Std support

[bjorn3]

Unimplemented stuff

     14 Drop for trait object
      1 load_value_pair TyLayout { ty: alloc_crate::boxed::Box<dyn alloc_crate::boxed::FnBox<(), Output=()>>, details: LayoutDetails { variants: Single { index: 0 }, fields: Arbitrary { offsets: [Size { raw: 0 }], memory_index: [0] }, abi: ScalarPair(Scalar { value: Pointer, valid_range: 1..=18446744073709551615 }, Scalar { value: Pointer, valid_range: 1..=18446744073709551615 }), align: Align { abi_pow2: 3, pref_pow2: 3 }, size: Size { raw: 16 } } }
      1 Non scalars are not yet supported for "C" abi (core::option::Option<unsafe extern "C" fn(*mut libc::c_void)>) is_return: false

Edit: hiding this because it is fixed in 1717cc4

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: IncompatibleDeclaration("__rdl_alloc")', libcore/result.rs:1009:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at libstd/sys_common/backtrace.rs:59
             at libstd/panicking.rs:211
   3: std::panicking::default_hook
             at libstd/panicking.rs:227
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:480
   6: std::panicking::continue_panic_fmt
             at libstd/panicking.rs:390
   7: rust_begin_unwind
             at libstd/panicking.rs:325
   8: core::panicking::panic_fmt
             at libcore/panicking.rs:77
   9: core::result::unwrap_failed
             at /rustc/65204a97d4876b897df0a70c0b9248b57e2bf057/src/libcore/macros.rs:26
  10: <core::result::Result<T, E>>::unwrap
             at /rustc/65204a97d4876b897df0a70c0b9248b57e2bf057/src/libcore/result.rs:808
  11: rustc_codegen_cranelift::allocator::codegen
             at src/allocator.rs:52
  12: rustc_codegen_cranelift::codegen_mono_items
             at src/lib.rs:498
  13: <rustc_codegen_cranelift::CraneliftCodegenBackend as rustc_codegen_utils::codegen_backend::CodegenBackend>::codegen_crate
             at src/lib.rs:395

Edit2: Patched out variadic functions

[bjorn3]

This is now blocked on #209.

[bjorn3]

#209 has been fixed. alloc_example as of 468a959 from the wip_fix_libstd branch now compiles and links, but it segfaults during libstd initialization.

[bjorn3]

The segfault happens after returning from _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4fd75c76394cfdb9 it should return to _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::heb211e3cfd701dc4, but it returns to an unknown symbol.

Backtrace at the first inst ([...] means a lot of ?? frames combined with some frames with the name of the function):

#0  0x00005613b1839100 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4fd75c76394cfdb9 ()
#1  0x00005613b183e535 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::heb211e3cfd701dc4 ()
[...]

Backtrace at the second inst:

#0  0x00005613b1839102 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4fd75c76394cfdb9 ()
#1  0x00007ffc6b5af730 in ?? ()
#2  0x00005613b183e535 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::heb211e3cfd701dc4 ()
[...]

Backtrace at the fourth inst:

#0  0x00005613b183910c in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h4fd75c76394cfdb9 ()
#1  0x00005613b39ac0a0 in ?? ()
#2  0x00005613b39ac0a0 in ?? ()
[...]

clif and asm of `try_with`

function u0:0(i64, i64, i64) system_v {
    ss0 = explicit_slot 0
    ss1 = explicit_slot 8
    ss2 = explicit_slot 8
    ss3 = explicit_slot 8
    ss4 = explicit_slot 0
    ss5 = explicit_slot 0
    ss6 = explicit_slot 0
    ss7 = explicit_slot 0
    ss8 = explicit_slot 0
    ss9 = explicit_slot 0
    ss10 = explicit_slot 0
    ss11 = explicit_slot 8
    ss12 = explicit_slot 8
    ss13 = explicit_slot 8
    sig0 = (i64) system_v
    sig1 = (i64, i64, i64) system_v
    sig2 = (i64, i64, i64) system_v
    sig3 = (i64, i64) system_v
    sig4 = (i64, i64) system_v
    sig5 = (i64) -> i64 system_v
    sig6 = (i64) -> i64 system_v
    sig7 = (i64, i64) system_v
    sig8 = (i64, i64) system_v
    sig9 = (i64, i64) system_v
    sig10 = (i64, i64) system_v
    sig11 = (i64, i64) -> i64 system_v
    sig12 = (i64, i64) -> i64 system_v
    sig13 = (i64, i64) system_v
    sig14 = (i64, i64) system_v
    fn0 = colocated u0:3591 sig2
    fn1 = u0:3592 sig4
    fn2 = u0:2722 sig6
    fn3 = u0:233 sig8
    fn4 = u0:3999 sig10
    fn5 = u0:3594 sig12
    fn6 = u0:4306 sig14
    jt0 = jump_table [ebb6, ebb7]
    jt1 = jump_table [ebb12, ebb13]

ebb0(v0: i64, v1: i64, v2: i64):
    v17 -> v1
    v46 -> v1
    v37 -> v46
    nop 
; ssa {_20: NOT_SSA, _3: (empty), _25: (empty), _11: (empty), _0: NOT_SSA, _1: (empty), _23: (empty), _10: NOT_SSA, _18: (empty), _8: NOT_SSA, _5: NOT_SSA, _4: NOT_SSA, _6: NOT_SSA, _26: (empty), _21: (empty), _2: NOT_SSA, _7: (empty), _12: (empty), _22: (empty), _13: NOT_SSA, _17: NOT_SSA, _15: NOT_SSA, _19: (empty), _9: NOT_SSA, _14: NOT_SSA, _16: NOT_SSA, _24: NOT_SSA}
; pass _1: &thread::local::LocalKey<core::cell::RefCell<core::option::Option<sys_common::thread_info::ThreadInfo>>> ByVal(types::I64)
; pass _2: [closure@sysroot_src/src/libstd/sys_common/thread_info.rs:47:22: 47:55] ByRef
    v3 = stack_addr.i64 ss0
    v4 = stack_addr.i64 ss1
    v5 = stack_addr.i64 ss2
    v6 = stack_addr.i64 ss3
    v7 = stack_addr.i64 ss4
    v8 = stack_addr.i64 ss5
    v9 = stack_addr.i64 ss6
    v10 = stack_addr.i64 ss7
    v11 = stack_addr.i64 ss8
    v12 = stack_addr.i64 ss9
    v13 = stack_addr.i64 ss10
    v14 = stack_addr.i64 ss11
    v15 = stack_addr.i64 ss12
    v16 = stack_addr.i64 ss13
    jump ebb1

