Assertion failed error on nightly-2017-04-22

[lloydmeta]

Trying to bench Frunk with the latest nightly gives me the following error:

Assertion failed: (ReqTy && "extractvalue indices invalid!"), function getExtractValue, file /Users/travis/build/rust-lang/rust/src/llvm/lib/IR/Constants.cpp, line 2096.

I was told to file a bug here by someone in the users forum

[lloydmeta]

Just wanted to add that it works with nightly-2017-04-21

[arielb1]

Which commit causes the assertion failure? Is it the latest one (e36e120)?

[lloydmeta]

Yep, that should do it.

My current nightly is at rustc 1.18.0-nightly (252d3da8a 2017-04-22), and running rustup run nightly cargo bench throws that error.

Edit: Some more details:

1. I'm on a Mac
2. I didn't need to change any code on my end to make this fail; it just started failing today after pulling in the updates on nightly.

[arielb1]

Can confirm LLVM assertion.

[arielb1]

INFO:rustc_trans::base: trans_instance(<coproduct::Coproduct<CH, CTail> as coproduct::CoproductFoldable<frunk_core::hlist::HCons<F, FTail>, R>><[closure@src/coproduct.rs:368:38: 368:62], std::string::String, frunk_core::hlist::HCons<[closure@src/coproduct.rs:369:38: 369:64], frunk_core::hlist::HCons<[closure@src/coproduct.rs:370:38: 370:81], frunk_core::hlist::HNil>>, i32, coproduct::Coproduct<f32, coproduct::Coproduct<bool, coproduct::CNil>>>::fold)

#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007ffff735c3fa in __GI_abort () at abort.c:89
#2  0x00007ffff7353e37 in __assert_fail_base (fmt=<optimized out>, 
    assertion=assertion@entry=0x7ffff3406a40 "ReqTy && \"extractvalue indices invalid!\"", 
    file=file@entry=0x7ffff34041b8 "rust://rust/src/llvm/lib/IR/Constants.cpp", line=line@entry=2096, 
    function=function@entry=0x7ffff3407f00 <llvm::ConstantExpr::getExtractValue(llvm::Constant*, llvm::ArrayRef<unsigned int>, llvm::Type*)::__PRETTY_FUNCTION__> "static llvm::Constant* llvm::ConstantExpr::getExtractValue(llvm::Constant*, llvm::ArrayRef<unsigned int>, llvm::Type*)") at assert.c:92
#3  0x00007ffff7353ee2 in __GI___assert_fail (
    assertion=0x7ffff3406a40 "ReqTy && \"extractvalue indices invalid!\"", 
    file=0x7ffff34041b8 "rust://rust/src/llvm/lib/IR/Constants.cpp", 
    line=2096, 
    function=0x7ffff3407f00 <llvm::ConstantExpr::getExtractValue(llvm::Constant*, llvm::ArrayRef<unsigned int>, llvm::Type*)::__PRETTY_FUNCTION__> "static llvm::Constant* llvm::ConstantExpr::getExtractValue(llvm::Constant*, llvm::ArrayRef<unsigned int>, llvm::Type*)") at assert.c:101
#4  0x00007ffff24b4c23 in llvm::ConstantExpr::getExtractValue(llvm::Constant*, llvm::ArrayRef<unsigned int>, llvm::Type*) ()
   from rust://rust/build-debug-assertions/build/x86_64-unknown-linux-gnu/stage2/bin/../lib/../lib/librustc_llvm-6974c8fa2ebb71c2.so
#5  0x00007ffff24c0279 in LLVMBuildExtractValue ()
   from rust://rust/build-debug-assertions/build/x86_64-unknown-linux-gnu/stage2/bin/../lib/../lib/librustc_llvm-6974c8fa2ebb71c2.so
#6  0x00007ffff6eb1f22 in rustc_trans::builder::Builder::extract_value ()
    at rust://rust/src/librustc_trans/builder.rs:956
#7  rustc_trans::mir::operand::OperandRef::unpack_if_pair ()
    at rust://rust/src/librustc_trans/mir/operand.rs:159
#8  0x00007ffff6eb25c7 in rustc_trans::mir::MirContext::trans_consume ()
    at rust://rust/src/librustc_trans/mir/operand.rs:255
#9  0x00007ffff6eb27c3 in rustc_trans::mir::MirContext::trans_operand ()
    at rust://rust/src/librustc_trans/mir/operand.rs:279
#10 0x00007ffff6eb3dba in rustc_trans::mir::MirContext::trans_rvalue_operand ()
    at rust://rust/src/librustc_trans/mir/rvalue.rs:462
#11 0x00007ffff6e9ff44 in rustc_trans::mir::MirContext::trans_statement ()
    at rust://rust/src/librustc_trans/mir/statement.rs:52
#12 rustc_trans::mir::MirContext::trans_block ()
    at rust://rust/src/librustc_trans/mir/block.rs:109
#13 0x00007ffff6e9c258 in rustc_trans::mir::trans_mir ()
    at rust://rust/src/librustc_trans/mir/mod.rs:326
#14 0x00007ffff6ec12ce in rustc_trans::base::trans_instance ()
    at rust://rust/src/librustc_trans/base.rs:608
#15 rustc_trans::trans_item::TransItem::define ()
    at rust://rust/src/librustc_trans/trans_item.rs:103
#16 0x00007ffff6e4fbd1 in rustc_trans::base::trans_crate::module_translation ()
    at rust://rust/src/librustc_trans/base.rs:1189
#17 rustc::dep_graph::graph::DepGraph::with_task<rustc::dep_graph::safe::AssertDepGraphSafe<&rustc_trans::context::SharedCrateContext>,rustc::dep_graph::safe::AssertDepGraphSafe<rustc_trans::partitioning::CodegenUnit>,(rustc_trans::context::Stats, rustc_trans::ModuleTranslation)> ()
    at rust://rust/src/librustc/dep_graph/graph.rs:111
#18 rustc_trans::base::trans_crate::{{closure}} ()
    at rust://rust/src/librustc_trans/base.rs:1122

