From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:44981) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TAeMe-0005dd-0z for qemu-devel@nongnu.org; Sun, 09 Sep 2012 06:03:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TAeMc-0002OZ-OR for qemu-devel@nongnu.org; Sun, 09 Sep 2012 06:03:39 -0400 Received: from hall.aurel32.net ([88.191.126.93]:33804) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TAeMc-0002OT-Hr for qemu-devel@nongnu.org; Sun, 09 Sep 2012 06:03:38 -0400 Date: Sun, 9 Sep 2012 12:03:35 +0200 From: Aurelien Jarno Message-ID: <20120909100335.GQ17750@hall.aurel32.net> References: <1347138767-19941-1-git-send-email-aurelien@aurel32.net> <1347138767-19941-4-git-send-email-aurelien@aurel32.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: Aurelien Jarno Subject: Re: [Qemu-devel] [PATCH 4/5] target-ppc: use the softfloat float32_muladd function List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: qemu-devel@nongnu.org, Alexander Graf On Sun, Sep 09, 2012 at 10:51:20AM +0100, Peter Maydell wrote: > On 8 September 2012 22:12, Aurelien Jarno wrote: > > +#define VARITHFPFMA(suffix, type) \ > > + void helper_v##suffix(CPUPPCState *env, ppc_avr_t *r, ppc_avr_t *a, \ > > + ppc_avr_t *b, ppc_avr_t *c) \ > > + { \ > > + int i; \ > > + for (i = 0; i < ARRAY_SIZE(r->f); i++) { \ > > + r->f[i] = float32_muladd(a->f[i], c->f[i], b->f[i], \ > > + type, &env->vec_status); \ > > + } \ > > + } > > +VARITHFPFMA(maddfp, 0); > > +VARITHFPFMA(nmsubfp, float_muladd_negate_result); > > +#undef VARITHFPFMA > > + > > #define VARITHSAT_CASE(type, op, cvt, element) \ > > { \ > > type result = (type)a->element[i] op (type)b->element[i]; \ > > -void helper_vnmsubfp(CPUPPCState *env, ppc_avr_t *r, ppc_avr_t *a, > > - ppc_avr_t *b, ppc_avr_t *c) > > -{ > > - int i; > > - > > - for (i = 0; i < ARRAY_SIZE(r->f); i++) { > > - HANDLE_NAN3(r->f[i], a->f[i], b->f[i], c->f[i]) { > > - /* Need to do the computation is higher precision and round > > - * once at the end. */ > > - float64 af, bf, cf, t; > > - > > - af = float32_to_float64(a->f[i], &env->vec_status); > > - bf = float32_to_float64(b->f[i], &env->vec_status); > > - cf = float32_to_float64(c->f[i], &env->vec_status); > > - t = float64_mul(af, cf, &env->vec_status); > > - t = float64_sub(t, bf, &env->vec_status); > > - t = float64_chs(t); > > - r->f[i] = float64_to_float32(t, &env->vec_status); > > - } > > - } > > -} > > I mentioned this in my comment on the other patch, but just to attach > it to the right patch for the benefit of the archives: > the code here for vnmsub is (correctly) doing a subtraction of bf > and then negating the final result, so you need to pass float_muladd > the flags negate_result | negate_c, not just negate_result. > Correct, or alternatively it could use negate_product. I'll send an updated patch later. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net