internal/cpu: detect cpu features in internal/cpu package

change hash/crc32 package to use cpu package instead of using
runtime internal variables to check crc32 instruction

Change-Id: I8f88d2351bde8ed4e256f9adf822a08b9a00f532
Reviewed-on: https://go-review.googlesource.com/76490
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/internal/cpu/cpu.go b/src/internal/cpu/cpu.go
index 38fedc4e2b..22fc561002 100644
--- a/src/internal/cpu/cpu.go
+++ b/src/internal/cpu/cpu.go
@@ -57,3 +57,21 @@ type ppc64 struct {
 	IsPOWER9   bool // ISA v3.00 (POWER9)
 	_          [CacheLineSize]byte
 }
+
+var ARM64 arm64
+
+// The booleans in arm64 contain the correspondingly named cpu feature bit.
+// The struct is padded to avoid false sharing.
+type arm64 struct {
+	_          [CacheLineSize]byte
+	HasFP      bool
+	HasASIMD   bool
+	HasEVTSTRM bool
+	HasAES     bool
+	HasPMULL   bool
+	HasSHA1    bool
+	HasSHA2    bool
+	HasCRC32   bool
+	HasATOMICS bool
+	_          [CacheLineSize]byte
+}