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Date: Mon, 06 Aug 2012 12:34:33 +0200
From: Alain Frisch <alain@frisch.fr>
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To: Dmitry Bely <dmitry.bely@gmail.com>
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Subject: Re: [Caml-list] Compiler bug?

On 08/06/2012 12:20 PM, Dmitry Bely wrote:
> I always thought that local roots are memory-based. How GC knows that
> in this case [ebx] should be updated? (remember, the parameter was
> passed in [eax]) Could you point me to the relevant part of Ocaml
> compiler sources?

The compiler generates 'frame descriptors', which associate to each 
possible GC call site the set of registers and stack slots which hold 
values.

Look for caml_frame_descriptors.  The logic to scan frame descriptors is 
in asmrun/roots.c.  The implementation of caml_call_gc (e.g. in amd64.S) 
saves/restored machine registers to/from caml_gc_regs.


Alain