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Disable top down MIR inlining #105119

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Merged
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Dec 6, 2022
Merged

Disable top down MIR inlining #105119

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28 changes: 6 additions & 22 deletions compiler/rustc_mir_transform/src/inline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@ use rustc_middle::mir::visit::*;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
use rustc_session::config::OptLevel;
use rustc_span::def_id::DefId;
use rustc_span::{hygiene::ExpnKind, ExpnData, LocalExpnId, Span};
use rustc_target::abi::VariantIdx;
use rustc_target::spec::abi::Abi;
Expand Down Expand Up @@ -87,13 +86,8 @@ fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {

let param_env = tcx.param_env_reveal_all_normalized(def_id);

let mut this = Inliner {
tcx,
param_env,
codegen_fn_attrs: tcx.codegen_fn_attrs(def_id),
history: Vec::new(),
changed: false,
};
let mut this =
Inliner { tcx, param_env, codegen_fn_attrs: tcx.codegen_fn_attrs(def_id), changed: false };
let blocks = BasicBlock::new(0)..body.basic_blocks.next_index();
this.process_blocks(body, blocks);
this.changed
Expand All @@ -104,12 +98,6 @@ struct Inliner<'tcx> {
param_env: ParamEnv<'tcx>,
/// Caller codegen attributes.
codegen_fn_attrs: &'tcx CodegenFnAttrs,
/// Stack of inlined instances.
/// We only check the `DefId` and not the substs because we want to
/// avoid inlining cases of polymorphic recursion.
/// The number of `DefId`s is finite, so checking history is enough
/// to ensure that we do not loop endlessly while inlining.
history: Vec<DefId>,
/// Indicates that the caller body has been modified.
changed: bool,
}
Expand All @@ -134,12 +122,12 @@ impl<'tcx> Inliner<'tcx> {
debug!("not-inlined {} [{}]", callsite.callee, reason);
continue;
}
Ok(new_blocks) => {
Ok(_) => {
debug!("inlined {}", callsite.callee);
self.changed = true;
self.history.push(callsite.callee.def_id());
self.process_blocks(caller_body, new_blocks);
self.history.pop();
// We could process the blocks returned by `try_inlining` here. However, that
// leads to exponential compile times due to the top-down nature of this kind
// of inlining.
}
}
}
Expand Down Expand Up @@ -313,10 +301,6 @@ impl<'tcx> Inliner<'tcx> {
return None;
}

if self.history.contains(&callee.def_id()) {
return None;
}

let fn_sig = self.tcx.bound_fn_sig(def_id).subst(self.tcx, substs);

return Some(CallSite {
Expand Down
23 changes: 12 additions & 11 deletions src/test/mir-opt/inline/cycle.g.Inline.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,6 @@
+ let _3: (); // in scope 1 at $DIR/cycle.rs:6:5: 6:8
+ let mut _4: &fn() {main}; // in scope 1 at $DIR/cycle.rs:6:5: 6:6
+ let mut _5: (); // in scope 1 at $DIR/cycle.rs:6:5: 6:8
+ scope 2 (inlined <fn() {main} as Fn<()>>::call - shim(fn() {main})) { // at $DIR/cycle.rs:6:5: 6:8
+ }
+ }

bb0: {
Expand All @@ -29,7 +27,10 @@
+ StorageLive(_4); // scope 1 at $DIR/cycle.rs:6:5: 6:6
+ _4 = &_2; // scope 1 at $DIR/cycle.rs:6:5: 6:6
+ StorageLive(_5); // scope 1 at $DIR/cycle.rs:6:5: 6:8
+ _3 = move (*_4)() -> [return: bb4, unwind: bb2]; // scope 2 at $SRC_DIR/core/src/ops/function.rs:LL:COL
+ _3 = <fn() {main} as Fn<()>>::call(move _4, move _5) -> [return: bb2, unwind: bb3]; // scope 1 at $DIR/cycle.rs:6:5: 6:8
+ // mir::Constant
+ // + span: $DIR/cycle.rs:6:5: 6:6
+ // + literal: Const { ty: for<'a> extern "rust-call" fn(&'a fn() {main}, ()) -> <fn() {main} as FnOnce<()>>::Output {<fn() {main} as Fn<()>>::call}, val: Value(<ZST>) }
}

