[powerpc] fesetenv: optimize FPSCR access

fesetenv() reads the current value of the Floating-Point Status and Control
Register (FPSCR) to determine the difference between the current state of
exception enables and the newly requested state.  All of these bits are also
returned by the lighter weight 'mffsl' instruction used by fegetenv_status().
Use that instead.

Also, remove a local macro _FPU_MASK_ALL in favor of a common macro,
FPU_ENABLES_MASK from fenv_libc.h.

Finally, use a local variable ('new') in favor of a pointer dereference
('*envp').

1 files changed, 6 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index d4e56d7588..9824660f6d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2019-08-28  Paul A. Clarke  <pc@us.ibm.com>
     
+    	* sysdeps/powerpc/fpu/fesetenv.c (__fesetenv):  Utilize lightweight
+    	FPSCR read.
+    	(_FPU_MASK_ALL):  Delete.
+
+2019-08-28  Paul A. Clarke  <pc@us.ibm.com>
+    
     	* sysdeps/powerpc/fpu/fenv_private.h (libc_feholdsetround_ppc_ctx):
     	Utilize lightweight FPSCR read if possible, set fewer FPSCR bits
     	if possible.