[PATCH v3 06/16] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero

From: Aleksandar Markovic
Date: Fri Jul 21 2017 - 10:12:40 EST


From: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx>

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

The relevant example:

MAX.S fd,fs,ft:
If fs contains +0, and ft contains -0, fd is going to contain 0
(without this patch, it used to contain -0).

Signed-off-by: Miodrag Dinic <miodrag.dinic@xxxxxxxxxx>
Signed-off-by: Goran Ferenc <goran.ferenc@xxxxxxxxxx>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx>
---
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(-)

diff --git a/arch/mips/math-emu/dp_fmax.c b/arch/mips/math-emu/dp_fmax.c
index 567fc33..9517572 100644
--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -82,9 +82,7 @@ union ieee754dp ieee754dp_fmax(union ieee754dp x, union ieee754dp y)
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;
@@ -184,9 +182,7 @@ union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
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;
diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
index 77f7ca9..7069320 100644
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -82,9 +82,7 @@ union ieee754dp ieee754dp_fmin(union ieee754dp x, union ieee754dp y)
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;
@@ -184,9 +182,7 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
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;
diff --git a/arch/mips/math-emu/sp_fmax.c b/arch/mips/math-emu/sp_fmax.c
index d46e8e4..d72111a 100644
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -82,9 +82,7 @@ union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
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;
@@ -184,9 +182,7 @@ union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
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;
diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
index b528c4b..61ff9c6 100644
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -82,9 +82,7 @@ union ieee754sp ieee754sp_fmin(union ieee754sp x, union ieee754sp y)
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;
@@ -184,9 +182,7 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
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;
--
2.7.4