rust/compiler/rustc_mir/src/transform/inline.rs
Tomasz Miąsko 6ca43aca1d inliner: Copy unevaluated constants only after successful inlining
Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.

Organize the code moving items from callee to the caller together in one
place to avoid the issue.
2020-11-05 00:00:00 +00:00

852 lines
34 KiB
Rust

//! Inlining pass for MIR functions
use rustc_attr as attr;
use rustc_index::bit_set::BitSet;
use rustc_index::vec::Idx;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
use rustc_middle::mir::visit::*;
use rustc_middle::mir::*;
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::{self, ConstKind, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
use rustc_span::{hygiene::ExpnKind, ExpnData, Span};
use rustc_target::spec::abi::Abi;
use super::simplify::{remove_dead_blocks, CfgSimplifier};
use crate::transform::MirPass;
use std::collections::VecDeque;
use std::iter;
use std::ops::RangeFrom;
const DEFAULT_THRESHOLD: usize = 50;
const HINT_THRESHOLD: usize = 100;
const INSTR_COST: usize = 5;
const CALL_PENALTY: usize = 25;
const LANDINGPAD_PENALTY: usize = 50;
const RESUME_PENALTY: usize = 45;
const UNKNOWN_SIZE_COST: usize = 10;
pub struct Inline;
#[derive(Copy, Clone, Debug)]
struct CallSite<'tcx> {
callee: Instance<'tcx>,
bb: BasicBlock,
source_info: SourceInfo,
}
impl<'tcx> MirPass<'tcx> for Inline {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
if tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
if tcx.sess.opts.debugging_opts.instrument_coverage {
// The current implementation of source code coverage injects code region counters
// into the MIR, and assumes a 1-to-1 correspondence between MIR and source-code-
// based function.
debug!("function inlining is disabled when compiling with `instrument_coverage`");
} else {
Inliner {
tcx,
param_env: tcx.param_env_reveal_all_normalized(body.source.def_id()),
codegen_fn_attrs: tcx.codegen_fn_attrs(body.source.def_id()),
}
.run_pass(body);
}
}
}
}
struct Inliner<'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
codegen_fn_attrs: &'tcx CodegenFnAttrs,
}
impl Inliner<'tcx> {
fn run_pass(&self, caller_body: &mut Body<'tcx>) {
// Keep a queue of callsites to try inlining on. We take
// advantage of the fact that queries detect cycles here to
// allow us to try and fetch the fully optimized MIR of a
// call; if it succeeds, we can inline it and we know that
// they do not call us. Otherwise, we just don't try to
// inline.
//
// We use a queue so that we inline "broadly" before we inline
// in depth. It is unclear if this is the best heuristic,
// really, but that's true of all the heuristics in this
// file. =)
let mut callsites = VecDeque::new();
let def_id = caller_body.source.def_id();
// Only do inlining into fn bodies.
let self_hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
if self.tcx.hir().body_owner_kind(self_hir_id).is_fn_or_closure()
&& caller_body.source.promoted.is_none()
{
for (bb, bb_data) in caller_body.basic_blocks().iter_enumerated() {
if let Some(callsite) = self.get_valid_function_call(bb, bb_data, caller_body) {
callsites.push_back(callsite);
}
}
} else {
return;
}
let mut changed = false;
while let Some(callsite) = callsites.pop_front() {
debug!("checking whether to inline callsite {:?}", callsite);
if let InstanceDef::Item(_) = callsite.callee.def {
if !self.tcx.is_mir_available(callsite.callee.def_id()) {
debug!("checking whether to inline callsite {:?} - MIR unavailable", callsite,);
continue;
}
}
let callee_body = if let Some(callee_def_id) = callsite.callee.def_id().as_local() {
let callee_hir_id = self.tcx.hir().local_def_id_to_hir_id(callee_def_id);
// Avoid a cycle here by only using `instance_mir` only if we have
// a lower `HirId` than the callee. This ensures that the callee will
// not inline us. This trick only works without incremental compilation.