bb1: {
Expand All @@ -39,19 +40,19 @@
return; // scope 0 at $DIR/cycle.rs:+2:2: +2:2
+ }
+
+ bb2 (cleanup): {
+ drop(_2) -> bb3; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ bb2: {
+ StorageDead(_5); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_4); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_3); // scope 1 at $DIR/cycle.rs:6:8: 6:9
+ drop(_2) -> bb1; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ }
+
+ bb3 (cleanup): {
+ resume; // scope 1 at $DIR/cycle.rs:5:1: 7:2
+ drop(_2) -> bb4; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ }
+
+ bb4: {
+ StorageDead(_5); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_4); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_3); // scope 1 at $DIR/cycle.rs:6:8: 6:9
+ drop(_2) -> bb1; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ bb4 (cleanup): {
+ resume; // scope 1 at $DIR/cycle.rs:5:1: 7:2
}
}

40 changes: 12 additions & 28 deletions src/test/mir-opt/inline/cycle.main.Inline.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -10,18 +10,6 @@
+ let _3: (); // in scope 1 at $DIR/cycle.rs:6:5: 6:8
+ let mut _4: &fn() {g}; // in scope 1 at $DIR/cycle.rs:6:5: 6:6
+ let mut _5: (); // in scope 1 at $DIR/cycle.rs:6:5: 6:8
+ scope 2 (inlined <fn() {g} as Fn<()>>::call - shim(fn() {g})) { // at $DIR/cycle.rs:6:5: 6:8
+ scope 3 (inlined g) { // at $SRC_DIR/core/src/ops/function.rs:LL:COL
+ let mut _6: fn() {main}; // in scope 3 at $DIR/cycle.rs:12:5: 12:12
+ scope 4 (inlined f::<fn() {main}>) { // at $DIR/cycle.rs:12:5: 12:12
+ debug g => _6; // in scope 4 at $DIR/cycle.rs:5:6: 5:7
+ let _7: (); // in scope 4 at $DIR/cycle.rs:6:5: 6:8
+ let mut _8: &fn() {main}; // in scope 4 at $DIR/cycle.rs:6:5: 6:6
+ scope 5 (inlined <fn() {main} as Fn<()>>::call - shim(fn() {main})) { // at $DIR/cycle.rs:6:5: 6:8
+ }
+ }
+ }
+ }
+ }

bb0: {
Expand All @@ -39,11 +27,10 @@
+ StorageLive(_4); // scope 1 at $DIR/cycle.rs:6:5: 6:6
+ _4 = &_2; // scope 1 at $DIR/cycle.rs:6:5: 6:6
+ StorageLive(_5); // scope 1 at $DIR/cycle.rs:6:5: 6:8
+ StorageLive(_6); // scope 3 at $DIR/cycle.rs:12:5: 12:12
+ StorageLive(_7); // scope 4 at $DIR/cycle.rs:6:5: 6:8
+ StorageLive(_8); // scope 4 at $DIR/cycle.rs:6:5: 6:6
+ _8 = &_6; // scope 4 at $DIR/cycle.rs:6:5: 6:6
+ _7 = move (*_8)() -> [return: bb4, unwind: bb2]; // scope 5 at $SRC_DIR/core/src/ops/function.rs:LL:COL
+ _3 = <fn() {g} as Fn<()>>::call(move _4, move _5) -> [return: bb2, unwind: bb3]; // scope 1 at $DIR/cycle.rs:6:5: 6:8
+ // mir::Constant
+ // + span: $DIR/cycle.rs:6:5: 6:6
+ // + literal: Const { ty: for<'a> extern "rust-call" fn(&'a fn() {g}, ()) -> <fn() {g} as FnOnce<()>>::Output {<fn() {g} as Fn<()>>::call}, val: Value(<ZST>) }
}

