segfault during stage2 build of dist x86_64-apple-darwin xcode 7.3

[oli-obk]

So far not reproducible on newer xcode versions.

cc @varkor @kennytm

52dec0e obviously did not fix it and can be reverted.

Happens inside

rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::h069c687f17acced0 + 760

whenever it happens, but it's random during which crate's compilation it happens or whether it occurs at all.

Guesses so far are

• alignment issues with Span, which is repr(packed) and only has a u32 field
• something to do with the CACHE thread_local (just because miri touched statics)

Is is possible to produce better stacktraces (with line info e.g.) on macs?

[kennytm]

Interestingly this seems to be quite deterministic on #48326. The bug happened twice so far and only on that PR (besides the miri PR).

[pietroalbini]

Also happened on #48757

[pietroalbini]

Both #48757 (log) and #48388 (log) failed building the first two crates of cargo stage2 in parallel, receiving a SIGSEGV on both the rustc processes. The sets of crates failing are different across the builds.

[kennytm]

Reproduced on Travis and the offending artifact should have been uploaded to S3.

Edit: That artifacts segfaults locally.

(lldb) bt
* thread #2, name = 'rustc', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
  * frame #0: 0x000000010162c7e8 librustc-863c36ebb34cad14.dylib`rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::h8d48a4ca8ec2db40 + 760
    frame #1: 0x00000001016373a9 librustc-863c36ebb34cad14.dylib`rustc::ich::impls_syntax::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$$u5b$syntax..ast..Attribute$u5d$$GT$::hash_stable::hcbeec66e1d823fad + 2681
    frame #2: 0x00000001015fe649 librustc-863c36ebb34cad14.dylib`_$LT$rustc..hir..map..collector..HirItemLike$LT$T$GT$$u20$as$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$hir$GT$$GT$$GT$::hash_stable::hbcbbaf6c54b1cc3e + 201
    frame #3: 0x000000010156ea4c librustc-863c36ebb34cad14.dylib`rustc::dep_graph::graph::DepGraph::with_task::h2676a93b883dbd65 + 2764
    frame #4: 0x00000001015fbee2 librustc-863c36ebb34cad14.dylib`_$LT$rustc..hir..map..collector..NodeCollector$LT$$u27$a$C$$u20$$u27$hir$GT$$u20$as$u20$rustc..hir..intravisit..Visitor$LT$$u27$hir$GT$$GT$::visit_item::h8804047228cc6c2e + 338
    frame #5: 0x000000010160de38 librustc-863c36ebb34cad14.dylib`rustc::hir::map::map_crate::h81da5cba736e888a + 4744
    frame #6: 0x00000001001623a3 librustc_driver-316df4eccf83bc20.dylib`rustc_driver::driver::compile_input::h50b15af9e8f0bc9e + 9907
    frame #7: 0x000000010017f60f librustc_driver-316df4eccf83bc20.dylib`rustc_driver::run_compiler::he5fca2bf13208946 + 4479
    frame #8: 0x00000001000a7b56 librustc_driver-316df4eccf83bc20.dylib`std::sys_common::backtrace::__rust_begin_short_backtrace::he6dd637274e4e34c + 1046
    frame #9: 0x0000000102d997ff libstd-ab14014bac7f480c.dylib`__rust_maybe_catch_panic + 31
    frame #10: 0x00000001000e4366 librustc_driver-316df4eccf83bc20.dylib`_$LT$F$u20$as$u20$alloc..boxed..FnBox$LT$A$GT$$GT$::call_box::h3dd84feee2236c8c + 134
    frame #11: 0x0000000102d8e41c libstd-ab14014bac7f480c.dylib`std::sys::unix::thread::Thread::new::thread_start::h8d626b697ba2edfb + 140
    frame #12: 0x00007fff7a5406c1 libsystem_pthread.dylib`_pthread_body + 340
    frame #13: 0x00007fff7a54056d libsystem_pthread.dylib`_pthread_start + 377
    frame #14: 0x00007fff7a53fc5d libsystem_pthread.dylib`thread_start + 13
(lldb) disass
librustc-863c36ebb34cad14.dylib`rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::h8d48a4ca8ec2db40:
    0x10162c4f0 <+0>:    push   rbp
    0x10162c4f1 <+1>:    mov    rbp, rsp
    0x10162c4f4 <+4>:    push   r15
    0x10162c4f6 <+6>:    push   r14
