[glibc/maskray/grte] RISC-V: fmax/fmin: Handle signalling NaNs correctly.

[glibc/maskray/grte] RISC-V: fmax/fmin: Handle signalling NaNs correctly.

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=012483cf93fd62162233a9d1be1879c664dd149a

commit 012483cf93fd62162233a9d1be1879c664dd149a
Author: Andrew Waterman <andrew@sifive.com>
Date:   Thu Feb 22 14:31:54 2018 -0500

    RISC-V: fmax/fmin: Handle signalling NaNs correctly.
    
    RISC-V's fmax(sNAN,4) returns 4 but glibc expects it to return qNAN.
    
            * sysdeps/riscv/rvd/s_fmax.c (__fmax): Handle sNaNs correctly.
            * sysdeps/riscv/rvd/s_fmin.c (__fmin): Likewise.
            * sysdeps/riscv/rvf/s_fmaxf.c (__fmaxf): Likewise.
            * sysdeps/riscv/rvf/s_fminf.c (__fminf): Likewise.
    
    (cherry picked from commit fdcc625376505eacb1125a6aeba57501407a30ec)

Diff:
---
 ChangeLog                   |  7 +++++++
 sysdeps/riscv/rvd/s_fmax.c  | 11 +++++++++--
 sysdeps/riscv/rvd/s_fmin.c  | 11 +++++++++--
 sysdeps/riscv/rvf/s_fmaxf.c | 11 +++++++++--
 sysdeps/riscv/rvf/s_fminf.c | 11 +++++++++--
 5 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8b859f637d..394f670363 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-02-22  Andrew Waterman <andrew@sifive.com>
+
+	* sysdeps/riscv/rvd/s_fmax.c (__fmax): Handle sNaNs correctly.
+	* sysdeps/riscv/rvd/s_fmin.c (__fmin): Likewise.
+	* sysdeps/riscv/rvf/s_fmaxf.c (__fmaxf): Likewise.
+	* sysdeps/riscv/rvf/s_fminf.c (__fminf): Likewise.
+
 2018-02-22  DJ Delorie  <dj@delorie.com>
 
 	* sysdeps/riscv/tls-macros.h: Do not initialize $gp.
diff --git a/sysdeps/riscv/rvd/s_fmax.c b/sysdeps/riscv/rvd/s_fmax.c
index ef8f1344ce..22e91bfc4b 100644
--- a/sysdeps/riscv/rvd/s_fmax.c
+++ b/sysdeps/riscv/rvd/s_fmax.c
@@ -17,12 +17,19 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math_private.h>
 #include <libm-alias-double.h>
 
 double
 __fmax (double x, double y)
 {
-  asm ("fmax.d %0, %1, %2" : "=f" (x) : "f" (x), "f" (y));
-  return x;
+  double res;
+
+  if (__glibc_unlikely ((_FCLASS (x) | _FCLASS (y)) & _FCLASS_SNAN))
+    return x + y;
+  else
+    asm ("fmax.d %0, %1, %2" : "=f" (res) : "f" (x), "f" (y));
+
+  return res;
 }
 libm_alias_double (__fmax, fmax)
diff --git a/sysdeps/riscv/rvd/s_fmin.c b/sysdeps/riscv/rvd/s_fmin.c
index c6ff24cefb..7b35230cac 100644
--- a/sysdeps/riscv/rvd/s_fmin.c
+++ b/sysdeps/riscv/rvd/s_fmin.c
@@ -17,12 +17,19 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math_private.h>
 #include <libm-alias-double.h>
 
 double
 __fmin (double x, double y)
 {
-  asm ("fmin.d %0, %1, %2" : "=f" (x) : "f" (x), "f" (y));
-  return x;
+  double res;
+
+  if (__glibc_unlikely ((_FCLASS (x) | _FCLASS (y)) & _FCLASS_SNAN))
+    return x + y;
+  else
+    asm ("fmin.d %0, %1, %2" : "=f" (res) : "f" (x), "f" (y));
+
+  return res;
 }
 libm_alias_double (__fmin, fmin)
diff --git a/sysdeps/riscv/rvf/s_fmaxf.c b/sysdeps/riscv/rvf/s_fmaxf.c
index 3293f2f41c..63f7e3d664 100644
--- a/sysdeps/riscv/rvf/s_fmaxf.c
+++ b/sysdeps/riscv/rvf/s_fmaxf.c
@@ -17,12 +17,19 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math_private.h>
 #include <libm-alias-float.h>
 
 float
 __fmaxf (float x, float y)
 {
-  asm ("fmax.s %0, %1, %2" : "=f" (x) : "f" (x), "f" (y));
-  return x;
+  float res;
+
+  if (__glibc_unlikely ((_FCLASS (x) | _FCLASS (y)) & _FCLASS_SNAN))
+    return x + y;
+  else
+    asm ("fmax.s %0, %1, %2" : "=f" (res) : "f" (x), "f" (y));
+
+  return res;
 }
 libm_alias_float (__fmax, fmax)
diff --git a/sysdeps/riscv/rvf/s_fminf.c b/sysdeps/riscv/rvf/s_fminf.c
index e4411f04b2..82cca4e37d 100644
--- a/sysdeps/riscv/rvf/s_fminf.c
+++ b/sysdeps/riscv/rvf/s_fminf.c
@@ -17,12 +17,19 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math_private.h>
 #include <libm-alias-float.h>
 
 float
 __fminf (float x, float y)
 {
-  asm ("fmin.s %0, %1, %2" : "=f" (x) : "f" (x), "f" (y));
-  return x;
+  float res;
+
+  if (__glibc_unlikely ((_FCLASS (x) | _FCLASS (y)) & _FCLASS_SNAN))
+    return x + y;
+  else
+    asm ("fmin.s %0, %1, %2" : "=f" (res) : "f" (x), "f" (y));
+
+  return res;
 }
 libm_alias_float (__fmin, fmin)