// So don't do it if that is enabled. Also avoid inlining into generators,
// since their `optimized_mir` is used for layout computation, which can
// create a cycle, even when no attempt is made to inline the function
// in the other direction.
if !self.tcx.dep_graph.is_fully_enabled()
&& self_hir_id < callee_hir_id
&& caller_body.generator_kind.is_none()
{
self.tcx.instance_mir(callsite.callee.def)
} else {
continue;
}
} else {
// This cannot result in a cycle since the callee MIR is from another crate
// and is already optimized.
self.tcx.instance_mir(callsite.callee.def)
};
let callee_body: &Body<'tcx> = &*callee_body;
let callee_body = if self.consider_optimizing(callsite, callee_body) {
self.tcx.subst_and_normalize_erasing_regions(
&callsite.callee.substs,
self.param_env,
callee_body,
)
} else {
continue;
};
let start = caller_body.basic_blocks().len();
debug!("attempting to inline callsite {:?} - body={:?}", callsite, callee_body);
if !self.inline_call(callsite, caller_body, callee_body) {
debug!("attempting to inline callsite {:?} - failure", callsite);
continue;
}
debug!("attempting to inline callsite {:?} - success", callsite);
// Add callsites from inlined function
for (bb, bb_data) in caller_body.basic_blocks().iter_enumerated().skip(start) {
if let Some(new_callsite) = self.get_valid_function_call(bb, bb_data, caller_body) {
// Don't inline the same function multiple times.
if callsite.callee != new_callsite.callee {
callsites.push_back(new_callsite);
}
}
}
changed = true;
}
// Simplify if we inlined anything.
if changed {
debug!("running simplify cfg on {:?}", caller_body.source);
CfgSimplifier::new(caller_body).simplify();
remove_dead_blocks(caller_body);
}
}
fn get_valid_function_call(
&self,
bb: BasicBlock,
bb_data: &BasicBlockData<'tcx>,
caller_body: &Body<'tcx>,
) -> Option<CallSite<'tcx>> {
// Don't inline calls that are in cleanup blocks.
if bb_data.is_cleanup {
return None;
}
// Only consider direct calls to functions
let terminator = bb_data.terminator();
if let TerminatorKind::Call { func: ref op, .. } = terminator.kind {
if let ty::FnDef(callee_def_id, substs) = *op.ty(caller_body, self.tcx).kind() {
// To resolve an instance its substs have to be fully normalized, so
// we do this here.
let normalized_substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
let callee =
Instance::resolve(self.tcx, self.param_env, callee_def_id, normalized_substs)
.ok()
.flatten()?;
if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def {
return None;
}
return Some(CallSite { callee, bb, source_info: terminator.source_info });
}
}
None
}
fn consider_optimizing(&self, callsite: CallSite<'tcx>, callee_body: &Body<'tcx>) -> bool {
debug!("consider_optimizing({:?})", callsite);
self.should_inline(callsite, callee_body)
&& self.tcx.consider_optimizing(|| {
format!("Inline {:?} into {:?}", callee_body.span, callsite)
})
}
fn should_inline(&self, callsite: CallSite<'tcx>, callee_body: &Body<'tcx>) -> bool {
debug!("should_inline({:?})", callsite);
let tcx = self.tcx;
// Cannot inline generators which haven't been transformed yet
if callee_body.yield_ty.is_some() {
debug!(" yield ty present - not inlining");
return false;
}
let codegen_fn_attrs = tcx.codegen_fn_attrs(callsite.callee.def_id());
let self_features = &self.codegen_fn_attrs.target_features;
let callee_features = &codegen_fn_attrs.target_features;
if callee_features.iter().any(|feature| !self_features.contains(feature)) {
debug!("`callee has extra target features - not inlining");
return false;
}
let self_no_sanitize =
self.codegen_fn_attrs.no_sanitize & self.tcx.sess.opts.debugging_opts.sanitizer;
let callee_no_sanitize =
codegen_fn_attrs.no_sanitize & self.tcx.sess.opts.debugging_opts.sanitizer;
if self_no_sanitize != callee_no_sanitize {
debug!("`callee has incompatible no_sanitize attribute - not inlining");
return false;
}
let hinted = match codegen_fn_attrs.inline {
// Just treat inline(always) as a hint for now,
// there are cases that prevent inlining that we
// need to check for first.
