[Vm-dev] regression: TestObjectsAsMethods crash in 4.19.5 (not in 4.16.7)

[David T. Lewis]

Thanks.

Confirmed on Linux amd64, so it is not Solaris/OpenIndiana issue.

Dave

On Sun, Feb 21, 2021 at 04:02:38PM +0100, stes at PANDORA.BE wrote:
>  
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> As can be seen in the screenshot at:
> 
> http://docs.openindiana.org/handbook/community/squeak/index.html
> 
> I'm deselecting the Tests-ObjectsAsMethods test (1 test),
> because it causes (reproducible) SIGSEGV on Solaris cc/OpenIndiana gcc.
> 
> I think the segmentation fault is new in recent 4.19, I think it didn't happen
> a while ago in 4.16.
> 
> I can test this as follows: when I install an older version
> 
> squeak -version
> 4.16.7-3775
> 
> then I go into test runner: Tests-ObjectsAsMethods and select 
> TestObjectsAsMethods that works in 4.16.7
> 
> Test Runner
> 
> ...
> TestObjectsAsMethods
> 
> 3 run, 3 passes, 0 expected failures, 0 failures, 0 errors, 0 unexpected passes
> 
> But it stopped working in 4.19.x which is from I believe from:
> 
> ContextInterpreter VMMaker-dtl.422 uuid: e72b95a0-204e-45a1-a4e4-3ac3c9e7a51a
> 
> the interp.c file is automatically generated from VMMaker-dtl.422.
> 
> It's reproducible in the sense that if I deselect all tests, and just select
> that one single test, I can repeatedly and reproducible SIGSEGV the VM.
> 
> When I run the VM under a debugger:
> 
> dbx: warning: Bad transition in runtime linker interface. CONSISTENT->CONSISTENT
> t at 1 (l at 1) signal SEGV (no mapping at the fault address) in interpret at line 9120 in file "interp.c"
>  9120   					foo->freeContexts = longAt((newContext + (BASE_HEADER_SIZE)) + (0 << (SHIFT_FOR_WORD)));
> 
> (dbx) where
> current thread: t at 1
> =>[1] interpret(), line 9120 in "interp.c"
>   [2] main(argc = 1, argv = 0xfeffe250, envp = 0xfeffe258), line 1484 in "sqUnixMain.c"
> 
> The above is from Solaris with cc/dbx but the same thing appears to happen
> for me on OpenIndiana with gcc/gdb.
> 
> Unfortunately because the code of interp.c is automatically generated,
> it looks complicated to me and I don't see what's wrong with those "
> freeContext" code.
> 
> The crash appears to be in:
> 
>                                 /* begin internalActivateNewMethod */
>                                 methodHeader = longAt((foo->newMethod + (BASE_HEADER_SIZE)) + (HeaderIndex << (SHIFT_FOR_WORD)));
>                                 needsLarge = methodHeader & LargeContextBit;
>                                 if ((needsLarge == 0) && (foo->freeContexts != NilContext)) {
>                                         newContext = foo->freeContexts;
>                                         /* begin setFreeContextsAfter: */
>                                         foo->freeContexts = longAt((newContext + (BASE_HEADER_SIZE)) + (0 << (SHIFT_FOR_WORD)));
>                                 } else {
>                                         /* begin externalizeIPandSP */
> 
> Has anyone seen this ?
> 
> Also what is the test 
> TestObjectsAsMethods
> actually doing please ? what is it testing ?
> 
> 
> Regards,
> David Stes
> 
> 
> 
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