cpu: add support for amx detection

Added detection for x86 AMX,
including AMX-Tile, AMX-INT8 and AMX-BF16
instruction sets.

Change-Id: Ib3d663430b64d46b46b22bdd05d40f1992e37ee0
GitHub-Last-Rev: 7986ed6
GitHub-Pull-Request: #170
Reviewed-on: https://go-review.googlesource.com/c/sys/+/516815
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

cpu/cpu.go

@@ -54,6 +54,9 @@ var X86 struct {
 	HasAVX512VBMI2      bool // Advanced vector extension 512 Vector Byte Manipulation Instructions 2
 	HasAVX512BITALG     bool // Advanced vector extension 512 Bit Algorithms
 	HasAVX512BF16       bool // Advanced vector extension 512 BFloat16 Instructions
+	HasAMXTile          bool // Advanced Matrix Extension Tile instructions
+	HasAMXInt8          bool // Advanced Matrix Extension Int8 instructions
+	HasAMXBF16          bool // Advanced Matrix Extension BFloat16 instructions
 	HasBMI1             bool // Bit manipulation instruction set 1
 	HasBMI2             bool // Bit manipulation instruction set 2
 	HasCX16             bool // Compare and exchange 16 Bytes

cpu/cpu_x86.go

@@ -37,6 +37,9 @@ func initOptions() {
 		{Name: "avx512vbmi2", Feature: &X86.HasAVX512VBMI2},
 		{Name: "avx512bitalg", Feature: &X86.HasAVX512BITALG},
 		{Name: "avx512bf16", Feature: &X86.HasAVX512BF16},
+		{Name: "amxtile", Feature: &X86.HasAMXTile},
+		{Name: "amxint8", Feature: &X86.HasAMXInt8},
+		{Name: "amxbf16", Feature: &X86.HasAMXBF16},
 		{Name: "bmi1", Feature: &X86.HasBMI1},
 		{Name: "bmi2", Feature: &X86.HasBMI2},
 		{Name: "cx16", Feature: &X86.HasCX16},
@@ -138,6 +141,10 @@ func archInit() {
 		eax71, _, _, _ := cpuid(7, 1)
 		X86.HasAVX512BF16 = isSet(5, eax71)
 	}
+
+	X86.HasAMXTile = isSet(24, edx7)
+	X86.HasAMXInt8 = isSet(25, edx7)
+	X86.HasAMXBF16 = isSet(22, edx7)
 }
 
 func isSet(bitpos uint, value uint32) bool {