Wow. Great, John! Thanks. This should keep me at bay for a good while.
From: mrj...@gmail.com
Date: Thu, 16 Aug 2012 08:10:31 -0700
To: factor-talk@lists.sourceforge.net
Subject: Re: [Factor-talk] Any way of making sense of what's in the boot
image?
In the listener, if you run this code:
IN: scratchpad clear IN: scratchpad "value" "key" associate
Then step over to [ set-at ] keep
If at this point you just keep stepping "into" things, you should do a deep
dive into all the parts, including the 4 slot { array } declare which should
give you something like { ~tombstone~ ~tombstone~ ~tombstone~ ~tombstone~ } (an
array full of "tombstone" elements which indicate no key or value is present).
A hashtable with deleted elements will have "~empty~". A hashtable with
key/value will have { "key" "value" } at some point in the array. The array is
flattened key/value pairs, so a 4 bucket hashtable will have an 8 element array
storing key/value side-by-side starting at the even indices.
I'm not sure what the 26-slot hash table is that you are looking at, so I put a
clear in the code above to make sure your data stack is empty before walking.
It is also possible that you are tracing some code which is traversing the
namespaces (a vector of hashtables containing symbolic variables used in parts
of the code, with names like the ones you mention).
A hashtable has 3 slots (the 0 slot is a numeric value), see:
```IN: scratchpad \ hashtable "slots" word-prop .{ T{ slot-spec
{ name "count" } { offset 2 } { class array-capacity }
{ initial 0 } } T{ slot-spec { name "deleted" }
{ offset 3 } { class array-capacity } { initial 0 } }
T{ slot-spec { name "array" } { offset 4 }
{ class array } { initial { } } }}```
You might also like to try "describe", and poke around at the various word
properties (see "props" below):
```IN: scratchpad \ hashtable describeIN: hashtables SYMBOL: hashtablehashcode
251442479911733628name "hashtable"vocabulary "hashtables"
def [ \ hashtable ]props H{ { "help-parent" "hashtables" } {
"slots" ~array~ } { ...pic-def fpic-tail-def fsub-primitive f
```
On Thu, Aug 16, 2012 at 6:01 AM, Michael Clagett <mclag...@hotmail.com> wrote:
Hi --
Okay. I'm going to ask for my first lifeline. :) I'm tracing through some
arcane stuff indeed. Everything is going along swimmingly. I get to the word
"new-key@", which at its start wants to execute [ array>> 2dup hash@ 0 f
(new-key@) ] with the "keep" combinator. All good so far. "array>>" resolves
to [ 4 slot { array } declare ], which I believe should mean "get the 4th slot
of the object on top of stack and declare to Factor that you know for sure it
is an array". The object on the top of the stack, according to the Inspector,
is a 26-slot hash table that includes such keys as "architecture", "auto-use?",
"bootstrap-syntax", "bootsrapping?", etc.
Now comes the part that baffles me. When I get to executing "slot" (whether I
try to step past it or descend into it), the Walker simply moves me all the way
to the end of the qotation (past "declare") and I see the hash-table and index
from the top of the data stack replaced with a 128-element array that has the
26 key-value pairs from the former hash table spread out through the array
interspersed by tombstone objects; each of these key-value pairs that appear
occupy two adjacent array slots. But I'm completely mystified as to how the
contents of the hash-table got mapped to the array slots they now occupy (there
doesn't seem to be any rhyme or reason). And I have little insight into the
code that accomplished this. Moreover I apparently can't see the 4th slot of
the original object in the Inspector, as it only shows me three slots on the
data stack trace, but organizes them alphabetically when I double-click to open
the Inspector window.
Don't know if any of this was intelligble. But maybe one of you compiler guys
can give me a clue as to how I can understand this. I'm having to reverse
engineer my understanding of all of this, so a break in the logical chain
presents difficulties.
Sorry for the long post.
Regards,
Mike
> Date: Wed, 15 Aug 2012 08:30:10 -0700
> From: doug.cole...@gmail.com
> To: factor-talk@lists.sourceforge.net
> Subject: Re: [Factor-talk] Any way of making sense of what's in the boot
> image?