    0x10162c4f8 <+8>:    push   r13
    0x10162c4fa <+10>:   push   r12
    0x10162c4fc <+12>:   push   rbx
    0x10162c4fd <+13>:   sub    rsp, 0xc8
    0x10162c504 <+20>:   mov    r14, rdx
    0x10162c507 <+23>:   mov    r12, rsi
    0x10162c50a <+26>:   mov    rbx, rdi
    0x10162c50d <+29>:   mov    qword ptr [rbp - 0x50], r12
    0x10162c511 <+33>:   cmp    byte ptr [r12 + 0xb8], 0x0
    0x10162c51a <+42>:   je     0x10162c656               ; <+358>
    0x10162c520 <+48>:   lea    rsi, [rip + 0x448879]     ; str.1zW + 33680
    0x10162c527 <+55>:   mov    rdi, rbx
    0x10162c52a <+58>:   call   0x1019dcc2e               ; symbol stub for: _$LT$syntax_pos..span_encoding..Span$u20$as$u20$core..cmp..PartialEq$GT$::eq::h0e56e2d603ee2cd2
    0x10162c52f <+63>:   test   al, al
    0x10162c531 <+65>:   jne    0x10162c637               ; <+327>
    0x10162c537 <+71>:   mov    esi, dword ptr [rbx]
    0x10162c539 <+73>:   lea    rdi, [rbp - 0x48]
    0x10162c53d <+77>:   call   0x1013c2410               ; syntax_pos::span_encoding::Span::data::h6f31e1db7305e513
    0x10162c542 <+82>:   mov    r15d, dword ptr [rbp - 0x48]
    0x10162c546 <+86>:   mov    r13d, dword ptr [rbp - 0x44]
    0x10162c54a <+90>:   cmp    r13d, r15d
    0x10162c54d <+93>:   jb     0x10162c637               ; <+327>
    0x10162c553 <+99>:   lea    rbx, [r12 + 0x30]
    0x10162c558 <+104>:  cmp    qword ptr [r12 + 0x30], 0x0
    0x10162c55e <+110>:  jne    0x10162c5cf               ; <+223>
    0x10162c560 <+112>:  mov    rsi, qword ptr [r12 + 0x28]
    0x10162c565 <+117>:  lea    rdi, [rbp - 0xd8]
    0x10162c56c <+124>:  call   0x10162ba30               ; rustc::ich::caching_codemap_view::CachingCodemapView::new::h8caa73032c4551e5
    0x10162c571 <+129>:  cmp    qword ptr [r12 + 0x30], 0x0
    0x10162c577 <+135>:  je     0x10162c5b1               ; <+193>
    0x10162c579 <+137>:  lea    rax, [r12 + 0x60]
    0x10162c57e <+142>:  mov    qword ptr [rbp - 0x30], rax
    0x10162c582 <+146>:  lea    rdi, [r12 + 0x48]
    0x10162c587 <+151>:  call   0x10141e640               ; core::ptr::drop_in_place::h756bf3ffd5133862
    0x10162c58c <+156>:  lea    rax, [r12 + 0x88]
    0x10162c594 <+164>:  mov    qword ptr [rbp - 0x30], rax
    0x10162c598 <+168>:  lea    rdi, [r12 + 0x70]
    0x10162c59d <+173>:  call   0x10141e640               ; core::ptr::drop_in_place::h756bf3ffd5133862
    0x10162c5a2 <+178>:  add    r12, 0x98
    0x10162c5a9 <+185>:  mov    rdi, r12
    0x10162c5ac <+188>:  call   0x10141e640               ; core::ptr::drop_in_place::h756bf3ffd5133862
    0x10162c5b1 <+193>:  lea    rsi, [rbp - 0xd8]
    0x10162c5b8 <+200>:  mov    edx, 0x88
    0x10162c5bd <+205>:  mov    rdi, rbx
    0x10162c5c0 <+208>:  call   0x1019dd246               ; symbol stub for: memcpy
    0x10162c5c5 <+213>:  cmp    qword ptr [rbx], 0x0
    0x10162c5c9 <+217>:  je     0x10162c8bd               ; <+973>
    0x10162c5cf <+223>:  lea    rdi, [rbp - 0xf0]
    0x10162c5d6 <+230>:  mov    rsi, rbx
    0x10162c5d9 <+233>:  mov    edx, r15d
    0x10162c5dc <+236>:  call   0x10162bbd0               ; rustc::ich::caching_codemap_view::CachingCodemapView::byte_pos_to_line_and_col::hf3c0193086c7751b
    0x10162c5e1 <+241>:  mov    r12, qword ptr [rbp - 0xf0]
    0x10162c5e8 <+248>:  test   r12, r12
    0x10162c5eb <+251>:  je     0x10162c637               ; <+327>
    0x10162c5ed <+253>:  mov    rbx, qword ptr [rbp - 0xe8]
    0x10162c5f4 <+260>:  movzx  eax, byte ptr [rbp - 0xe0]
    0x10162c5fb <+267>:  mov    qword ptr [rbp - 0x38], r12
    0x10162c5ff <+271>:  cmp    dword ptr [r12 + 0x104], r13d
    0x10162c607 <+279>:  ja     0x10162c613               ; <+291>
