rust/compiler/rustc_mir/src/transform/inline.rs

880 lines
35 KiB
Rust
Raw Normal View History

//! Inlining pass for MIR functions
2020-03-29 10:19:48 -05:00
use rustc_attr as attr;
use rustc_hir as hir;
2020-03-29 10:19:48 -05:00
use rustc_index::bit_set::BitSet;
use rustc_index::vec::Idx;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
2020-03-29 09:41:09 -05:00
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_session::config::MIR_OPT_LEVEL_DEFAULT;
use rustc_span::{hygiene::ExpnKind, ExpnData, Span};
use rustc_target::spec::abi::Abi;
2019-12-22 16:42:04 -06:00
use super::simplify::{remove_dead_blocks, CfgSimplifier};
use crate::transform::MirPass;
use std::iter;
use std::ops::{Range, RangeFrom};
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>,
fn_sig: ty::PolyFnSig<'tcx>,
block: BasicBlock,
target: Option<BasicBlock>,
source_info: SourceInfo,
}
2019-08-04 15:20:00 -05:00
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.unwrap_or(MIR_OPT_LEVEL_DEFAULT) < 2 {
return;
}
if inline(tcx, body) {
debug!("running simplify cfg on {:?}", body.source);
CfgSimplifier::new(body).simplify();
remove_dead_blocks(body);
}
}
}
fn inline(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
let def_id = body.source.def_id();
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
// Only do inlining into fn bodies.
if !tcx.hir().body_owner_kind(hir_id).is_fn_or_closure() {
return false;
}
if body.source.promoted.is_some() {
return false;
}
let mut this = 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()),
hir_id,
history: Vec::new(),
changed: false,
};
let blocks = BasicBlock::new(0)..body.basic_blocks().next_index();
this.process_blocks(body, blocks);
this.changed
}
struct Inliner<'tcx> {
2019-06-13 16:48:52 -05:00
tcx: TyCtxt<'tcx>,
2020-10-05 04:04:25 -05:00
param_env: ParamEnv<'tcx>,
/// Caller codegen attributes.
codegen_fn_attrs: &'tcx CodegenFnAttrs,
/// Caller HirID.
hir_id: hir::HirId,
/// Stack of inlined instances.
history: Vec<Instance<'tcx>>,
/// Indicates that the caller body has been modified.
changed: bool,
}
impl Inliner<'tcx> {
fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range<BasicBlock>) {
for bb in blocks {
let callsite = match self.get_valid_function_call(bb, &caller_body[bb], caller_body) {
None => continue,
Some(it) => it,
};
if !self.is_mir_available(&callsite.callee, caller_body) {
debug!("MIR unavailable {}", callsite.callee);
continue;
}
let callee_body = self.tcx.instance_mir(callsite.callee.def);
if !self.should_inline(callsite, callee_body) {
continue;
}
if !self.tcx.consider_optimizing(|| {
format!("Inline {:?} into {}", callee_body.span, callsite.callee)
}) {
return;
}
let callee_body = callsite.callee.subst_mir_and_normalize_erasing_regions(
self.tcx,
self.param_env,
2020-10-23 19:21:18 -05:00
callee_body.clone(),
);
let old_blocks = caller_body.basic_blocks().next_index();
self.inline_call(callsite, caller_body, callee_body);
let new_blocks = old_blocks..caller_body.basic_blocks().next_index();
self.changed = true;
self.history.push(callsite.callee);
self.process_blocks(caller_body, new_blocks);
self.history.pop();
}
}
fn is_mir_available(&self, callee: &Instance<'tcx>, caller_body: &Body<'tcx>) -> bool {
if let InstanceDef::Item(_) = callee.def {
if !self.tcx.is_mir_available(callee.def_id()) {
return false;
}
}
if let Some(callee_def_id) = 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.
!self.tcx.dep_graph.is_fully_enabled()
&& self.hir_id < callee_hir_id
&& caller_body.generator_kind.is_none()
} else {
// This cannot result in a cycle since the callee MIR is from another crate
// and is already optimized.
true
}
}
2019-12-22 16:42:04 -06:00
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.
2019-12-22 16:42:04 -06:00
if bb_data.is_cleanup {
return None;
}
// Only consider direct calls to functions
let terminator = bb_data.terminator();
if let TerminatorKind::Call { ref func, ref destination, .. } = terminator.kind {
let func_ty = func.ty(caller_body, self.tcx);
if let ty::FnDef(def_id, substs) = *func_ty.kind() {
// To resolve an instance its substs have to be fully normalized.