ebb1:
    nop 
; _7 = ((*_1).0: unsafe fn() -> core::option::Option<&core::cell::UnsafeCell<core::option::Option<T>>>)
    v18 = load.i64 v17
; 
; _6 = move _7()
    call_indirect sig0, v18(v6)
    jump ebb2

ebb2:
    nop 
; (_8.0: ()) = move _9
; 
; _5 = const <core::option::Option<T>>::ok_or(move _6, move _8)
    call fn0(v5, v6, v7)
    jump ebb3

ebb3:
    nop 
; 
; _4 = const core::ops::Try::into_result(move _5)
    call fn1(v4, v5)
    jump ebb4

ebb4:
    nop 
; _12 = discriminant(_4)
    v19 = load.i64 v4
    v20 = icmp_imm eq v19, 0
    v21 = iconst.i64 1
    v22 = iconst.i64 0
    v23 = select v20, v21, v22
; 
; switchInt(move _12)
    v24 = icmp_imm uge v23, 0
    brnz v24, ebb17
    jump ebb5

ebb17:
    v25 = iadd_imm.i64 v23, 0
    br_table v25, ebb5, jt0

ebb5:
    nop 
; 
; unreachable
    trap user65535

ebb6:
    nop 
; _11 = ((_4 as Ok).0: &core::cell::UnsafeCell<core::option::Option<T>>)
    v26 = load.i64 v4
    v47 -> v26
    v38 -> v47
; _3 = _11
; _16 = move _2
; _21 = _3
; 
; _20 = const <core::cell::UnsafeCell<T>>::get(move _21)
    v27 = call fn2(v26)
    store v27, v15
    jump ebb11

ebb7:
    nop 
; _10 = move ((_4 as Err).0: thread::local::AccessError)
; _14 = move _10
; 
; _13 = const core::convert::From::from(move _14)
    call fn3(v10, v11)
    jump ebb8

ebb8:
    nop 
; 
; _0 = const core::ops::Try::from_error(move _13)
    call fn4(v0, v10)
    jump ebb9

ebb9:
    nop 
; 
; drop(_2)
    jump ebb10

ebb10:
    nop 
; 
; return
    return

ebb11:
    nop 
; _23 = discriminant((*_20))
    v28 = load.i64 v15
    v29 = iadd_imm v28, 8
    v30 = load.i64 v29
    v31 = icmp_imm eq v30, 3
    v32 = iconst.i64 0
    v33 = iconst.i64 1
    v34 = select v31, v32, v33
; 
; switchInt(move _23)
    v35 = icmp_imm uge v34, 0
    brnz v35, ebb18
    jump ebb5

ebb18:
    v36 = iadd_imm.i64 v34, 0
    br_table v36, ebb5, jt1

ebb12:
    nop 
; _25 = _1
; _26 = _3
; 
; _24 = const <thread::local::LocalKey<T>>::init(move _25, move _26)
    v39 = call fn5(v37, v38)
    store v39, v16
    jump ebb15

ebb13:
    nop 
; _22 = &(((*_20) as Some).0: T)
    v40 = load.i64 v15
; _19 = _22
; 
; goto
    jump ebb14(v40)

ebb14(v41: i64):
    nop 
; _18 = _19
; (_17.0: &T) = move _18
    store v41, v14
; 
; _15 = const core::ops::FnOnce::call_once(move _16, move _17)
    v42 = load.i64 v14
    call fn6(v13, v42)
    jump ebb16

ebb15:
    nop 
; _19 = _24
    v43 = load.i64 v16
; 
; goto
    jump ebb14(v43)

ebb16:
    nop 
; ((_0 as Ok).0: R) = move _15
    v44 = iadd_imm.i64 v0, 1
; discriminant(_0) = 0
    v45 = iconst.i8 0
    store v45, v0
; 
; goto
    jump ebb10
}