attr::InlineAttr::Always => true,
attr::InlineAttr::Never => {
debug!("`#[inline(never)]` present - not inlining");
return false;
}
attr::InlineAttr::Hint => true,
attr::InlineAttr::None => false,
};
// Only inline local functions if they would be eligible for cross-crate
// inlining. This is to ensure that the final crate doesn't have MIR that
// reference unexported symbols
if callsite.callee.def_id().is_local() {
if callsite.callee.substs.non_erasable_generics().count() == 0 && !hinted {
debug!(" callee is an exported function - not inlining");
return false;
}
}
let mut threshold = if hinted { HINT_THRESHOLD } else { DEFAULT_THRESHOLD };
// Significantly lower the threshold for inlining cold functions
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
threshold /= 5;
}
// Give a bonus functions with a small number of blocks,
// We normally have two or three blocks for even
// very small functions.
if callee_body.basic_blocks().len() <= 3 {
threshold += threshold / 4;
}
debug!(" final inline threshold = {}", threshold);
// FIXME: Give a bonus to functions with only a single caller
let mut first_block = true;
let mut cost = 0;
// Traverse the MIR manually so we can account for the effects of
// inlining on the CFG.
let mut work_list = vec![START_BLOCK];
let mut visited = BitSet::new_empty(callee_body.basic_blocks().len());
while let Some(bb) = work_list.pop() {
if !visited.insert(bb.index()) {
continue;
}
let blk = &callee_body.basic_blocks()[bb];
for stmt in &blk.statements {
// Don't count StorageLive/StorageDead in the inlining cost.
match stmt.kind {
StatementKind::StorageLive(_)
| StatementKind::StorageDead(_)
| StatementKind::Nop => {}
_ => cost += INSTR_COST,
}
}
let term = blk.terminator();
let mut is_drop = false;
match term.kind {
TerminatorKind::Drop { ref place, target, unwind }
| TerminatorKind::DropAndReplace { ref place, target, unwind, .. } => {
is_drop = true;
work_list.push(target);
// If the place doesn't actually need dropping, treat it like
// a regular goto.
let ty = place.ty(callee_body, tcx).subst(tcx, callsite.callee.substs).ty;
if ty.needs_drop(tcx, self.param_env) {
cost += CALL_PENALTY;
if let Some(unwind) = unwind {
cost += LANDINGPAD_PENALTY;
work_list.push(unwind);
}
} else {
cost += INSTR_COST;
}
}
TerminatorKind::Unreachable | TerminatorKind::Call { destination: None, .. }
if first_block =>
{
// If the function always diverges, don't inline
// unless the cost is zero
threshold = 0;
}
TerminatorKind::Call { func: Operand::Constant(ref f), cleanup, .. } => {
if let ty::FnDef(def_id, _) = *f.literal.ty.kind() {
// Don't give intrinsics the extra penalty for calls
let f = tcx.fn_sig(def_id);
if f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic {
cost += INSTR_COST;
} else {
cost += CALL_PENALTY;
}
} else {
cost += CALL_PENALTY;
}
if cleanup.is_some() {
cost += LANDINGPAD_PENALTY;
}
}
TerminatorKind::Assert { cleanup, .. } => {
cost += CALL_PENALTY;
if cleanup.is_some() {
cost += LANDINGPAD_PENALTY;
}
}
TerminatorKind::Resume => cost += RESUME_PENALTY,
_ => cost += INSTR_COST,
}
if !is_drop {
for &succ in term.successors() {
work_list.push(succ);
}
}
first_block = false;
}
// Count up the cost of local variables and temps, if we know the size
// use that, otherwise we use a moderately-large dummy cost.
