[PATCH v2 4/6] [powerpc] libc_feholdsetround_noex_ppc_ctx: optimize FPSCR write

Paul A. Clarke pc@us.ibm.com
Thu Sep 19 18:47:00 GMT 2019


From: "Paul A. Clarke" <pc@us.ibm.com>

libc_feholdsetround_noex_ppc_ctx currently does, basically:
1. Read FPSCR, save to context.
2. Create new FPSCR value: clear enables and set new rounding mode.
3. Write new value to FPSCR.

Since other bits just pass through, there is no need to write them.

Instead, write just the changed values (enables and rounding mode),
which can be a bit more efficient.

2019-09-19  Paul A. Clarke  <pc@us.ibm.com>

	* sysdeps/powerpc/fpu/fenv_private.h
	(libc_feholdsetround_noex_ppc_ctx): Call fesetenv_mode instead
	of fesetenv_register.
---
v2: No change.

 sysdeps/powerpc/fpu/fenv_private.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/powerpc/fpu/fenv_private.h b/sysdeps/powerpc/fpu/fenv_private.h
index 9496026..ade0bfa 100644
--- a/sysdeps/powerpc/fpu/fenv_private.h
+++ b/sysdeps/powerpc/fpu/fenv_private.h
@@ -142,7 +142,7 @@ libc_feholdsetround_noex_ppc_ctx (struct rm_ctx *ctx, int r)
   if (__glibc_unlikely (new.l != old.l))
     {
       __TEST_AND_ENTER_NON_STOP (old.l, 0ULL);
-      fesetenv_register (new.fenv);
+      fesetenv_mode (new.fenv);
       ctx->updated_status = true;
     }
   else
-- 
1.8.3.1



More information about the Libc-alpha mailing list