[PATCH v2] powerpc: Refactor fenvinline.h

[Rogerio Alves]

This patch refactor fenviline.h replaces some statements for
builtins.

---

 * Changes in v2: Per Adhemerval review: don not redefine _buitins use a        
 macro instead. Use of __builtin_popcount allows do eliminate the             
 if (e == 0) test. __builtin_popcount(e) == 1 for e = 0 validate false        
 while (e & (e - 1)) == 0 validate true if e = 0. Appended a comment          
 about the weird asm constrain i#*X. The warning only appear at GCC           
 versions 3 and below. If we even stops to support GCC 3 for installed        
 headers we may replace that for plain `i`.   
 sysdeps/powerpc/bits/fenvinline.h | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/sysdeps/powerpc/bits/fenvinline.h b/sysdeps/powerpc/bits/fenvinline.h
index 70689664e2..7b2b75e5ef 100644
--- a/sysdeps/powerpc/bits/fenvinline.h
+++ b/sysdeps/powerpc/bits/fenvinline.h
@@ -51,9 +51,19 @@
 # define fegetround() __fegetround ()
 
 # ifndef __NO_MATH_INLINES
+
+/* Builtins to mtfsb0 and mtfsb1 was introduced on GCC 9.  */
+#  if !__GNUC_PREREQ(9, 0)
 /* The weird 'i#*X' constraints on the following suppress a gcc
    warning when __excepts is not a constant.  Otherwise, they mean the
-   same as just plain 'i'.  */
+   same as just plain 'i'. This warning only happens in old GCC 
+   versions (gcc 3 or less). Otherwise plain 'i' works fine.  */
+#   define __mtfsb0(__b) __asm__ __volatile__ ("mtfsb0 %0" : : "i#*X" (__b))
+#   define __mtfsb1(__b) __asm__ __volatile__ ("mtfsb1 %0" : : "i#*X" (__b))
+#  else
+#   define __mtfsb0(__b) __builtin_mtfsb0 (__b)
+#   define __mtfsb1(__b) __builtin_mtfsb1 (__b)
+#  endif
 
 #  if __GNUC_PREREQ(3, 4)
 
@@ -61,15 +71,12 @@
 #   define feraiseexcept(__excepts) \
   (__extension__  ({ 							      \
     int __e = __excepts;						      \
-    int __ret;								      \
+    int __ret = 0;							      \
     if (__builtin_constant_p (__e)					      \
-        && (__e & (__e - 1)) == 0					      \
+        && (__builtin_popcount (__e) == 1)				      \
         && __e != FE_INVALID)						      \
       {									      \
-	if (__e != 0)							      \
-	  __asm__ __volatile__ ("mtfsb1 %0"				      \
-				: : "i#*X" (__builtin_clz (__e)));	      \
-        __ret = 0;							      \
+	  __mtfsb1 ((__builtin_clz (__e)));				      \
       }									      \
     else								      \
       __ret = feraiseexcept (__e);					      \
@@ -80,15 +87,12 @@
 #   define feclearexcept(__excepts) \
   (__extension__  ({ 							      \
     int __e = __excepts;						      \
-    int __ret;								      \
+    int __ret = 0;							      \
     if (__builtin_constant_p (__e)					      \
-        && (__e & (__e - 1)) == 0					      \
+        && (__builtin_popcount (__e) == 1)				      \
         && __e != FE_INVALID)						      \
       {									      \
-	if (__e != 0)							      \
-	  __asm__ __volatile__ ("mtfsb0 %0"				      \
-				: : "i#*X" (__builtin_clz (__e)));	      \
-        __ret = 0;							      \
+	  __mtfsb0 ((__builtin_clz (__e)));				      \
       }									      \
     else								      \
       __ret = feclearexcept (__e);					      \
-- 
2.17.1