[rfc/patch] extract/store typed floating ()

[rfc/patch] extract/store typed floating ()

[Andrew Cagney]

Hello,

This patch introduces two new functions:

	extract_typed_floating()
	store_typed_floating()

The new functions take a ``struct type'' that exactly describes the 
floating point number to be extracted / stored.

The old extract/store floating functions:

	extract_floating()
	store_floating()

are documented as deprecated (outside of doublest.c).  Several uses do 
still remain:

o 
targets still use them.  I think is an obvious
	fix and I'll add this to the ARI ready for
	a rainy day.

o 
symbol table readers and the XXX-lang.c code still
	create ``struct type'' floats that specify just
	the TYPE_LENGTH and not the TYPE_FLOATFORMAT (sigh).
	Consequently extract/store typed floating() use them.

If you're wondering, the new functions take their names from a 
combination of extract_typed_address(), extract_address() and 
extract_floating().

Assuming that there are no concerns raised, I'll check this in in a few 
days.

And the good news?  This endith the core-gdb floating-point overhaul. 
Just need to encourage target maintainers to make use of it and clean up 
the loose ends :-)

	Andrew
From dhoward@redhat.com Thu Sep 20 16:11:00 2001
From: Don Howard <dhoward@redhat.com>
To: Andrew Cagney <ac131313@cygnus.com>
Cc: Fernando Nasser <fnasser@cygnus.com>, Michael Snyder <msnyder@cygnus.com>, <gdb-patches@sources.redhat.com>
Subject: Re: [RFA] deleting breakpoints inside of 'commands' [Repost]
Date: Thu, 20 Sep 2001 16:11:00 -0000
Message-id: <Pine.LNX.4.33.0109201609080.9139-100000@theotherone>
References: <Pine.LNX.4.33.0109201305160.9139-100000@theotherone>
X-SW-Source: 2001-09/msg00281.html
Content-length: 3310

I thought of a problem with this patch: It could change a command list
(adding additional commands) if a breakpoint is hit while processing
another breakpoint.  Bugger.  Maybe I could add a field to struct
command_line for managing orphans?


On Thu, 20 Sep 2001, Don Howard wrote:

>
>
> Here is a patch that I hope will satisfy all sides.  The patch below
> changes free_command_lines() to check if we are currently
> 'executing_breakpoint_commands'.  If so, the command list is appended to
> a list of 'orphaned_command_lines'.  When the execution of the command
> list completes, the orphaned_command_lines are then deleted.
>
> Should I make the global variables static and add accessor/mutator
> functions?  What is the policy on globals?
>
> Comments?
>
>
>
> 2001-09-20  Don Howard  <dhoward@redhat.com>
>
> 	* cli/cli-script.c (free_command_lines): Avoid deleting
> 	command_line lists while executing that list.
> 	* breakpoint.c: (executing_breakpoint_commands): Make this
> 	global visible to other compilation units.
> 	(orphaned_breakpoint_commands) New global.
> 	(bpstat_do_actions): Free orphaned command_line structures once
> 	done executing them.
>
>
> Index: gdb/breakpoint.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/breakpoint.c,v
> retrieving revision 1.53
> diff -p -u -w -r1.53 breakpoint.c
> --- breakpoint.c	2001/09/18 05:00:48	1.53
> +++ breakpoint.c	2001/09/20 22:18:17
> @@ -221,8 +221,11 @@ extern int addressprint;	/* Print machin
>  static int internal_breakpoint_number = -1;
>
>  /* Are we executing breakpoint commands?  */
> -static int executing_breakpoint_commands;
> +int executing_breakpoint_commands;
>
> +/* List of breakpoint commands to be cleaned up after we are done executing them. */
> +struct command_line * orphaned_breakpoint_commands;
> +
>  /* Walk the following statement or block through all breakpoints.
>     ALL_BREAKPOINTS_SAFE does so even if the statment deletes the current
>     breakpoint.  */
> @@ -1845,6 +1848,7 @@ top:
>      }
>
>    executing_breakpoint_commands = 0;
> +  free_command_lines (&orphaned_breakpoint_commands);
>    discard_cleanups (old_chain);
>  }
>
> Index: gdb/cli/cli-script.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/cli/cli-script.c,v
> retrieving revision 1.7
> diff -p -u -w -r1.7 cli-script.c
> --- cli-script.c	2001/06/17 15:16:12	1.7
> +++ cli-script.c	2001/09/20 22:18:17
> @@ -1014,7 +1014,25 @@ free_command_lines (struct command_line
>    register struct command_line *next;
>    struct command_line **blist;
>    int i;
> +  extern int executing_breakpoint_commands;
> +  extern struct command_line * orphaned_breakpoint_commands;
>
> +  /* Avoid deleting command_line lists while executing that list. */
> +  if (executing_breakpoint_commands)
> +    {
> +      struct command_line **b = NULL;
> +
> +      /* Find the end of the orphaned_breakpoint_commands list */
> +      for (b = &orphaned_breakpoint_commands; *b; b = &((*b)->next))
> +	/* Nothing */
> +	;
> +
> +      /* Append the passed-in list */
> +      *b = *lptr;
> +      *lptr = NULL;
> +      return;
> +    }
> +
>    while (l)
>      {
>        if (l->body_count > 0)
>
>
>

