From 987322bc0b170570a7bd539480252453fcc7a6f5 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Date: Fri, 29 Mar 2013 18:15:28 -0500
Subject: [PATCH 23/42] PowerPC: remove branch prediction from rint
implementation
The branch prediction hints is actually hurts performance in this case.
The assembly implementation make two assumptions: 1. 'fabs (x) < 2^52'
is unlikely and 2. 'x > 0.0' is unlike (if 1. is true). Since it a
general floating point function, expected input is not bounded and then
it is better to let the hardware handle the branches.
(backported from commit 60c414c346a1d5ef0510ffbdc0ab75f288ee4d3f)
This backport does not include the benchmark tests from the original
commit.
---
sysdeps/powerpc/powerpc32/fpu/s_rint.S | 6 +++---
sysdeps/powerpc/powerpc32/fpu/s_rintf.S | 6 +++---
sysdeps/powerpc/powerpc64/fpu/s_rint.S | 6 +++---
sysdeps/powerpc/powerpc64/fpu/s_rintf.S | 6 +++---
4 files changed, 12 insertions(+), 12 deletions(-)
diff --git glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rint.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rint.S
index 0ab9e6c..c28e7f6 100644
--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rint.S
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rint.S
@@ -45,14 +45,14 @@ ENTRY (__rint)
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
- bnllr- cr7
- bng- cr6,.L4
+ bnllr cr7
+ bng cr6,.L4
fadd fp1,fp1,fp13 /* x+= TWO52; */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) */
blr /* x = 0.0; */
.L4:
- bnllr- cr6 /* if (x < 0.0) */
+ bnllr cr6 /* if (x < 0.0) */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fadd fp1,fp1,fp13 /* x+= TWO52; */
fnabs fp1,fp1 /* if (x == 0.0) */
diff --git glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rintf.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rintf.S
index ddb47db..69aed9c 100644
--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rintf.S
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/fpu/s_rintf.S
@@ -41,14 +41,14 @@ ENTRY (__rintf)
fsubs fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO23) */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
- bnllr- cr7
- bng- cr6,.L4
+ bnllr cr7
+ bng cr6,.L4
fadds fp1,fp1,fp13 /* x+= TWO23; */
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fabs fp1,fp1 /* if (x == 0.0) */
blr /* x = 0.0; */
.L4:
- bnllr- cr6 /* if (x < 0.0) */
+ bnllr cr6 /* if (x < 0.0) */
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fadds fp1,fp1,fp13 /* x+= TWO23; */
fnabs fp1,fp1 /* if (x == 0.0) */
diff --git glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rint.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rint.S
index db62405..560905a 100644
--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rint.S
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rint.S
@@ -34,14 +34,14 @@ EALIGN (__rint, 4, 0)
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
- bnllr- cr7
- bng- cr6,.L4
+ bnllr cr7
+ bng cr6,.L4
fadd fp1,fp1,fp13 /* x+= TWO52; */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) */
blr /* x = 0.0; */
.L4:
- bnllr- cr6 /* if (x < 0.0) */
+ bnllr cr6 /* if (x < 0.0) */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fadd fp1,fp1,fp13 /* x+= TWO52; */
fnabs fp1,fp1 /* if (x == 0.0) */
diff --git glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rintf.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rintf.S
index 248649d..c120d91 100644
--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rintf.S
+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/fpu/s_rintf.S
@@ -30,14 +30,14 @@ EALIGN (__rintf, 4, 0)
fsubs fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO23) */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
- bnllr- cr7
- bng- cr6,.L4
+ bnllr cr7
+ bng cr6,.L4
fadds fp1,fp1,fp13 /* x+= TWO23; */
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fabs fp1,fp1 /* if (x == 0.0) */
blr /* x = 0.0; */
.L4:
- bnllr- cr6 /* if (x < 0.0) */
+ bnllr cr6 /* if (x < 0.0) */
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fadds fp1,fp1,fp13 /* x+= TWO23; */
fnabs fp1,fp1 /* if (x == 0.0) */
--
1.7.11.7