    0x10162c609 <+281>:  cmp    dword ptr [r12 + 0x108], r13d
    0x10162c611 <+289>:  jae    0x10162c668               ; <+376>
    0x10162c613 <+291>:  mov    byte ptr [rbp - 0xd8], 0x1
    0x10162c61a <+298>:  lea    rsi, [rbp - 0xd8]
    0x10162c621 <+305>:  mov    edx, 0x1
    0x10162c626 <+310>:  mov    rdi, r14
    0x10162c629 <+313>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c62e <+318>:  inc    qword ptr [r14 + 0x48]
    0x10162c632 <+322>:  jmp    0x10162c7cc               ; <+732>
    0x10162c637 <+327>:  mov    byte ptr [rbp - 0xd8], 0x1
    0x10162c63e <+334>:  lea    rsi, [rbp - 0xd8]
    0x10162c645 <+341>:  mov    edx, 0x1
    0x10162c64a <+346>:  mov    rdi, r14
    0x10162c64d <+349>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c652 <+354>:  inc    qword ptr [r14 + 0x48]
    0x10162c656 <+358>:  add    rsp, 0xc8
    0x10162c65d <+365>:  pop    rbx
    0x10162c65e <+366>:  pop    r12
    0x10162c660 <+368>:  pop    r13
    0x10162c662 <+370>:  pop    r14
    0x10162c664 <+372>:  pop    r15
    0x10162c666 <+374>:  pop    rbp
    0x10162c667 <+375>:  ret    
    0x10162c668 <+376>:  mov    dword ptr [rbp - 0x30], eax
    0x10162c66b <+379>:  mov    byte ptr [rbp - 0xd8], 0x0
    0x10162c672 <+386>:  lea    rsi, [rbp - 0xd8]
    0x10162c679 <+393>:  mov    edx, 0x1
    0x10162c67e <+398>:  mov    rdi, r14
    0x10162c681 <+401>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c686 <+406>:  inc    qword ptr [r14 + 0x48]
    0x10162c68a <+410>:  mov    rax, qword ptr [r12 + 0xf0]
    0x10162c692 <+418>:  mov    qword ptr [rbp - 0xd8], rax
    0x10162c699 <+425>:  lea    rsi, [rbp - 0xd8]
    0x10162c6a0 <+432>:  mov    edx, 0x8
    0x10162c6a5 <+437>:  mov    rdi, r14
    0x10162c6a8 <+440>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c6ad <+445>:  add    qword ptr [r14 + 0x48], 0x8
    0x10162c6b2 <+450>:  mov    edi, r13d
    0x10162c6b5 <+453>:  mov    esi, r15d
    0x10162c6b8 <+456>:  call   0x1019dcc04               ; symbol stub for: _$LT$syntax_pos..BytePos$u20$as$u20$core..ops..arith..Sub$GT$::sub::hdb689f5a05767d93
    0x10162c6bd <+461>:  and    rbx, 0xffffff
    0x10162c6c4 <+468>:  shl    rbx, 0x8
    0x10162c6c8 <+472>:  mov    ecx, dword ptr [rbp - 0x30]
    0x10162c6cb <+475>:  or     rcx, rbx
    0x10162c6ce <+478>:  shl    rax, 0x20
    0x10162c6d2 <+482>:  or     rax, rcx
    0x10162c6d5 <+485>:  mov    qword ptr [rbp - 0xd8], rax
    0x10162c6dc <+492>:  lea    rsi, [rbp - 0xd8]
    0x10162c6e3 <+499>:  mov    edx, 0x8
    0x10162c6e8 <+504>:  mov    rdi, r14
    0x10162c6eb <+507>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c6f0 <+512>:  add    qword ptr [r14 + 0x48], 0x8
    0x10162c6f5 <+517>:  cmp    dword ptr [rbp - 0x40], 0x0
    0x10162c6f9 <+521>:  je     0x10162c7a8               ; <+696>
    0x10162c6ff <+527>:  mov    byte ptr [rbp - 0xd8], 0x0
    0x10162c706 <+534>:  lea    rsi, [rbp - 0xd8]
    0x10162c70d <+541>:  mov    edx, 0x1
    0x10162c712 <+546>:  mov    rdi, r14
    0x10162c715 <+549>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c71a <+554>:  inc    qword ptr [r14 + 0x48]
    0x10162c71e <+558>:  lea    rdi, [rip + 0x4f723b]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c725 <+565>:  call   qword ptr [rdi]
    0x10162c727 <+567>:  cmp    byte ptr [rax + 0x21], 0x0
    0x10162c72b <+571>:  jne    0x10162c8cb               ; <+987>
    0x10162c731 <+577>:  lea    rdi, [rip + 0x4f7228]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c738 <+584>:  call   qword ptr [rdi]
    0x10162c73a <+586>:  cmp    byte ptr [rax + 0x20], 0x0
    0x10162c73e <+590>:  jne    0x10162c765               ; <+629>
