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MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero

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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: a79f5f9ba5 ("MIPS: math-emu: Add support for the MIPS R6 MAX{, A} FPU instruction")
Fixes: 4e9561b20e ("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: <stable@vger.kernel.org> # 4.3+
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>
This commit is contained in:
Aleksandar Markovic 2017-07-27 18:08:49 +02:00 committed by Ralf Baechle
parent e78bf0dc47
commit 15560a58bf
4 changed files with 8 additions and 24 deletions
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8
arch/mips/math-emu/dp_fmax.c
View File

@ -92,9 +92,7 @@ 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;
@ -204,9 +202,7 @@ 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;

8
arch/mips/math-emu/dp_fmin.c
View File

@ -92,9 +92,7 @@ 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;
@ -204,9 +202,7 @@ 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;

8
arch/mips/math-emu/sp_fmax.c
View File

@ -92,9 +92,7 @@ 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;
@ -204,9 +202,7 @@ 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;

8
arch/mips/math-emu/sp_fmin.c
View File

@ -92,9 +92,7 @@ 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;
@ -204,9 +202,7 @@ 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;