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Merged
merged 1 commit into from
Nov 11, 2018
Merged

Don't inline virtual calls (take 2) #55802

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94 changes: 49 additions & 45 deletions src/librustc_mir/transform/inline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ use rustc_data_structures::indexed_vec::{Idx, IndexVec};

use rustc::mir::*;
use rustc::mir::visit::*;
use rustc::ty::{self, Instance, InstanceDef, Ty, TyCtxt};
use rustc::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
use rustc::ty::subst::{Subst,Substs};

use std::collections::VecDeque;
Expand Down Expand Up @@ -85,39 +85,16 @@ impl<'a, 'tcx> Inliner<'a, 'tcx> {
// Only do inlining into fn bodies.
let id = self.tcx.hir.as_local_node_id(self.source.def_id).unwrap();
let body_owner_kind = self.tcx.hir.body_owner_kind(id);

if let (hir::BodyOwnerKind::Fn, None) = (body_owner_kind, self.source.promoted) {

for (bb, bb_data) in caller_mir.basic_blocks().iter_enumerated() {
// Don't inline calls that are in cleanup blocks.
if bb_data.is_cleanup { continue; }

// 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_mir, self.tcx).sty {
if let Some(instance) = Instance::resolve(self.tcx,
param_env,
callee_def_id,
substs) {
let is_virtual =
if let InstanceDef::Virtual(..) = instance.def {
true
} else {
false
};

if !is_virtual {
callsites.push_back(CallSite {
callee: instance.def_id(),
substs: instance.substs,
bb,
location: terminator.source_info
});
}
}
}
}
if let Some(callsite) = self.get_valid_function_call(bb,
bb_data,
caller_mir,
param_env) {
callsites.push_back(callsite);
}
}
} else {
return;
Expand Down Expand Up @@ -163,20 +140,13 @@ impl<'a, 'tcx> Inliner<'a, 'tcx> {

// Add callsites from inlined function
for (bb, bb_data) in caller_mir.basic_blocks().iter_enumerated().skip(start) {
// Only consider direct calls to functions
let terminator = bb_data.terminator();
if let TerminatorKind::Call {
func: Operand::Constant(ref f), .. } = terminator.kind {
if let ty::FnDef(callee_def_id, substs) = f.ty.sty {
// Don't inline the same function multiple times.
if callsite.callee != callee_def_id {
callsites.push_back(CallSite {
callee: callee_def_id,
substs,
bb,
location: terminator.source_info
});
}
if let Some(new_callsite) = self.get_valid_function_call(bb,
bb_data,
caller_mir,
param_env) {
// Don't inline the same function multiple times.
if callsite.callee != new_callsite.callee {
callsites.push_back(new_callsite);
}
}
}
Expand All @@ -198,6 +168,40 @@ impl<'a, 'tcx> Inliner<'a, 'tcx> {
}
}

fn get_valid_function_call(&self,
bb: BasicBlock,
bb_data: &BasicBlockData<'tcx>,
caller_mir: &Mir<'tcx>,
param_env: ParamEnv<'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_mir, self.tcx).sty {
let instance = Instance::resolve(self.tcx,
param_env,
callee_def_id,
substs)?;

if let InstanceDef::Virtual(..) = instance.def {
return None;
}

return Some(CallSite {
callee: instance.def_id(),
substs: instance.substs,
bb,
location: terminator.source_info
});
}
}

None
}

fn consider_optimizing(&self,
callsite: CallSite<'tcx>,
callee_mir: &Mir<'tcx>)
Expand Down
36 changes: 36 additions & 0 deletions src/test/mir-opt/inline-trait-method_2.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
// compile-flags: -Z span_free_formats -Z mir-opt-level=3

#[inline]
fn test(x: &dyn X) -> bool {
x.y()
}

fn test2(x: &dyn X) -> bool {
test(x)
}

trait X {
fn y(&self) -> bool {
false
}
}

impl X for () {
fn y(&self) -> bool {
true
}
}

fn main() {
println!("Should be true: {}", test2(&()));
}

// END RUST SOURCE
// START rustc.test2.Inline.after.mir
// ...
// bb0: {
// ...
// _0 = const X::y(move _2) -> bb1;
// }
// ...
// END rustc.test2.Inline.after.mir