bb1: {
Expand All @@ -53,22 +40,19 @@
return; // scope 0 at $DIR/cycle.rs:+2:2: +2:2
+ }
+
+ bb2 (cleanup): {
+ drop(_2) -> bb3; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ bb2: {
+ StorageDead(_5); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_4); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_3); // scope 1 at $DIR/cycle.rs:6:8: 6:9
+ drop(_2) -> bb1; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ }
+
+ bb3 (cleanup): {
+ resume; // scope 1 at $DIR/cycle.rs:5:1: 7:2
+ drop(_2) -> bb4; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ }
+
+ bb4: {
+ StorageDead(_8); // scope 4 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_7); // scope 4 at $DIR/cycle.rs:6:8: 6:9
+ StorageDead(_6); // scope 3 at $DIR/cycle.rs:12:5: 12:12
+ StorageDead(_5); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_4); // scope 1 at $DIR/cycle.rs:6:7: 6:8
+ StorageDead(_3); // scope 1 at $DIR/cycle.rs:6:8: 6:9
+ drop(_2) -> bb1; // scope 1 at $DIR/cycle.rs:7:1: 7:2
+ bb4 (cleanup): {
+ resume; // scope 1 at $DIR/cycle.rs:5:1: 7:2
}
}

50 changes: 50 additions & 0 deletions src/test/mir-opt/inline/exponential_runtime.main.Inline.diff
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
- // MIR for `main` before Inline
+ // MIR for `main` after Inline

fn main() -> () {
let mut _0: (); // return place in scope 0 at $DIR/exponential_runtime.rs:+0:11: +0:11
let _1: (); // in scope 0 at $DIR/exponential_runtime.rs:+1:5: +1:22
+ scope 1 (inlined <() as G>::call) { // at $DIR/exponential_runtime.rs:86:5: 86:22
+ let _2: (); // in scope 1 at $DIR/exponential_runtime.rs:73:9: 73:25
+ let _3: (); // in scope 1 at $DIR/exponential_runtime.rs:74:9: 74:25
+ let _4: (); // in scope 1 at $DIR/exponential_runtime.rs:75:9: 75:25
+ }

bb0: {
StorageLive(_1); // scope 0 at $DIR/exponential_runtime.rs:+1:5: +1:22
- _1 = <() as G>::call() -> bb1; // scope 0 at $DIR/exponential_runtime.rs:+1:5: +1:22
+ StorageLive(_2); // scope 1 at $DIR/exponential_runtime.rs:73:9: 73:25
+ _2 = <() as F>::call() -> bb1; // scope 1 at $DIR/exponential_runtime.rs:73:9: 73:25
// mir::Constant
- // + span: $DIR/exponential_runtime.rs:86:5: 86:20
- // + literal: Const { ty: fn() {<() as G>::call}, val: Value(<ZST>) }
+ // + span: $DIR/exponential_runtime.rs:73:9: 73:23
+ // + literal: Const { ty: fn() {<() as F>::call}, val: Value(<ZST>) }
}

