RE: [cc65] Re: Patch for reading a 'volatile' pointer

I don't think you should apply the patch. A language platform should either
support or not 
support a given keyword. In this case, the general utility to be gained is
very small, and 
the potential harm ( mostly in the form of confusion and perhaps wasted time
) is larger. 

-----Original Message-----
From: owner-cc65@musoftware.de [mailto:owner-cc65@musoftware.de] On Behalf
Of Dave Dribin
Sent: Friday, December 17, 2010 10:44 PM
To: cc65@musoftware.de
Subject: Re: [cc65] Re: Patch for reading a 'volatile' pointer

On Sun, Dec 12, 2010 at 2:58 PM, Ullrich von Bassewitz <uz@musoftware.de>
wrote:
> Your code is almost exactly identical to what I would have written, when
> implementing it without changing the compiler structure. But it is just
about
> 10-15% of what has to be done, and the missing parts are the reason why I
> didn't do it. Each and every optimizer routine that removes or rewrites
code
> has to check the new CodeEntry flag for every code line in question,
otherwise
> volatile processing might work in a few cases, but fail in many others. So
> while it's a start, it is just that.

Yeah.  I pretty much just hacked in support for the one case I needed. ;)

> So how to proceed? I'm willing to apply the patch in this or a similar
form,
> but everybody has to realize that this will change the current situation
only
> a bit. Instead of "volatile is parsed but ignored", which is a clear and
> unambiguous statement, it would then be "volatile is parsed and might
> sometimes work". If this is considered an improvement, I will apply the
patch.

This is a good question.... I'm not quite I can provide any valuable
input.  Is 10% of volatile better than 0%?  It is if you're the one
who wants to use that 10%. ;)  Also, does this help a common case for
using volatile?  Given the PEEK/POKE macros, accessing specific
address is pretty common, and often those addresses are hardware
registers.

Some questions... is volatile something you'd like to eventually fully
support?  Does this patch help get you there?  If so, perhaps full
volatile support could be added piecemeal, over time, rather than
waiting for some grand redesign, in which case this patch is the first
step towards that.

-Dave
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