0000000000023200 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE>:
   23200:       40 55                   rex push %rbp
   23202:       48 89 e5                mov    %rsp,%rbp
   23205:       48 81 ec a0 00 00 00    sub    $0xa0,%rsp
   2320c:       48 89 bc 24 68 00 00    mov    %rdi,0x68(%rsp)
   23213:       00 
   23214:       48 89 b4 24 60 00 00    mov    %rsi,0x60(%rsp)
   2321b:       00 
   2321c:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   23223:       00 
   23224:       48 8d 84 24 98 00 00    lea    0x98(%rsp),%rax
   2322b:       00 
   2322c:       48 89 84 24 58 00 00    mov    %rax,0x58(%rsp)
   23233:       00 
   23234:       48 8d 84 24 90 00 00    lea    0x90(%rsp),%rax
   2323b:       00 
   2323c:       48 89 84 24 50 00 00    mov    %rax,0x50(%rsp)
   23243:       00 
   23244:       48 8d 84 24 88 00 00    lea    0x88(%rsp),%rax
   2324b:       00 
   2324c:       48 89 84 24 48 00 00    mov    %rax,0x48(%rsp)
   23253:       00 
   23254:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   2325b:       00 
   2325c:       48 89 84 24 40 00 00    mov    %rax,0x40(%rsp)
   23263:       00 
   23264:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   2326b:       00 
   2326c:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   23273:       00 
   23274:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   2327b:       00 
   2327c:       48 89 84 24 38 00 00    mov    %rax,0x38(%rsp)
   23283:       00 
   23284:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   2328b:       00 
   2328c:       48 89 84 24 30 00 00    mov    %rax,0x30(%rsp)
   23293:       00 
   23294:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   2329b:       00 
   2329c:       48 8d 84 24 00 00 00    lea    0x0(%rsp),%rax
   232a3:       00 
   232a4:       48 89 84 24 28 00 00    mov    %rax,0x28(%rsp)
   232ab:       00 
   232ac:       48 8d 84 24 80 00 00    lea    0x80(%rsp),%rax
   232b3:       00 
   232b4:       48 89 84 24 20 00 00    mov    %rax,0x20(%rsp)
   232bb:       00 
   232bc:       48 8d 84 24 78 00 00    lea    0x78(%rsp),%rax
   232c3:       00 
   232c4:       48 89 84 24 18 00 00    mov    %rax,0x18(%rsp)
   232cb:       00 
   232cc:       48 8d 84 24 70 00 00    lea    0x70(%rsp),%rax
   232d3:       00 
   232d4:       48 89 84 24 10 00 00    mov    %rax,0x10(%rsp)
   232db:       00 
   232dc:       48 8b 84 24 60 00 00    mov    0x60(%rsp),%rax
   232e3:       00 
   232e4:       48 8b 00                mov    (%rax),%rax
   232e7:       48 8b 8c 24 48 00 00    mov    0x48(%rsp),%rcx
   232ee:       00 
   232ef:       48 89 cf                mov    %rcx,%rdi
   232f2:       40 ff d0                rex callq *%rax
   232f5:       48 8b 84 24 50 00 00    mov    0x50(%rsp),%rax
   232fc:       00 
   232fd:       48 8b 8c 24 48 00 00    mov    0x48(%rsp),%rcx
   23304:       00 
   23305:       48 8b 94 24 40 00 00    mov    0x40(%rsp),%rdx
   2330c:       00 
   2330d:       48 89 c7                mov    %rax,%rdi
   23310:       48 89 ce                mov    %rcx,%rsi
   23313:       e8 f8 01 00 00          callq  23510 <_ZN38_$LT$core..option..Option$LT$T$GT$$GT$5ok_or17hc08dcc56df316dd4E>
   23318:       48 8b 84 24 58 00 00    mov    0x58(%rsp),%rax
   2331f:       00 
   23320:       48 8b 8c 24 50 00 00    mov    0x50(%rsp),%rcx
   23327:       00 
   23328:       48 89 c7                mov    %rax,%rdi
   2332b:       48 89 ce                mov    %rcx,%rsi
   2332e:       e8 0d 03 00 00          callq  23640 <_ZN78_$LT$core..result..Result$LT$T$C$$u20$E$GT$$u20$as$u20$core..ops..try..Try$GT$11into_result17h020ad5f0907363fdE>
   23333:       48 8b 84 24 58 00 00    mov    0x58(%rsp),%rax
   2333a:       00 
   2333b:       48 8b 00                mov    (%rax),%rax
   2333e:       48 83 f8 00             cmp    $0x0,%rax
   23342:       0f 94 c0                sete   %al
   23345:       40 b9 01 00 00 00       rex mov $0x1,%ecx
   2334b:       40 ba 00 00 00 00       rex mov $0x0,%edx
   23351:       40 84 c0                test   %al,%al
   23354:       75 06                   jne    2335c <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x15c>
   23356:       48 89 d0                mov    %rdx,%rax
   23359:       48 89 c1                mov    %rax,%rcx
   2335c:       48 83 f9 00             cmp    $0x0,%rcx
   23360:       0f 93 c0                setae  %al
   23363:       40 84 c0                test   %al,%al
   23366:       75 03                   jne    2336b <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x16b>
   23368:       40 eb 21                rex jmp 2338c <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x18c>
   2336b:       48 83 c1 00             add    $0x0,%rcx
   2336f:       48 83 f9 02             cmp    $0x2,%rcx
   23373:       0f 93 c0                setae  %al
   23376:       40 84 c0                test   %al,%al
   23379:       75 11                   jne    2338c <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x18c>
   2337b:       48 8d 05 79 01 00 00    lea    0x179(%rip),%rax        # 234fb <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x2fb>
   23382:       48 63 0c 88             movslq (%rax,%rcx,4),%rcx
   23386:       48 01 c8                add    %rcx,%rax
   23389:       40 ff e0                rex jmpq *%rax
   2338c:       0f 0b                   ud2    
   2338e:       48 8b 84 24 58 00 00    mov    0x58(%rsp),%rax
   23395:       00 
   23396:       48 8b 00                mov    (%rax),%rax
   23399:       48 89 84 24 08 00 00    mov    %rax,0x8(%rsp)
   233a0:       00 
   233a1:       48 8b 84 24 08 00 00    mov    0x8(%rsp),%rax
   233a8:       00 
   233a9:       48 89 c7                mov    %rax,%rdi
   233ac:       e8 7f 83 ff ff          callq  1b730 <_ZN40_$LT$core..cell..UnsafeCell$LT$T$GT$$GT$3get17hdeb583042ffbf290E>
