miri: ICE on invalid terminators

[RalfJung]

We've run a lot of MIR in Miri (including some generators) and never seen these.

@tmandry is it correct that Yield and GeneratorDrop get lowered away?

@eddyb @oli-obk what's with this Abort that does not seem to ever actually exist? Codegen does seem to handle it, so I wonder why Miri can get away without that. In fact, codegen handles it twice:

rust/src/librustc_codegen_ssa/mir/block.rs

Line 796 in 1d5241c

mir::TerminatorKind::Abort => {

rust/src/librustc_codegen_ssa/mir/mod.rs

Line 296 in 1d5241c

Some(&mir::TerminatorKind::Abort) => {

[rust-highfive]

r? @eddyb

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

[jonas-schievink]

is it correct that Yield and GeneratorDrop get lowered away?

They get lowered by the generator transform, so if you run before that you'll still encounter them. If you run after it they should all be gone though.

[RalfJung]

Yeah we definitely run after that.

[matthewjasper]

Abort is used instead of Resume for functions annotated with #[unwind(aborts)] when compiling with -Cpanic=unwind.

[RalfJung]

@matthewjasper Ah! Here's a Miri reproducer then:

#![feature(unwind_attributes)]

#[unwind(aborts)]
fn panic_abort() { panic!() }

fn main() {
    panic_abort();
}

[RalfJung]

All right, I think this is ready now.
r? @oli-obk

[oli-obk]

Shouldn't the abort intrinsic also forward to this new machine hook?

You can probably run your miri repro under unleash, too.

[RalfJung]

Shouldn't the abort intrinsic also forward to this new machine hook?

So far the core Miri engine knows nothing about the abort intrinsic. You want to see it added to librustc_mir/interpret/intrinsics.rs?

You can probably run your miri repro under unleash, too.

Yeah but we don't actually support aborting in CTFE so I am not entirely sure about the point of that...^^

[RalfJung]

I added the abort intrinsic. At some point we should probably just move all the intrinsics from Miri to here... well, all except atomics and those requiring host floating point maybe.

[oli-obk]

@bors r+

[bors]

📌 Commit 911c75f has been approved by oli-obk