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