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Re: [PATCH] x86-64: Check Prefer_FSRM in ifunc-memmove.h
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 21 May 2018 11:21:31 -0700
- Subject: Re: [PATCH] x86-64: Check Prefer_FSRM in ifunc-memmove.h
- References: <20180521173740.GA12107@intel.com>
On Mon, May 21, 2018 at 10:37 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> Although the Fast Short REP MOVSB (FSRM) implementations of memmove,
> memcpy and mempcpy aren't used by the current processors, this patch
> adds Prefer_FSRM check in ifunc-memmove.h so that they can be used in
> the future.
>
> * sysdeps/x86/cpu-features.h (bit_arch_Prefer_FSRM): New.
> (index_arch_Prefer_FSRM): Likewise.
> * sysdeps/x86/cpu-tunables.c (TUNABLE_CALLBACK (set_hwcaps)):
> Also check Prefer_FSRM.
> * sysdeps/x86_64/multiarch/ifunc-memmove.h (IFUNC_SELECTOR):
> Also return OPTIMIZE (erms) for Prefer_FSRM.
This is the patch I am going to check in shortly.
--
H.J.
From 59235849bb8e6955c3358fbe8da5897f1f124818 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 21 May 2018 10:25:33 -0700
Subject: [PATCH] x86-64: Check Prefer_FSRM in ifunc-memmove.h
Although the REP MOVSB implementations of memmove, memcpy and mempcpy
aren't used by the current processors, this patch adds Prefer_FSRM
check in ifunc-memmove.h so that they can be used in the future.
* sysdeps/x86/cpu-features.h (bit_arch_Prefer_FSRM): New.
(index_arch_Prefer_FSRM): Likewise.
* sysdeps/x86/cpu-tunables.c (TUNABLE_CALLBACK (set_hwcaps)):
Also check Prefer_FSRM.
* sysdeps/x86_64/multiarch/ifunc-memmove.h (IFUNC_SELECTOR):
Also return OPTIMIZE (erms) for Prefer_FSRM.
---
sysdeps/x86/cpu-features.h | 2 ++
sysdeps/x86/cpu-tunables.c | 2 ++
sysdeps/x86_64/multiarch/ifunc-memmove.h | 3 ++-
3 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
index 2088bd73ee..624e681e96 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/cpu-features.h
@@ -40,6 +40,7 @@
#define bit_arch_Prefer_No_AVX512 (1 << 20)
#define bit_arch_MathVec_Prefer_No_AVX512 (1 << 21)
#define bit_arch_XSAVEC_Usable (1 << 22)
+#define bit_arch_Prefer_FSRM (1 << 23)
/* CPUID Feature flags. */
@@ -264,6 +265,7 @@ extern const struct cpu_features *__get_cpu_features (void)
# define index_arch_Prefer_No_AVX512 FEATURE_INDEX_1
# define index_arch_MathVec_Prefer_No_AVX512 FEATURE_INDEX_1
# define index_arch_XSAVEC_Usable FEATURE_INDEX_1
+# define index_arch_Prefer_FSRM FEATURE_INDEX_1
#endif /* !__ASSEMBLER__ */
diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
index a21a615ec2..af761dcbbc 100644
--- a/sysdeps/x86/cpu-tunables.c
+++ b/sysdeps/x86/cpu-tunables.c
@@ -241,6 +241,8 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
CHECK_GLIBC_IFUNC_ARCH_NEED_CPU_BOTH (n, cpu_features,
Slow_SSE4_2, SSE4_2,
disable, 11);
+ CHECK_GLIBC_IFUNC_ARCH_BOTH (n, cpu_features, Prefer_FSRM,
+ disable, 11);
break;
case 13:
if (disable)
diff --git a/sysdeps/x86_64/multiarch/ifunc-memmove.h b/sysdeps/x86_64/multiarch/ifunc-memmove.h
index a2ffba0531..5b1eb1c92c 100644
--- a/sysdeps/x86_64/multiarch/ifunc-memmove.h
+++ b/sysdeps/x86_64/multiarch/ifunc-memmove.h
@@ -41,7 +41,8 @@ IFUNC_SELECTOR (void)
{
const struct cpu_features* cpu_features = __get_cpu_features ();
- if (CPU_FEATURES_ARCH_P (cpu_features, Prefer_ERMS))
+ if (CPU_FEATURES_ARCH_P (cpu_features, Prefer_ERMS)
+ || CPU_FEATURES_ARCH_P (cpu_features, Prefer_FSRM))
return OPTIMIZE (erms);
if (CPU_FEATURES_ARCH_P (cpu_features, AVX512F_Usable)
--
2.17.0