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

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wesleywiser
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When I fixed the previous mis-optimizations, I didn't realize there were
actually two different places where we mutate callsites and both of
them should have the same behavior.

As a result, if a function was inlined and that function contained
virtual function calls, they were incorrectly being inlined. I also
added a test case which covers this.

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r? @michaelwoerister

(rust_highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 9, 2018
@michaelwoerister
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Thanks for the PR, @wesleywiser!

@rust-lang/compiler, who is best suited for reviewing MIR inlining changes?

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@oli-obk oli-obk left a comment

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Just some nits

substs) {
let is_virtual =
if let InstanceDef::Virtual(..) = instance.def {
true
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Since this is now its own function, you can get rid of is_virtual and just return None here.

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,
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This can now just be let instance = Instance::resolve(....)?;

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bors commented Nov 9, 2018

☔ The latest upstream changes (presumably #55803) made this pull request unmergeable. Please resolve the merge conflicts.

When I fixed the previous mis-optimizations, I didn't realize there were
actually two different places where we mutate `callsites` and both of
them should have the same behavior.

As a result, if a function was inlined and that function contained
virtual function calls, they were incorrectly being inlined. I also
added a test case which covers this.
@wesleywiser wesleywiser force-pushed the inlined_calls_2_electric_boogaloo branch from f80b1a3 to 3cce5c7 Compare November 10, 2018 03:11
@wesleywiser
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Good ideas @oli-obk!

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nagisa commented Nov 10, 2018

@bors r+

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bors commented Nov 10, 2018

📌 Commit 3cce5c7 has been approved by nagisa

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 10, 2018
pietroalbini added a commit to pietroalbini/rust that referenced this pull request Nov 10, 2018
…c_boogaloo, r=nagisa

Don't inline virtual calls (take 2)

When I fixed the previous mis-optimizations, I didn't realize there were
actually two different places where we mutate `callsites` and both of
them should have the same behavior.

As a result, if a function was inlined and that function contained
virtual function calls, they were incorrectly being inlined. I also
added a test case which covers this.
bors added a commit that referenced this pull request Nov 11, 2018
Rollup of 17 pull requests

Successful merges:

 - #55630 (resolve: Filter away macro prelude in modules with `#[no_implicit_prelude]` on 2018 edition)
 - #55687 (Take supertraits into account when calculating associated types)
 - #55745 (Convert `outlives_components`' return value to a `SmallVec` outparam.)
 - #55764 (Fix Rc/Arc allocation layout)
 - #55792 (Prevent ICE in const-prop array oob check)
 - #55799 (Removed unneeded instance of `// revisions` from a lint test)
 - #55800 (Fix ICE in `return_type_impl_trait`)
 - #55801 (NLL: Update box insensitivity test)
 - #55802 (Don't inline virtual calls (take 2))
 - #55816 (Use `SmallVec` to avoid allocations in `from_decimal_string`.)
 - #55819 (Typecheck patterns of all match arms first, so we get types for bindings)
 - #55822 (ICE with #![feature(nll)] and elided lifetimes)
 - #55828 (Add missing `rustc_promotable` attribute to unsigned `min_value` and `max_value`)
 - #55839 (Fix docstring spelling mistakes)
 - #55844 (Fix documentation typos.)
 - #55845 (Set BINARYEN_TRAP_MODE=clamp)
 - #55856 (rustdoc: refactor: move all static-file include!s into a single module)
@bors bors merged commit 3cce5c7 into rust-lang:master Nov 11, 2018
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6 participants