let ptr_size = tcx.data_layout.pointer_size.bytes();
for v in callee_body.vars_and_temps_iter() {
let v = &callee_body.local_decls[v];
let ty = v.ty.subst(tcx, callsite.callee.substs);
// Cost of the var is the size in machine-words, if we know
// it.
if let Some(size) = type_size_of(tcx, self.param_env, ty) {
cost += (size / ptr_size) as usize;
} else {
cost += UNKNOWN_SIZE_COST;
}
}
if let attr::InlineAttr::Always = codegen_fn_attrs.inline {
debug!("INLINING {:?} because inline(always) [cost={}]", callsite, cost);
true
} else {
if cost <= threshold {
debug!("INLINING {:?} [cost={} <= threshold={}]", callsite, cost, threshold);
true
} else {
debug!("NOT inlining {:?} [cost={} > threshold={}]", callsite, cost, threshold);
false
}
}
}
fn inline_call(
&self,
callsite: CallSite<'tcx>,
caller_body: &mut Body<'tcx>,
mut callee_body: Body<'tcx>,
) -> bool {
let terminator = caller_body[callsite.bb].terminator.take().unwrap();
match terminator.kind {
// FIXME: Handle inlining of diverging calls
TerminatorKind::Call { args, destination: Some(destination), cleanup, .. } => {
debug!("inlined {:?} into {:?}", callsite.callee, caller_body.source);
// If the call is something like `a[*i] = f(i)`, where
// `i : &mut usize`, then just duplicating the `a[*i]`
// Place could result in two different locations if `f`
// writes to `i`. To prevent this we need to create a temporary
// borrow of the place and pass the destination as `*temp` instead.
fn dest_needs_borrow(place: Place<'_>) -> bool {
for elem in place.projection.iter() {
match elem {
ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
_ => {}
}
}
false
}
let dest = if dest_needs_borrow(destination.0) {
debug!("creating temp for return destination");
let dest = Rvalue::Ref(
self.tcx.lifetimes.re_erased,
BorrowKind::Mut { allow_two_phase_borrow: false },
destination.0,
);
let ty = dest.ty(caller_body, self.tcx);
let temp = LocalDecl::new(ty, callsite.source_info.span);
let tmp = caller_body.local_decls.push(temp);
let tmp = Place::from(tmp);
let stmt = Statement {
source_info: callsite.source_info,
kind: StatementKind::Assign(box (tmp, dest)),
};
caller_body[callsite.bb].statements.push(stmt);
self.tcx.mk_place_deref(tmp)
} else {
destination.0
};
let return_block = destination.1;
// Copy the arguments if needed.
let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, return_block);
let mut integrator = Integrator {
args: &args,
new_locals: Local::new(caller_body.local_decls.len())..,
new_scopes: SourceScope::new(caller_body.source_scopes.len())..,
new_blocks: BasicBlock::new(caller_body.basic_blocks().len())..,
destination: dest,
return_block,
cleanup_block: cleanup,
in_cleanup_block: false,
tcx: self.tcx,
callsite_span: callsite.source_info.span,
body_span: callee_body.span,
};
// Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones
// (or existing ones, in a few special cases) in the caller.
integrator.visit_body(&mut callee_body);
for scope in &mut callee_body.source_scopes {
// FIXME(eddyb) move this into a `fn visit_scope_data` in `Integrator`.
if scope.parent_scope.is_none() {
let callsite_scope = &caller_body.source_scopes[callsite.source_info.scope];
// Attach the outermost callee scope as a child of the callsite
// scope, via the `parent_scope` and `inlined_parent_scope` chains.