   233b1:       48 8b 8c 24 18 00 00    mov    0x18(%rsp),%rcx
   233b8:       00 
   233b9:       48 89 01                mov    %rax,(%rcx)
   233bc:       40 eb 40                rex jmp 233ff <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x1ff>
   233bf:       48 8b 84 24 38 00 00    mov    0x38(%rsp),%rax
   233c6:       00 
   233c7:       48 8b 8c 24 30 00 00    mov    0x30(%rsp),%rcx
   233ce:       00 
   233cf:       48 89 c7                mov    %rax,%rdi
   233d2:       48 89 ce                mov    %rcx,%rsi
   233d5:       e8 26 4c ff ff          callq  18000 <_ZN50_$LT$T$u20$as$u20$core..convert..From$LT$T$GT$$GT$4from17h9bd35ba97d141524E>
   233da:       48 8b 84 24 68 00 00    mov    0x68(%rsp),%rax
   233e1:       00 
   233e2:       48 8b 8c 24 38 00 00    mov    0x38(%rsp),%rcx
   233e9:       00 
   233ea:       48 89 c7                mov    %rax,%rdi
   233ed:       48 89 ce                mov    %rcx,%rsi
   233f0:       e8 1b 4c ff ff          callq  18010 <_ZN78_$LT$core..result..Result$LT$T$C$$u20$E$GT$$u20$as$u20$core..ops..try..Try$GT$10from_error17h39d75f165c72b959E>
   233f5:       48 81 c4 a0 00 00 00    add    $0xa0,%rsp
   233fc:       40 5d                   rex pop %rbp
   233fe:       c3                      retq   
   233ff:       48 8b 84 24 18 00 00    mov    0x18(%rsp),%rax
   23406:       00 
   23407:       48 8b 00                mov    (%rax),%rax
   2340a:       48 83 c0 08             add    $0x8,%rax
   2340e:       48 8b 00                mov    (%rax),%rax
   23411:       48 83 f8 03             cmp    $0x3,%rax
   23415:       0f 94 c0                sete   %al
   23418:       40 b9 00 00 00 00       rex mov $0x0,%ecx
   2341e:       40 ba 01 00 00 00       rex mov $0x1,%edx
   23424:       40 84 c0                test   %al,%al
   23427:       75 06                   jne    2342f <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x22f>
   23429:       48 89 d0                mov    %rdx,%rax
   2342c:       48 89 c1                mov    %rax,%rcx
   2342f:       48 83 f9 00             cmp    $0x0,%rcx
   23433:       0f 93 c0                setae  %al
   23436:       40 84 c0                test   %al,%al
   23439:       75 06                   jne    23441 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x241>
   2343b:       40 e9 4b ff ff ff       rex jmpq 2338c <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x18c>
   23441:       48 83 c1 00             add    $0x0,%rcx
   23445:       48 83 f9 02             cmp    $0x2,%rcx
   23449:       0f 93 c0                setae  %al
   2344c:       40 84 c0                test   %al,%al
   2344f:       0f 85 37 ff ff ff       jne    2338c <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x18c>
   23455:       48 8d 05 a7 00 00 00    lea    0xa7(%rip),%rax        # 23503 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x303>
   2345c:       48 63 0c 88             movslq (%rax,%rcx,4),%rcx
   23460:       48 01 c8                add    %rcx,%rax
   23463:       40 ff e0                rex jmpq *%rax
   23466:       48 8b 84 24 60 00 00    mov    0x60(%rsp),%rax
   2346d:       00 
   2346e:       48 8b 8c 24 08 00 00    mov    0x8(%rsp),%rcx
   23475:       00 
   23476:       48 89 c7                mov    %rax,%rdi
   23479:       48 89 ce                mov    %rcx,%rsi
   2347c:       e8 ef 01 00 00          callq  23670 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$4init17h46b41a9e98f5bef7E>
   23481:       48 8b 8c 24 10 00 00    mov    0x10(%rsp),%rcx
   23488:       00 
   23489:       48 89 01                mov    %rax,(%rcx)
   2348c:       40 eb 37                rex jmp 234c6 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x2c6>
   2348f:       48 8b 84 24 18 00 00    mov    0x18(%rsp),%rax
   23496:       00 
   23497:       48 8b 00                mov    (%rax),%rax
   2349a:       48 8b 8c 24 20 00 00    mov    0x20(%rsp),%rcx
   234a1:       00 
   234a2:       48 89 01                mov    %rax,(%rcx)
   234a5:       48 8b 84 24 20 00 00    mov    0x20(%rsp),%rax
   234ac:       00 
   234ad:       48 8b 00                mov    (%rax),%rax
   234b0:       48 8b 8c 24 28 00 00    mov    0x28(%rsp),%rcx
   234b7:       00 
   234b8:       48 89 cf                mov    %rcx,%rdi
   234bb:       48 89 c6                mov    %rax,%rsi
   234be:       e8 2d d5 fe ff          callq  109f0 <_ZN3std10sys_common11thread_info3set28_$u7b$$u7b$closure$u7d$$u7d$17h70f50255323bfa80E>
   234c3:       40 eb 0e                rex jmp 234d4 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x2d4>
   234c6:       48 8b 84 24 10 00 00    mov    0x10(%rsp),%rax
   234cd:       00 
   234ce:       48 8b 00                mov    (%rax),%rax
   234d1:       40 eb c6                rex jmp 2349a <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x29a>
   234d4:       48 8b 84 24 68 00 00    mov    0x68(%rsp),%rax
   234db:       00 
   234dc:       48 83 c0 01             add    $0x1,%rax
   234e0:       40 b8 00 00 00 00       rex mov $0x0,%eax
   234e6:       40 0f b6 c0             movzbl %al,%eax
   234ea:       48 8b 8c 24 68 00 00    mov    0x68(%rsp),%rcx
   234f1:       00 
   234f2:       40 88 01                mov    %al,(%rcx)
   234f5:       40 e9 fa fe ff ff       rex jmpq 233f5 <_ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE+0x1f5>
   234fb:       93                      xchg   %eax,%ebx
   234fc:       fe                      (bad)  
   234fd:       ff                      (bad)  
   234fe:       ff c4                   inc    %esp
   23500:       fe                      (bad)  
   23501:       ff                      (bad)  
   23502:       ff 63 ff                jmpq   *-0x1(%rbx)
   23505:       ff                      (bad)  
   23506:       ff 8c ff ff ff 0f 1f    decl   0x1f0fffff(%rdi,%rdi,8)
   2350d:       44 00 00                add    %r8b,(%rax)

