Use let else to reduce indentation
This commit is contained in:
Tomasz Miąsko
parent
d19980e1ce
commit
525a64fa81
@ -541,142 +541,141 @@ fn inline_call(
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mut callee_body: Body<'tcx>,
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) {
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let terminator = caller_body[callsite.block].terminator.take().unwrap();
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match terminator.kind {
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TerminatorKind::Call { args, destination, unwind, .. } => {
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// If the call is something like `a[*i] = f(i)`, where
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// `i : &mut usize`, then just duplicating the `a[*i]`
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// Place could result in two different locations if `f`
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// writes to `i`. To prevent this we need to create a temporary
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// borrow of the place and pass the destination as `*temp` instead.
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fn dest_needs_borrow(place: Place<'_>) -> bool {
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for elem in place.projection.iter() {
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match elem {
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ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
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_ => {}
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}
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}
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let TerminatorKind::Call { args, destination, unwind, .. } = terminator.kind else {
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bug!("unexpected terminator kind {:?}", terminator.kind);
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};
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false
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// If the call is something like `a[*i] = f(i)`, where
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// `i : &mut usize`, then just duplicating the `a[*i]`
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// Place could result in two different locations if `f`
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// writes to `i`. To prevent this we need to create a temporary
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// borrow of the place and pass the destination as `*temp` instead.
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fn dest_needs_borrow(place: Place<'_>) -> bool {
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for elem in place.projection.iter() {
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match elem {
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ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
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_ => {}
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}
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let dest = if dest_needs_borrow(destination) {
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trace!("creating temp for return destination");
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let dest = Rvalue::Ref(
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self.tcx.lifetimes.re_erased,
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BorrowKind::Mut { kind: MutBorrowKind::Default },
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destination,
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);
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let dest_ty = dest.ty(caller_body, self.tcx);
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let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty));
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caller_body[callsite.block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::Assign(Box::new((temp, dest))),
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});
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self.tcx.mk_place_deref(temp)
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} else {
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destination
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};
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// Always create a local to hold the destination, as `RETURN_PLACE` may appear
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// where a full `Place` is not allowed.
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let (remap_destination, destination_local) = if let Some(d) = dest.as_local() {
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(false, d)
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} else {
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(
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true,
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self.new_call_temp(
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caller_body,
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&callsite,
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destination.ty(caller_body, self.tcx).ty,
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),
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)
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};
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// Copy the arguments if needed.
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let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body);
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let mut integrator = Integrator {
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args: &args,
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new_locals: Local::new(caller_body.local_decls.len())..,
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new_scopes: SourceScope::new(caller_body.source_scopes.len())..,
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new_blocks: BasicBlock::new(caller_body.basic_blocks.len())..,
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destination: destination_local,
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callsite_scope: caller_body.source_scopes[callsite.source_info.scope].clone(),
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callsite,
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cleanup_block: unwind,
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in_cleanup_block: false,
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tcx: self.tcx,
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always_live_locals: BitSet::new_filled(callee_body.local_decls.len()),
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};
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// Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones
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// (or existing ones, in a few special cases) in the caller.
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integrator.visit_body(&mut callee_body);
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// If there are any locals without storage markers, give them storage only for the
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// duration of the call.
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for local in callee_body.vars_and_temps_iter() {
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if integrator.always_live_locals.contains(local) {
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let new_local = integrator.map_local(local);
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caller_body[callsite.block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::StorageLive(new_local),
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});
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}
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}
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if let Some(block) = callsite.target {
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// To avoid repeated O(n) insert, push any new statements to the end and rotate
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// the slice once.
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let mut n = 0;
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if remap_destination {
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caller_body[block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::Assign(Box::new((
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dest,
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Rvalue::Use(Operand::Move(destination_local.into())),
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))),
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});
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n += 1;
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}
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for local in callee_body.vars_and_temps_iter().rev() {
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if integrator.always_live_locals.contains(local) {
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let new_local = integrator.map_local(local);
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caller_body[block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::StorageDead(new_local),
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});
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n += 1;
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}
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}
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caller_body[block].statements.rotate_right(n);
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}
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// Insert all of the (mapped) parts of the callee body into the caller.
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caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
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caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
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caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
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caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
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caller_body[callsite.block].terminator = Some(Terminator {
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source_info: callsite.source_info,
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kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
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});
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// Copy only unevaluated constants from the callee_body into the caller_body.