let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
let callee =
Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?;
if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def {
return None;
}
let fn_sig = self.tcx.fn_sig(def_id).subst(self.tcx, substs);
return Some(CallSite {
callee,
fn_sig,
block: bb,
target: destination.map(|(_, target)| target),
source_info: terminator.source_info,
});
}
}
None
}
2019-12-22 16:42:04 -06:00
fn should_inline(&self, callsite: CallSite<'tcx>, callee_body: &Body<'tcx>) -> bool {
debug!("should_inline({:?})", callsite);
let tcx = self.tcx;
2020-11-10 18:00:00 -06:00
if callsite.fn_sig.c_variadic() {
debug!("callee is variadic - 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;
}
if self.codegen_fn_attrs.no_sanitize != codegen_fn_attrs.no_sanitize {
debug!("`callee has incompatible no_sanitize attribute - not inlining");
return false;
}
2018-05-08 08:10:16 -05:00
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");
2019-12-22 16:42:04 -06:00
return false;
}
attr::InlineAttr::Hint => true,
attr::InlineAttr::None => false,
};
2017-02-08 11:31:47 -06:00
// 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 {
self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold
} else {
self.tcx.sess.opts.debugging_opts.inline_mir_threshold
};
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
debug!("#[naked] present - not inlining");
return false;
}
2018-05-08 08:10:16 -05:00
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
debug!("#[cold] present - not inlining");
return false;
}
// 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() {
2019-12-22 16:42:04 -06:00
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 {
2019-12-22 16:42:04 -06:00
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 = callsite.callee.subst_mir(self.tcx, &place.ty(callee_body, tcx).ty);
2020-10-05 04:04:25 -05:00
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;
}
}
2019-12-22 16:42:04 -06:00
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, substs) =
*callsite.callee.subst_mir(self.tcx, &f.literal.ty).kind()
{
let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
if let Ok(Some(instance)) =
Instance::resolve(self.tcx, self.param_env, def_id, substs)
{
if callsite.callee == instance || self.history.contains(&instance) {
debug!("`callee is recursive - not inlining");
return false;
}
}
// 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,
2019-12-22 16:42:04 -06:00
_ => 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 ty = callsite.callee.subst_mir(self.tcx, &callee_body.local_decls[v].ty);
// Cost of the var is the size in machine-words, if we know
// it.
2020-10-05 04:04:25 -05:00
if let Some(size) = type_size_of(tcx, self.param_env, ty) {
cost += (size / ptr_size) as usize;
} else {
cost += UNKNOWN_SIZE_COST;
}
}
2018-05-08 08:10:16 -05:00
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
}
}
}
2019-12-22 16:42:04 -06:00
fn inline_call(
&self,
callsite: CallSite<'tcx>,
2020-04-12 12:31:00 -05:00
caller_body: &mut Body<'tcx>,
mut callee_body: Body<'tcx>,
) {
let terminator = caller_body[callsite.block].terminator.take().unwrap();
match terminator.kind {
TerminatorKind::Call { args, destination, cleanup, .. } => {
// If the call is something like `a[*i] = f(i)`, where
// `i : &mut usize`, then just duplicating the `a[*i]`
2017-12-01 06:31:47 -06:00
// 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 {
2019-12-22 16:42:04 -06:00
ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
_ => {}
}
}
false
}
let dest = if let Some((destination_place, _)) = destination {
if dest_needs_borrow(destination_place) {
trace!("creating temp for return destination");
let dest = Rvalue::Ref(
self.tcx.lifetimes.re_erased,
BorrowKind::Mut { allow_two_phase_borrow: false },
destination_place,
);
let dest_ty = dest.ty(caller_body, self.tcx);
let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty));
caller_body[callsite.block].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::Assign(box (temp, dest)),
});
self.tcx.mk_place_deref(temp)
} else {
destination_place
}
} else {
trace!("creating temp for return place");
Place::from(self.new_call_temp(caller_body, &callsite, callee_body.return_ty()))
};
// Copy the arguments if needed.
let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body);
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: callsite.target,
cleanup_block: cleanup,
2019-08-05 20:11:55 -05:00
in_cleanup_block: false,
2019-10-20 15:11:04 -05:00
tcx: self.tcx,
callsite_span: callsite.source_info.span,
body_span: callee_body.span,
always_live_locals: BitSet::new_filled(callee_body.local_decls.len()),
};
// 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));
}
}
// If there are any locals without storage markers, give them storage only for the
// duration of the call.
for local in callee_body.vars_and_temps_iter() {
if integrator.always_live_locals.contains(local) {
let new_local = integrator.map_local(local);
caller_body[callsite.block].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageLive(new_local),
});
}
}
if let Some(block) = callsite.target {
// To avoid repeated O(n) insert, push any new statements to the end and rotate
// the slice once.
let mut n = 0;
for local in callee_body.vars_and_temps_iter().rev() {
if integrator.always_live_locals.contains(local) {
let new_local = integrator.map_local(local);
caller_body[block].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageDead(new_local),
});
n += 1;
}
}
caller_body[block].statements.rotate_right(n);
}
// 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.block].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(_, _, _))
}),
);
}
kind => bug!("unexpected terminator kind {:?}", kind),
}
}
fn make_call_args(
&self,
args: Vec<Operand<'tcx>>,
callsite: &CallSite<'tcx>,
2020-04-12 12:31:00 -05:00
caller_body: &mut Body<'tcx>,
callee_body: &Body<'tcx>,
) -> 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`)
2018-05-08 08:10:16 -05:00
// 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]`.
if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
let mut args = args.into_iter();
let self_ = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
let tuple = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
assert!(args.next().is_none());
let tuple = Place::from(tuple);
2020-08-02 17:49:11 -05:00
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.
