This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [Bug target/65614] [5 Regression] PowerPC VSX systems should use XSCPSGNDP to copy scalar fp data to/from Altivec registers
- From: Michael Meissner <meissner at linux dot vnet dot ibm dot com>
- To: David Edelsohn <dje dot gcc at gmail dot com>
- Cc: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 6 Apr 2015 23:25:10 -0400
- Subject: Re: [Bug target/65614] [5 Regression] PowerPC VSX systems should use XSCPSGNDP to copy scalar fp data to/from Altivec registers
- Authentication-results: sourceware.org; auth=none
- References: <bug-65614-15150 at http dot gcc dot gnu dot org/bugzilla/> <bug-65614-15150-TdBMEeJ70A at http dot gcc dot gnu dot org/bugzilla/> <20150406171026 dot GA6005 at ibm-tiger dot the-meissners dot org> <CAGWvnyk9geM461UA4soRfCnwVB5A4DGyzZBKn6Wo6TBwvip0ow at mail dot gmail dot com>
On Mon, Apr 06, 2015 at 07:56:53PM -0400, David Edelsohn wrote:
> Okay.
>
> What's the source of COSTS_N_INSNS(3) value?
It is the basic cost of a FP insn (i.e. it duplicates what rs6000_cost->fp
would be -- all of the simple FP ops are this value, XSADDDP, XSMULDP,
etc. including the two move insns XSCPSGNDP and FMR). On the power7 and
power8, each basic FP op is 6 cycles, and all of the costs use the fact that
COSTS_N_INSNS multiplies by 2.
Obviously in the grand scheme of things, we need to rewrite the cost
infrastructure, and bring it up to date, but for now, I used the values for the
other insns.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797