Patchwork [powerpc] libc_feholdsetround_noex_ppc_ctx: optimize FPSCR write

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Submitter Paul Clarke
Date Sept. 9, 2019, 4:21 p.m.
Message ID <1568046067-6314-1-git-send-email-pc@us.ibm.com>
Download mbox | patch
Permalink /patch/34456/
State New
Headers show

Comments

Paul Clarke - Sept. 9, 2019, 4:21 p.m.
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.

2019-09-09  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.
---
Note: this patch probably depends on previously posted patch,
"[powerpc] fenv_private.h clean up" to apply properly.

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

Patch

diff --git a/sysdeps/powerpc/fpu/fenv_private.h b/sysdeps/powerpc/fpu/fenv_private.h
index 806a385..3286b4e 100644
--- a/sysdeps/powerpc/fpu/fenv_private.h
+++ b/sysdeps/powerpc/fpu/fenv_private.h
@@ -177,7 +177,7 @@  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