2019-12-22 16:42:04 -06:00
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()));
2019-12-22 16:42:04 -06:00
// Spill to a local to make e.g., `tmp0`.
self.create_temp_if_necessary(tuple_field, callsite, caller_body)
2019-12-22 16:42:04 -06:00
});
closure_ref_arg.chain(tuple_tmp_args).collect()
} else {
args.into_iter()
.map(|a| self.create_temp_if_necessary(a, callsite, caller_body))
.collect()
}
}
2017-11-10 11:05:29 -06:00
/// 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>,
2020-04-12 12:31:00 -05:00
caller_body: &mut Body<'tcx>,
) -> Local {
// Reuse the operand if it is a moved temporary.
if let Operand::Move(place) = &arg {
if let Some(local) = place.as_local() {
if caller_body.local_kind(local) == LocalKind::Temp {
return local;
}
}
2017-11-10 11:05:29 -06:00
}
// Otherwise, create a temporary for the argument.
trace!("creating temp for argument {:?}", arg);
let arg_ty = arg.ty(caller_body, self.tcx);
let local = self.new_call_temp(caller_body, callsite, arg_ty);
caller_body[callsite.block].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::Assign(box (Place::from(local), Rvalue::Use(arg))),
});
local
}
/// Introduces a new temporary into the caller body that is live for the duration of the call.
fn new_call_temp(
&self,
caller_body: &mut Body<'tcx>,
callsite: &CallSite<'tcx>,
ty: Ty<'tcx>,
) -> Local {
let local = caller_body.local_decls.push(LocalDecl::new(ty, callsite.source_info.span));
caller_body[callsite.block].statements.push(Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageLive(local),
});
if let Some(block) = callsite.target {
caller_body[block].statements.insert(
0,
Statement {
source_info: callsite.source_info,
kind: StatementKind::StorageDead(local),
},
);
}
local
}
}
fn type_size_of<'tcx>(
2019-06-13 16:48:52 -05:00
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>,
2017-12-01 06:31:47 -06:00
destination: Place<'tcx>,
return_block: Option<BasicBlock>,
cleanup_block: Option<BasicBlock>,
in_cleanup_block: bool,
2019-10-20 15:11:04 -05:00
tcx: TyCtxt<'tcx>,
callsite_span: Span,
body_span: Span,
always_live_locals: BitSet<Local>,
}
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()))
}
};
trace!("mapping local `{:?}` to `{:?}`", local, new);
new
}
fn map_scope(&self, scope: SourceScope) -> SourceScope {
let new = SourceScope::new(self.new_scopes.start.index() + scope.index());
trace!("mapping scope `{:?}` to `{:?}`", scope, new);
new
}
fn map_block(&self, block: BasicBlock) -> BasicBlock {
let new = BasicBlock::new(self.new_blocks.start.index() + block.index());
trace!("mapping block `{:?}` to `{:?}`", block, new);
new
}
}
impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
2019-10-20 15:11:04 -05:00
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
2019-12-22 16:42:04 -06:00
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) {
for elem in place.projection {
// FIXME: Make sure that return place is not used in an indexing projection, since it
// won't be rebased as it is supposed to be.
assert_ne!(ProjectionElem::Index(RETURN_PLACE), elem);
}
// 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;
}
2019-12-22 16:42:04 -06:00
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_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) {
if let StatementKind::StorageLive(local) | StatementKind::StorageDead(local) =
statement.kind
{
self.always_live_locals.remove(local);
}
self.super_statement(statement, location);
}
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 {
2019-12-22 16:42:04 -06:00
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);
}
}
2019-12-22 16:42:04 -06:00
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
2018-08-19 08:30:23 -05:00
// 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
2018-08-19 08:30:23 -05:00
// 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
2018-08-19 08:30:23 -05:00
// the original call's cleanup block
*cleanup = self.cleanup_block;
}
}
TerminatorKind::Return => {
terminator.kind = if let Some(tgt) = self.return_block {
TerminatorKind::Goto { target: tgt }
} else {
TerminatorKind::Unreachable
}
}
TerminatorKind::Resume => {
if let Some(tgt) = self.cleanup_block {
terminator.kind = TerminatorKind::Goto { target: tgt }
}
}
2019-12-22 16:42:04 -06:00
TerminatorKind::Abort => {}
TerminatorKind::Unreachable => {}
2020-06-02 02:15:24 -05:00
TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => {
*real_target = self.map_block(*real_target);
*imaginary_target = self.map_block(*imaginary_target);
}
2019-12-22 16:42:04 -06:00
TerminatorKind::FalseUnwind { real_target: _, unwind: _ } =>
// see the ordering of passes in the optimized_mir query.
{
bug!("False unwinds should have been removed before inlining")
2019-12-22 16:42:04 -06:00
}
2020-02-14 12:17:50 -06:00
TerminatorKind::InlineAsm { ref mut destination, .. } => {
if let Some(ref mut tgt) = *destination {
*tgt = self.map_block(*tgt);
2020-02-14 12:17:50 -06:00
}
}
}
}
}