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1155 lines
46 KiB
Rust
1155 lines
46 KiB
Rust
//! Inlining pass for MIR functions.
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use crate::deref_separator::deref_finder;
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use rustc_attr::InlineAttr;
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use rustc_hir::def::DefKind;
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use rustc_hir::def_id::DefId;
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use rustc_index::bit_set::BitSet;
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use rustc_index::Idx;
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use rustc_middle::bug;
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use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
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use rustc_middle::mir::visit::*;
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use rustc_middle::mir::*;
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use rustc_middle::ty::TypeVisitableExt;
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use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt, TypeFlags};
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use rustc_session::config::{DebugInfo, OptLevel};
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use rustc_span::source_map::Spanned;
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use rustc_span::sym;
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use rustc_target::abi::FieldIdx;
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use rustc_target::spec::abi::Abi;
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use crate::cost_checker::CostChecker;
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use crate::simplify::simplify_cfg;
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use crate::util;
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use crate::validate::validate_types;
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use std::iter;
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use std::ops::{Range, RangeFrom};
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pub(crate) mod cycle;
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const TOP_DOWN_DEPTH_LIMIT: usize = 5;
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pub struct Inline;
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#[derive(Copy, Clone, Debug)]
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struct CallSite<'tcx> {
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callee: Instance<'tcx>,
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fn_sig: ty::PolyFnSig<'tcx>,
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block: BasicBlock,
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source_info: SourceInfo,
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}
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impl<'tcx> MirPass<'tcx> for Inline {
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fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
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// FIXME(#127234): Coverage instrumentation currently doesn't handle inlined
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// MIR correctly when Modified Condition/Decision Coverage is enabled.
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if sess.instrument_coverage_mcdc() {
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return false;
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}
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if let Some(enabled) = sess.opts.unstable_opts.inline_mir {
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return enabled;
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}
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match sess.mir_opt_level() {
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0 | 1 => false,
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2 => {
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(sess.opts.optimize == OptLevel::Default
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|| sess.opts.optimize == OptLevel::Aggressive)
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&& sess.opts.incremental == None
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}
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_ => true,
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}
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}
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fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
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let span = trace_span!("inline", body = %tcx.def_path_str(body.source.def_id()));
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let _guard = span.enter();
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if inline(tcx, body) {
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debug!("running simplify cfg on {:?}", body.source);
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simplify_cfg(body);
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deref_finder(tcx, body);
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}
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}
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}
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fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
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let def_id = body.source.def_id().expect_local();
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// Only do inlining into fn bodies.
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if !tcx.hir().body_owner_kind(def_id).is_fn_or_closure() {
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return false;
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}
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if body.source.promoted.is_some() {
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return false;
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}
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// Avoid inlining into coroutines, since their `optimized_mir` is used for layout computation,
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// which can create a cycle, even when no attempt is made to inline the function in the other
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// direction.
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if body.coroutine.is_some() {
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return false;
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}
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let param_env = tcx.param_env_reveal_all_normalized(def_id);
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let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
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let mut this = Inliner {
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tcx,
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param_env,
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codegen_fn_attrs,
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history: Vec::new(),
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changed: false,
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caller_is_inline_forwarder: matches!(
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codegen_fn_attrs.inline,
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InlineAttr::Hint | InlineAttr::Always
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) && body_is_forwarder(body),
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};
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let blocks = START_BLOCK..body.basic_blocks.next_index();
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this.process_blocks(body, blocks);
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this.changed
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}
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struct Inliner<'tcx> {
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tcx: TyCtxt<'tcx>,
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param_env: ParamEnv<'tcx>,
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/// Caller codegen attributes.
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codegen_fn_attrs: &'tcx CodegenFnAttrs,
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/// Stack of inlined instances.
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/// We only check the `DefId` and not the args because we want to
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/// avoid inlining cases of polymorphic recursion.
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/// The number of `DefId`s is finite, so checking history is enough
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/// to ensure that we do not loop endlessly while inlining.
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history: Vec<DefId>,
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/// Indicates that the caller body has been modified.
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changed: bool,
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/// Indicates that the caller is #[inline] and just calls another function,
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/// and thus we can inline less into it as it'll be inlined itself.
