ICE: "Got a scalar pair where a scalar was expected" -Zmir-opt-level=4 --emit=mir #96169

matthiaskrgr · 2022-04-18T06:13:08Z

Code

// run-rustfix
#![allow(unused)]
fn a() -> usize { 0 }
//~^ ERROR return types are denoted using `->`

fn bar(_: u32) {}

fn baz() -> *const dyn Fn(u32) { unimplemented!() }

fn foo() {
    match () {
        _ if baz() == &bar as &dyn Fn(u32) => (),
        () => (),
    }
}

fn main() {
}

Error output

Backtrace

error: internal compiler error: /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/compiler/rustc_const_eval/src/interpret/operand.rs:77:42: Got a scalar pair where a scalar was expected

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/compiler/rustc_errors/src/lib.rs:1349:9
stack backtrace:
   0:     0x7f0edf49d7fd - std::backtrace_rs::backtrace::libunwind::trace::h533af29c806df9d1
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f0edf49d7fd - std::backtrace_rs::backtrace::trace_unsynchronized::hdb4c2ff88b52ef66
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0edf49d7fd - std::sys_common::backtrace::_print_fmt::h68495a06222c4efb
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/sys_common/backtrace.rs:66:5
   3:     0x7f0edf49d7fd - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h91043f683408357d
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/sys_common/backtrace.rs:45:22
   4:     0x7f0edf4f8eec - core::fmt::write::hcc15453d8963f001
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/core/src/fmt/mod.rs:1194:17
   5:     0x7f0edf48ef51 - std::io::Write::write_fmt::h5217846c280e1260
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/io/mod.rs:1655:15
   6:     0x7f0edf4a0515 - std::sys_common::backtrace::_print::h88be4bfce1061450
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/sys_common/backtrace.rs:48:5
   7:     0x7f0edf4a0515 - std::sys_common::backtrace::print::he017a6566e010988
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/sys_common/backtrace.rs:35:9
   8:     0x7f0edf4a0515 - std::panicking::default_hook::{{closure}}::hb793c4d82607bce7
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/panicking.rs:295:22
   9:     0x7f0edf4a0189 - std::panicking::default_hook::hc3c558385f484fdc
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/panicking.rs:314:9
  10:     0x7f0edfcd1421 - rustc_driver[19d608e2c8daf1f4]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f0edf4a0ce6 - std::panicking::rust_panic_with_hook::h28c3b2fc9e3a60cd
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/panicking.rs:702:17
  12:     0x7f0ee0d28881 - std[cd658a55527ed977]::panicking::begin_panic::<rustc_errors[9417c7ccc58903d8]::ExplicitBug>::{closure#0}
  13:     0x7f0ee0d27d96 - std[cd658a55527ed977]::sys_common::backtrace::__rust_end_short_backtrace::<std[cd658a55527ed977]::panicking::begin_panic<rustc_errors[9417c7ccc58903d8]::ExplicitBug>::{closure#0}, !>
  14:     0x7f0ee0cbddef - std[cd658a55527ed977]::panicking::begin_panic::<rustc_errors[9417c7ccc58903d8]::ExplicitBug>
  15:     0x7f0ee0c6f166 - std[cd658a55527ed977]::panic::panic_any::<rustc_errors[9417c7ccc58903d8]::ExplicitBug>
  16:     0x7f0ee0c6afe5 - <rustc_errors[9417c7ccc58903d8]::HandlerInner>::bug::<&alloc[c0e4610846cb0c5f]::string::String>
  17:     0x7f0ee0c6ad50 - <rustc_errors[9417c7ccc58903d8]::Handler>::bug::<&alloc[c0e4610846cb0c5f]::string::String>
  18:     0x7f0ee0d314bd - rustc_middle[77cffc0d0a9caf4f]::ty::context::tls::with_opt::<rustc_middle[77cffc0d0a9caf4f]::util::bug::opt_span_bug_fmt<rustc_span[ae9ba53627e4b7a2]::span_encoding::Span>::{closure#0}, ()>
  19:     0x7f0ee0d33f46 - rustc_middle[77cffc0d0a9caf4f]::util::bug::opt_span_bug_fmt::<rustc_span[ae9ba53627e4b7a2]::span_encoding::Span>
  20:     0x7f0ee0d33eb3 - rustc_middle[77cffc0d0a9caf4f]::util::bug::bug_fmt
  21:     0x7f0edfebeecf - <rustc_const_eval[2c45cfb8cbd0596a]::interpret::operand::Immediate>::to_scalar
  22:     0x7f0ee10cd5e2 - <rustc_mir_transform[30431bd415c4c272]::const_prop::ConstPropagator as rustc_middle[77cffc0d0a9caf4f]::mir::visit::MutVisitor>::visit_body
  23:     0x7f0ee10c9264 - <rustc_mir_transform[30431bd415c4c272]::const_prop::ConstProp as rustc_middle[77cffc0d0a9caf4f]::mir::MirPass>::run_pass
  24:     0x7f0ee110903e - rustc_mir_transform[30431bd415c4c272]::pass_manager::run_passes
  25:     0x7f0ee10f43de - rustc_mir_transform[30431bd415c4c272]::optimized_mir
