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runtime: use internal/cpu variables in assembler code

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Using internal/cpu variables has the benefit of avoiding false sharing
(as those are padded) and allows memory and cache usage for these variables
to be shared by multiple packages.

Change-Id: I2bf68d03091bf52b466cf689230d5d25d5950037
Reviewed-on: https://go-review.googlesource.com/126599
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Martin Möhrmann 2018-07-28 10:56:48 +02:00
parent d8cf1514ca
commit c15c04d9e8
9 changed files with 30 additions and 16 deletions
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2
src/runtime/asm_386.s
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@ -881,7 +881,7 @@ TEXT runtime·stackcheck(SB), NOSPLIT, $0-0
// func cputicks() int64
TEXT runtime·cputicks(SB),NOSPLIT,$0-8
CMPB runtime·support_sse2(SB), $1
CMPB internal∕cpu·X86+const_offset_x86_HasSSE2(SB), $1
JNE done
CMPB runtime·lfenceBeforeRdtsc(SB), $1
JNE mfence

17
src/runtime/cpuflags.go Normal file
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@ -0,0 +1,17 @@
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import (
"internal/cpu"
"unsafe"
)
// Offsets into internal/cpu records for use in assembly.
const (
offset_x86_HasAVX2 = unsafe.Offsetof(cpu.X86.HasAVX2)
offset_x86_HasERMS = unsafe.Offsetof(cpu.X86.HasERMS)
offset_x86_HasSSE2 = unsafe.Offsetof(cpu.X86.HasSSE2)
)

6
src/runtime/cpuflags_amd64.go
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@ -6,12 +6,6 @@ package runtime
import (
"internal/cpu"
"unsafe"
)
// Offsets into internal/cpu records for use in assembly.
const (
offsetX86HasAVX2 = unsafe.Offsetof(cpu.X86.HasAVX2)
)
var useAVXmemmove bool

3
src/runtime/memclr_386.s
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@ -4,6 +4,7 @@
// +build !plan9
#include "go_asm.h"
#include "textflag.h"
// NOTE: Windows externalthreadhandler expects memclr to preserve DX.
@ -28,7 +29,7 @@ tail:
JBE _5through8
CMPL BX, $16
JBE _9through16
CMPB runtime·support_sse2(SB), $1
CMPB internal∕cpu·X86+const_offset_x86_HasSSE2(SB), $1
JNE nosse2
PXOR X0, X0
CMPL BX, $32

2
src/runtime/memclr_amd64.s
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@ -38,7 +38,7 @@ tail:
JBE _65through128
CMPQ BX, $256
JBE _129through256
CMPB internal∕cpu·X86+const_offsetX86HasAVX2(SB), $1
CMPB internal∕cpu·X86+const_offset_x86_HasAVX2(SB), $1
JE loop_preheader_avx2
// TODO: for really big clears, use MOVNTDQ, even without AVX2.

5
src/runtime/memmove_386.s
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@ -25,6 +25,7 @@
// +build !plan9
#include "go_asm.h"
#include "textflag.h"
// func memmove(to, from unsafe.Pointer, n uintptr)
@ -51,7 +52,7 @@ tail:
JBE move_5through8
CMPL BX, $16
JBE move_9through16
CMPB runtime·support_sse2(SB), $1
CMPB internal∕cpu·X86+const_offset_x86_HasSSE2(SB), $1
JNE nosse2
CMPL BX, $32
JBE move_17through32
@ -72,7 +73,7 @@ nosse2:
*/
forward:
// If REP MOVSB isn't fast, don't use it
CMPB runtime·support_erms(SB), $1 // enhanced REP MOVSB/STOSB
CMPB internal∕cpu·X86+const_offset_x86_HasERMS(SB), $1 // enhanced REP MOVSB/STOSB
JNE fwdBy4
// Check alignment

3
src/runtime/memmove_amd64.s
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@ -25,6 +25,7 @@
// +build !plan9
#include "go_asm.h"
#include "textflag.h"
// func memmove(to, from unsafe.Pointer, n uintptr)
@ -83,7 +84,7 @@ forward:
JLS move_256through2048
// If REP MOVSB isn't fast, don't use it
CMPB runtime·support_erms(SB), $1 // enhanced REP MOVSB/STOSB
CMPB internal∕cpu·X86+const_offset_x86_HasERMS(SB), $1 // enhanced REP MOVSB/STOSB
JNE fwdBy8
// Check alignment

3
src/runtime/proc.go
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@ -507,7 +507,8 @@ func cpuinit() {
cpu.Initialize(env)
support_erms = cpu.X86.HasERMS
// Support cpu feature variables are used in code generated by the compiler
// to guard execution of instructions that can not be assumed to be always supported.
support_popcnt = cpu.X86.HasPOPCNT
support_sse2 = cpu.X86.HasSSE2
support_sse41 = cpu.X86.HasSSE41

5
src/runtime/runtime2.go
View File

@ -836,16 +836,15 @@ var (
newprocs int32
// Information about what cpu features are available.
// Set on startup in runtime.cpuinit.
// Packages outside the runtime should not use these
// as they are not an external api.
// TODO: deprecate these; use internal/cpu directly.
// Set on startup in asm_{386,amd64,amd64p32}.s
processorVersionInfo uint32
isIntel bool
lfenceBeforeRdtsc bool
// Set in runtime.cpuinit.
support_erms bool
// TODO: deprecate these; use internal/cpu directly.
support_popcnt bool
support_sse2 bool
support_sse41 bool