scope.parent_scope = Some(callsite.source_info.scope);
assert_eq!(scope.inlined_parent_scope, None);
scope.inlined_parent_scope = if callsite_scope.inlined.is_some() {
Some(callsite.source_info.scope)
} else {
callsite_scope.inlined_parent_scope
};
// Mark the outermost callee scope as an inlined one.
assert_eq!(scope.inlined, None);
scope.inlined = Some((callsite.callee, callsite.source_info.span));
} else if scope.inlined_parent_scope.is_none() {
// Make it easy to find the scope with `inlined` set above.
scope.inlined_parent_scope =
Some(integrator.map_scope(OUTERMOST_SOURCE_SCOPE));
}
}
// Insert all of the (mapped) parts of the callee body into the caller.
caller_body.local_decls.extend(
// FIXME(eddyb) make `Range<Local>` iterable so that we can use
// `callee_body.local_decls.drain(callee_body.vars_and_temps())`
callee_body
.vars_and_temps_iter()
.map(|local| callee_body.local_decls[local].clone()),
);
caller_body.source_scopes.extend(callee_body.source_scopes.drain(..));
caller_body.var_debug_info.extend(callee_body.var_debug_info.drain(..));
caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
caller_body[callsite.bb].terminator = Some(Terminator {
source_info: callsite.source_info,
kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
});
// Copy only unevaluated constants from the callee_body into the caller_body.
// Although we are only pushing `ConstKind::Unevaluated` consts to
// `required_consts`, here we may not only have `ConstKind::Unevaluated`
// because we are calling `subst_and_normalize_erasing_regions`.
caller_body.required_consts.extend(
callee_body.required_consts.iter().copied().filter(|&constant| {
matches!(constant.literal.val, ConstKind::Unevaluated(_, _, _))
}),
);
true
}
kind => {
caller_body[callsite.bb].terminator =
Some(Terminator { source_info: terminator.source_info, kind });
false
}
}
}
fn make_call_args(
&self,
args: Vec<Operand<'tcx>>,
callsite: &CallSite<'tcx>,
caller_body: &mut Body<'tcx>,
return_block: BasicBlock,
) -> Vec<Local> {
let tcx = self.tcx;
// There is a bit of a mismatch between the *caller* of a closure and the *callee*.
// The caller provides the arguments wrapped up in a tuple:
//
// tuple_tmp = (a, b, c)
// Fn::call(closure_ref, tuple_tmp)
//
// meanwhile the closure body expects the arguments (here, `a`, `b`, and `c`)
// as distinct arguments. (This is the "rust-call" ABI hack.) Normally, codegen has
// the job of unpacking this tuple. But here, we are codegen. =) So we want to create
// a vector like
//
// [closure_ref, tuple_tmp.0, tuple_tmp.1, tuple_tmp.2]
//
// Except for one tiny wrinkle: we don't actually want `tuple_tmp.0`. It's more convenient
// if we "spill" that into *another* temporary, so that we can map the argument
// variable in the callee MIR directly to an argument variable on our side.
// So we introduce temporaries like:
//
// tmp0 = tuple_tmp.0
// tmp1 = tuple_tmp.1
// tmp2 = tuple_tmp.2
//
// and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
// FIXME(eddyb) make this check for `"rust-call"` ABI combined with
// `callee_body.spread_arg == None`, instead of special-casing closures.
if tcx.is_closure(callsite.callee.def_id()) {
let mut args = args.into_iter();
let self_ = self.create_temp_if_necessary(
args.next().unwrap(),
callsite,
caller_body,
return_block,
);
let tuple = self.create_temp_if_necessary(
args.next().unwrap(),
callsite,
caller_body,
return_block,
);
assert!(args.next().is_none());
let tuple = Place::from(tuple);
let tuple_tys = if let ty::Tuple(s) = tuple.ty(caller_body, tcx).ty.kind() {
s
} else {
bug!("Closure arguments are not passed as a tuple");
};
// The `closure_ref` in our example above.
