mgo

README

mgo

Build your code for multiple GOAMD64 variants and bundle all of them in a launcher capable of picking at runtime the most appropriate variant for the processor in use.

This is mostly useful if you want to provide GOAMD64 variants because of the extra runtime performance this yields, but you have no control over which processor microarchitecture the executable will be run on.

Install

go install github.com/CAFxX/mgo@latest

Usage

When building your code just replace go build [...] with mgo [...]: the resulting executable will contain 4 variants, each optimized for one of GOAMD64=v1, GOAMD64=v2, GOAMD64=v3 and GOAMD64=v4, and a launcher that will pick the appropriate one at runtime.

At runtime it is possible to override which variant is used by specifying in the GOAMD64 environment variable one of the values v1, v2, v3, or v4.

Notes

• mgo requires Go >= 1.18 (older versions do not support GOAMD64)
• The resulting executable will be over 4 times as large as a normal build output
• Startup of the resulting executable is going to be a bit slower (tens of milliseconds)
• Currently only GOOS=linux and GOARCH=amd64 are supported, and only in buildmodes that produce executables (not archives, plugins, or libraries)

Quick sanity check

echo stage0 && go build &&\
echo stage1 && ./mgo -o vmgo && sha1sum vmgo &&\
echo stage2 && ./vmgo -o vmgo2 && sha1sum vmgo2 &&\
echo stage3 && ./vmgo2 -o vmgo3 && sha1sum vmgo3

This command should succeed and produce three identical hashes.