cc @sunfishcode (I believe this is a miscompilation from cranelift)

[bjorn3]

One thing I noticed is that cranelift emits a rex prefix for the push rbp, while gcc doesn't. (Changing it to nop doesn't fix the crash though)

[bjorn3]

Every single function created by cranelift has the backtrace behavior described above:

$ gdb target/out/mini_core_hello_world # a non crashing program
(gdb) break main
Breakpoint 1 at 0x1c40
(gdb) run
Starting program: /home/bjorn/Documenten/rustc_codegen_cranelift/target/out/mini_core_hello_world 

Breakpoint 1, 0x0000555555555c40 in main ()
(gdb) disassemble 
Dump of assembler code for function main:
=> 0x0000555555555c40 <+0>:     rex push %rbp
   0x0000555555555c42 <+2>:     mov    %rsp,%rbp
   0x0000555555555c45 <+5>:     lea    -0xf3c(%rip),%rax        # 0x555555554d10 <_ZN21mini_core_hello_world4main17he1655d58f9d91204E>
   0x0000555555555c4c <+12>:    mov    %rsi,%rdx
   0x0000555555555c4f <+15>:    mov    %rdi,%rsi
   0x0000555555555c52 <+18>:    mov    %rax,%rdi
   0x0000555555555c55 <+21>:    callq  0x555555554b10 <_ZN21mini_core_hello_world5start17h1e715bf6fab28115E>
   0x0000555555555c5a <+26>:    rex pop %rbp
   0x0000555555555c5c <+28>:    retq   
End of assembler dump.
(gdb) si 7
0x0000555555554b10 in mini_core_hello_world::start::h1e715bf6fab28115 ()
(gdb) disassemble 
Dump of assembler code for function _ZN21mini_core_hello_world5start17h1e715bf6fab28115E:
=> 0x0000555555554b10 <+0>:     rex push %rbp
   0x0000555555554b12 <+2>:     mov    %rsp,%rbp
   0x0000555555554b15 <+5>:     sub    $0x20,%rsp
   0x0000555555554b19 <+9>:     lea    0x1c(%rsp),%rax
   0x0000555555554b21 <+17>:    mov    %rax,0x8(%rsp)
   0x0000555555554b29 <+25>:    lea    0x0(%rsp),%rax
   0x0000555555554b31 <+33>:    mov    %rax,0x10(%rsp)
   0x0000555555554b39 <+41>:    rex callq *%rdi
   0x0000555555554b3c <+44>:    mov    0x10(%rsp),%rax
   0x0000555555554b44 <+52>:    mov    %rax,%rdi
   0x0000555555554b47 <+55>:    callq  0x555555554b70 <_ZN63_$LT$$LP$$RP$$u20$as$u20$mini_core_hello_world..Termination$GT$6report17hdb0778df210e78ccE>
   0x0000555555554b4c <+60>:    mov    0x8(%rsp),%rcx
   0x0000555555554b54 <+68>:    rex mov %eax,(%rcx)
   0x0000555555554b57 <+71>:    mov    0x8(%rsp),%rax
   0x0000555555554b5f <+79>:    rex mov (%rax),%eax
   0x0000555555554b62 <+82>:    movslq %eax,%rax
   0x0000555555554b65 <+85>:    add    $0x20,%rsp
   0x0000555555554b69 <+89>:    rex pop %rbp
   0x0000555555554b6b <+91>:    retq   
End of assembler dump.
(gdb) bt
#0  0x0000555555554b10 in mini_core_hello_world::start::h1e715bf6fab28115 ()
#1  0x0000555555555c5a in main ()
(gdb) si
0x0000555555554b12 in mini_core_hello_world::start::h1e715bf6fab28115 ()
(gdb) bt
#0  0x0000555555554b12 in mini_core_hello_world::start::h1e715bf6fab28115 ()
#1  0x00007fffffffdd80 in ?? ()
#2  0x0000555555555c5a in main ()
(gdb) si
0x0000555555554b15 in mini_core_hello_world::start::h1e715bf6fab28115 ()
(gdb) bt
#0  0x0000555555554b15 in mini_core_hello_world::start::h1e715bf6fab28115 ()
#1  0x00007fffffffdd80 in ?? ()
#2  0x0000555555555c5a in main ()
(gdb) si
0x0000555555554b19 in mini_core_hello_world::start::h1e715bf6fab28115 ()
(gdb) bt
#0  0x0000555555554b19 in mini_core_hello_world::start::h1e715bf6fab28115 ()
#1  0x0000000000000000 in ?? ()

I suspect there is a stack alignment problem. (didn't investigate it though)

[bjorn3]

I am almost sure the problem of at least gdb backtraces is stack alignment. While gcc always does sub $(x*16+8), %rsp, cranelift does sub $(x*16), $rsp, which violates the System V abi requirement that the stack is 16 byte aligned. (call pushes 8 bytes, then you need to add another 8 bytes to align the stack again)

Edit: filled CraneStation/cranelift#630

[sunfishcode]

The extra rex is harmless, and is an artifact of the way Cranelift's register allocator works. We optimize away many of the rex prefixes with opt-level=best right now, and in the future I expect we'll do something similar to CraneStation/cranelift#552 to avoid generating unnecessary rex prefixes in the first place.

I think the reason why GCC does x*16+8 is that it's doing frame-pointer elimination, so it needs the extra +8 to compensate for the space where the frame pointer would have been pushed. Cranelift currently always pushes the frame pointer, so it doesn't need the extra +8. Can you test whether %rsp is actually misaligned within the body?

[bjorn3]

First: oops meant rustc + llvm not gcc :)

rustc:

0000000000005dc0 <_ZN11simple_main4main17hb13a4a470fc2f2b2E>:
    5dc0:       48 83 ec 38             sub    $0x38,%rsp
    5dc4:       48 8d 05 ed 93 22 00    lea    0x2293ed(%rip),%rax        # 22f1b8 <__JCR_END__+0x8>
    5dcb:       48 8d 0d 46 fe 01 00    lea    0x1fe46(%rip),%rcx        # 25c18 <_fini+0x14>
    5dd2:       31 d2                   xor    %edx,%edx
    5dd4:       41 89 d0                mov    %edx,%r8d
    5dd7:       48 8d 7c 24 08          lea    0x8(%rsp),%rdi
    5ddc:       48 89 c6                mov    %rax,%rsi
    5ddf:       ba 01 00 00 00          mov    $0x1,%edx
    5de4:       e8 37 01 00 00          callq  5f20 <_ZN4core3fmt9Arguments6new_v117h5ae58c641f8553b9E>
    5de9:       48 8d 7c 24 08          lea    0x8(%rsp),%rdi
    5dee:       ff 15 9c af 22 00       callq  *0x22af9c(%rip)        # 230d90 <_GLOBAL_OFFSET_TABLE_+0x310>
    5df4:       48 83 c4 38             add    $0x38,%rsp
    5df8:       c3                      retq   
    5df9:       0f 1f 80 00 00 00 00    nopl   0x0(%rax)

cranelift:

    4120:       40 55                   rex push %rbp
    4122:       48 89 e5                mov    %rsp,%rbp
    4125:       48 81 ec 90 00 00 00    sub    $0x90,%rsp
    412c:       40 b8 00 00 00 00       rex mov $0x0,%eax
    4132:       48 8d 84 24 88 00 00    lea    0x88(%rsp),%rax
    4139:       00 
    413a:       48 89 84 24 70 00 00    mov    %rax,0x70(%rsp)
    4141:       00 
    4142:       48 8d 84 24 80 00 00    lea    0x80(%rsp),%rax
[...]

