From: Paul A. Clarke <pc@us.ibm.com>
Date: Thu, 19 Sep 2019 16:31:31 +0000 (-0500)
Subject: [powerpc] libc_feholdsetround_noex_ppc_ctx: optimize FPSCR write
X-Git-Tag: changelog-ends-here~35
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=36c17c7079a5243a890ba43affff326a041775a9;p=thirdparty%2Fglibc.git

[powerpc] libc_feholdsetround_noex_ppc_ctx: optimize FPSCR write

libc_feholdsetround_noex_ppc_ctx currently performs:
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.
---

diff --git a/ChangeLog b/ChangeLog
index 6c28351c37e..3c792b4317b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-09-27  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.
+
 2019-09-27  Paul A. Clarke  <pc@us.ibm.com>
 
 	* sysdeps/powerpc/fpu/fenv_libc.h (fegetenv_status): Rename to
diff --git a/sysdeps/powerpc/fpu/fenv_private.h b/sysdeps/powerpc/fpu/fenv_private.h
index 94960262dde..ade0bfaf5f4 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