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cpu: support darwin/arm64 CPU feature detection
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Support ARM64 features detection. The CPU features which are supported by
Apple Silicon M1 are assumed as the minimal set of features for Go programs
running on darwin/arm64.

The ARM64 supporting features are referred to
https://en.wikichip.org/wiki/arm/armv8#ARMv8_Extensions_and_Processor_Features
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howjmay committed Sep 4, 2022
1 parent d48e67d commit 44d7b39
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Showing 4 changed files with 87 additions and 3 deletions.
2 changes: 1 addition & 1 deletion cpu/cpu_arm64.go
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ func archInit() {
switch runtime.GOOS {
case "freebsd":
readARM64Registers()
case "linux", "netbsd", "openbsd":
case "linux", "netbsd", "openbsd", "darwin":
doinit()
default:
// Many platforms don't seem to allow reading these registers.
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55 changes: 55 additions & 0 deletions cpu/cpu_darwin_arm64.go
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@@ -0,0 +1,55 @@
// Copyright 2021 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.

//go:build darwin && arm64 && !ios
// +build darwin,arm64,!ios

package cpu

const (
commpageHasNeonFP16 = 0x00000008 // ARM v8.2 NEON FP16 supported
commpageHasNeon = 0x00000100 // Advanced SIMD is supported
commpageHasNeonHPFP = 0x00000200 // Advanced SIMD half-precision
commpageHasVfp = 0x00000400 // VFP is supported
commpageHasEvent = 0x00001000 // WFE/SVE and period event wakeup
commpageHasARMv82FHM = 0x00004000 // Optional ARMv8.2 FMLAL/FMLSL instructions (required in ARMv8.4)
commpageHasARMv8Crypto = 0x01000000 // Optional ARMv8 Crypto extensions
commpageHasARMv81Atomics = 0x02000000 // ARMv8.1 Atomic instructions supported
commpageHasARMv8Crc32 = 0x04000000 // Optional ARMv8 crc32 instructions (required in ARMv8.1)
commpageHasARMv82SHA512 = 0x80000000 // Optional ARMv8.2 SHA512 instructions
commpageHasARMv82SHA3 = 0x0000000100000000 // Optional ARMv8.2 SHA3 instructions
)

func doinit() {
ARM64.HasFP = darwinCheckFeatureEnabled(commpageHasVfp)
ARM64.HasASIMD = darwinCheckFeatureEnabled(commpageHasNeon)
ARM64.HasCRC32 = darwinCheckFeatureEnabled(commpageHasARMv8Crc32)
ARM64.HasATOMICS = darwinCheckFeatureEnabled(commpageHasARMv81Atomics)
ARM64.HasFPHP = darwinCheckFeatureEnabled(commpageHasNeonFP16)
ARM64.HasASIMDHP = darwinCheckFeatureEnabled(commpageHasNeonHPFP)
ARM64.HasSHA3 = darwinCheckFeatureEnabled(commpageHasARMv82SHA3)
ARM64.HasSHA512 = darwinCheckFeatureEnabled(commpageHasARMv82SHA512)
ARM64.HasASIMDFHM = darwinCheckFeatureEnabled(commpageHasARMv82FHM)
ARM64.HasSVE = darwinCheckFeatureEnabled(commpageHasEvent)

// There are no hw.optional sysctl values for the below features on Mac OS 11.0
// to detect their supported state dynamically. Assume the CPU features that
// Apple Silicon M1 supports to be available as a minimal set of features
// to all Go programs running on darwin/arm64.
ARM64.HasEVTSTRM = true
ARM64.HasAES = true
ARM64.HasPMULL = true
ARM64.HasSHA1 = true
ARM64.HasSHA2 = true
ARM64.HasCPUID = true
ARM64.HasASIMDRDM = true
ARM64.HasJSCVT = true
ARM64.HasLRCPC = true
ARM64.HasDCPOP = true
ARM64.HasSM3 = true
ARM64.HasSM4 = true
ARM64.HasASIMDDP = true
}

func darwinCheckFeatureEnabled(feature_vec uint64) bool
29 changes: 29 additions & 0 deletions cpu/cpu_darwin_arm64.s
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//go:build arm64 && gc
// +build arm64
// +build gc

#include "textflag.h"

// func darwinCheckFeatureEnabled(feature_vec uint64) bool
TEXT ·darwinCheckFeatureEnabled(SB), NOSPLIT, $0-8
MOVD feature_vec+0(FP), R0
MOVD $0, ret+0(FP) // default to false
MOVD $1, R2 // set R2 as true boolean constan

#ifdef GOOS_darwin // return if not darwin
#ifdef GOARCH_arm64 // return if not arm64
// These values from:
// https://github.com/apple/darwin-xnu/blob/main/osfmk/arm/cpu_capabilities.h
#define arm_commpage64_base_address 0x0000000fffffc000
#define arm_commpage64_cpu_capabilities64 (arm_commpage64_base_address+0x010)
MOVD $0xffffc000, R1
MOVK $(0xf<<32), R1
MOVD (R1), R1
AND R1, R0
CBZ R0, no_feature
MOVD R2, ret+8(FP)

no_feature:
#endif
#endif
RET
4 changes: 2 additions & 2 deletions cpu/cpu_other_arm64.go
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Expand Up @@ -2,8 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !linux && !netbsd && !openbsd && arm64
// +build !linux,!netbsd,!openbsd,arm64
//go:build !linux && !netbsd && !openbsd && arm64 && !darwin
// +build !linux,!netbsd,!openbsd,arm64,!darwin

package cpu

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