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caller_is_inline_forwarder: bool,
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}
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impl<'tcx> Inliner<'tcx> {
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fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range<BasicBlock>) {
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// How many callsites in this body are we allowed to inline? We need to limit this in order
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// to prevent super-linear growth in MIR size
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let inline_limit = match self.history.len() {
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0 => usize::MAX,
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1..=TOP_DOWN_DEPTH_LIMIT => 1,
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_ => return,
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};
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let mut inlined_count = 0;
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for bb in blocks {
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let bb_data = &caller_body[bb];
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if bb_data.is_cleanup {
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continue;
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}
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let Some(callsite) = self.resolve_callsite(caller_body, bb, bb_data) else {
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continue;
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};
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let span = trace_span!("process_blocks", %callsite.callee, ?bb);
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let _guard = span.enter();
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match self.try_inlining(caller_body, &callsite) {
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Err(reason) => {
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debug!("not-inlined {} [{}]", callsite.callee, reason);
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continue;
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}
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Ok(new_blocks) => {
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debug!("inlined {}", callsite.callee);
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self.changed = true;
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self.history.push(callsite.callee.def_id());
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self.process_blocks(caller_body, new_blocks);
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self.history.pop();
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inlined_count += 1;
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if inlined_count == inline_limit {
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debug!("inline count reached");
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return;
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}
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}
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}
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}
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}
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/// Attempts to inline a callsite into the caller body. When successful returns basic blocks
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/// containing the inlined body. Otherwise returns an error describing why inlining didn't take
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/// place.
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fn try_inlining(
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&self,
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caller_body: &mut Body<'tcx>,
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callsite: &CallSite<'tcx>,
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) -> Result<std::ops::Range<BasicBlock>, &'static str> {
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self.check_mir_is_available(caller_body, callsite.callee)?;
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let callee_attrs = self.tcx.codegen_fn_attrs(callsite.callee.def_id());
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let cross_crate_inlinable = self.tcx.cross_crate_inlinable(callsite.callee.def_id());
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self.check_codegen_attributes(callsite, callee_attrs, cross_crate_inlinable)?;
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// Intrinsic fallback bodies are automatically made cross-crate inlineable,
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// but at this stage we don't know whether codegen knows the intrinsic,
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// so just conservatively don't inline it.
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if self.tcx.has_attr(callsite.callee.def_id(), sym::rustc_intrinsic) {
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return Err("Callee is an intrinsic, do not inline fallback bodies");
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}
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let terminator = caller_body[callsite.block].terminator.as_ref().unwrap();
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let TerminatorKind::Call { args, destination, .. } = &terminator.kind else { bug!() };
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let destination_ty = destination.ty(&caller_body.local_decls, self.tcx).ty;
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for arg in args {
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if !arg.node.ty(&caller_body.local_decls, self.tcx).is_sized(self.tcx, self.param_env) {
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// We do not allow inlining functions with unsized params. Inlining these functions
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// could create unsized locals, which are unsound and being phased out.
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return Err("Call has unsized argument");
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}
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}
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let callee_body = try_instance_mir(self.tcx, callsite.callee.def)?;
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self.check_mir_body(callsite, callee_body, callee_attrs, cross_crate_inlinable)?;
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if !self.tcx.consider_optimizing(|| {
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format!("Inline {:?} into {:?}", callsite.callee, caller_body.source)
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}) {
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return Err("optimization fuel exhausted");
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}
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let Ok(callee_body) = callsite.callee.try_instantiate_mir_and_normalize_erasing_regions(
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self.tcx,
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self.param_env,
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ty::EarlyBinder::bind(callee_body.clone()),
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) else {
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return Err("failed to normalize callee body");
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};
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// Normally, this shouldn't be required, but trait normalization failure can create a
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// validation ICE.
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if !validate_types(
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self.tcx,
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MirPhase::Runtime(RuntimePhase::Optimized),
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self.param_env,
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&callee_body,
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&caller_body,
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)
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.is_empty()
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{
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return Err("failed to validate callee body");
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}
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// Check call signature compatibility.
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// Normally, this shouldn't be required, but trait normalization failure can create a
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// validation ICE.
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let output_type = callee_body.return_ty();
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if !util::relate_types(self.tcx, self.param_env, ty::Covariant, output_type, destination_ty)
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{
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trace!(?output_type, ?destination_ty);
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return Err("failed to normalize return type");
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}
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if callsite.fn_sig.abi() == Abi::RustCall {
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// FIXME: Don't inline user-written `extern "rust-call"` functions,
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// since this is generally perf-negative on rustc, and we hope that
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// LLVM will inline these functions instead.
