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From: Aleksandar Markovic <aleksandar.markovic@rt-rk.com>
To: linux-mips@linux-mips.org
Cc: Aleksandar Markovic <aleksandar.markovic@imgtec.com>,
	Miodrag Dinic <miodrag.dinic@imgtec.com>,
	Goran Ferenc <goran.ferenc@imgtec.com>,
	"# 4 . 7+" <stable@vger.kernel.org>, Bo Hu <bohu@google.com>,
	Douglas Leung <douglas.leung@imgtec.com>,
	James Hogan <james.hogan@imgtec.com>,
	Jin Qian <jinqian@google.com>,
	linux-kernel@vger.kernel.org,
	Paul Burton <paul.burton@imgtec.com>,
	Petar Jovanovic <petar.jovanovic@imgtec.com>,
	Raghu Gandham <raghu.gandham@imgtec.com>,
	Ralf Baechle <ralf@linux-mips.org>
Subject: [PATCH v4 11/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix NaN propagation
Date: Thu, 27 Jul 2017 18:08:54 +0200	[thread overview]
Message-ID: <1501171791-23690-12-git-send-email-aleksandar.markovic@rt-rk.com> (raw)
In-Reply-To: <1501171791-23690-1-git-send-email-aleksandar.markovic@rt-rk.com>

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

Fix the cases of <MADDF|MSUBF>.<D|S> when any of three inputs is any
NaN. Correct behavior of <MADDF|MSUBF>.<D|S> fd, fs, ft is following:

  - if any of inputs is sNaN, return a sNaN using following rules: if
    only one input is sNaN, return that one; if more than one input is
    sNaN, order of precedence for return value is fd, fs, ft
  - if no input is sNaN, but at least one of inputs is qNaN, return a
    qNaN using following rules: if only one input is qNaN, return that
    one; if more than one input is qNaN, order of precedence for
    return value is fd, fs, ft

The previous code contained correct handling of some above cases, but
not all. Also, such handling was scattered into various cases of
"switch (CLPAIR(xc, yc))" statement, and elsewhere. With this patch,
this logic is placed in one place, and "switch (CLPAIR(xc, yc))" is
significantly simplified.

A relevant example:

MADDF.S fd,fs,ft:
  If fs contains qNaN1, ft contains qNaN2, and fd contains qNaN3, fd
  is going to contain qNaN3 (without this patch, it used to contain
  qNaN1).

Fixes: e24c3bec3e8e ("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction")
Fixes: 83d43305a1df ("MIPS: math-emu: Add support for the MIPS R6 MSUBF 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>
Cc: <stable@vger.kernel.org> # 4.7+
Reviewed-by: James Hogan <james.hogan@imgtec.com>
---
 arch/mips/math-emu/dp_maddf.c | 66 +++++++++++++------------------------------
 arch/mips/math-emu/sp_maddf.c | 66 ++++++++++++++-----------------------------
 2 files changed, 41 insertions(+), 91 deletions(-)

diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index caa62f2..8b1bd42 100644
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -48,52 +48,34 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 
 	ieee754_clearcx();
 
-	switch (zc) {
-	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
+	/*
+	 * Handle the cases when at least one of x, y or z is a NaN.
+	 * Order of precedence is sNaN, qNaN and z, x, y.
+	 */
+	if (zc == IEEE754_CLASS_SNAN)
 		return ieee754dp_nanxcpt(z);
-	case IEEE754_CLASS_DNORM:
-		DPDNORMZ;
-	/* QNAN and ZERO cases are handled separately below */
-	}
-
-	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
-		return ieee754dp_nanxcpt(y);
-
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
+	if (xc == IEEE754_CLASS_SNAN)
 		return ieee754dp_nanxcpt(x);
-
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
+	if (yc == IEEE754_CLASS_SNAN)
+		return ieee754dp_nanxcpt(y);
+	if (zc == IEEE754_CLASS_QNAN)
+		return z;
+	if (xc == IEEE754_CLASS_QNAN)
+		return x;
+	if (yc == IEEE754_CLASS_QNAN)
 		return y;
 
