package main
import (
"fmt"
"github.com/klauspost/cpuid"
)
func main() {
if cpuid.CPU.AVX() {
fmt.Println("AVX: supported")
} else {
fmt.Println("AVX: unsupported")
}
}-
Compiler auto-vectorization
Let the compiler figure out how to use SIMD
-
Intrinsic functions
Special low-level functions that easily map to processor instructions
-
Implement in another language, link with Go
-
Google’s Go compiler does not support auto-vectorization
-
gccgo can do auto-vectorization
Pass -ftree-vectorize (or -O3) option to gccgo
Set -march option to enable additional SIMD extensions
-march=native to use everything available on host
Enable -ffast-math to unlock additional floating-point vectorization opportunities (use with care: it affects results)
With go utility: go build
-compiler=gccgo -gccgoflags=”-O3 -march=native -ffast-math”
Go provides 4 mechanisms to call into code implemented in other languages:
- Built-in assembler
- syso
- cgo
- extern
Both Google’s and gccgo toolchains include assemblers, but the syntax is quite different:
gccgo toolchain uses GNU assembler, which accepts traditional AT&T and Intel syntax Google’s Go assembler (6a) follows Plan 9 syntax, which is different from everything!
6a assembler weirdness:
Unconventional names for instructions and registers Branch instructions use names from Motorola 68020 arch! Some widely used constructs are not supported E.g. alignment, jump tables 6a lacks SIMD instructions later than SSE3 (2004) Can be inserted directly as opcode bytes Function names must start with Unicode middle dot character!
PeachPy is a Python framework for writing high-performance low-level codes.
For Go users, PeachPy can generate SysO, Plan 9 assembly, as well as object files for Windows, Linux, and OS X