Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1738540

[PATCH 4.4 22/66] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero

Path csiph.com!goblin1!goblin2!goblin.stu.neva.ru!news.unit0.net!news.panservice.it!bofh.it!news.nic.it!robomod
From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.4 22/66] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero
Date Sun, 24 Sep 2017 23:30:02 +0200
Message-ID <utmDo-5ss-23@gated-at.bofh.it> (permalink)
References <utlQZ-4Ti-3@gated-at.bofh.it>
X-Mailer git-send-email 2.14.1
User-Agent quilt/0.65
MIME-Version 1.0
Content-Type text/plain; charset=UTF-8
Sender robomod@news.nic.it
List-ID <linux-kernel.vger.kernel.org>
X-Mailing-List linux-kernel@vger.kernel.org
Approved robomod@news.nic.it
Lines 151
Organization linux.* mail to news gateway
X-Original-Cc Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org, Miodrag Dinic <miodrag.dinic@imgtec.com>, Goran Ferenc <goran.ferenc@imgtec.com>, Aleksandar Markovic <aleksandar.markovic@imgtec.com>, James Hogan <james.hogan@imgtec.com>, Bo Hu <bohu@google.com>, Douglas Leung <douglas.leung@imgtec.com>, Jin Qian <jinqian@google.com>, Paul Burton <paul.burton@imgtec.com>, Petar Jovanovic <petar.jovanovic@imgtec.com>, Raghu Gandham <raghu.gandham@imgtec.com>, linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>
X-Original-Date Sun, 24 Sep 2017 22:31:17 +0200
X-Original-Message-ID <20170924202921.498046906@linuxfoundation.org>
X-Original-References <20170924202920.581603259@linuxfoundation.org>
X-Original-Sender linux-kernel-owner@vger.kernel.org
Xref csiph.com linux.kernel:1738540

Show key headers only | View raw

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>

commit 15560a58bfd4ff82cdd16b2270d4ef9b06d2cc4d upstream.

Fix the value returned by <MAX|MAXA|MIN|MINA>.<D|S>, if both inputs
are zeros. The right behavior in such cases is stated in instruction
reference manual and is as follows:

   fs  ft       MAX     MIN       MAXA    MINA
  ---------------------------------------------
    0   0        0       0         0       0
    0  -0        0      -0         0      -0
   -0   0        0      -0         0      -0
   -0  -0       -0      -0        -0      -0

Prior to this patch, some of the above cases were yielding correct
results. However, for the sake of code consistency, all such cases
are rewritten in this patch.

A relevant example:

MAX.S fd,fs,ft:
  If fs contains +0.0, and ft contains -0.0, fd is going to contain
  +0.0 (without this patch, it used to contain -0.0).

Fixes: a79f5f9ba508 ("MIPS: math-emu: Add support for the MIPS R6 MAX{, A} FPU instruction")
Fixes: 4e9561b20e2f ("MIPS: math-emu: Add support for the MIPS R6 MIN{, A} FPU instruction")

Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Bo Hu <bohu@google.com>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: Jin Qian <jinqian@google.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16881/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/math-emu/dp_fmax.c |    8 ++------
 arch/mips/math-emu/dp_fmin.c |    8 ++------
 arch/mips/math-emu/sp_fmax.c |    8 ++------
 arch/mips/math-emu/sp_fmin.c |    8 ++------
 4 files changed, 8 insertions(+), 24 deletions(-)

--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -92,9 +92,7 @@ union ieee754dp ieee754dp_fmax(union iee
 		return ys ? x : y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
@@ -204,9 +202,7 @@ union ieee754dp ieee754dp_fmaxa(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -92,9 +92,7 @@ union ieee754dp ieee754dp_fmin(union iee
 		return ys ? y : x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
@@ -204,9 +202,7 @@ union ieee754dp ieee754dp_fmina(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -92,9 +92,7 @@ union ieee754sp ieee754sp_fmax(union iee
 		return ys ? x : y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
@@ -204,9 +202,7 @@ union ieee754sp ieee754sp_fmaxa(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -92,9 +92,7 @@ union ieee754sp ieee754sp_fmin(union iee
 		return ys ? y : x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
@@ -204,9 +202,7 @@ union ieee754sp ieee754sp_fmina(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[PATCH 4.4 22/66] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:30 +0200

csiph-web