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if callee_body.spread_arg.is_some() {
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return Err("do not inline user-written rust-call functions");
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}
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let (self_arg, arg_tuple) = match &args[..] {
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[arg_tuple] => (None, arg_tuple),
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[self_arg, arg_tuple] => (Some(self_arg), arg_tuple),
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_ => bug!("Expected `rust-call` to have 1 or 2 args"),
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};
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let self_arg_ty =
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self_arg.map(|self_arg| self_arg.node.ty(&caller_body.local_decls, self.tcx));
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let arg_tuple_ty = arg_tuple.node.ty(&caller_body.local_decls, self.tcx);
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let ty::Tuple(arg_tuple_tys) = *arg_tuple_ty.kind() else {
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bug!("Closure arguments are not passed as a tuple");
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};
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for (arg_ty, input) in
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self_arg_ty.into_iter().chain(arg_tuple_tys).zip(callee_body.args_iter())
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{
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let input_type = callee_body.local_decls[input].ty;
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if !util::relate_types(self.tcx, self.param_env, ty::Covariant, input_type, arg_ty)
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{
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trace!(?arg_ty, ?input_type);
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return Err("failed to normalize tuple argument type");
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}
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}
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} else {
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for (arg, input) in args.iter().zip(callee_body.args_iter()) {
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let input_type = callee_body.local_decls[input].ty;
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let arg_ty = arg.node.ty(&caller_body.local_decls, self.tcx);
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if !util::relate_types(self.tcx, self.param_env, ty::Covariant, input_type, arg_ty)
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{
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trace!(?arg_ty, ?input_type);
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return Err("failed to normalize argument type");
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}
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}
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}
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let old_blocks = caller_body.basic_blocks.next_index();
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self.inline_call(caller_body, callsite, callee_body);
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let new_blocks = old_blocks..caller_body.basic_blocks.next_index();
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Ok(new_blocks)
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}
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fn check_mir_is_available(
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&self,
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caller_body: &Body<'tcx>,
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callee: Instance<'tcx>,
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) -> Result<(), &'static str> {
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let caller_def_id = caller_body.source.def_id();
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let callee_def_id = callee.def_id();
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if callee_def_id == caller_def_id {
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return Err("self-recursion");
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}
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match callee.def {
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InstanceKind::Item(_) => {
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// If there is no MIR available (either because it was not in metadata or
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// because it has no MIR because it's an extern function), then the inliner
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// won't cause cycles on this.
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if !self.tcx.is_mir_available(callee_def_id) {
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return Err("item MIR unavailable");
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}
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}
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// These have no own callable MIR.
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InstanceKind::Intrinsic(_) | InstanceKind::Virtual(..) => {
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return Err("instance without MIR (intrinsic / virtual)");
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}
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// FIXME(#127030): `ConstParamHasTy` has bad interactions with
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// the drop shim builder, which does not evaluate predicates in
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// the correct param-env for types being dropped. Stall resolving
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// the MIR for this instance until all of its const params are
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// substituted.
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InstanceKind::DropGlue(_, Some(ty)) if ty.has_type_flags(TypeFlags::HAS_CT_PARAM) => {
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return Err("still needs substitution");
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}
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// This cannot result in an immediate cycle since the callee MIR is a shim, which does
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// not get any optimizations run on it. Any subsequent inlining may cause cycles, but we
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// do not need to catch this here, we can wait until the inliner decides to continue
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// inlining a second time.
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InstanceKind::VTableShim(_)
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| InstanceKind::ReifyShim(..)
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| InstanceKind::FnPtrShim(..)
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| InstanceKind::ClosureOnceShim { .. }
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| InstanceKind::ConstructCoroutineInClosureShim { .. }
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| InstanceKind::CoroutineKindShim { .. }
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| InstanceKind::DropGlue(..)
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| InstanceKind::CloneShim(..)
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| InstanceKind::ThreadLocalShim(..)
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| InstanceKind::FnPtrAddrShim(..)
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| InstanceKind::AsyncDropGlueCtorShim(..) => return Ok(()),
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}
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if self.tcx.is_constructor(callee_def_id) {
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trace!("constructors always have MIR");
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// Constructor functions cannot cause a query cycle.
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return Ok(());
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}
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if callee_def_id.is_local() {
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// Avoid a cycle here by only using `instance_mir` only if we have
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// a lower `DefPathHash` than the callee. This ensures that the callee will
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// not inline us. This trick even works with incremental compilation,
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// since `DefPathHash` is stable.
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if self.tcx.def_path_hash(caller_def_id).local_hash()
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< self.tcx.def_path_hash(callee_def_id).local_hash()
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{
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return Ok(());
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}
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// If we know for sure that the function we're calling will itself try to
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// call us, then we avoid inlining that function.
