From 512f3e778dccd5b8fb263889a607239a1a38847b Mon Sep 17 00:00:00 2001
From: rinor <rinorhoxha@gmail.com>
Date: Fri, 17 May 2024 20:45:42 +0000
Subject: [PATCH] chore: get rid of the golang.org/x/sys/cpu

---
 README.md          |  2 +-
 simd/cpu_amd64.go  | 34 ++++++++++++++++++++++++++++
 simd/cpu_amd64.s   | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 simd/cpu_other.go  |  7 ++++++
 simd/simd_amd64.go |  4 +---
 5 files changed, 98 insertions(+), 4 deletions(-)
 create mode 100644 simd/cpu_amd64.go
 create mode 100644 simd/cpu_amd64.s
 create mode 100644 simd/cpu_other.go

diff --git a/README.md b/README.md
index 90ae1f3..1f7d42e 100644
--- a/README.md
+++ b/README.md
@@ -177,7 +177,7 @@ For the full interface see the Godoc: <https://pkg.go.dev/github.com/philippgill
   - Operators (`$and`, `$or` etc.)
 - Storage:
   - JSON as second encoding format
-  - Write-ahead log (WAL) as second file format)
+  - Write-ahead log (WAL) as second file format
   - Optional remote storage (S3, PostgreSQL, ...)
 - Data types:
   - Images
diff --git a/simd/cpu_amd64.go b/simd/cpu_amd64.go
new file mode 100644
index 0000000..94a9883
--- /dev/null
+++ b/simd/cpu_amd64.go
@@ -0,0 +1,34 @@
+package simd
+
+// cpuid is implemented in cpu_amd64.s
+func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+
+// xgetbv with ecx = 0 is implemented in cpu_amd64.s
+func xgetbv() (eax, edx uint32)
+
+// useSIMD reports the availability of FMA and AVX2 cpu features
+func useSIMD() bool {
+	var (
+		hasAVX2 bool
+		hasFMA  bool
+
+		isSet = func(bitpos uint, value uint32) bool {
+			return value&(1<<bitpos) != 0
+		}
+	)
+
+	if maxID, _, _, _ := cpuid(0, 0); maxID < 7 {
+		return false
+	}
+	_, _, ecx1, _ := cpuid(1, 0)
+
+	hasFMA = isSet(12, ecx1)
+
+	if hasOSXSAVE := isSet(27, ecx1); hasOSXSAVE {
+		eax, _ := xgetbv() // For XGETBV, OSXSAVE bit is required and sufficient.
+		_, ebx7, _, _ := cpuid(7, 0)
+		hasAVX2 = isSet(1, eax) && isSet(2, eax) && isSet(5, ebx7)
+	}
+
+	return hasAVX2 && hasFMA
+}
diff --git a/simd/cpu_amd64.s b/simd/cpu_amd64.s
new file mode 100644
index 0000000..358bce2
--- /dev/null
+++ b/simd/cpu_amd64.s
@@ -0,0 +1,55 @@
+/* This file is a copy of https://cs.opensource.google/go/x/sys/+/master:cpu/cpu_x86.s.
+Here is its license, which only applies to the copied parts and not to the rest of chromem-go,
+which is licensed under the GNU Affero General Public License.
+
+BSD 3-clause license
+
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "textflag.h"
+
+// func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+TEXT ·cpuid(SB), NOSPLIT, $0-24
+	MOVL eaxArg+0(FP), AX
+	MOVL ecxArg+4(FP), CX
+	CPUID
+	MOVL AX, eax+8(FP)
+	MOVL BX, ebx+12(FP)
+	MOVL CX, ecx+16(FP)
+	MOVL DX, edx+20(FP)
+	RET
+
+// func xgetbv() (eax, edx uint32)
+TEXT ·xgetbv(SB),NOSPLIT,$0-8
+	MOVL $0, CX
+	XGETBV
+	MOVL AX, eax+0(FP)
+	MOVL DX, edx+4(FP)
+	RET
diff --git a/simd/cpu_other.go b/simd/cpu_other.go
new file mode 100644
index 0000000..5eb6d75
--- /dev/null
+++ b/simd/cpu_other.go
@@ -0,0 +1,7 @@
+//go:build !amd64
+
+package simd
+
+func useSIMD() bool {
+	return false
+}
diff --git a/simd/simd_amd64.go b/simd/simd_amd64.go
index 251db4a..953ded4 100644
--- a/simd/simd_amd64.go
+++ b/simd/simd_amd64.go
@@ -29,8 +29,6 @@ package simd
 
 import (
 	"runtime"
-
-	"golang.org/x/sys/cpu" // TODO: Can we get rid of this dependency?
 )
 
-var UseAVX2 bool = cpu.X86.HasAVX2 && cpu.X86.HasFMA && runtime.GOOS != "darwin"
+var UseAVX2 bool = useSIMD() && runtime.GOOS != "darwin"