Source file src/pkg/vendor/golang.org/x/sys/cpu/cpu_x86.go

     1	// Copyright 2018 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	// +build 386 amd64 amd64p32
     6	
     7	package cpu
     8	
     9	const cacheLineSize = 64
    10	
    11	func init() {
    12		Initialized = true
    13	
    14		maxID, _, _, _ := cpuid(0, 0)
    15	
    16		if maxID < 1 {
    17			return
    18		}
    19	
    20		_, _, ecx1, edx1 := cpuid(1, 0)
    21		X86.HasSSE2 = isSet(26, edx1)
    22	
    23		X86.HasSSE3 = isSet(0, ecx1)
    24		X86.HasPCLMULQDQ = isSet(1, ecx1)
    25		X86.HasSSSE3 = isSet(9, ecx1)
    26		X86.HasFMA = isSet(12, ecx1)
    27		X86.HasSSE41 = isSet(19, ecx1)
    28		X86.HasSSE42 = isSet(20, ecx1)
    29		X86.HasPOPCNT = isSet(23, ecx1)
    30		X86.HasAES = isSet(25, ecx1)
    31		X86.HasOSXSAVE = isSet(27, ecx1)
    32		X86.HasRDRAND = isSet(30, ecx1)
    33	
    34		osSupportsAVX := false
    35		// For XGETBV, OSXSAVE bit is required and sufficient.
    36		if X86.HasOSXSAVE {
    37			eax, _ := xgetbv()
    38			// Check if XMM and YMM registers have OS support.
    39			osSupportsAVX = isSet(1, eax) && isSet(2, eax)
    40		}
    41	
    42		X86.HasAVX = isSet(28, ecx1) && osSupportsAVX
    43	
    44		if maxID < 7 {
    45			return
    46		}
    47	
    48		_, ebx7, _, _ := cpuid(7, 0)
    49		X86.HasBMI1 = isSet(3, ebx7)
    50		X86.HasAVX2 = isSet(5, ebx7) && osSupportsAVX
    51		X86.HasBMI2 = isSet(8, ebx7)
    52		X86.HasERMS = isSet(9, ebx7)
    53		X86.HasRDSEED = isSet(18, ebx7)
    54		X86.HasADX = isSet(19, ebx7)
    55	}
    56	
    57	func isSet(bitpos uint, value uint32) bool {
    58		return value&(1<<bitpos) != 0
    59	}
    60	

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