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if self.tcx.mir_callgraph_reachable((callee, caller_def_id.expect_local())) {
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return Err("caller might be reachable from callee (query cycle avoidance)");
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}
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Ok(())
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} else {
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// This cannot result in an immediate cycle since the callee MIR is from another crate
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// and is already optimized. Any subsequent inlining may cause cycles, but we do
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// not need to catch this here, we can wait until the inliner decides to continue
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// inlining a second time.
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trace!("functions from other crates always have MIR");
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Ok(())
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}
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}
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fn resolve_callsite(
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&self,
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caller_body: &Body<'tcx>,
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bb: BasicBlock,
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bb_data: &BasicBlockData<'tcx>,
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) -> Option<CallSite<'tcx>> {
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// Only consider direct calls to functions
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let terminator = bb_data.terminator();
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// FIXME(explicit_tail_calls): figure out if we can inline tail calls
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if let TerminatorKind::Call { ref func, fn_span, .. } = terminator.kind {
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let func_ty = func.ty(caller_body, self.tcx);
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if let ty::FnDef(def_id, args) = *func_ty.kind() {
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// To resolve an instance its args have to be fully normalized.
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let args = self.tcx.try_normalize_erasing_regions(self.param_env, args).ok()?;
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let callee =
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Instance::try_resolve(self.tcx, self.param_env, def_id, args).ok().flatten()?;
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if let InstanceKind::Virtual(..) | InstanceKind::Intrinsic(_) = callee.def {
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return None;
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}
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if self.history.contains(&callee.def_id()) {
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return None;
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}
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let fn_sig = self.tcx.fn_sig(def_id).instantiate(self.tcx, args);
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// Additionally, check that the body that we're inlining actually agrees
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// with the ABI of the trait that the item comes from.
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if let InstanceKind::Item(instance_def_id) = callee.def
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&& self.tcx.def_kind(instance_def_id) == DefKind::AssocFn
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&& let instance_fn_sig = self.tcx.fn_sig(instance_def_id).skip_binder()
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&& instance_fn_sig.abi() != fn_sig.abi()
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{
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return None;
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}
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let source_info = SourceInfo { span: fn_span, ..terminator.source_info };
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return Some(CallSite { callee, fn_sig, block: bb, source_info });
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}
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}
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None
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}
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/// Returns an error if inlining is not possible based on codegen attributes alone. A success
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/// indicates that inlining decision should be based on other criteria.
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fn check_codegen_attributes(
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&self,
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callsite: &CallSite<'tcx>,
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callee_attrs: &CodegenFnAttrs,
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cross_crate_inlinable: bool,
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) -> Result<(), &'static str> {
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if self.tcx.has_attr(callsite.callee.def_id(), sym::rustc_no_mir_inline) {
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return Err("#[rustc_no_mir_inline]");
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}
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if let InlineAttr::Never = callee_attrs.inline {
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return Err("never inline hint");
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}
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// Reachability pass defines which functions are eligible for inlining. Generally inlining
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// other functions is incorrect because they could reference symbols that aren't exported.
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let is_generic = callsite
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.callee
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.args
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.non_erasable_generics(self.tcx, callsite.callee.def_id())
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.next()
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.is_some();
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if !is_generic && !cross_crate_inlinable {
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return Err("not exported");
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}
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if callsite.fn_sig.c_variadic() {
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return Err("C variadic");
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}
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|
|
if callee_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
|
|
return Err("cold");
|
|
}
|
|
|
|
if callee_attrs.no_sanitize != self.codegen_fn_attrs.no_sanitize {
|
|
return Err("incompatible sanitizer set");
|
|
}
|
|
|
|
// Two functions are compatible if the callee has no attribute (meaning
|
|
// that it's codegen agnostic), or sets an attribute that is identical
|
|
// to this function's attribute.
|
|
if callee_attrs.instruction_set.is_some()
|
|
&& callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set
|
|
{
|
|
return Err("incompatible instruction set");
|
|
}
|
|
|
|
if callee_attrs.target_features != self.codegen_fn_attrs.target_features {
|
|
// In general it is not correct to inline a callee with target features that are a
|
|
// subset of the caller. This is because the callee might contain calls, and the ABI of
|
|
// those calls depends on the target features of the surrounding function. By moving a
|
|
// `Call` terminator from one MIR body to another with more target features, we might
|
|
// change the ABI of that call!
|
|
return Err("incompatible target features");
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Returns inlining decision that is based on the examination of callee MIR body.
|
|
/// Assumes that codegen attributes have been checked for compatibility already.
