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 13/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of zero inputs
Date: Thu, 27 Jul 2017 18:08:56 +0200 [thread overview]
Message-ID: <1501171791-23690-14-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 two multiplicands is
+0 or -0, and the third input is also +0 or -0. Depending on the signs
of inputs, certain special cases must be handled.
A relevant example:
MADDF.S fd,fs,ft:
If fs contains +0.0, ft contains -0.0, and fd contains 0.0, fd is
going to contain +0.0 (without this patch, it used to contain -0.0).
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 | 18 +++++++++++++++++-
arch/mips/math-emu/sp_maddf.c | 18 +++++++++++++++++-
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index 557a0a1..c38fe1b 100644
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -113,7 +113,23 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
if (zc == IEEE754_CLASS_INF)
return ieee754dp_inf(zs);
- /* Multiplication is 0 so just return z */
+ if (zc == IEEE754_CLASS_ZERO) {
+ /* Handle cases +0 + (-0) and similar ones. */
+ if ((!(flags & maddf_negate_product)
+ && (zs == (xs ^ ys))) ||
+ ((flags & maddf_negate_product)
+ && (zs != (xs ^ ys))))
+ /*
+ * Cases of addition of zeros of equal signs
+ * or subtraction of zeroes of opposite signs.
+ * The sign of the resulting zero is in any
+ * such case determined only by the sign of z.
+ */
+ return z;
+
+ return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
+ }
+ /* x*y is here 0, and z is not 0, so just return z */
return z;
case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c
index 0d8d25f..4241ec1 100644
--- a/arch/mips/math-emu/sp_maddf.c
+++ b/arch/mips/math-emu/sp_maddf.c
@@ -114,7 +114,23 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
if (zc == IEEE754_CLASS_INF)
return ieee754sp_inf(zs);
- /* Multiplication is 0 so just return z */
+ if (zc == IEEE754_CLASS_ZERO) {
+ /* Handle cases +0 + (-0) and similar ones. */
+ if ((!(flags & maddf_negate_product)
+ && (zs == (xs ^ ys))) ||
+ ((flags & maddf_negate_product)
+ && (zs != (xs ^ ys))))
+ /*
+ * Cases of addition of zeros of equal signs
+ * or subtraction of zeroes of opposite signs.
+ * The sign of the resulting zero is in any
+ * such case determined only by the sign of z.
+ */
+ return z;
+
+ return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);
+ }
+ /* x*y is here 0, and z is not 0, so just return z */
return z;
case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
--
2.7.4
next prev parent reply other threads:[~2017-07-27 16:13 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 ` [PATCH v4 11/16] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix NaN propagation Aleksandar Markovic
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 ` Aleksandar Markovic [this message]
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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