Second:

(rr) disassemble
[...]
   0x0000561a3dce93f5 <+501>:   add    $0xa0,%rsp
=> 0x0000561a3dce93fc <+508>:   rex pop %rbp
---Type <return> to continue, or q <return> to quit---
   0x0000561a3dce93fe <+510>:   retq   
   0x0000561a3dce93ff <+511>:   mov    0x18(%rsp),%rax
[...]
(rr) info registers
[...]
rbp            0x7ffda0bbacc0   0x7ffda0bbacc0
rsp            0x7ffda0bbacc0   0x7ffda0bbacc0
[...]
(rr) disassemble    
Dump of assembler code for function _ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h36cfa393b9d2739bE:
   0x0000561a3dce9200 <+0>:     rex push %rbp
   0x0000561a3dce9202 <+2>:     mov    %rsp,%rbp
=> 0x0000561a3dce9205 <+5>:     sub    $0xa0,%rsp
   0x0000561a3dce920c <+12>:    mov    %rdi,0x68(%rsp)
   0x0000561a3dce9214 <+20>:    mov    %rsi,0x60(%rsp)
   0x0000561a3dce921c <+28>:    lea    0x0(%rsp),%rax
   0x0000561a3dce9224 <+36>:    lea    0x98(%rsp),%rax
   0x0000561a3dce922c <+44>:    mov    %rax,0x58(%rsp)
   0x0000561a3dce9234 <+52>:    lea    0x90(%rsp),%rax
   0x0000561a3dce923c <+60>:    mov    %rax,0x50(%rsp)
   0x0000561a3dce9244 <+68>:    lea    0x88(%rsp),%rax
   0x0000561a3dce924c <+76>:    mov    %rax,0x48(%rsp)
   0x0000561a3dce9254 <+84>:    lea    0x0(%rsp),%rax
   0x0000561a3dce925c <+92>:    mov    %rax,0x40(%rsp)
   0x0000561a3dce9264 <+100>:   lea    0x0(%rsp),%rax
   0x0000561a3dce926c <+108>:   lea    0x0(%rsp),%rax
   0x0000561a3dce9274 <+116>:   lea    0x0(%rsp),%rax
   0x0000561a3dce927c <+124>:   mov    %rax,0x38(%rsp)
   0x0000561a3dce9284 <+132>:   lea    0x0(%rsp),%rax
   0x0000561a3dce928c <+140>:   mov    %rax,0x30(%rsp)
   0x0000561a3dce9294 <+148>:   lea    0x0(%rsp),%rax
   0x0000561a3dce929c <+156>:   lea    0x0(%rsp),%rax
   0x0000561a3dce92a4 <+164>:   mov    %rax,0x28(%rsp)
   0x0000561a3dce92ac <+172>:   lea    0x80(%rsp),%rax
   0x0000561a3dce92b4 <+180>:   mov    %rax,0x20(%rsp)
   0x0000561a3dce92bc <+188>:   lea    0x78(%rsp),%rax
   0x0000561a3dce92c4 <+196>:   mov    %rax,0x18(%rsp)
   0x0000561a3dce92cc <+204>:   lea    0x70(%rsp),%rax
   0x0000561a3dce92d4 <+212>:   mov    %rax,0x10(%rsp)
   0x0000561a3dce92dc <+220>:   mov    0x60(%rsp),%rax
   0x0000561a3dce92e4 <+228>:   mov    (%rax),%rax
   0x0000561a3dce92e7 <+231>:   mov    0x48(%rsp),%rcx
   0x0000561a3dce92ef <+239>:   mov    %rcx,%rdi
   0x0000561a3dce92f2 <+242>:   rex callq *%rax
   0x0000561a3dce92f5 <+245>:   mov    0x50(%rsp),%rax
   0x0000561a3dce92fd <+253>:   mov    0x48(%rsp),%rcx
   0x0000561a3dce9305 <+261>:   mov    0x40(%rsp),%rdx
   0x0000561a3dce930d <+269>:   mov    %rax,%rdi
   0x0000561a3dce9310 <+272>:   mov    %rcx,%rsi
   0x0000561a3dce9313 <+275>:   callq  0x561a3dce9510 <_ZN38_$LT$core..option..Option$LT$T$GT$$GT$5ok_or17hc08dcc56df316dd4E>
   0x0000561a3dce9318 <+280>:   mov    0x58(%rsp),%rax
   0x0000561a3dce9320 <+288>:   mov    0x50(%rsp),%rcx
   0x0000561a3dce9328 <+296>:   mov    %rax,%rdi
   0x0000561a3dce932b <+299>:   mov    %rcx,%rsi
   0x0000561a3dce932e <+302>:   callq  0x561a3dce9640 <_ZN78_$LT$core..result..Result$LT$T$C$$u20$E$GT$$u20$as$u20$core..ops..try..Try$GT$11into_result17h020ad5f0907363fdE>
---Type <return> to continue, or q <return> to quit---q
Quit
(rr) bt
#0  0x0000561a3dce9205 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h36cfa393b9d2739b ()
#1  0x00007ffda0bbad10 in ?? ()
#2  0x0000561a3dcf1065 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::h3a43c45273ccf36f ()
#3  0x0000561a3f47a040 in ?? ()
#4  0x0000000000000005 in ?? ()
#5  0x00007ffda0bbad30 in ?? ()
#6  0x00007ffda0bbad38 in ?? ()
#7  0x00007ffda0bbace0 in ?? ()
#8  0x00007ffda0bbad0f in ?? ()
#9  0x00007ffda0bbacd0 in ?? ()
#10 0x00007ffda0bbac70 in ?? ()
#11 0x00007ffda0bbad80 in ?? ()
#12 0x0000561a3dcf0f75 in std::sys_common::thread_info::set::head7c9f27ff8aec1 ()
#13 0x00007ffda0bbac60 in ?? ()
#14 0x00007ffda0bbaec8 in ?? ()
#15 0x0000000000000000 in ?? ()
(rr) si
0x0000561a3dce920c in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h36cfa393b9d2739b ()
(rr) info registers 
rbp            0x7ffda0bbacc0   0x7ffda0bbacc0
rsp            0x7ffda0bbac20   0x7ffda0bbac20
[...]

Seems the stack is aligned after all.

[bjorn3]

I am still puzzled by the gdb backtraces though.

[sunfishcode]

Oh, it's possible that gdb is trying to parse the prologue and getting confused by the rex prefixes. Let me investigate a little more.

[bjorn3]

Let me investigate a little more.

Thanks

[sunfishcode]

Yes, that looks like it. You can see it in a simple .s file like this:

.globl foo
foo:
       rex push %rbp
       mov    %rsp,%rbp
       sub    $0x20,%rsp
       nop
       add    $0x20,%rsp
       pop %rbp
       retq

gdb has trouble printing back traces in the middle of this function, and removing the rex prefix fixes it.

[sunfishcode]

It looks like opt_level=best is a workaround, as that enables the shrink pass which eliminates the rex prefix. But that's just a workaound, of course we'll want to fix it so that we always avoid the rex prefix so that backtraces work.

[bjorn3]

It looks like opt_level=best is a workaround

Rebuilding sysroot with -Copt-level=3 right now. Hope it fixes at least gdb backtraces.

