please help about garbage collector.

please help about garbage collector.

[alin soare]

/* When scanning the C stack for live Lisp objects, Emacs keeps track
   of what memory allocated via lisp_malloc is intended for what
   purpose.  This enumeration specifies the type of memory.  */

Could you explain me what kind of Lisp Objects are keps on the stack ? What kind
of Lisp objects are kept on the stack ?

Where and why such objects are allocated ?

Thanks.


Alin.

Re: please help about garbage collector.

[Andreas Schwab]

alin soare <as1789@gmail.com> writes:

> Could you explain me what kind of Lisp Objects are keps on the stack ?

Anything in automatic varables that the compiler puts there.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: please help about garbage collector.

[Alin Soare]

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> > Could you explain me what kind of Lisp Objects are keps on the stack ?
>
> Anything in automatic varables that the compiler puts there.
>

How can you detect that at a given address on the stack there is a lisp
object, and not something else ?

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Re: please help about garbage collector.

[Andreas Schwab]

Alin Soare <as1789@gmail.com> writes:

> How can you detect that at a given address on the stack there is a lisp
> object, and not something else ?

By heuristic.  Read about conservative garbage collection in your
favorite text book.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: please help about garbage collector.

[Stefan Monnier]

>> > Could you explain me what kind of Lisp Objects are keps on the stack ?
>> Anything in automatic varables that the compiler puts there.
> How can you detect that at a given address on the stack there is a lisp
> object, and not something else ?

You can't, but we do it anyway.  It's called "conservative stack scanning".


        Stefan

Re: please help about garbage collector.

[Alin Soare]

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> How can you detect that at a given address on the stack there is a lisp
> > object, and not something else ?
>
> By heuristic.  Read about conservative garbage collection in your
> favorite text book.
>
>
Very interesting... I did not know about this kind of algorithm.

Thanks a lot.

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