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Re: [perl #18127] [PATCH] Implicit stack direction probe

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From:
Leopold Toetsch
Date:
October 29, 2002 05:43
Subject:
Re: [perl #18127] [PATCH] Implicit stack direction probe
Message ID:
3DBE8FBE.8030908@toetsch.at
Jason Gloudon (via RT) wrote:

> # New Ticket Created by  Jason Gloudon 
> # Please include the string:  [perl #18127]
> # in the subject line of all future correspondence about this issue. 
> # <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=18127 >


I have problems to understand the line below:

(not voting against your patch - original line is similar)

> +        cur_var_ptr = (size_t)((ptrdiff_t)cur_var_ptr + PARROT_PTR_ALIGNMENT)

When PARROT_PTR_ALIGNMENT is not 1, that much pointers -1 are skipped 
during stack scanning by incrementing cur_var_ptr by sizeof(size_t) * 
PARROT_PTR_ALIGNMENT bytes.

As a side note: applying your patch slows down e.g. life.pasm by ~2%.
(I really don't see why).

leo
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