-- 
-Don
dhoward@redhat.com
gdb engineering

Re: [rfc/patch] extract/store typed floating ()

[Andrew Cagney]

> 
> I'm not sure whether zeroing out the buffer in store_typed_floating()
> is desirable.  I've (almost) convinced myself that it isn't.  Here's a
> part of a comment that I added to the doublest.c in my current tree:
> 
>       /* ...
> 
>          It is debatable whether we should zero out any remaining
>          bytes in the target buffer, when converting from a type that
>          has a smaller length than the target type.  Right now we
>          don't do that.  A typical case where this situation arises is
>          when we convert a i387 floating-point register to a `long
>          double' in memory.  On the target, that operation only stores
>          the first 10 bytes, and leaves alone the remaining 2 bytes.
>          It makes sense to mimick this behaviour here.  */
> 
> This comment comes from a function convert_floating() that I intend to
> add to doublest.c.  I'll submit a patch after you've checked yours in.

Don't forget that the routines are expecting to manipulate a GDB 
internal buffer freshly allocated from the heap and not target memory. 
Failing to initialize it would leave it containing complete garbage 
(perhaphs I should set it to 0xdeadbeef).  That garbage would then be 
written back to the target since (well from memory) GDB writes all 
length bytes from a value buffer.

To ``do the write thing'', I suspect ``struct value'' and the value <-> 
memory transfer routines would all need to be modified so that they only 
write a sub-section of the buffer.  Other ideas also come to mind: 
edit_typed_floating() that edits an floating point buffer in place; add 
an ``old buffer'' parameter that can be used to optionally initialize 
unused bytes; or use  the raw floatformat routines(1) where needed.

The case that would worry me is with i387 registers.  For that, I think 
the target should just specify the 10 byte FP type so that GDB won't 
touch any padding bytes.

Andrew

(1) Would need to fix the problem of TYPE_FLOATFORMAT not always being 
initialized.

Re: [rfc/patch] extract/store typed floating ()

[Andrew Cagney]

> Andrew Cagney <ac131313@cygnus.com> writes:
> 
> 
>> Hello,
>> 
>> This patch introduces two new functions:
>> 
>> extract_typed_floating()
>> store_typed_floating()
>> 
>> The new functions take a ``struct type'' that exactly describes the 
>> floating point number to be extracted / stored.
> 
> 
> The new names sound a lot better than the extract_doublest() you
> proposed earlier.  I'd say, go for it  [:-)] .

It is in. (Some times I think the hardest thing about hacking on GDB is 
comming up with reasonable names for files and functional interfaces :-)

	Andrew