MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix quiet NaN propagation

Fix the value returned by <MAX|MAXA|MIN|MINA>.<D|S> fd,fs,ft, if both
inputs are quiet NaNs. The <MAX|MAXA|MIN|MINA>.<D|S> specifications
state that the returned value in such cases should be the quiet NaN
contained in register fs.

A relevant example:

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

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: <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/16880/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/math-emu/dp_fmax.c b/arch/mips/math-emu/dp_fmax.c
index fd71b8d..41bd6ed 100644 (file)
--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -47,14 +47,26 @@ union ieee754dp ieee754dp_fmax(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):
@@ -147,14 +159,26 @@ union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):

diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
index c1072b0..53fb8c9 100644 (file)
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -47,14 +47,26 @@ union ieee754dp ieee754dp_fmin(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):
@@ -147,14 +159,26 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):

diff --git a/arch/mips/math-emu/sp_fmax.c b/arch/mips/math-emu/sp_fmax.c
index 4d00084..d0d73c3 100644 (file)
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -47,14 +47,26 @@ union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):
@@ -147,14 +159,26 @@ union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):

diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
index 4eb1bb9..011692e 100644 (file)
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -47,14 +47,26 @@ union ieee754sp ieee754sp_fmin(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):
@@ -147,14 +159,26 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        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 x;
 
-       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):