[SR-4429] Linux: segfault when storing @convention(block) functions

[swift-ci]

Previous ID	SR-4429
Radar	None
Original Reporter	jberkel (JIRA User)
Type	Bug

Environment

Ubuntu 16.04, Swift 3.1

$ swiftc -version
Swift version 3.1 (swift-3.1-RELEASE)
Target: x86_64-unknown-linux-gnu
$ uname -a
Linux tbuntu 4.4.0-59-generic #​80-Ubuntu SMP Fri Jan 6 17:47:47 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, Linux, RunTimeCrash, Runtime
Assignee	None
Priority	Medium

md5: 3f0022818fa972b721701158b4dc15f0

Issue Description:

test.swift:

let f: @convention(block) () -> () = {}
let functions = [ f ]

compile & run:

$ swiftc test.swift -ldispatch && lldb test -o run
(lldb) target create "test"
Current executable set to 'test' (x86_64).
(lldb) run
Process 3024 stopped
* thread #​1, name = 'test', stop reason = signal SIGSEGV: invalid address (fault address: 0x18b598b)
    frame #&#8203;0: 0x00007ffff7af9012 libswiftCore.so`Swift._allocateUninitializedArray <A> (Builtin.Word) -> (Swift.Array<A>, Builtin.RawPointer) + 50
libswiftCore.so`Swift._allocateUninitializedArray <A> (Builtin.Word) -> (Swift.Array<A>, Builtin.RawPointer):
->  0x7ffff7af9012 <+50>: movq   0x90(%rcx), %rdx
    0x7ffff7af9019 <+57>: movzwl %dx, %esi
    0x7ffff7af901c <+60>: addq   $0x20, %rsi
    0x7ffff7af9020 <+64>: orq    $-0x10000, %rdx
$

[belkadan]

@jckarter, are there known issues around this?

[jckarter]

Does this only affect Linux?

[jckarter]

…do we even really support blocks on Linux? Works for me on Darwin, so may be a bug in the ported blocks runtime. I don't know what's being used there.

[belkadan]

IIRC we do support blocks on Linux. SourceKit is using them.

[swift-ci]

Comment by Jan Berkel (JIRA)

This is still an issue on Swift 5.4.