>
> 1) Factor loads a ~/.factor-rc file every time it starts. You can put
> things there:
>
> USE: tools.scaffold
> scaffold-factor-rc
>
> Click it, edit it and add:
>
> USING: prettyprint.config namespaces ;
> 16 number-base set-global
>
>
>
> 2) Alternately, there's a boot rc file that gets loaded after bootstrap:
>
> USE: tools.scaffold
> scaffold-factor-boot-rc
>
> Click it, edit it and add:
>
> USING: prettyprint.config namespaces ;
> 16 number-base set-global
>
> To load it without bootstrapping, call 'run-bootstrap-init' and then
> 'save' your image.
>
>
> Doug
>
>
> On Wed, Aug 15, 2012 at 8:22 AM, Michael Clagett <mclag...@hotmail.com> wrote:
> > Thanks. I knew it had to be something like that. And if I want it to be
> > the default every time I load the Listener, I'm sure there must be a way to
> > set that up?
> >
> > Sent from my iPhone
> >
> > On Aug 15, 2012, at 11:01 AM, "John Benediktsson" <mrj...@gmail.com> wrote:
> >
> > If you want all numbers to print in hex, the easiest way is:
> >
> > ```
> > IN: scratchpad 16 number-base set-global
> > ```
> >
> >
> > On Wed, Aug 15, 2012 at 4:04 AM, Michael Clagett <mclag...@hotmail.com>
> > wrote:
> >>
> >> Quick question. Any way of having the data and retain stack panes of the
> >> Walker display values in hex?
> >>
> >> > Date: Mon, 13 Aug 2012 12:21:52 -0400
> >> > From: arc...@gmail.com
> >> > To: factor-talk@lists.sourceforge.net
> >> > Subject: Re: [Factor-talk] Any way of making sense of what's in the boot
> >> > image?
> >> >
> >> > On Mon, Aug 13, 2012 at 11:52 AM, Michael Clagett <mclag...@hotmail.com>
> >> > wrote:
> >> > > Here's an obscure question that is of interest to me in my current
> >> > > quest,
> >> > > but probably not to anyone else. So if there is a better forum for me
> >> > > to
> >> > > ask such things, I would love to be instructed; until I hear
> >> > > otherwise,
> >> > > however, I will continue to use this list.
> >> > >
> >> > > Is there any place where I can penetrate the meaning of the following
> >> > > constants:
> >> > >
> >> > > CONSTANT: rt-dlsym 0
> >> > > CONSTANT: rt-entry-point 1
> >> > > CONSTANT: rt-entry-point-pic 2
> >> > > CONSTANT: rt-entry-point-pic-tail 3
> >> > > CONSTANT: rt-here 4
> >> > > CONSTANT: rt-this 5
> >> > > CONSTANT: rt-literal 6
> >> > > CONSTANT: rt-untagged 7
> >> > > CONSTANT: rt-megamorphic-cache-hits 8
> >> > > CONSTANT: rt-vm 9
> >> > > CONSTANT: rt-cards-offset 10
> >> > > CONSTANT: rt-decks-offset 11
> >> > > CONSTANT: rt-exception-handler 12
> >> > > CONSTANT: rt-dlsym-toc 13
> >> > > CONSTANT: rt-inline-cache-miss 14
> >> > > CONSTANT: rt-safepoint 15
> >> > >
> >> > > So far I've only encountered rt-here and I've only seen it encoded
> >> > > into a
> >> > > relocation entry and not really used anywhere yet. But this strikes me
> >> > > as
> >> > > the kind of thing it would be useful to know as I am slogging through
> >> > > this
> >> > > stuff.
> >> > >
> >> > > Not a hugely pressing question, as I'm sure I'll muddle through it.
> >> > > But if
> >> > > anyone has a moment to illuminate, it would be nice.
> >> >
> >> > Those are relocation record types. When the compiler generates code
> >> > for a word, it also needs to generate relocation entries every time it
> >> > references another word in a jump or call statement, much like a
> >> > native C compiler needs to do for symbols in other modules.
> >> > The VM uses these relocation entries to update the operands of jump
> >> > and call instructions when code is written to the code heap, when the
> >> > code heap is compacted, or if code is moved in memory for any reason.
> >> > The different rt-* constants are used to describe what kind of object
> >> > a relocation refers to, such as a foreign function in a DLL (dlsym), a
> >> > word entry point (entry-point-*), the current address (here), etc.
> >> >
> >> > -Joe
> >> >
> >> >
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