|
|
#[instrument(level = "debug", skip(self, callee_body))]
|
|
fn check_mir_body(
|
|
&self,
|
|
callsite: &CallSite<'tcx>,
|
|
callee_body: &Body<'tcx>,
|
|
callee_attrs: &CodegenFnAttrs,
|
|
cross_crate_inlinable: bool,
|
|
) -> Result<(), &'static str> {
|
|
let tcx = self.tcx;
|
|
|
|
let mut threshold = if self.caller_is_inline_forwarder {
|
|
self.tcx.sess.opts.unstable_opts.inline_mir_forwarder_threshold.unwrap_or(30)
|
|
} else if cross_crate_inlinable {
|
|
self.tcx.sess.opts.unstable_opts.inline_mir_hint_threshold.unwrap_or(100)
|
|
} else {
|
|
self.tcx.sess.opts.unstable_opts.inline_mir_threshold.unwrap_or(50)
|
|
};
|
|
|
|
// 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 checker =
|
|
CostChecker::new(self.tcx, self.param_env, Some(callsite.callee), callee_body);
|
|
|
|
checker.add_function_level_costs();
|
|
|
|
// 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];
|
|
checker.visit_basic_block_data(bb, blk);
|
|
|
|
let term = blk.terminator();
|
|
if let TerminatorKind::Drop { ref place, target, unwind, replace: _ } = term.kind {
|
|
work_list.push(target);
|
|
|
|
// If the place doesn't actually need dropping, treat it like a regular goto.
|
|
let ty = callsite.callee.instantiate_mir(
|
|
self.tcx,
|
|
ty::EarlyBinder::bind(&place.ty(callee_body, tcx).ty),
|
|
);
|
|
if ty.needs_drop(tcx, self.param_env)
|
|
&& let UnwindAction::Cleanup(unwind) = unwind
|
|
{
|
|
work_list.push(unwind);
|
|
}
|
|
} else if callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set
|
|
&& matches!(term.kind, TerminatorKind::InlineAsm { .. })
|
|
{
|
|
// During the attribute checking stage we allow a callee with no
|
|
// instruction_set assigned to count as compatible with a function that does
|
|
// assign one. However, during this stage we require an exact match when any
|
|
// inline-asm is detected. LLVM will still possibly do an inline later on
|
|
// if the no-attribute function ends up with the same instruction set anyway.
|
|
return Err("Cannot move inline-asm across instruction sets");
|
|
} else if let TerminatorKind::TailCall { .. } = term.kind {
|
|
// FIXME(explicit_tail_calls): figure out how exactly functions containing tail calls can be inlined (and if they even should)
|
|
return Err("can't inline functions with tail calls");
|
|
} else {
|
|
work_list.extend(term.successors())
|
|
}
|
|
}
|
|
|
|
// N.B. We still apply our cost threshold to #[inline(always)] functions.
|
|
// That attribute is often applied to very large functions that exceed LLVM's (very
|
|
// generous) inlining threshold. Such functions are very poor MIR inlining candidates.
|
|
// Always inlining #[inline(always)] functions in MIR, on net, slows down the compiler.
|
|
let cost = checker.cost();
|
|
if cost <= threshold {
|
|
debug!("INLINING {:?} [cost={} <= threshold={}]", callsite, cost, threshold);
|
|
Ok(())
|
|
} else {
|
|
debug!("NOT inlining {:?} [cost={} > threshold={}]", callsite, cost, threshold);
|
|
Err("cost above threshold")
|
|
}
|
|
}
|
|
|
|
fn inline_call(
|
|
&self,
|
|
caller_body: &mut Body<'tcx>,
|
|
callsite: &CallSite<'tcx>,
|
|
mut callee_body: Body<'tcx>,
|
|
) {
|
|
let terminator = caller_body[callsite.block].terminator.take().unwrap();
|
|
let TerminatorKind::Call { func, args, destination, unwind, target, .. } = terminator.kind
|
|
else {
|
|
bug!("unexpected terminator kind {:?}", terminator.kind);
|
|
};
|
|
|
|
let return_block = if let Some(block) = target {
|
|
// Prepare a new block for code that should execute when call returns. We don't use
|
|
// target block directly since it might have other predecessors.