let closure_ref_arg = iter::once(self_);
// The `tmp0`, `tmp1`, and `tmp2` in our example abonve.
let tuple_tmp_args = tuple_tys.iter().enumerate().map(|(i, ty)| {
// This is e.g., `tuple_tmp.0` in our example above.
let tuple_field =
Operand::Move(tcx.mk_place_field(tuple, Field::new(i), ty.expect_ty()));
// Spill to a local to make e.g., `tmp0`.
self.create_temp_if_necessary(tuple_field, callsite, caller_body, return_block)
});
closure_ref_arg.chain(tuple_tmp_args).collect()
} else {
args.into_iter()
.map(|a| self.create_temp_if_necessary(a, callsite, caller_body, return_block))
.collect()
}
}
/// If `arg` is already a temporary, returns it. Otherwise, introduces a fresh
/// temporary `T` and an instruction `T = arg`, and returns `T`.
fn create_temp_if_necessary(
&self,
arg: Operand<'tcx>,
callsite: &CallSite<'tcx>,
caller_body: &mut Body<'tcx>,
return_block: BasicBlock,
) -> Local {
// FIXME: Analysis of the usage of the arguments to avoid
// unnecessary temporaries.
if let Operand::Move(place) = &arg {
if let Some(local) = place.as_local() {
if caller_body.local_kind(local) == LocalKind::Temp {
// Reuse the operand if it's a temporary already
return local;
}
}
}
debug!("creating temp for argument {:?}", arg);
// Otherwise, create a temporary for the arg
let arg = Rvalue::Use(arg);
let ty = arg.ty(caller_body, self.tcx);
let arg_tmp = LocalDecl::new(ty, callsite.source_info.span);
let arg_tmp = caller_body.local_decls.push(arg_tmp);
caller_body[callsite.bb].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageLive(arg_tmp),
});
caller_body[callsite.bb].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::Assign(box (Place::from(arg_tmp), arg)),
});
caller_body[return_block].statements.insert(
0,
Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageDead(arg_tmp),
},
);
arg_tmp
}
}
fn type_size_of<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
) -> Option<u64> {
tcx.layout_of(param_env.and(ty)).ok().map(|layout| layout.size.bytes())
}
/**
* Integrator.
*
* Integrates blocks from the callee function into the calling function.
* Updates block indices, references to locals and other control flow
* stuff.
*/
struct Integrator<'a, 'tcx> {
args: &'a [Local],
new_locals: RangeFrom<Local>,
new_scopes: RangeFrom<SourceScope>,
new_blocks: RangeFrom<BasicBlock>,
destination: Place<'tcx>,
return_block: BasicBlock,
cleanup_block: Option<BasicBlock>,
in_cleanup_block: bool,
tcx: TyCtxt<'tcx>,
callsite_span: Span,
body_span: Span,
}
impl<'a, 'tcx> Integrator<'a, 'tcx> {
fn map_local(&self, local: Local) -> Local {
let new = if local == RETURN_PLACE {
self.destination.local
} else {
let idx = local.index() - 1;
if idx < self.args.len() {
self.args[idx]
} else {
Local::new(self.new_locals.start.index() + (idx - self.args.len()))
}
};
debug!("mapping local `{:?}` to `{:?}`", local, new);
new
}
fn map_scope(&self, scope: SourceScope) -> SourceScope {
let new = SourceScope::new(self.new_scopes.start.index() + scope.index());
debug!("mapping scope `{:?}` to `{:?}`", scope, new);
new
}
fn map_block(&self, block: BasicBlock) -> BasicBlock {
let new = BasicBlock::new(self.new_blocks.start.index() + block.index());
debug!("mapping block `{:?}` to `{:?}`", block, new);
new
}
}
impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn visit_local(&mut self, local: &mut Local, _ctxt: PlaceContext, _location: Location) {
*local = self.map_local(*local);
}
fn visit_source_scope(&mut self, scope: &mut SourceScope) {
*scope = self.map_scope(*scope);
}
fn visit_span(&mut self, span: &mut Span) {
// Make sure that all spans track the fact that they were inlined.
