[M3devel] dbxout_static_chain_decl?

[Tony Hosking]

Argh!!!!!
No!  We don't want to do work in the front-end to get rid of nesting.
It is terribly important for performance (e.g., register allocation) that we retain the gcc-based support.



Antony Hosking | Associate Professor | Computer Science | Purdue University
305 N. University Street | West Lafayette | IN 47907 | USA
Office +1 765 494 6001 | Mobile +1 765 427 5484




On 26 May 2010, at 18:53, Jay K wrote:

> 
> Rodney, When you get back to it, can you just dig it out of history?
> 
> 
> I still think we should try to avoid gcc's nested function functionality.
> 
> 
> Where you use the static chain, not using the nested function functionality should
> "automatically" be debuggable -- "automatic" as in, once the work is done
> in the frontend to transform out nesting.
> 
> 
> "debuggable" as in, you could follow the links yourself in the debugger.
> The debugger need not search lexically nested functions that have function
> calls dividing them.
> 
> 
> ?
> 
> 
> There's stuff I still need to understand better -- particularly the affect of nested functions
> on non-nested functions. Is there *always* an extra parameter to *all* functions?
> It appears so.
> And I haven't figured out how to merge with 4.5 what I think achieves that.
> 
> 
> Maybe a good test of test cases here?
> 
> 
> 
> - Jay
> 
> 
> ----------------------------------------
>> Date: Wed, 26 May 2010 17:37:07 -0500
>> From: rodney_bates at lcwb.coop
>> To: m3devel at elegosoft.com
>> Subject: Re: [M3devel] dbxout_static_chain_decl?
>> 
>> I left it in because it is a work in progress. I *really* want to get it to
>> work, and I don't what to have to reinvent what is already there when I get
>> to it. I use nested procedures extensively in certain situations, and good
>> debugger support of them is important to me. It all works fine on older code
>> generators than the gcc that added tree-nested.c.
>> 
>> Jay K wrote:
>>> Rodney, you added this function, along with a comment that says it doesn't actually work.
>>> Does it work?
>>> Does it accomplish anything?
>>> Can I remove it and its calls?
>>> 
>>> /* Special-purpose function to write stabs for the static_chain_decl.
>>> So far, this is not working. m3gdb needs the place in the activation
>>> record where the SL is stored. Right now, the SL is not necessarily
>>> stored at all, but may just be kept in a register. DECL_RTL and
>>> DECL_INCOMING_RTL may both have register expressions. But stabs
>>> entries for register variables, of kind N_RSYM, are currently ignored
>>> by gdb in dbxread.c, and making it read them could create problems
>>> elsewhere, because there can be other variables for which both an
>>> N_RSYM and an N_LSYM stabs entry are created.
>>> */
>>> static int
>>> dbxout_static_chain_decl (tree decl)
>>> 
>>> It was added 19 months ago by:
>>> http://modula3.elegosoft.com/cgi-bin/cvsweb.cgi/cm3/m3-sys/m3cc/gcc/gcc/dbxout.c.diff?r1=1.8;r2=1.9
>>> 
>>> as well, do we need the #if 0 code added then?
>>> 
>>> - Jay
>>> 		 	   		  

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