[LLVMdev] Fast-math flags in constant expressions

Sergey Dmitrouk sdmitrouk at accesssoftek.com
Thu Dec 4 01:38:36 PST 2014

On Wed, Dec 03, 2014 at 11:26:48PM -0800, Owen Anderson wrote:
> That's the opposite of what fast math flags do.

Well, still quite close.  Function arguments turned out to be a bad
choice, so Hal suggested using fast-math flags instead.  I guess there
isn't many other options.

> If you want to solve that problem, I believe you want to prevent the
> folding of floating point instructions into constant expressions.

Yes, that's what I did at the end.  Probably wasn't clear enough in my
previous email.

> The direction you're going seems like a pretty major violation of the
> intended functionality of constant expressions.

If you're talking about adding fast-math flags to constant expressions,
then I'm not going to try that.  It just that Language Reference doesn't
note this difference for binary operations inside/outside constant
expressions (maybe I didn't find it, but I was looking there).


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