[PATCH] Flag to enable IEEE-754 friendly FP optimizations

[Stephen Canon]

> On Oct 24, 2014, at 12:23 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> 
> ----- Original Message -----
>> From: "Stephen Canon" <scanon at apple.com <mailto:scanon at apple.com>>
>> To: "Hal Finkel" <hfinkel at anl.gov <mailto:hfinkel at anl.gov>>
>> Cc: "Sergey Dmitrouk" <sdmitrouk at accesssoftek.com <mailto:sdmitrouk at accesssoftek.com>>, "llvm-commits" <llvm-commits at cs.uiuc.edu <mailto:llvm-commits at cs.uiuc.edu>>, "Owen Anderson"
>> <owen at apple.com <mailto:owen at apple.com>>
>> Sent: Friday, October 24, 2014 11:13:10 AM
>> Subject: Re: [PATCH] Flag to enable IEEE-754 friendly FP optimizations
>> 
>> As a necessary piece of building support for FENV_ACCESS, yes, I
>> think this is worth pursuing.  Note, however, that actually
>> providing full FENV_ACCESS support is likely to be a significant
>> undertaking, and I expect that the pieces that go into it are
>> basically useless until all of them are in place.  That’s not to say
>> that it isn’t worth doing, just that it’s a big thankless job.
> 
> Steve, so long as you're willing to serve as the expert reviewer here, I'm happy to help move this forward as well. We should, however, probably have a plan for the rest of it. Maybe this is as simple as: when FP exceptions are enabled, we treat all FP operations as if they might write to memory (except that AA confirms that they don't actually alias with any address in particular, but we say nothing about function calls). What do you think?

From a numerical point of view, something along those lines could be workable, yes.

– Steve
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