  26:     0x7f0ee16f4720 - rustc_query_system[f27402853dfb6133]::query::plumbing::try_execute_query::<rustc_query_impl[604497a8fc516067]::plumbing::QueryCtxt, rustc_query_system[f27402853dfb6133]::query::caches::DefaultCache<rustc_span[ae9ba53627e4b7a2]::def_id::DefId, &rustc_middle[77cffc0d0a9caf4f]::mir::Body>>
  27:     0x7f0ee17e6d0e - <rustc_query_impl[604497a8fc516067]::Queries as rustc_middle[77cffc0d0a9caf4f]::ty::query::QueryEngine>::optimized_mir
  28:     0x7f0ee1bd753d - <rustc_middle[77cffc0d0a9caf4f]::ty::context::TyCtxt>::instance_mir
  29:     0x7f0ee0c9998f - rustc_middle[77cffc0d0a9caf4f]::mir::pretty::write_mir_pretty
  30:     0x7f0edff0bd10 - rustc_mir_transform[30431bd415c4c272]::dump_mir::emit_mir
  31:     0x7f0ee1d29b86 - <rustc_interface[c2767953942b9161]::queries::Queries>::ongoing_codegen
  32:     0x7f0ee1cf02fb - <rustc_interface[c2767953942b9161]::interface::Compiler>::enter::<rustc_driver[19d608e2c8daf1f4]::run_compiler::{closure#1}::{closure#2}, core[9a854ec5d686c1fc]::result::Result<core[9a854ec5d686c1fc]::option::Option<rustc_interface[c2767953942b9161]::queries::Linker>, rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>
  33:     0x7f0ee1d18ecf - rustc_span[ae9ba53627e4b7a2]::with_source_map::<core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>, rustc_interface[c2767953942b9161]::interface::create_compiler_and_run<core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>, rustc_driver[19d608e2c8daf1f4]::run_compiler::{closure#1}>::{closure#1}>
  34:     0x7f0ee1cf0ee7 - <scoped_tls[673d87c3fad674a0]::ScopedKey<rustc_span[ae9ba53627e4b7a2]::SessionGlobals>>::set::<rustc_interface[c2767953942b9161]::interface::run_compiler<core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>, rustc_driver[19d608e2c8daf1f4]::run_compiler::{closure#1}>::{closure#0}, core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>
  35:     0x7f0ee1d062ff - std[cd658a55527ed977]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[c2767953942b9161]::util::run_in_thread_pool_with_globals<rustc_interface[c2767953942b9161]::interface::run_compiler<core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>, rustc_driver[19d608e2c8daf1f4]::run_compiler::{closure#1}>::{closure#0}, core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>::{closure#0}, core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>
  36:     0x7f0ee1d06439 - <<std[cd658a55527ed977]::thread::Builder>::spawn_unchecked_<rustc_interface[c2767953942b9161]::util::run_in_thread_pool_with_globals<rustc_interface[c2767953942b9161]::interface::run_compiler<core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>, rustc_driver[19d608e2c8daf1f4]::run_compiler::{closure#1}>::{closure#0}, core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>::{closure#0}, core[9a854ec5d686c1fc]::result::Result<(), rustc_errors[9417c7ccc58903d8]::ErrorGuaranteed>>::{closure#1} as core[9a854ec5d686c1fc]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  37:     0x7f0edf4aab93 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::ha55af26f35189599
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/alloc/src/boxed.rs:1866:9
  38:     0x7f0edf4aab93 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6a841b0f36efd076
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/alloc/src/boxed.rs:1866:9
  39:     0x7f0edf4aab93 - std::sys::unix::thread::Thread::new::thread_start::h4d154f7a3783bf9b
                               at /rustc/878c7833f6c1ff10e2fd89074e5bd4ef5ff15936/library/std/src/sys/unix/thread.rs:108:17
  40:     0x7f0edf2835c2 - start_thread
  41:     0x7f0edf308584 - __clone
  42:                0x0 - <unknown>

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.62.0-nightly (878c7833f 2022-04-16) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z mir-opt-level=4

query stack during panic:
#0 [optimized_mir] optimizing MIR for `foo`
end of query stack
error: aborting due to previous error

The text was updated successfully, but these errors were encountered:

matthiaskrgr · 2022-04-27T21:52:28Z

Also reproducible in miri:

use std::fmt::Debug;
use std::ptr;

fn main() {
    let a: *const dyn Debug = &1 as &dyn Debug;
    let b: *const dyn Debug = &1 as &dyn Debug;
    let _ = a < b;
}

RalfJung · 2022-05-04T20:57:13Z

The second one looks very different from the first. That looks like a bug in the Miri implementation of <, which is not prepared for wide pointers.