*span = self.callsite_span.fresh_expansion(ExpnData {
def_site: self.body_span,
..ExpnData::default(ExpnKind::Inlined, *span, self.tcx.sess.edition(), None)
});
}
fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
// If this is the `RETURN_PLACE`, we need to rebase any projections onto it.
let dest_proj_len = self.destination.projection.len();
if place.local == RETURN_PLACE && dest_proj_len > 0 {
let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len());
projs.extend(self.destination.projection);
projs.extend(place.projection);
place.projection = self.tcx.intern_place_elems(&*projs);
}
// Handles integrating any locals that occur in the base
// or projections
self.super_place(place, context, location)
}
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);
self.in_cleanup_block = false;
}
fn visit_retag(&mut self, kind: &mut RetagKind, place: &mut Place<'tcx>, loc: Location) {
self.super_retag(kind, place, loc);
// We have to patch all inlined retags to be aware that they are no longer
// happening on function entry.
if *kind == RetagKind::FnEntry {
*kind = RetagKind::Default;
}
}
fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, loc: Location) {
// Don't try to modify the implicit `_0` access on return (`return` terminators are
// replaced down below anyways).
if !matches!(terminator.kind, TerminatorKind::Return) {
self.super_terminator(terminator, loc);
}
match terminator.kind {
TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } => bug!(),
TerminatorKind::Goto { ref mut target } => {
*target = self.map_block(*target);
}
TerminatorKind::SwitchInt { ref mut targets, .. } => {
for tgt in targets.all_targets_mut() {
*tgt = self.map_block(*tgt);
}
}
TerminatorKind::Drop { ref mut target, ref mut unwind, .. }
| TerminatorKind::DropAndReplace { ref mut target, ref mut unwind, .. } => {
*target = self.map_block(*target);
if let Some(tgt) = *unwind {
*unwind = Some(self.map_block(tgt));
} else if !self.in_cleanup_block {
// Unless this drop is in a cleanup block, add an unwind edge to
// the original call's cleanup block
*unwind = self.cleanup_block;
}
}
TerminatorKind::Call { ref mut destination, ref mut cleanup, .. } => {
if let Some((_, ref mut tgt)) = *destination {
*tgt = self.map_block(*tgt);
}
if let Some(tgt) = *cleanup {
*cleanup = Some(self.map_block(tgt));
} else if !self.in_cleanup_block {
// Unless this call is in a cleanup block, add an unwind edge to
// the original call's cleanup block
*cleanup = self.cleanup_block;
}
}
TerminatorKind::Assert { ref mut target, ref mut cleanup, .. } => {
*target = self.map_block(*target);
if let Some(tgt) = *cleanup {
*cleanup = Some(self.map_block(tgt));
} else if !self.in_cleanup_block {
// Unless this assert is in a cleanup block, add an unwind edge to
// the original call's cleanup block
*cleanup = self.cleanup_block;
}
}
TerminatorKind::Return => {
terminator.kind = TerminatorKind::Goto { target: self.return_block };
}
TerminatorKind::Resume => {
if let Some(tgt) = self.cleanup_block {
terminator.kind = TerminatorKind::Goto { target: tgt }
}
}
TerminatorKind::Abort => {}
TerminatorKind::Unreachable => {}
TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => {
*real_target = self.map_block(*real_target);
*imaginary_target = self.map_block(*imaginary_target);
}
TerminatorKind::FalseUnwind { real_target: _, unwind: _ } =>
// see the ordering of passes in the optimized_mir query.
{
bug!("False unwinds should have been removed before inlining")
}
TerminatorKind::InlineAsm { ref mut destination, .. } => {
if let Some(ref mut tgt) = *destination {
*tgt = self.map_block(*tgt);
}
}
}
}
}