb, _)| bb).collect();
for bb in postorder {
debug!(" processing {:?}", bb);
if let Some(unwind) = body[bb].terminator_mut().unwind_mut() {
if let UnwindAction::Cleanup(unwind_bb) = *unwind {
if nop_landing_pads.contains(unwind_bb) {
debug!(" removing noop landing pad");
landing_pads_removed += 1;
*unwind = UnwindAction::Continue;
}
}
}
for target in body[bb].terminator_mut().successors_mut() {
if *target != resume_block && nop_landing_pads.contains(*target) {
debug!(" folding noop jump to {:?} to resume block", target);
*target = resume_block;
jumps_folded += 1;
}
}
let is_nop_landing_pad = self.is_nop_landing_pad(bb, body, &nop_landing_pads);
if is_nop_landing_pad {
nop_landing_pads.insert(bb);
}
debug!(" is_nop_landing_pad({:?}) = {}", bb, is_nop_landing_pad);
}
debug!("removed {:?} jumps and {:?} landing pads", jumps_folded, landing_pads_removed);
}
}

48
compiler/rustc_mir_transform/src/simplify.rs
View File

@ -381,7 +381,29 @@ impl<'tcx> crate::MirPass<'tcx> for SimplifyLocals {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
trace!("running SimplifyLocals on {:?}", body.source);
simplify_locals(body, tcx);
// First, we're going to get a count of *actual* uses for every `Local`.
let mut used_locals = UsedLocals::new(body);
// 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.
remove_unused_definitions_helper(&mut used_locals, body);
// 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);
// 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_preserves_cfg(body);
body.local_decls.shrink_to_fit();
}
}
}
@ -397,30 +419,6 @@ pub(super) fn remove_unused_definitions<'tcx>(body: &mut Body<'tcx>) {
remove_unused_definitions_helper(&mut used_locals, body);
}
fn simplify_locals<'tcx>(body: &mut Body<'tcx>, tcx: TyCtxt<'tcx>) {
// First, we're going to get a count of *actual* uses for every `Local`.
let mut used_locals = UsedLocals::new(body);
// 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.
remove_unused_definitions_helper(&mut used_locals, body);
// 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);
// 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_preserves_cfg(body);
body.local_decls.shrink_to_fit();
}
}
/// Construct the mapping while swapping out unused stuff out from the `vec`.
fn make_local_map<V>(
local_decls: &mut IndexVec<Local, V>,