[SR-10504] No Stack Trace is produced on Linux Ubuntu 16.04/18.04 with AArch64 CPU

[futurejones]

Previous ID	SR-10504
Radar	None
Original Reporter	@futurejones
Type	Bug
Status	Closed
Resolution	Done

Environment

Linux Ubuntu 16.04/18.04 AArch64

Additional Detail from JIRA

Votes	0
Component/s	Standard Library
Labels	Bug, Runtime
Assignee	None
Priority	Medium

md5: 89c3bbd67c6b974a07f1d6df8c0c6da8

Issue Description:

No Stack Trace is being produced on Linux Ubuntu 16.04/18.04 with AArch64 CPU.
The following are the outputs from running the backtrace.swift test file.

x86

(lldb) target create backtrace
Current executable set to 'backtrace' (x86_64).
(lldb) r
Process 3130 launched: '/backtrace' (x86_64)
Fatal error: Unexpectedly found nil while unwrapping an Optional value
Current stack trace:
0    libswiftCore.so                    0x00007ffff7cce050 _swift_stdlib_reportFatalError + 69
1    libswiftCore.so                    0x00007ffff7bdbdc6 <unavailable> + 3280326
2    libswiftCore.so                    0x00007ffff7bdc145 <unavailable> + 3281221
3    libswiftCore.so                    0x00007ffff7a03bd0 _fatalErrorMessage(_:_:file:line:flags:) + 19
4    backtrace                          0x00005555555550eb <unavailable> + 4331
5    backtrace                          0x0000555555554ff4 <unavailable> + 4084
6    libc.so.6                          0x00007ffff6c70740 __libc_start_main + 240
7    backtrace                          0x0000555555554d79 <unavailable> + 3449
Process 3130 stopped
* thread #&#8203;1, name = 'backtrace', stop reason = Fatal error: Unexpectedly found nil while unwrapping an Optional value
    frame #&#8203;0: 0x00007ffff7c707c0 libswiftCore.so`_swift_runtime_on_report
libswiftCore.so`_swift_runtime_on_report:
->  0x7ffff7c707c0 <+0>: retq
    0x7ffff7c707c1:      nopw   %cs:(%rax,%rax)
libswiftCore.so`_swift_reportToDebugger:
    0x7ffff7c707d0 <+0>: jmp    0x7ffff7c707c0            ; _swift_runtime_on_report
    0x7ffff7c707d5:      nopw   %cs:(%rax,%rax)
Target 0: (backtrace) stopped.
(lldb)

aarch64

(lldb) target create backtrace
Current executable set to 'backtrace' (aarch64).
(lldb) r
Process 1085 launched: '/backtrace' (aarch64)
Fatal error: Unexpectedly found nil while unwrapping an Optional value
Current stack trace:
Process 1085 stopped
* thread #​1, name = 'backtrace', stop reason = Fatal error: Unexpectedly found nil while unwrapping an Optional value
    frame #​0: 0x0000007fb7e297b4 libswiftCore.so`_swift_runtime_on_report
libswiftCore.so`_swift_runtime_on_report:
->  0x7fb7e297b4 <+0>: ret

libswiftCore.so`_swift_reportToDebugger:
    0x7fb7e297b8 <+0>: b      0x7fb7e297b4              ; _swift_runtime_on_report

libswiftCore.so`_swift_shouldReportFatalErrorsToDebugger:
    0x7fb7e297bc <+0>: adrp   x8, 292
    0x7fb7e297c0 <+4>: ldrb   w0, [x8, #&#8203;0x490]
Target 0: (backtrace) stopped.
(lldb)

As there is no stack trace being produced the linux-fatal-bracktrace test is failing on aarch64.

[belkadan]

It looks like the implementation for this is in swift::printCurrentBacktrace in stdlib/public/runtime/Errors.cpp, if you want to check it out. It's just calling backtrace(3), though, so you or someone would have to look into why that might be failing on AArch64.

[futurejones]

Closing this as the test is now passing.