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// Although we are only pushing `ConstKind::Unevaluated` consts to
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// `required_consts`, here we may not only have `ConstKind::Unevaluated`
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// because we are calling `instantiate_and_normalize_erasing_regions`.
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caller_body.required_consts.extend(
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callee_body.required_consts.iter().copied().filter(|&ct| match ct.const_ {
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Const::Ty(_) => {
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bug!("should never encounter ty::UnevaluatedConst in `required_consts`")
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}
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Const::Val(..) | Const::Unevaluated(..) => true,
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}),
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);
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}
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kind => bug!("unexpected terminator kind {:?}", kind),
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false
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}
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let dest = if dest_needs_borrow(destination) {
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trace!("creating temp for return destination");
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let dest = Rvalue::Ref(
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self.tcx.lifetimes.re_erased,
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BorrowKind::Mut { kind: MutBorrowKind::Default },
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destination,
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);
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let dest_ty = dest.ty(caller_body, self.tcx);
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let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty));
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caller_body[callsite.block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::Assign(Box::new((temp, dest))),
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});
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self.tcx.mk_place_deref(temp)
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} else {
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destination
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};
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// Always create a local to hold the destination, as `RETURN_PLACE` may appear
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// where a full `Place` is not allowed.
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let (remap_destination, destination_local) = if let Some(d) = dest.as_local() {
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(false, d)
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} else {
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(
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true,
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self.new_call_temp(
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caller_body,
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&callsite,
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destination.ty(caller_body, self.tcx).ty,
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),
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)
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};
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// Copy the arguments if needed.
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let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body);
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let mut integrator = Integrator {
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args: &args,
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new_locals: Local::new(caller_body.local_decls.len())..,
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new_scopes: SourceScope::new(caller_body.source_scopes.len())..,
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new_blocks: BasicBlock::new(caller_body.basic_blocks.len())..,
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destination: destination_local,
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callsite_scope: caller_body.source_scopes[callsite.source_info.scope].clone(),
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callsite,
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cleanup_block: unwind,
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in_cleanup_block: false,
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tcx: self.tcx,
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always_live_locals: BitSet::new_filled(callee_body.local_decls.len()),
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};
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// Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones
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// (or existing ones, in a few special cases) in the caller.
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integrator.visit_body(&mut callee_body);
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// If there are any locals without storage markers, give them storage only for the
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// duration of the call.
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for local in callee_body.vars_and_temps_iter() {
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if integrator.always_live_locals.contains(local) {
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let new_local = integrator.map_local(local);
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caller_body[callsite.block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::StorageLive(new_local),
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});
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}
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}
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if let Some(block) = callsite.target {
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// To avoid repeated O(n) insert, push any new statements to the end and rotate
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// the slice once.
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let mut n = 0;
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if remap_destination {
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caller_body[block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::Assign(Box::new((
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dest,
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Rvalue::Use(Operand::Move(destination_local.into())),
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))),
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});
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n += 1;
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}
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for local in callee_body.vars_and_temps_iter().rev() {
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if integrator.always_live_locals.contains(local) {
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let new_local = integrator.map_local(local);
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caller_body[block].statements.push(Statement {
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source_info: callsite.source_info,
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kind: StatementKind::StorageDead(new_local),
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});
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n += 1;
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}
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}
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caller_body[block].statements.rotate_right(n);
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}
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// Insert all of the (mapped) parts of the callee body into the caller.
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caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
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caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
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caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
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caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
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caller_body[callsite.block].terminator = Some(Terminator {
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source_info: callsite.source_info,
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kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
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});
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// Copy only unevaluated constants from the callee_body into the caller_body.
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// Although we are only pushing `ConstKind::Unevaluated` consts to
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// `required_consts`, here we may not only have `ConstKind::Unevaluated`
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// because we are calling `instantiate_and_normalize_erasing_regions`.
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caller_body.required_consts.extend(callee_body.required_consts.iter().copied().filter(
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|&ct| match ct.const_ {
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Const::Ty(_) => {
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bug!("should never encounter ty::UnevaluatedConst in `required_consts`")
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}
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Const::Val(..) | Const::Unevaluated(..) => true,
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},
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));
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}
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fn make_call_args(
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