RalfJung · 2022-07-06T01:00:34Z

I cannot reproduce the original example any more. And in fact main is empty so I don't think Miri even did anything. The backtrace points to ConstProp, which would make this a rustc bug, not a Miri bug. Not sure if there is anything actionable here.

The second one still ICEs.

RalfJung · 2022-07-06T01:02:40Z

@bjorn3 do you know the codegen behavior of < on wide pointers? Does it do anything with the metadata?
(==/!= also compares the metadata, as far as I know).

RalfJung · 2022-07-06T01:15:55Z

Actually testing indicates that it is... lexicographic?!?

bjorn3 · 2022-07-06T11:21:56Z

Indeed. This is the actual implementation:

rust/compiler/rustc_codegen_ssa/src/mir/rvalue.rs

Lines 625 to 639 in 5b8cf49

    
           mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => { 
        
               // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1) 
        
               let (op, strict_op) = match op { 
        
                   mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT), 
        
                   mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT), 
        
                   mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT), 
        
                   mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT), 
        
                   _ => bug!(), 
        
               }; 
        
               let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr); 
        
               let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr); 
        
               let and_rhs = bx.icmp(op, lhs_extra, rhs_extra); 
        
               let rhs = bx.and(and_lhs, and_rhs); 
        
               bx.or(lhs, rhs) 
        
           }

matthiaskrgr · 2022-07-06T14:24:10Z

Example #1 still crashes with -Zmir-opt-level=4 as noted in the title, reopening.

RalfJung · 2022-07-06T14:40:46Z

I tried it with opt-level 4 and it didn't crash for me... which rustc are you using?

$ rustc --version
rustc 1.64.0-nightly (f342bea9d 2022-07-05)

matthiaskrgr · 2022-07-06T14:50:48Z

did you also pass --emit=mir ?

RalfJung · 2022-07-06T14:51:49Z

D'oh, I should read what you are saying, sorry...

RalfJung · 2022-07-06T15:27:20Z

Wow, that backtrace is completely useless. All the relevant line numbers are missing.

I added some track_caller and tracked it to this line:

rust/compiler/rustc_mir_transform/src/const_prop.rs

Line 657 in 4f0a647

let arg_value = const_arg.to_scalar()?.to_bits(const_arg.layout.size)?;

fix ICE in ConstProp Fixes rust-lang#96169

matthiaskrgr added I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. C-bug Category: This is a bug. labels Apr 18, 2022

rust-lang-glacier-bot added the glacier ICE tracked in rust-lang/glacier. label Apr 23, 2022

matthiaskrgr added the A-miri Area: The miri tool label Apr 27, 2022

RalfJung mentioned this issue Jul 6, 2022

fix comparing wide raw pointers rust-lang/miri#2336

Merged

bors closed this as completed in rust-lang/miri@36d8f5c Jul 6, 2022

matthiaskrgr reopened this Jul 6, 2022

matthiaskrgr removed the A-miri Area: The miri tool label Jul 6, 2022

RalfJung mentioned this issue Jul 6, 2022

fix ICE in ConstProp #98980

Merged

Dylan-DPC added a commit to Dylan-DPC/rust that referenced this issue Jul 9, 2022

Rollup merge of rust-lang#98980 - RalfJung:const-prop-ice, r=oli-obk

fa8f6b6

fix ICE in ConstProp Fixes rust-lang#96169

bors closed this as completed in a6c6166 Jul 9, 2022

github-actions bot mentioned this issue Jul 10, 2022

ices/96169.sh: fixed with no errors rust-lang/glacier#1336

Merged

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ICE: "Got a scalar pair where a scalar was expected" -Zmir-opt-level=4 --emit=mir #96169

ICE: "Got a scalar pair where a scalar was expected" -Zmir-opt-level=4 --emit=mir #96169

matthiaskrgr commented Apr 18, 2022

matthiaskrgr commented Apr 27, 2022

RalfJung commented May 4, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022

bjorn3 commented Jul 6, 2022

matthiaskrgr commented Jul 6, 2022

RalfJung commented Jul 6, 2022

matthiaskrgr commented Jul 6, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022

ICE: "Got a scalar pair where a scalar was expected" -Zmir-opt-level=4 --emit=mir #96169

ICE: "Got a scalar pair where a scalar was expected" -Zmir-opt-level=4 --emit=mir #96169

Comments

matthiaskrgr commented Apr 18, 2022

Code

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Error output

matthiaskrgr commented Apr 27, 2022

RalfJung commented May 4, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022

bjorn3 commented Jul 6, 2022

matthiaskrgr commented Jul 6, 2022

RalfJung commented Jul 6, 2022

matthiaskrgr commented Jul 6, 2022

RalfJung commented Jul 6, 2022

RalfJung commented Jul 6, 2022