powerpc/math-emu: Adopt new version of _FP_CHOOSENAN

Move to using the same macro definition for _FP_CHOOSENAN as s390,
sh, sparc32/64.  The original author didn't understand this and
matched what sparc64 was doing and they have updated to this definition.

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 17 insertions, 9 deletions

diff --git a/arch/powerpc/include/asm/sfp-machine.h b/arch/powerpc/include/asm/sfp-machine.h
index da12ea79cb99..88af036b1fef 100644
--- a/arch/powerpc/include/asm/sfp-machine.h
+++ b/arch/powerpc/include/asm/sfp-machine.h
@@ -111,16 +111,24 @@
 #define FP_EX_DIVZERO         (1 << (31 - 5))
 #define FP_EX_INEXACT         (1 << (31 - 6))
 
-/* This macro appears to be called when both X and Y are NaNs, and
- * has to choose one and copy it to R. i386 goes for the larger of the
- * two, sparc64 just picks Y. I don't understand this at all so I'll
- * go with sparc64 because it's shorter :->   -- PMM
+/*
+ * If one NaN is signaling and the other is not,
+ * we choose that one, otherwise we choose X.
  */
-#define _FP_CHOOSENAN(fs, wc, R, X, Y, OP)              \
-  do {                                                  \
-    R##_s = Y##_s;                                      \
-    _FP_FRAC_COPY_##wc(R,Y);                            \
-    R##_c = FP_CLS_NAN;                                 \
+#define _FP_CHOOSENAN(fs, wc, R, X, Y, OP)                      \
+  do {                                                          \
+    if ((_FP_FRAC_HIGH_RAW_##fs(Y) & _FP_QNANBIT_##fs)          \
+        && !(_FP_FRAC_HIGH_RAW_##fs(X) & _FP_QNANBIT_##fs))     \
+      {                                                         \
+        R##_s = X##_s;                                          \
+        _FP_FRAC_COPY_##wc(R,X);                                \
+      }                                                         \
+    else                                                        \
+      {                                                         \
+        R##_s = Y##_s;                                          \
+        _FP_FRAC_COPY_##wc(R,Y);                                \
+      }                                                         \
+    R##_c = FP_CLS_NAN;                                         \
   } while (0)