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

Fix the value returned by <MAXA|MINA>.<D|S> fd,fs,ft, if both inputs
are infinite. The previous implementation returned always the value
contained in ft in such cases. The correct behavior is specified
in Mips instruction set manual and is as follows:

    fs    ft        MAXA     MINA
  ---------------------------------
    inf   inf        inf      inf
    inf  -inf        inf     -inf
   -inf   inf        inf     -inf
   -inf  -inf       -inf     -inf

A relevant example:

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

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/16884/
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 81d12bfa6d5eb28c512d5b203913d4a08c98781f..5bec64f2884eb14103e53726e42a6e29563ff6b5 100644 (file)
--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -202,6 +202,9 @@ union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
        /*
         * Infinity and zero handling
         */
+       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+               return ieee754dp_inf(xs & ys);
+
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
@@ -209,7 +212,6 @@ union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):

diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
index 4574f04b44cede3387f04624252326b3759cc4ab..2495bd7333f5d80f6467cba614d948288fbe1b8b 100644 (file)
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -202,6 +202,9 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
        /*
         * Infinity and zero handling
         */
+       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+               return ieee754dp_inf(xs | ys);
+
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
@@ -209,7 +212,6 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):

diff --git a/arch/mips/math-emu/sp_fmax.c b/arch/mips/math-emu/sp_fmax.c
index fb41497621017ae5361fe81a308b5a7a6cb80fc4..74a5a00d2f22b87917cae25c02f9b4f568569dd0 100644 (file)
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -202,6 +202,9 @@ union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
        /*
         * Infinity and zero handling
         */
+       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+               return ieee754sp_inf(xs & ys);
+
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
@@ -209,7 +212,6 @@ union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):

diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
index 7915b9430f68895ad9b57156e4442c1ea6b42c30..42ec4315e66caca73d93d62562fdcb8038c20227 100644 (file)
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -202,6 +202,9 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
        /*
         * Infinity and zero handling
         */
+       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+               return ieee754sp_inf(xs | ys);
+
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
@@ -209,7 +212,6 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):