llvm dev - Jun 2013 - [LLVMdev] bug or expected behaviour?

On Jun 4, 2013, at 4:23 PM, Tyler Hardin <tghardin1 at catamount.wcu.edu>
wrote:
> If this were a problem with an omitted statement involving a normal
variable, I'd guess you're missing a volatile qualifier. I'm not
100% sure volatile is a valid qualifier for functions, but try it.
Well, yes, if I change the signature to:

	void test(char * volatile x)

It works, but that's because I'm hamstringing the optimizers.  I
don't really see how that has anything to do with the question, though.  If
I change the signature to:

        void test(int x)

It works too... what's special about 'char *'?
> If RTOS stands for real time OS, then reading up on volatile would be a
really good idea.
I'm familiar with 'volatile' semantics, thanks.
> P.S. Sorry Carl, you're going to receive this twice. I forget to CC the
list.
No problem.

-- Carl

I was suggesting to add it to the function, like
volatile void func(..);
Theoretically, this would tell the compiler not to omit seemingly
superfluous calls to func.

On Jun 4, 2013, at 4:23 PM, Tyler Hardin <tghardin1 at catamount.wcu.edu>
wrote:
> If this were a problem with an omitted statement involving a normal
variable, I'd guess you're missing a volatile qualifier. I'm not
100% sure
volatile is a valid qualifier for functions, but try it.

Well, yes, if I change the signature to:

        void test(char * volatile x)

It works, but that's because I'm hamstringing the optimizers.  I
don't
really see how that has anything to do with the question, though.  If I
change the signature to:

        void test(int x)

It works too... what's special about 'char *'?
> If RTOS stands for real time OS, then reading up on volatile would be a
really good idea.

I'm familiar with 'volatile' semantics, thanks.
> P.S. Sorry Carl, you're going to receive this twice. I forget to CC the
list.

No problem.

-- Carl


_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20130604/bc9bb5d9/attachment.html>

On Jun 4, 2013, at 4:42 PM, Tyler Hardin <tghardin1 at catamount.wcu.edu>
wrote:
> I was suggesting to add it to the function, like
> volatile void func(..);
> Theoretically, this would tell the compiler not to omit seemingly
superfluous calls to func.
'volatile' can't apply to a function, so I'm not sure what you
mean.  In your example, 'volatile' modifies the 'void'.  So I
think "theoretically", it doesn't do anything at all.

-- Carl