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RE: "SSE instruction set disabled?"
- From: "Scott Robert Ladd" <scott at coyotegulch dot com>
- To: "Jan Hubicka" <hubicka at ucw dot cz>, <Robert_K_Cook at comerica dot com>
- Cc: "Jakub Jelinek" <jakub at redhat dot com>, <gcc at gcc dot gnu dot org>,"Jan Hubicka" <jh at suse dot cz>
- Date: Wed, 4 Dec 2002 20:00:24 -0500
- Subject: RE: "SSE instruction set disabled?"
> -mfpmath=sse changes behaviour of floating point execution by not using
> 80bit temporaries like x87 code does. This breaks some things (glibc)
> and makes other happy (those who want numberic stability).
> I am inclined to argue to make -mfpmath=sse default when SSE is
> available however last time I lost the battle.
I hadn't even considered this problem -- and I was just about to send off a
raft of questions about gcc and IEC 60559 compliance, so floating-point is
definitely on my mind. I have a major free documentation project underway
about numerical programming in C99...
I need to dig out the Intel processor docs again; it's been a while since I
looked over all the various instructions sets and their implications.
Implied -fpmath=sse may *not* be a good thing under certain circumstances...
..Scott