|
|
let mut data = BasicBlockData::new(Some(Terminator {
|
|
source_info: terminator.source_info,
|
|
kind: TerminatorKind::Goto { target: block },
|
|
}));
|
|
data.is_cleanup = caller_body[block].is_cleanup;
|
|
Some(caller_body.basic_blocks_mut().push(data))
|
|
} else {
|
|
None
|
|
};
|
|
|
|
// 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) {
|
|
trace!("creating temp for return destination");
|
|
let dest = Rvalue::Ref(
|
|
self.tcx.lifetimes.re_erased,
|
|
BorrowKind::Mut { kind: MutBorrowKind::Default },
|
|
destination,
|
|
);
|
|
let dest_ty = dest.ty(caller_body, self.tcx);
|
|
let temp =
|
|
Place::from(self.new_call_temp(caller_body, &callsite, dest_ty, return_block));
|
|
caller_body[callsite.block].statements.push(Statement {
|
|
source_info: callsite.source_info,
|
|
kind: StatementKind::Assign(Box::new((temp, dest))),
|
|
});
|
|
self.tcx.mk_place_deref(temp)
|
|
} else {
|
|
destination
|
|
};
|
|
|
|
// Always create a local to hold the destination, as `RETURN_PLACE` may appear
|
|
// where a full `Place` is not allowed.
|
|
let (remap_destination, destination_local) = if let Some(d) = dest.as_local() {
|
|
(false, d)
|
|
} else {
|
|
(
|
|
true,
|
|
self.new_call_temp(
|
|
caller_body,
|
|
&callsite,
|
|
destination.ty(caller_body, self.tcx).ty,
|
|
return_block,
|
|
),
|
|
)
|
|
};
|
|
|
|
// Copy the arguments if needed.
|
|
let args = self.make_call_args(args, &callsite, caller_body, &callee_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: destination_local,
|
|
callsite_scope: caller_body.source_scopes[callsite.source_info.scope].clone(),
|
|
callsite,
|
|
cleanup_block: unwind,
|
|
in_cleanup_block: false,
|
|
return_block,
|
|
tcx: self.tcx,
|
|
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);
|
|
|
|
// 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) = return_block {
|
|
// To avoid repeated O(n) insert, push any new statements to the end and rotate
|
|
// the slice once.
|
|
let mut n = 0;
|
|
if remap_destination {
|
|
caller_body[block].statements.push(Statement {
|
|
source_info: callsite.source_info,
|
|
kind: StatementKind::Assign(Box::new((
|
|
dest,
|
|
Rvalue::Use(Operand::Move(destination_local.into())),
|
|
))),
|
|
});
|
|
n += 1;
|
|
}
|
|
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(callee_body.drain_vars_and_temps());
|
|
caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
|
|
if self
|
|
.tcx
|
|
.sess
|
|
.opts
|
|
.unstable_opts
|
|
.inline_mir_preserve_debug
|
|
.unwrap_or(self.tcx.sess.opts.debuginfo != DebugInfo::None)
|
|
{
|
|
// Note that we need to preserve these in the standard library so that
|
|
// people working on rust can build with or without debuginfo while
|
|
// still getting consistent results from the mir-opt tests.
|
|
caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
|
|
}
|
|
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 required constants from the callee_body into the caller_body. Although we are only
|
|
// pushing unevaluated consts to `required_consts`, here they may have been evaluated
|
|
// because we are calling `instantiate_and_normalize_erasing_regions` -- so we filter again.
|
|
caller_body.required_consts.extend(
|
|
callee_body.required_consts.into_iter().filter(|ct| ct.const_.is_required_const()),
|
|
);
|
|
// Now that we incorporated the callee's `required_consts`, we can remove the callee from
|
|
// `mentioned_items` -- but we have to take their `mentioned_items` in return. This does
|
|
// some extra work here to save the monomorphization collector work later. It helps a lot,
|
|
// since monomorphization can avoid a lot of work when the "mentioned items" are similar to
|
|
// the actually used items. By doing this we can entirely avoid visiting the callee!
|
|
// We need to reconstruct the `required_item` for the callee so that we can find and
|
|
// remove it.
|
|
let callee_item = MentionedItem::Fn(func.ty(caller_body, self.tcx));
|
|
if let Some(idx) =
|
|
caller_body.mentioned_items.iter().position(|item| item.node == callee_item)
|
|
{
|
|
// We found the callee, so remove it and add its items instead.
|
|
caller_body.mentioned_items.remove(idx);
|
|
caller_body.mentioned_items.extend(callee_body.mentioned_items);
|
|
} else {
|
|
// If we can't find the callee, there's no point in adding its items. Probably it
|
|
// already got removed by being inlined elsewhere in the same function, so we already
|
|
// took its items.