    0x10162c740 <+592>:  lea    rdi, [rip + 0x4f7219]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c747 <+599>:  call   qword ptr [rdi]
    0x10162c749 <+601>:  lea    rsi, [rip - 0x2513f0]     ; std::thread::local::fast::destroy_value::h795e0dcafb24f001
    0x10162c750 <+608>:  mov    rdi, rax
    0x10162c753 <+611>:  call   0x1019dcdc0               ; symbol stub for: std::sys::unix::fast_thread_local::register_dtor::h4e4cabb233ebf8c9
    0x10162c758 <+616>:  lea    rdi, [rip + 0x4f7201]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c75f <+623>:  call   qword ptr [rdi]
    0x10162c761 <+625>:  mov    byte ptr [rax + 0x20], 0x1
    0x10162c765 <+629>:  lea    rdi, [rip + 0x4f71f4]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c76c <+636>:  call   qword ptr [rdi]
    0x10162c76e <+638>:  cmp    qword ptr [rax + 0x18], 0x0
    0x10162c773 <+643>:  je     0x10162c7da               ; <+746>
    0x10162c775 <+645>:  lea    rdi, [rip + 0x4f71e4]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c77c <+652>:  call   qword ptr [rdi]
    0x10162c77e <+654>:  lea    rdi, [rbp - 0x48]
    0x10162c782 <+658>:  lea    rsi, [rbp - 0x50]
    0x10162c786 <+662>:  mov    rdx, rax
    0x10162c789 <+665>:  call   0x10162c940               ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::_$u7b$$u7b$closure$u7d$$u7d$::h3094acc762e79e5f
    0x10162c78e <+670>:  mov    qword ptr [rbp - 0xd8], rax
    0x10162c795 <+677>:  mov    ebx, 0x8
    0x10162c79a <+682>:  lea    rsi, [rbp - 0xd8]
    0x10162c7a1 <+689>:  mov    edx, 0x8
    0x10162c7a6 <+694>:  jmp    0x10162c7c0               ; <+720>
    0x10162c7a8 <+696>:  mov    byte ptr [rbp - 0xd8], 0x1
    0x10162c7af <+703>:  mov    ebx, 0x1
    0x10162c7b4 <+708>:  lea    rsi, [rbp - 0xd8]
    0x10162c7bb <+715>:  mov    edx, 0x1
    0x10162c7c0 <+720>:  mov    rdi, r14
    0x10162c7c3 <+723>:  call   0x1013cea80               ; rustc_data_structures::sip128::SipHasher128::short_write::hddbede9409661ad5
    0x10162c7c8 <+728>:  add    qword ptr [r14 + 0x48], rbx
    0x10162c7cc <+732>:  lea    rdi, [rbp - 0x38]
    0x10162c7d0 <+736>:  call   0x10141e640               ; core::ptr::drop_in_place::h756bf3ffd5133862
    0x10162c7d5 <+741>:  jmp    0x10162c656               ; <+358>
    0x10162c7da <+746>:  call   0x1019dcd30               ; symbol stub for: std::collections::hash::map::DefaultResizePolicy::new::h7e59c95758f35a6c
    0x10162c7df <+751>:  lea    rdi, [rip + 0x4f717a]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c7e6 <+758>:  call   qword ptr [rdi]
->  0x10162c7e8 <+760>:  movdqa xmm0, xmmword ptr [rax]
    0x10162c7ec <+764>:  movdqa xmm1, xmmword ptr [rax + 0x10]
    0x10162c7f1 <+769>:  mov    rcx, -0x1
    0x10162c7f8 <+776>:  movq   xmm2, rcx
    0x10162c7fd <+781>:  pslldq xmm2, 0x8                 ; xmm2 = zero,zero,zero,zero,zero,zero,zero,zero,xmm2[0,1,2,3,4,5,6,7] 
    0x10162c802 <+786>:  movdqa xmmword ptr [rax], xmm2
    0x10162c806 <+790>:  mov    ecx, 0x1
    0x10162c80b <+795>:  movq   xmm2, rcx
    0x10162c810 <+800>:  pslldq xmm2, 0x8                 ; xmm2 = zero,zero,zero,zero,zero,zero,zero,zero,xmm2[0,1,2,3,4,5,6,7] 
    0x10162c815 <+805>:  movdqa xmmword ptr [rax + 0x10], xmm2
    0x10162c81a <+810>:  pshufd xmm1, xmm1, 0x4e          ; xmm1 = xmm1[2,3,0,1] 
    0x10162c81f <+815>:  movq   rbx, xmm1
    0x10162c824 <+820>:  test   rbx, rbx
    0x10162c827 <+823>:  je     0x10162c775               ; <+645>
    0x10162c82d <+829>:  pshufd xmm0, xmm0, 0x4e          ; xmm0 = xmm0[2,3,0,1] 
    0x10162c832 <+834>:  movq   rcx, xmm0
    0x10162c837 <+839>:  inc    rcx
    0x10162c83a <+842>:  je     0x10162c775               ; <+645>
    0x10162c840 <+848>:  lea    rsi, [8*rcx]