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
-		return x;
+	if (zc == IEEE754_CLASS_DNORM)
+		DPDNORMZ;
+	/* ZERO z cases are handled separately below */
 
+	switch (CLPAIR(xc, yc)) {
 
 	/*
 	 * Infinity handling
 	 */
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
 		return ieee754dp_indef();
 
@@ -102,8 +84,6 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
 		return ieee754dp_inf(xs ^ ys);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
@@ -120,25 +100,19 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 		DPDNORMX;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		DPDNORMY;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		DPDNORMX;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		/* fall through to real computations */
 	}
diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c
index c91d5e5..6cdaa2a 100644
--- a/arch/mips/math-emu/sp_maddf.c
+++ b/arch/mips/math-emu/sp_maddf.c
@@ -48,51 +48,35 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
 
 	ieee754_clearcx();
 
-	switch (zc) {
-	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
+	/*
+	 * Handle the cases when at least one of x, y or z is a NaN.
+	 * Order of precedence is sNaN, qNaN and z, x, y.
+	 */
+	if (zc == IEEE754_CLASS_SNAN)
 		return ieee754sp_nanxcpt(z);
-	case IEEE754_CLASS_DNORM:
-		SPDNORMZ;
-	/* QNAN and ZERO cases are handled separately below */
-	}
-
-	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+	if (xc == IEEE754_CLASS_SNAN)
+		return ieee754sp_nanxcpt(x);
+	if (yc == IEEE754_CLASS_SNAN)
 		return ieee754sp_nanxcpt(y);
+	if (zc == IEEE754_CLASS_QNAN)
+		return z;
+	if (xc == IEEE754_CLASS_QNAN)
+		return x;
+	if (yc == IEEE754_CLASS_QNAN)
+		return y;
 
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		return ieee754sp_nanxcpt(x);
+	if (zc == IEEE754_CLASS_DNORM)
+		SPDNORMZ;
+	/* ZERO z cases are handled separately below */
 
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
-		return y;
+	switch (CLPAIR(xc, yc)) {
 
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
-		return x;
 
 	/*
 	 * Infinity handling
 	 */
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
 		return ieee754sp_indef();
 
@@ -101,8 +85,6 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
 		return ieee754sp_inf(xs ^ ys);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
@@ -119,25 +101,19 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
 		SPDNORMX;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		SPDNORMY;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		SPDNORMX;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		/* fall through to real computations */
 	}
-- 
2.7.4

  parent reply	other threads:[~2017-07-27 16:12 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-27 16:08 [PATCH v4 00/16] MIPS: Miscellaneous fixes related to Android Mips emulator Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 01/16] input: goldfish: Fix multitouch event handling Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 02/16] tty: goldfish: Use streaming DMA for r/w operations on Ranchu platforms Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 03/16] tty: goldfish: Implement support for kernel 'earlycon' parameter Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 04/16] MIPS: VDSO: Fix clobber lists in fallback code paths Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 05/16] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix quiet NaN propagation Aleksandar Markovic
2017-08-07 10:09   ` Ralf Baechle
2017-07-27 16:08 ` [PATCH v4 06/16] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 07/16] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 08/16] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of input values with opposite signs Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 09/16] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of both infinite inputs Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs Aleksandar Markovic
2017-07-27 16:08 ` Aleksandar Markovic [this message]
2017-07-27 16:08 ` [PATCH v4 12/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of infinite inputs Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 13/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of zero inputs Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 14/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Clean up "maddf_flags" enumeration Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 15/16] MIPS: math-emu: <MADDF|MSUBF>.S: Fix accuracy (32-bit case) Aleksandar Markovic
2017-07-27 16:08 ` [PATCH v4 16/16] MIPS: math-emu: <MADDF|MSUBF>.D: Fix accuracy (64-bit case) Aleksandar Markovic

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