|
|
}
|
|
}
|
|
|
|
fn make_call_args(
|
|
&self,
|
|
args: Box<[Spanned<Operand<'tcx>>]>,
|
|
callsite: &CallSite<'tcx>,
|
|
caller_body: &mut Body<'tcx>,
|
|
callee_body: &Body<'tcx>,
|
|
return_block: Option<BasicBlock>,
|
|
) -> Box<[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]`.
|
|
if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
|
|
// FIXME(edition_2024): switch back to a normal method call.
|
|
let mut args = <_>::into_iter(args);
|
|
let self_ = self.create_temp_if_necessary(
|
|
args.next().unwrap().node,
|
|
callsite,
|
|
caller_body,
|
|
return_block,
|
|
);
|
|
let tuple = self.create_temp_if_necessary(
|
|
args.next().unwrap().node,
|
|
callsite,
|
|
caller_body,
|
|
return_block,
|
|
);
|
|
assert!(args.next().is_none());
|
|
|
|
let tuple = Place::from(tuple);
|
|
let ty::Tuple(tuple_tys) = tuple.ty(caller_body, tcx).ty.kind() 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 above.
|
|
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, FieldIdx::new(i), 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 {
|
|
// FIXME(edition_2024): switch back to a normal method call.
|
|
<_>::into_iter(args)
|
|
.map(|a| self.create_temp_if_necessary(a.node, 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: Option<BasicBlock>,
|
|
) -> Local {
|
|
// Reuse the operand if it is a moved temporary.
|
|
if let Operand::Move(place) = &arg
|
|
&& let Some(local) = place.as_local()
|
|
&& caller_body.local_kind(local) == LocalKind::Temp
|
|
{
|
|
return local;
|
|
}
|
|
|
|
// 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, return_block);
|
|
caller_body[callsite.block].statements.push(Statement {
|
|
source_info: callsite.source_info,
|
|
kind: StatementKind::Assign(Box::new((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>,
|
|
return_block: Option<BasicBlock>,
|
|
) -> 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) = return_block {
|
|
caller_body[block].statements.insert(
|
|
0,
|
|
Statement {
|
|
source_info: callsite.source_info,
|
|
kind: StatementKind::StorageDead(local),
|
|
},
|
|
);
|
|
}
|
|
|
|
local
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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: Local,
|
|
callsite_scope: SourceScopeData<'tcx>,
|
|
callsite: &'a CallSite<'tcx>,
|
|
cleanup_block: UnwindAction,
|
|
in_cleanup_block: bool,
|
|
return_block: Option<BasicBlock>,
|
|
tcx: TyCtxt<'tcx>,
|
|
always_live_locals: BitSet<Local>,
|
|
}
|
|
|
|
impl Integrator<'_, '_> {
|
|
fn map_local(&self, local: Local) -> Local {
|
|
let new = if local == RETURN_PLACE {
|
|
self.destination
|
|
} 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
|
|
}
|
|
|
|
fn map_unwind(&self, unwind: UnwindAction) -> UnwindAction {
|
|
if self.in_cleanup_block {
|
|
match unwind {
|
|
UnwindAction::Cleanup(_) | UnwindAction::Continue => {
|
|
bug!("cleanup on cleanup block");
|
|
}
|
|
UnwindAction::Unreachable | UnwindAction::Terminate(_) => return unwind,
|
|
}
|
|
}
|
|
|
|
match unwind {
|
|
UnwindAction::Unreachable | UnwindAction::Terminate(_) => unwind,
|
|
UnwindAction::Cleanup(target) => UnwindAction::Cleanup(self.map_block(target)),
|
|
// Add an unwind edge to the original call's cleanup block
|
|
UnwindAction::Continue => self.cleanup_block,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> MutVisitor<'tcx> for Integrator<'_, '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_data(&mut self, scope_data: &mut SourceScopeData<'tcx>) {
|
|
self.super_source_scope_data(scope_data);
|
|
if scope_data.parent_scope.is_none() {
|
|
// Attach the outermost callee scope as a child of the callsite
|
|
// scope, via the `parent_scope` and `inlined_parent_scope` chains.
|
|
scope_data.parent_scope = Some(self.callsite.source_info.scope);
|
|
assert_eq!(scope_data.inlined_parent_scope, None);
|
|
scope_data.inlined_parent_scope = if self.callsite_scope.inlined.is_some() {
|
|
Some(self.callsite.source_info.scope)
|
|
} else {
|
|
self.callsite_scope.inlined_parent_scope
|
|
};
|
|
|
|
// Mark the outermost callee scope as an inlined one.
