[M3devel] deeper meaning of in_memory?

[Jay K]

> structs volatile

Mainly paranoia.But I do wonder if the breakage I saw in gcc's "sra" optimization pass (structure replaced by aggregate) by feeding it trees can be reproduced from C. I should look into that...

 - Jay

Subject: Re: [M3devel] deeper meaning of in_memory?
From: hosking at cs.purdue.edu
Date: Fri, 28 Sep 2012 10:11:49 -0400
CC: m3devel at elegosoft.com
To: jay.krell at cornell.edu

in_memory does not mean volatile.  It is simply a sign that its address is needed.So, yes, taking its address is good enough.An example of a local in memory is something passed by VAR.
So, NOT VOLATILE.
Why do structs need to be C volatile?


On Sep 27, 2012, at 10:57 PM, Jay K <jay.krell at cornell.edu> wrote:In M3CG, what is the deeper meaning of in_memory?I know it means -- "put the thing in memory".But why and exactly what?
Presumably it can also be in a register, just that the in-memory value must be kept up to date.Like, stores should be volatile, but reads don't have to be?Does it mean the value will be used in an exception/finally handler?Maybe reads do need to be volatile? Maybe it is accessed by another thread w/o a lock?

If I take the address of something, is that good enough?

I should just look where m3front uses it, I know.For now I'll probably take it to mean "volatile".I already mark all structs as volatile. But I don't make everything volatile (like how m3cc long did).

Thanks, - Jay



 		 	   		  
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