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// Copyright 2017 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.
// +build 386 amd64
package cpu
const CacheLinePadSize = 64
// cpuid is implemented in cpu_x86.s.
func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
// xgetbv with ecx = 0 is implemented in cpu_x86.s.
func xgetbv() (eax, edx uint32)
const (
// edx bits
cpuid_SSE2 = 1 << 26
// ecx bits
cpuid_SSE3 = 1 << 0
cpuid_PCLMULQDQ = 1 << 1
cpuid_SSSE3 = 1 << 9
cpuid_FMA = 1 << 12
cpuid_SSE41 = 1 << 19
cpuid_SSE42 = 1 << 20
cpuid_POPCNT = 1 << 23
cpuid_AES = 1 << 25
cpuid_OSXSAVE = 1 << 27
cpuid_AVX = 1 << 28
// ebx bits
cpuid_BMI1 = 1 << 3
cpuid_AVX2 = 1 << 5
cpuid_BMI2 = 1 << 8
cpuid_ERMS = 1 << 9
cpuid_ADX = 1 << 19
)
var maxExtendedFunctionInformation uint32
func doinit() {
options = []option{
{Name: "adx", Feature: &X86.HasADX},
{Name: "aes", Feature: &X86.HasAES},
{Name: "avx", Feature: &X86.HasAVX},
{Name: "avx2", Feature: &X86.HasAVX2},
{Name: "bmi1", Feature: &X86.HasBMI1},
{Name: "bmi2", Feature: &X86.HasBMI2},
{Name: "erms", Feature: &X86.HasERMS},
{Name: "fma", Feature: &X86.HasFMA},
{Name: "pclmulqdq", Feature: &X86.HasPCLMULQDQ},
{Name: "popcnt", Feature: &X86.HasPOPCNT},
{Name: "sse3", Feature: &X86.HasSSE3},
{Name: "sse41", Feature: &X86.HasSSE41},
{Name: "sse42", Feature: &X86.HasSSE42},
{Name: "ssse3", Feature: &X86.HasSSSE3},
// These capabilities should always be enabled on amd64:
{Name: "sse2", Feature: &X86.HasSSE2, Required: GOARCH == "amd64"},
}
maxID, _, _, _ := cpuid(0, 0)
if maxID < 1 {
return
}
maxExtendedFunctionInformation, _, _, _ = cpuid(0x80000000, 0)
_, _, ecx1, edx1 := cpuid(1, 0)
X86.HasSSE2 = isSet(edx1, cpuid_SSE2)
X86.HasSSE3 = isSet(ecx1, cpuid_SSE3)
X86.HasPCLMULQDQ = isSet(ecx1, cpuid_PCLMULQDQ)
X86.HasSSSE3 = isSet(ecx1, cpuid_SSSE3)
X86.HasSSE41 = isSet(ecx1, cpuid_SSE41)
X86.HasSSE42 = isSet(ecx1, cpuid_SSE42)
X86.HasPOPCNT = isSet(ecx1, cpuid_POPCNT)
X86.HasAES = isSet(ecx1, cpuid_AES)
// OSXSAVE can be false when using older Operating Systems
// or when explicitly disabled on newer Operating Systems by
// e.g. setting the xsavedisable boot option on Windows 10.
X86.HasOSXSAVE = isSet(ecx1, cpuid_OSXSAVE)
// The FMA instruction set extension only has VEX prefixed instructions.
// VEX prefixed instructions require OSXSAVE to be enabled.
// See Intel 64 and IA-32 Architecture Software Developer’s Manual Volume 2
// Section 2.4 "AVX and SSE Instruction Exception Specification"
X86.HasFMA = isSet(ecx1, cpuid_FMA) && X86.HasOSXSAVE
osSupportsAVX := false
// For XGETBV, OSXSAVE bit is required and sufficient.
if X86.HasOSXSAVE {
eax, _ := xgetbv()
// Check if XMM and YMM registers have OS support.
osSupportsAVX = isSet(eax, 1<<1) && isSet(eax, 1<<2)
}
X86.HasAVX = isSet(ecx1, cpuid_AVX) && osSupportsAVX
if maxID < 7 {
return
}
_, ebx7, _, _ := cpuid(7, 0)
X86.HasBMI1 = isSet(ebx7, cpuid_BMI1)
X86.HasAVX2 = isSet(ebx7, cpuid_AVX2) && osSupportsAVX
X86.HasBMI2 = isSet(ebx7, cpuid_BMI2)
X86.HasERMS = isSet(ebx7, cpuid_ERMS)
X86.HasADX = isSet(ebx7, cpuid_ADX)
}
func isSet(hwc uint32, value uint32) bool {
return hwc&value != 0
}
// Name returns the CPU name given by the vendor.
// If the CPU name can not be determined an
// empty string is returned.
func Name() string {
if maxExtendedFunctionInformation < 0x80000004 {
return ""
}
data := make([]byte, 0, 3*4*4)
var eax, ebx, ecx, edx uint32
eax, ebx, ecx, edx = cpuid(0x80000002, 0)
data = appendBytes(data, eax, ebx, ecx, edx)
eax, ebx, ecx, edx = cpuid(0x80000003, 0)
data = appendBytes(data, eax, ebx, ecx, edx)
eax, ebx, ecx, edx = cpuid(0x80000004, 0)
data = appendBytes(data, eax, ebx, ecx, edx)
// Trim leading spaces.
for len(data) > 0 && data[0] == ' ' {
data = data[1:]
}
// Trim tail after and including the first null byte.
for i, c := range data {
if c == '\x00' {
data = data[:i]
break
}
}
return string(data)
}
func appendBytes(b []byte, args ...uint32) []byte {
for _, arg := range args {
b = append(b,
byte((arg >> 0)),
byte((arg >> 8)),
byte((arg >> 16)),
byte((arg >> 24)))
}
return b
}
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