DEBUG:rustc_trans::mir::operand: trans_operand(operand=(_4.1: FTail))
DEBUG:rustc_trans::mir::operand: trans_consume(lvalue=(_4.1: FTail))
DEBUG:rustc_trans::mir::operand: Operand::unpack_if_pair: unpacking OperandRef(Immediate(([0 x i8]:[0 x i8] zeroinitializer)) @ frunk_core::hlist::HCons<[closure@src/coproduct.rs:369:38: 369:64], frunk_core::hlist::HCons<[closure@src/coproduct.rs:370:38: 370:81], frunk_core::hlist::HNil>>)

Looks like a ZST pair.

[bitshifter]

That's most likely from 6d841da. cc @eddyb

[bitshifter]

Looking at the rustc code, these lines probably need to take account of padding fields if the type is a struct https://github.com/rust-lang/rust/blob/master/src/librustc_trans/mir/operand.rs#L159-L160. I'll take a look.

[bitshifter]

It would be good to come up with a simple test case which exhibits this crash, the code in question is in a macro, so not that easy to see what it's doing.

[bitshifter]

Reduced failing code down to https://pastebin.com/RFKDmsbZ. Probably as far as I can easily go.

[eddyb]

@bitshifter That's correct - it's hard to see it in a diff, but if packing changed, unpacking should too.

[bitshifter]

Seems it's not the indexing in this case, although that does look wrong. The OperandRef::ty in this case is a zero pad field:

DEBUG:rustc_trans::mir::operand: Operand::unpack_if_pair: unpacking OperandRef(Immediate(([0 x i8]:[0 x i8] zeroinitializer)) @ HCons<[closure@issue-41479.rs:42:62: 42:74], HNil>)

Which doesn't look right.

[bitshifter]

PR at #41529. Not sure if I should add https://pastebin.com/RFKDmsbZ as a test. I haven't been able to come up with a simpler reproduction. And it's a copy of code from https://github.com/lloydmeta/frunk, not sure if that's OK.

[eddyb]

@bitshifter Okay let me try.

[eddyb]

fn split<A, B>(pair: (A, B)) {
    let _a = pair.0;
    let _b = pair.1;
}

fn main() {
    split(((), ((), ())));
}

[nikomatsakis]

triage: P-high (regression)