[bjorn3]

Yes, it fixes the backtraces 🎉

[bjorn3]

Found the corrupting instruction. I don't know why it does corrupt though.

(rr) backtrace
#0  0x000055e6c58b2866 in std::sys_common::thread_info::THREAD_INFO::__init::h84a096a88e66c68a ()
#1  0x000055e6c58a6581 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h72e6de457ec8a4ce ()
#2  0x000055e6c58ab0a6 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::hf9d1413c59690409 ()
#3  0x000055e6c58ba11e in std::sys_common::thread_info::set::h9c22d4252436490b ()
#4  0x000055e6c58ba332 in std::rt::lang_start_internal::h1f8bf9c0dec3faf8 ()
#5  0x000055e6c5894742 in std::rt::lang_start::h9f2ee4672fdbaa85 ()
#6  0x000055e6c5894c19 in main ()
(rr) disassemble
Dump of assembler code for function _ZN3std10sys_common11thread_info11THREAD_INFO6__init17h84a096a88e66c68aE:
   0x000055e6c58b27f0 <+0>:  push   %rbp
   0x000055e6c58b27f1 <+1>:  mov    %rsp,%rbp
   0x000055e6c58b27f4 <+4>:  push   %rbx
   0x000055e6c58b27f5 <+5>:  sub    $0x58,%rsp
   0x000055e6c58b27f9 <+9>:  lea    0x20(%rsp),%rax
   0x000055e6c58b2801 <+17>:  lea    0x0(%rsp),%rcx
   0x000055e6c58b2809 <+25>:  lea    0x50(%rsp),%rdx
   0x000055e6c58b2811 <+33>:  lea    0x48(%rsp),%rbx
   0x000055e6c58b2819 <+41>:  mov    $0x2,%esi
   0x000055e6c58b281e <+46>:  mov    %rsi,(%rax)
   0x000055e6c58b2821 <+49>:  mov    (%rax),%rsi
   0x000055e6c58b2824 <+52>:  mov    %rsi,(%rcx)
   0x000055e6c58b2827 <+55>:  mov    0x8(%rax),%rsi
   0x000055e6c58b282b <+59>:  mov    %rsi,0x8(%rcx)
   0x000055e6c58b282f <+63>:  mov    0x10(%rax),%rsi
   0x000055e6c58b2833 <+67>:  mov    %rsi,0x10(%rcx)
   0x000055e6c58b2837 <+71>:  mov    0x18(%rax),%rax
   0x000055e6c58b283b <+75>:  mov    %rax,0x18(%rcx)
   0x000055e6c58b283f <+79>:  mov    $0x0,%eax
   0x000055e6c58b2844 <+84>:  mov    %rax,(%rbx)
   0x000055e6c58b2847 <+87>:  mov    (%rbx),%rax
   0x000055e6c58b284a <+90>:  mov    %rax,(%rdx)
   0x000055e6c58b284d <+93>:  mov    (%rdx),%rax
   0x000055e6c58b2850 <+96>:  mov    %rax,(%rdi)
   0x000055e6c58b2853 <+99>:  mov    (%rcx),%rax
   0x000055e6c58b2856 <+102>:  mov    %rax,0x8(%rdi)
   0x000055e6c58b285a <+106>:  mov    0x8(%rcx),%rax
   0x000055e6c58b285e <+110>:  mov    %rax,0x10(%rdi)
   0x000055e6c58b2862 <+114>:  mov    0x10(%rcx),%rax
=> 0x000055e6c58b2866 <+118>:  mov    %rax,0x18(%rdi)
   0x000055e6c58b286a <+122>:  mov    0x18(%rcx),%rax
   0x000055e6c58b286e <+126>:  mov    %rax,0x20(%rdi)
   0x000055e6c58b2872 <+130>:  add    $0x58,%rsp
   0x000055e6c58b2876 <+134>:  pop    %rbx
   0x000055e6c58b2877 <+135>:  pop    %rbp
   0x000055e6c58b2878 <+136>:  retq   
(rr) si
0x000055e6c58b286a in std::sys_common::thread_info::THREAD_INFO::__init::h84a096a88e66c68a ()
(rr) backtrace
#0  0x000055e6c58b286a in std::sys_common::thread_info::THREAD_INFO::__init::h84a096a88e66c68a ()
#1  0x000055e6c58a6581 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::try_with::h72e6de457ec8a4ce ()
#2  0x000055e6c58ab0a6 in _$LT$std..thread..local..LocalKey$LT$T$GT$$GT$::with::hf9d1413c59690409 ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

[sunfishcode]

Is it possible that the store to 0x18(%rdi) is somehow clobbering a return address on the stack?

[bjorn3]

That's possible. rdi is a bit higher than rsp.

rdi 0x7ffc3ea15ab8
rsp 0x7ffc3ea159f0

[bjorn3]

(rr) disassemble
Dump of assembler code for function _ZN46_$LT$std..thread..local..LocalKey$LT$T$GT$$GT$8try_with17h72e6de457ec8a4ceE:
   0x000055e6c58a64f0 <+0>:  push   %rbp
   0x000055e6c58a64f1 <+1>:  mov    %rsp,%rbp
   0x000055e6c58a64f4 <+4>:  push   %rbx
   0x000055e6c58a64f5 <+5>:  sub    $0x68,%rsp
   0x000055e6c58a64f9 <+9>:  mov    %rdi,0x40(%rsp)
   0x000055e6c58a6501 <+17>:  mov    %rsi,0x38(%rsp)
   0x000055e6c58a6509 <+25>:  lea    0x0(%rsp),%rax
   0x000055e6c58a6511 <+33>:  mov    %rax,0x30(%rsp)
   0x000055e6c58a6519 <+41>:  lea    0x60(%rsp),%rax
   0x000055e6c58a6521 <+49>:  mov    %rax,0x28(%rsp)
   0x000055e6c58a6529 <+57>:  lea    0x58(%rsp),%rax
=> 0x000055e6c58a6531 <+65>:  mov    %rax,0x20(%rsp)
(rr) info registers
rax            0x7ffc3ea15ab8   0x7ffc3ea15ab8
[...]

0x7ffc3ea15ab8 seems to be a normal part of try_with's stack frame. (offset 0x58 out of 0x68)

Edit: 0x58 + 0x18 = 0x70 which is bigger than 0x68. This seems to be the problem indeed.

