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

[stes@PANDORA.BE]

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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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