bb1: {
+ StorageDead(_2); // scope 1 at $DIR/exponential_runtime.rs:73:25: 73:26
+ StorageLive(_3); // scope 1 at $DIR/exponential_runtime.rs:74:9: 74:25
+ _3 = <() as F>::call() -> bb2; // scope 1 at $DIR/exponential_runtime.rs:74:9: 74:25
+ // mir::Constant
+ // + span: $DIR/exponential_runtime.rs:74:9: 74:23
+ // + literal: Const { ty: fn() {<() as F>::call}, val: Value(<ZST>) }
+ }
+
+ bb2: {
+ StorageDead(_3); // scope 1 at $DIR/exponential_runtime.rs:74:25: 74:26
+ StorageLive(_4); // scope 1 at $DIR/exponential_runtime.rs:75:9: 75:25
+ _4 = <() as F>::call() -> bb3; // scope 1 at $DIR/exponential_runtime.rs:75:9: 75:25
+ // mir::Constant
+ // + span: $DIR/exponential_runtime.rs:75:9: 75:23
+ // + literal: Const { ty: fn() {<() as F>::call}, val: Value(<ZST>) }
+ }
+
+ bb3: {
+ StorageDead(_4); // scope 1 at $DIR/exponential_runtime.rs:75:25: 75:26
StorageDead(_1); // scope 0 at $DIR/exponential_runtime.rs:+1:22: +1:23
_0 = const (); // scope 0 at $DIR/exponential_runtime.rs:+0:11: +2:2
return; // scope 0 at $DIR/exponential_runtime.rs:+2:2: +2:2
}
}

87 changes: 87 additions & 0 deletions src/test/mir-opt/inline/exponential_runtime.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,87 @@
// Checks that code with exponential runtime does not have exponential behavior in inlining.

trait A {
fn call();
}

trait B {
fn call();
}
impl<T: A> B for T {
#[inline]
fn call() {
<T as A>::call();
<T as A>::call();
<T as A>::call();
}
}

trait C {
fn call();
}
impl<T: B> C for T {
#[inline]
fn call() {
<T as B>::call();
<T as B>::call();
<T as B>::call();
}
}

trait D {
fn call();
}
impl<T: C> D for T {
#[inline]
fn call() {
<T as C>::call();
<T as C>::call();
<T as C>::call();
}
}

trait E {
fn call();
}
impl<T: D> E for T {
#[inline]
fn call() {
<T as D>::call();
<T as D>::call();
<T as D>::call();
}
}

trait F {
fn call();
}
impl<T: E> F for T {
#[inline]
fn call() {
<T as E>::call();
<T as E>::call();
<T as E>::call();
}
}

trait G {
fn call();
}
impl<T: F> G for T {
#[inline]
fn call() {
<T as F>::call();
<T as F>::call();
<T as F>::call();
}
}

impl A for () {
#[inline(never)]
fn call() {}
}

// EMIT_MIR exponential_runtime.main.Inline.diff
fn main() {
<() as G>::call();
}
11 changes: 4 additions & 7 deletions src/test/mir-opt/inline/inline_cycle.one.Inline.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -5,20 +5,17 @@
let mut _0: (); // return place in scope 0 at $DIR/inline_cycle.rs:+0:10: +0:10
let _1: (); // in scope 0 at $DIR/inline_cycle.rs:+1:5: +1:24
+ scope 1 (inlined <C as Call>::call) { // at $DIR/inline_cycle.rs:14:5: 14:24
+ scope 2 (inlined <A<C> as Call>::call) { // at $DIR/inline_cycle.rs:43:9: 43:23
+ scope 3 (inlined <B<C> as Call>::call) { // at $DIR/inline_cycle.rs:28:9: 28:31
+ }
+ }
+ }

bb0: {
StorageLive(_1); // scope 0 at $DIR/inline_cycle.rs:+1:5: +1:24
- _1 = <C as Call>::call() -> bb1; // scope 0 at $DIR/inline_cycle.rs:+1:5: +1:24
+ _1 = <C as Call>::call() -> bb1; // scope 3 at $DIR/inline_cycle.rs:36:9: 36:28
+ _1 = <A<C> as Call>::call() -> bb1; // scope 1 at $DIR/inline_cycle.rs:43:9: 43:23
// mir::Constant
- // + span: $DIR/inline_cycle.rs:14:5: 14:22
+ // + span: $DIR/inline_cycle.rs:36:9: 36:26
// + literal: Const { ty: fn() {<C as Call>::call}, val: Value(<ZST>) }
- // + literal: Const { ty: fn() {<C as Call>::call}, val: Value(<ZST>) }
+ // + span: $DIR/inline_cycle.rs:43:9: 43:21
+ // + literal: Const { ty: fn() {<A<C> as Call>::call}, val: Value(<ZST>) }
}

