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runtime: simplify detection of preference to use AVX memmove
Reduces cmd/go by 4464 bytes on amd64. Removes the duplicate detection of AVX support and presence of Intel processors. Change-Id: I4670189951a63760fae217708f68d65e94a30dc5 Reviewed-on: https://go-review.googlesource.com/41570 Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
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@ -67,14 +67,16 @@ has_cpuid:
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JNE notintel
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CMPL CX, $0x6C65746E // "ntel"
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JNE notintel
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MOVB $1, runtime·isIntel(SB)
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MOVB $1, runtime·lfenceBeforeRdtsc(SB)
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notintel:
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// Load EAX=1 cpuid flags
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MOVL $1, AX
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CPUID
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MOVL CX, AX // Move to global variable clobbers CX when generating PIC
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MOVL AX, runtime·cpuid_ecx(SB)
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MOVL CX, DI // Move to global variable clobbers CX when generating PIC
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MOVL AX, runtime·cpuid_eax(SB)
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MOVL DI, runtime·cpuid_ecx(SB)
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MOVL DX, runtime·cpuid_edx(SB)
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// Check for MMX support
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@ -41,12 +41,14 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
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JNE notintel
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CMPL CX, $0x6C65746E // "ntel"
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JNE notintel
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MOVB $1, runtime·isIntel(SB)
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MOVB $1, runtime·lfenceBeforeRdtsc(SB)
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notintel:
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// Load EAX=1 cpuid flags
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MOVQ $1, AX
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CPUID
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MOVL AX, runtime·cpuid_eax(SB)
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MOVL CX, runtime·cpuid_ecx(SB)
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MOVL DX, runtime·cpuid_edx(SB)
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@ -32,8 +32,19 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
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CPUID
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CMPQ AX, $0
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JE nocpuinfo
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CMPL BX, $0x756E6547 // "Genu"
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JNE notintel
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CMPL DX, $0x49656E69 // "ineI"
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JNE notintel
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CMPL CX, $0x6C65746E // "ntel"
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JNE notintel
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MOVB $1, runtime·isIntel(SB)
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notintel:
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MOVQ $1, AX
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CPUID
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MOVL AX, runtime·cpuid_eax(SB)
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MOVL CX, runtime·cpuid_ecx(SB)
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MOVL DX, runtime·cpuid_edx(SB)
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nocpuinfo:
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@ -4,72 +4,17 @@
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package runtime
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var vendorStringBytes [12]byte
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var maxInputValue uint32
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var featureFlags uint32
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var processorVersionInfo uint32
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var useRepMovs = true
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func hasFeature(feature uint32) bool {
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return (featureFlags & feature) != 0
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}
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func cpuid_low(arg1, arg2 uint32) (eax, ebx, ecx, edx uint32) // implemented in cpuidlow_amd64.s
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func xgetbv_low(arg1 uint32) (eax, edx uint32) // implemented in cpuidlow_amd64.s
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var useAVXmemmove bool
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func init() {
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const cfOSXSAVE uint32 = 1 << 27
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const cfAVX uint32 = 1 << 28
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leaf0()
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leaf1()
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enabledAVX := false
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// Let's check if OS has set CR4.OSXSAVE[bit 18]
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// to enable XGETBV instruction.
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if hasFeature(cfOSXSAVE) {
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eax, _ := xgetbv_low(0)
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// Let's check that XCR0[2:1] = ‘11b’
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// i.e. XMM state and YMM state are enabled by OS.
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enabledAVX = (eax & 0x6) == 0x6
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}
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isIntelBridgeFamily := (processorVersionInfo == 0x206A0 ||
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processorVersionInfo == 0x206D0 ||
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processorVersionInfo == 0x306A0 ||
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processorVersionInfo == 0x306E0) &&
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isIntel()
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useRepMovs = !(hasFeature(cfAVX) && enabledAVX) || isIntelBridgeFamily
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}
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func leaf0() {
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eax, ebx, ecx, edx := cpuid_low(0, 0)
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maxInputValue = eax
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int32ToBytes(ebx, vendorStringBytes[0:4])
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int32ToBytes(edx, vendorStringBytes[4:8])
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int32ToBytes(ecx, vendorStringBytes[8:12])
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}
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func leaf1() {
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if maxInputValue < 1 {
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return
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}
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eax, _, ecx, _ := cpuid_low(1, 0)
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// Let's remove stepping and reserved fields
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processorVersionInfo = eax & 0x0FFF3FF0
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featureFlags = ecx
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}
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processorVersionInfo := cpuid_eax & 0x0FFF3FF0
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func int32ToBytes(arg uint32, buffer []byte) {
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buffer[3] = byte(arg >> 24)
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buffer[2] = byte(arg >> 16)
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buffer[1] = byte(arg >> 8)
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buffer[0] = byte(arg)
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}
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isIntelBridgeFamily := isIntel &&
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(processorVersionInfo == 0x206A0 ||
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processorVersionInfo == 0x206D0 ||
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processorVersionInfo == 0x306A0 ||
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processorVersionInfo == 0x306E0)
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func isIntel() bool {
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intelSignature := [12]byte{'G', 'e', 'n', 'u', 'i', 'n', 'e', 'I', 'n', 't', 'e', 'l'}
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return vendorStringBytes == intelSignature
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useAVXmemmove = support_avx && !isIntelBridgeFamily
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}
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@ -1,22 +0,0 @@
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// func cpuid_low(arg1, arg2 uint32) (eax, ebx, ecx, edx uint32)
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TEXT ·cpuid_low(SB), 4, $0-24
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MOVL arg1+0(FP), AX
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MOVL arg2+4(FP), CX
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CPUID
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MOVL AX, eax+8(FP)
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MOVL BX, ebx+12(FP)
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MOVL CX, ecx+16(FP)
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MOVL DX, edx+20(FP)
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RET
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// func xgetbv_low(arg1 uint32) (eax, edx uint32)
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TEXT ·xgetbv_low(SB), 4, $0-16
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MOVL arg1+0(FP), CX
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// XGETBV
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BYTE $0x0F; BYTE $0x01; BYTE $0xD0
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MOVL AX,eax+8(FP)
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MOVL DX,edx+12(FP)
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RET
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@ -64,8 +64,8 @@ tail:
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JBE move_129through256
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// TODO: use branch table and BSR to make this just a single dispatch
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TESTB $1, runtime·useRepMovs(SB)
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JZ avxUnaligned
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TESTB $1, runtime·useAVXmemmove(SB)
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JNZ avxUnaligned
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/*
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* check and set for backwards
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@ -727,10 +727,12 @@ var (
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newprocs int32
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// Information about what cpu features are available.
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// Set on startup in asm_{x86,amd64}.s.
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// Set on startup in asm_{386,amd64,amd64p32}.s.
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cpuid_eax uint32
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cpuid_ecx uint32
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cpuid_edx uint32
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cpuid_ebx7 uint32
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cpuid_ebx7 uint32 // not set on amd64p32
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isIntel bool
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lfenceBeforeRdtsc bool
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support_avx bool
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support_avx2 bool
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