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Re: G++ could optimize ASM code more

From: Marc Glisse <marc dot glisse at inria dot fr>
To: Daniel Marschall <daniel-marschall at viathinksoft dot de>
Cc: gcc at gcc dot gnu dot org
Date: Wed, 9 May 2012 21:48:18 +0200 (CEST)
Subject: Re: G++ could optimize ASM code more
Mail-reply-to: gcc at gcc dot gnu dot org
References: <e8ff8edff20e117587346516e5dd7160@viathinksoft.de> <mcr1umte9qz.fsf@dhcp-172-18-216-180.mtv.corp.google.com> <7b04a9ad5115a2b237bd0fa53a845c58@viathinksoft.de> <mcrehqtb425.fsf@dhcp-172-18-216-180.mtv.corp.google.com> <24a579fb7f1d8985447fd6e2f6982291@viathinksoft.de>
Reply-to: gcc at gcc dot gnu dot org

On Wed, 9 May 2012, Daniel Marschall wrote:

1. I do not know my DisplayName/DisplayFamily (0f_2h or 0f_3h?).

Ask your processor (cpuid). Or your kernel (/proc/cpuinfo on linux).

3. Should I compare Latency or Throughput if I want to produce fast code? Or doesn't it matter which value I compare?

Both. And you also need to look at the code that is nearby, not just this one instruction. In short, don't bother. If you really want to know, benchmark both versions.

--
Marc Glisse

Follow-Ups:
- Re: G++ could optimize ASM code more
  - From: Daniel Marschall

References:
- G++ could optimize ASM code more
  - From: Daniel Marschall
- Re: G++ could optimize ASM code more
  - From: Ian Lance Taylor
- Re: G++ could optimize ASM code more
  - From: Daniel Marschall
- Re: G++ could optimize ASM code more
  - From: Ian Lance Taylor
- Re: G++ could optimize ASM code more
  - From: Daniel Marschall

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