bb1: {
Expand Down
23 changes: 7 additions & 16 deletions src/test/mir-opt/inline/inline_cycle.two.Inline.diff
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Original file line number Diff line number Diff line change
Expand Up @@ -9,11 +9,6 @@
+ debug f => _2; // in scope 1 at $DIR/inline_cycle.rs:53:22: 53:23
+ let _3: (); // in scope 1 at $DIR/inline_cycle.rs:54:5: 54:8
+ let mut _4: (); // in scope 1 at $DIR/inline_cycle.rs:54:5: 54:8
+ scope 2 (inlined <fn() {f} as FnOnce<()>>::call_once - shim(fn() {f})) { // at $DIR/inline_cycle.rs:54:5: 54:8
+ scope 3 (inlined f) { // at $SRC_DIR/core/src/ops/function.rs:LL:COL
+ let _5: (); // in scope 3 at $DIR/inline_cycle.rs:59:5: 59:12
+ }
+ }
+ }

bb0: {
Expand All @@ -23,23 +18,19 @@
+ _2 = f; // scope 0 at $DIR/inline_cycle.rs:+1:5: +1:12
// mir::Constant
- // + span: $DIR/inline_cycle.rs:49:5: 49:9
+ // + span: $DIR/inline_cycle.rs:49:10: 49:11
+ // + literal: Const { ty: fn() {f}, val: Value(<ZST>) }
- // + literal: Const { ty: fn(fn() {f}) {call::<fn() {f}>}, val: Value(<ZST>) }
- // mir::Constant
// + span: $DIR/inline_cycle.rs:49:10: 49:11
// + literal: Const { ty: fn() {f}, val: Value(<ZST>) }
+ StorageLive(_3); // scope 1 at $DIR/inline_cycle.rs:54:5: 54:8
+ StorageLive(_4); // scope 1 at $DIR/inline_cycle.rs:54:5: 54:8
+ StorageLive(_5); // scope 3 at $DIR/inline_cycle.rs:59:5: 59:12
+ _5 = call::<fn() {f}>(f) -> bb1; // scope 3 at $DIR/inline_cycle.rs:59:5: 59:12
+ _3 = <fn() {f} as FnOnce<()>>::call_once(move _2, move _4) -> bb1; // scope 1 at $DIR/inline_cycle.rs:54:5: 54:8
+ // mir::Constant
+ // + span: $DIR/inline_cycle.rs:59:5: 59:9
// + literal: Const { ty: fn(fn() {f}) {call::<fn() {f}>}, val: Value(<ZST>) }
// mir::Constant
- // + span: $DIR/inline_cycle.rs:49:10: 49:11
+ // + span: $DIR/inline_cycle.rs:59:10: 59:11
// + literal: Const { ty: fn() {f}, val: Value(<ZST>) }
+ // + span: $DIR/inline_cycle.rs:54:5: 54:6
+ // + literal: Const { ty: extern "rust-call" fn(fn() {f}, ()) -> <fn() {f} as FnOnce<()>>::Output {<fn() {f} as FnOnce<()>>::call_once}, val: Value(<ZST>) }
}

bb1: {
+ StorageDead(_5); // scope 3 at $DIR/inline_cycle.rs:59:12: 59:13
+ StorageDead(_4); // scope 1 at $DIR/inline_cycle.rs:54:7: 54:8
+ StorageDead(_3); // scope 1 at $DIR/inline_cycle.rs:54:8: 54:9
+ StorageDead(_2); // scope 0 at $DIR/inline_cycle.rs:+1:5: +1:12
Expand Down
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