[bjorn3]

I was able to work around this in d3dcf4d.

[bjorn3]

I am trying to compile ripgrep using this at the moment. Some build scripts fail, because of code replaced with unimplemented!() to workaround missing varargs support. (CraneStation/cranelift#212)

[bjorn3]

Status report:

For https://github.com/dropbox/rust-brotli-decompressor I get the following on Linux:

$ RUSTFLAGS="-Cpanic=abort -Zcodegen-backend=$(pwd)/../target/debug/librustc_codegen_cranelift.so --sysroot $(pwd)/../build_sysroot/sysroot" cargo run --release --bin brotli-decompressor
[...]
$ lldb target/release/brotli-decompressor
(lldb) target create "target/release/brotli-decompressor"
Current executable set to 'target/release/brotli-decompressor' (x86_64).
(lldb) run
Process 22547 launched: '/home/bjorn/Documenten/rustc_codegen_cranelift/rust-brotli-decompressor/target/release/brotli-decompressor' (x86_64)
Process 22547 stopped
* thread #1: tid = 22547, 0x00005555555bf148 brotli-decompressor`core::ptr::real_drop_in_place::h87a6e70141dee524 + 8 at ptr.rs:193, name = 'brotli-decompre', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
    frame #0: 0x00005555555bf148 brotli-decompressor`core::ptr::real_drop_in_place::h87a6e70141dee524 + 8 at ptr.rs:193
   190  // actually access it with raw pointers.
   191  #[lang = "drop_in_place"]
   192  #[allow(unconditional_recursion)]
-> 193  unsafe fn real_drop_in_place<T: ?Sized>(to_drop: &mut T) {
   194      // Code here does not matter - this is replaced by the
   195      // real drop glue by the compiler.
   196      real_drop_in_place(to_drop)
(lldb) bt
* thread #1: tid = 22547, 0x00005555555bf148 brotli-decompressor`core::ptr::real_drop_in_place::h87a6e70141dee524 + 8 at ptr.rs:193, name = 'brotli-decompre', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
  * frame #0: 0x00005555555bf148 brotli-decompressor`core::ptr::real_drop_in_place::h87a6e70141dee524 + 8 at ptr.rs:193
    frame #1: 0x00005555555bf12e brotli-decompressor`core::ptr::real_drop_in_place::h1288bec36c72e74e + 30 at ptr.rs:193
    frame #2: 0x00005555555bba91 brotli-decompressor`core::ptr::real_drop_in_place::hb04f20f9e1e029a3 + 49 at ptr.rs:193
    frame #3: 0x00005555555bba50 brotli-decompressor`core::ptr::real_drop_in_place::h95d80bc1fd152fa7 + 80 at ptr.rs:193
    frame #4: 0x00005555555b261e brotli-decompressor`core::ptr::real_drop_in_place::hd2b77ac6446ffd50 + 30 at ptr.rs:193
    frame #5: 0x00005555555ce8d9 brotli-decompressor`core::ptr::real_drop_in_place::hc504e28ab70ee02f + 73 at ptr.rs:193
    frame #6: 0x00005555555cddf3 brotli-decompressor`std::io::stdio::stdin::stdin_init::h074a1efd6ad98233 + 947 at stdio.rs:202
    frame #7: 0x00005555555c2e00 brotli-decompressor`_$LT$std..io..lazy..Lazy$LT$T$GT$$GT$::init::hd283afda3e37b21b + 256 at lazy.rs:58
    frame #8: 0x00005555555c2c13 brotli-decompressor`_$LT$std..io..lazy..Lazy$LT$T$GT$$GT$::get::h1cdf1ddd76678384 + 163 at lazy.rs:34
    frame #9: 0x00005555555ded82 brotli-decompressor`std::io::stdio::stdin::h72f7fa09a01a5196 + 82 at stdio.rs:193
    frame #10: 0x000055555558b461 brotli-decompressor`brotli_decompressor::main::h6cd6bd21167c7df1 + 2929
    frame #11: 0x000055555556ca3d brotli-decompressor`std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h5d5bdc3eceea0d27 + 45
    frame #12: 0x00005555555b34d4 brotli-decompressor`std::rt::lang_start_internal::_$u7b$$u7b$closure$u7d$$u7d$::h1ac2308b810b402a + 84 at rt.rs:52
    frame #13: 0x00005555555b3468 brotli-decompressor`std::panicking::try::do_call::hf50a45a4b02cb4f8 + 328 at panicking.rs:297
    frame #14: 0x00005555555e0080 brotli-decompressor`__rust_maybe_catch_panic + 32 at lib.rs:29
    frame #15: 0x00005555555cfc90 brotli-decompressor`std::panicking::try::hbf774221e207c402 + 256 at panicking.rs:276
    frame #16: 0x00005555555dff59 brotli-decompressor`std::rt::lang_start_internal::h0c159ce7acd430d1 + 521 at panic.rs:382
    frame #17: 0x0000555555576af2 brotli-decompressor`std::rt::lang_start::hb4be95bce08f0567 + 66
    frame #18: 0x00005555555a17d9 brotli-decompressor`main + 25
    frame #19: 0x00007ffff74312e1 libc.so.6`__libc_start_main + 241
    frame #20: 0x000055555555808a brotli-decompressor`_start + 42

Note: use lldb or rr, because gdb crashes itself.

[bjorn3]

Note to self: I need to promote any argument smaller than a C int to an int, and promote float to double. (Source: https://github.com/rust-lang/rfcs/blob/master/text/2137-variadic.md)

[bjorn3]

The std::io::stdin() crash from #146 (comment) seems to be caused by drop glue for the error case of a result being run, while the result was Ok.

[bjorn3]

I found a problem: storing a func ptr in a zero sized stack slot. That stack slot was probably meant for TyFnDef instead of TyFnPtr.

[...]
    ss4 = explicit_slot 0
[...]
; _1 = const <std::result::Result<T, E>>::map(move _2, const std::prelude::v1::Some)
@0000                               v6 = func_addr.i64 fn0
@0000                               v7 = load.i8 v2
@0000                               v8 = stack_addr.i64 ss4
[...]

[bjorn3]

Fixed it in 0d16dcf

[bjorn3]

Things crashing:

• ::std::iter::repeat('a' as u8).take(10).collect::<Vec<_>>()
• ::std::io::stderr().write_fmt(format_args!("thread '{}' panicked at ...", "<unknown>"));