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Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n

From: Richard Henderson <rth at redhat dot com>
To: Paolo Bonzini <bonzini at gnu dot org>
Cc: gcc-patches at gcc dot gnu dot org
Date: Sun, 26 Jun 2005 21:45:07 -0700
Subject: Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n
References: <20050619172501.GA20194@redhat.com> <OFA7F7C79E.BEFDF6B2-ONC2257026.002CCCDD-C2257026.005118FC@il.ibm.com> <20050620181455.GA22847@redhat.com> <d98dp9$3mj$1@sea.gmane.org>

On Tue, Jun 21, 2005 at 09:03:48AM +0200, Paolo Bonzini wrote:
> I think min and max should be implemented in term of unsigned saturated 
> subtraction for unsigned values.

Hmm, yes.

uminv8hi:
	movdqa	a, t1
	psubusw	b, t1	/* t1[n] == 0 iff b[n] >= a[n] */
	pxor	t2, t2
	pcmpeqw	t1, t2	/* t2[n] = b[n] < a[n] ? -1 : 0 */
	movdqa	t2, t3
	pand	a, t3
	pandn	b, t2
	por	t3, t2

I suppose that's just about comparable with what we'd need to
do to expand to wider operations.

I'll work on this...


r~

References:
- Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n
  - From: Richard Henderson
- Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n
  - From: Dorit Naishlos
- Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n
  - From: Richard Henderson
- Re: [patch] (4.1 stage 2 projects): vectorize reduction, part 3/n
  - From: Paolo Bonzini

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