|
|
assert_eq!(scope_data.inlined, None);
|
|
scope_data.inlined = Some((self.callsite.callee, self.callsite.source_info.span));
|
|
} else if scope_data.inlined_parent_scope.is_none() {
|
|
// Make it easy to find the scope with `inlined` set above.
|
|
scope_data.inlined_parent_scope = Some(self.map_scope(OUTERMOST_SOURCE_SCOPE));
|
|
}
|
|
}
|
|
|
|
fn visit_source_scope(&mut self, scope: &mut SourceScope) {
|
|
*scope = self.map_scope(*scope);
|
|
}
|
|
|
|
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_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 {
|
|
TerminatorKind::CoroutineDrop | 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, .. } => {
|
|
*target = self.map_block(*target);
|
|
*unwind = self.map_unwind(*unwind);
|
|
}
|
|
TerminatorKind::TailCall { .. } => {
|
|
// check_mir_body forbids tail calls
|
|
unreachable!()
|
|
}
|
|
TerminatorKind::Call { ref mut target, ref mut unwind, .. } => {
|
|
if let Some(ref mut tgt) = *target {
|
|
*tgt = self.map_block(*tgt);
|
|
}
|
|
*unwind = self.map_unwind(*unwind);
|
|
}
|
|
TerminatorKind::Assert { ref mut target, ref mut unwind, .. } => {
|
|
*target = self.map_block(*target);
|
|
*unwind = self.map_unwind(*unwind);
|
|
}
|
|
TerminatorKind::Return => {
|
|
terminator.kind = if let Some(tgt) = self.return_block {
|
|
TerminatorKind::Goto { target: tgt }
|
|
} else {
|
|
TerminatorKind::Unreachable
|
|
}
|
|
}
|
|
TerminatorKind::UnwindResume => {
|
|
terminator.kind = match self.cleanup_block {
|
|
UnwindAction::Cleanup(tgt) => TerminatorKind::Goto { target: tgt },
|
|
UnwindAction::Continue => TerminatorKind::UnwindResume,
|
|
UnwindAction::Unreachable => TerminatorKind::Unreachable,
|
|
UnwindAction::Terminate(reason) => TerminatorKind::UnwindTerminate(reason),
|
|
};
|
|
}
|
|
TerminatorKind::UnwindTerminate(_) => {}
|
|
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 targets, ref mut unwind, .. } => {
|
|
for tgt in targets.iter_mut() {
|
|
*tgt = self.map_block(*tgt);
|
|
}
|
|
*unwind = self.map_unwind(*unwind);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[instrument(skip(tcx), level = "debug")]
|
|
fn try_instance_mir<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
instance: InstanceKind<'tcx>,
|
|
) -> Result<&'tcx Body<'tcx>, &'static str> {
|
|
if let ty::InstanceKind::DropGlue(_, Some(ty))
|
|
| ty::InstanceKind::AsyncDropGlueCtorShim(_, Some(ty)) = instance
|
|
&& let ty::Adt(def, args) = ty.kind()
|
|
{
|
|
let fields = def.all_fields();
|
|
for field in fields {
|
|
let field_ty = field.ty(tcx, args);
|
|
if field_ty.has_param() && field_ty.has_aliases() {
|
|
return Err("cannot build drop shim for polymorphic type");
|
|
}
|
|
}
|
|
}
|
|
Ok(tcx.instance_mir(instance))
|
|
}
|
|
|
|
fn body_is_forwarder(body: &Body<'_>) -> bool {
|
|
let TerminatorKind::Call { target, .. } = body.basic_blocks[START_BLOCK].terminator().kind
|
|
else {
|
|
return false;
|
|
};
|
|
if let Some(target) = target {
|
|
let TerminatorKind::Return = body.basic_blocks[target].terminator().kind else {
|
|
return false;
|
|
};
|
|
}
|
|
|
|
let max_blocks = if !body.is_polymorphic {
|
|
2
|
|
} else if target.is_none() {
|
|
3
|
|
} else {
|
|
4
|
|
};
|
|
if body.basic_blocks.len() > max_blocks {
|
|
return false;
|
|
}
|
|
|
|
body.basic_blocks.iter_enumerated().all(|(bb, bb_data)| {
|
|
bb == START_BLOCK
|
|
|| matches!(
|
|
bb_data.terminator().kind,
|
|
TerminatorKind::Return
|
|
| TerminatorKind::Drop { .. }
|
|
| TerminatorKind::UnwindResume
|
|
| TerminatorKind::UnwindTerminate(_)
|
|
)
|
|
})
|
|
}
|