Re: Crash on Linux+Clang (NSTimer)

[Riccardo Mottola]

David Chisnall wrote:
> This one is slightly more complicated because we're passing the 
> address of `self` in the argument frame into slowMsgLookup, so our 
> stack looks something like this:
>
> { other args }
> _cmd
> self
> return address from objc_msgSend
> _cmd
> &self (the stored version a little way up the stack)
>
> To fix this, we need to add 4 bytes of padding before the second copy 
> of _cmd.
>
> I think the simplest way to do that is duplicate the push %ecx. We 
> then also need to fix the CFI directive and the add that does the 
> stack restore to compensate for the extra 4 bytes:
>
>
> ```
>     mov   \sel(%esp), %ecx
>     lea   \receiver(%esp), %eax
>
>     push  %ecx                           # Unused, stack alignment
>     push  %ecx                           # _cmd
>     push  %eax                           # &self
>     .cfi_def_cfa_offset 16
>     call  CDECL(slowMsgLookup)@PLT
>     add   $12, %esp                      # restore the stack
> ```
>
> Does that fix it for you?  If so, please can you raise a PR with that 
> change in it? 

It improves things definitely. Now gui apps start again.
Here the test-suite results:

76% tests passed, 44 tests failed out of 186

That's exactly the same number as before and the tests still fail, even 
if in "real world" things improved? That's mysterious.

I tried starting Ink and more complex GWorkspace, Gorm, GNUMail, they 
all come up, load bundles, etc. So I think it is better than before and 
branched.

        Start 125: objc_msgSend
125/186 Test #125: objc_msgSend 
......................................Child aborted***Exception: 0.00 sec
        Start 126: objc_msgSend_optimised
126/186 Test #126: objc_msgSend_optimised 
............................Child aborted***Exception:   0.00 sec
        Start 127: objc_msgSend_legacy
127/186 Test #127: objc_msgSend_legacy 
...............................Child aborted***Exception:   0.00 sec
        Start 128: objc_msgSend_legacy_optimised
128/186 Test #128: objc_msgSend_legacy_optimised 
.....................Child aborted***Exception:   0.00 sec


How can I give you more details on these (and the other) failures? there 
are quite a lot.

I don't know what differs from your setup, mine should be pretty 
"standard" in my intentions.

ccmake . shows I am using clang:

 CMAKE_CXX_COMPILER               /usr/lib/llvm/10/bin/clang++

and gnustep make:
./configure --prefix=/ --with-layout=gnustep 
--with-library-combo=ng-gnu-gnu


Thanks,
Riccardo