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Re: Alpha -mieee Patch
- From: Richard Henderson <rth at redhat dot com>
- To: Tyson Whitehead <twhitehe at uwo dot ca>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 21 Jul 2003 16:45:01 -0700
- Subject: Re: Alpha -mieee Patch
- References: <200307171900.57815.twhitehe@uwo.ca>
On Thu, Jul 17, 2003 at 07:00:57PM -0400, Tyson Whitehead wrote:
> Here's a patch (against CVS HEAD) that makes IEEE compliant math operations
> (support for denormalization, nan, inf, etc) the default on the Alpha unless
> it is specifically turned off with -mno-ieee.
I do not like this.
(1) This has been the status quo on alpha since the beginning of time.
Not just with GCC, but with DEC C as well. Why change now?
(2) Particularly with pre-ev6 cpus, this results in severe penalties
of the performance for maths.
(3) Every time I looked at a non-math user application that got SIGFPE
due to subnormals, it was due to an uninitialized data read.
I will not accept the patch as-is.
(A) At the extreme minimum, I require that -ffast-math result in
ieee math off, unless the user has explicitly enabled it for
some reason.
(B) I do not like a solution that changes the default for just one
operating system. That's a bit of inconsistency that grates.
That means you'll need to track down the other users of alpha gcc
and get agreement. I realize that this will be very difficult --
indeed, I *intend* for it to be difficult.
r~