    0x10162c848 <+856>:  shl    rcx, 0x4
    0x10162c84c <+860>:  lea    rdi, [rbp - 0xd8]
    0x10162c853 <+867>:  mov    edx, 0x8
    0x10162c858 <+872>:  mov    r8d, 0x8
    0x10162c85e <+878>:  call   0x1019dcd36               ; symbol stub for: std::collections::hash::table::calculate_allocation::h80671a357bb87ea0
    0x10162c863 <+883>:  mov    rdx, qword ptr [rbp - 0xd8]
    0x10162c86a <+890>:  mov    rsi, qword ptr [rbp - 0xd0]
    0x10162c871 <+897>:  mov    rax, rdx
    0x10162c874 <+900>:  neg    rax
    0x10162c877 <+903>:  cmp    rsi, rax
    0x10162c87a <+906>:  ja     0x10162c8d2               ; <+994>
    0x10162c87c <+908>:  lea    rax, [rdx - 0x1]
    0x10162c880 <+912>:  mov    rcx, rdx
    0x10162c883 <+915>:  or     rcx, -0x80000000
    0x10162c88a <+922>:  and    rcx, rax
    0x10162c88d <+925>:  jne    0x10162c8d2               ; <+994>
    0x10162c88f <+927>:  and    rbx, -0x2
    0x10162c893 <+931>:  mov    rdi, rbx
    0x10162c896 <+934>:  call   0x1019bf7e0               ; __rust_dealloc
    0x10162c89b <+939>:  lea    rdi, [rip + 0x4f70be]     ; rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::CACHE::__getit::__KEY::h765db91289e6600a
    0x10162c8a2 <+946>:  call   qword ptr [rdi]
    0x10162c8a4 <+948>:  cmp    qword ptr [rax + 0x18], 0x0
    0x10162c8a9 <+953>:  jne    0x10162c775               ; <+645>
    0x10162c8af <+959>:  lea    rdi, [rip + 0x4e3ada]
    0x10162c8b6 <+966>:  call   0x1019dd04e               ; symbol stub for: core::panicking::panic::h09bcda4b57fcbe39
    0x10162c8bb <+971>:  jmp    0x10162c8de               ; <+1006>
    0x10162c8bd <+973>:  lea    rdi, [rip + 0x4e3acc]
    0x10162c8c4 <+980>:  call   0x1019dd04e               ; symbol stub for: core::panicking::panic::h09bcda4b57fcbe39
    0x10162c8c9 <+985>:  ud2    
    0x10162c8cb <+987>:  call   0x101493c10               ; core::result::unwrap_failed::hdc4d27fde799a2d6
    0x10162c8d0 <+992>:  jmp    0x10162c8de               ; <+1006>
    0x10162c8d2 <+994>:  lea    rdi, [rip + 0x4e3ab7]
    0x10162c8d9 <+1001>: call   0x1019dd04e               ; symbol stub for: core::panicking::panic::h09bcda4b57fcbe39
    0x10162c8de <+1006>: ud2    
    0x10162c8e0 <+1008>: jmp    0x10162c8e4               ; <+1012>
    0x10162c8e2 <+1010>: jmp    0x10162c8e4               ; <+1012>
    0x10162c8e4 <+1012>: mov    r14, rax
    0x10162c8e7 <+1015>: lea    rdi, [rbp - 0x38]
    0x10162c8eb <+1019>: call   0x10141e640               ; core::ptr::drop_in_place::h756bf3ffd5133862
    0x10162c8f0 <+1024>: jmp    0x10162c932               ; <+1090>
    0x10162c8f2 <+1026>: jmp    0x10162c91b               ; <+1067>
    0x10162c8f4 <+1028>: mov    r15, qword ptr [rbp - 0x30]
    0x10162c8f8 <+1032>: mov    r14, rax
    0x10162c8fb <+1035>: add    r12, 0xb0
    0x10162c902 <+1042>: mov    rdi, r15
    0x10162c905 <+1045>: call   0x1014095b0               ; core::ptr::drop_in_place::h307e3bf3d12d15ea
    0x10162c90a <+1050>: mov    rax, r15
    0x10162c90d <+1053>: add    rax, 0x28
    0x10162c911 <+1057>: mov    r15, rax
    0x10162c914 <+1060>: cmp    r12, rax
    0x10162c917 <+1063>: jne    0x10162c902               ; <+1042>
    0x10162c919 <+1065>: jmp    0x10162c91e               ; <+1070>
    0x10162c91b <+1067>: mov    r14, rax
    0x10162c91e <+1070>: lea    rsi, [rbp - 0xd8]
    0x10162c925 <+1077>: mov    edx, 0x88
    0x10162c92a <+1082>: mov    rdi, rbx
    0x10162c92d <+1085>: call   0x1019dd246               ; symbol stub for: memcpy
    0x10162c932 <+1090>: mov    rdi, r14
    0x10162c935 <+1093>: call   0x1019dd1b0               ; symbol stub for: _Unwind_Resume
    0x10162c93a <+1098>: ud2    
    0x10162c93c <+1100>: nop    dword ptr [rax]

[kennytm]

@oli-obk

From the stack trace it is obviously caused by the CACHE TLS. The segfault happens during initialization of the CACHE i.e. when the HashMap was first created.

The instruction throwing the error is

(lldb) fr sel 0
frame #0: 0x000000010162c7e8 librustc-863c36ebb34cad14.dylib`rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::h8d48a4ca8ec2db40 + 760
librustc-863c36ebb34cad14.dylib`rustc::ich::hcx::_$LT$impl$u20$rustc_data_structures..stable_hasher..HashStable$LT$rustc..ich..hcx..StableHashingContext$LT$$u27$a$GT$$GT$$u20$for$u20$syntax_pos..span_encoding..Span$GT$::hash_stable::h8d48a4ca8ec2db40:
->  0x10162c7e8 <+760>: movdqa xmm0, xmmword ptr [rax]
    0x10162c7ec <+764>: movdqa xmm1, xmmword ptr [rax + 0x10]
    0x10162c7f1 <+769>: mov    rcx, -0x1
    0x10162c7f8 <+776>: movq   xmm2, rcx

where rax is not aligned on the 16-byte boundary. Thus the segfault is caused by unaligned access in the movdqa instruction.

(lldb) x $rax
0x104211488: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0x104211498: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

The rax should be the address of the CACHE. I don't know why it needs to be aligned, and why it isn't aligned in stage2.

If you've got a Mac you may try to debug it yourself. There's no line info though.

• Stage 1 artifact: https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rustc-builds-alt/7ad66eb8422bc359b0c8a1564dd9339380a6985f/stage1.xz
• Stage 2 artifact: https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rustc-builds-alt/7ad66eb8422bc359b0c8a1564dd9339380a6985f/stage2.xz

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Also, we may be switching to Xcode 9 for dist in #48891, and that bug might go away naturally 🤔