How to Understand Go's Calling Convention

Go's calling convention is an internal ABI detail managed by the compiler, not a manual configuration for developers. You control runtime behavior changes via the GODEBUG environment variable or //go:debug directives in your source code. To check the effective defaults for your module, run:

go list -f '{{.DefaultGODEBUG}}' ./...

To override a specific behavior like panicnil, set the environment variable:

export GODEBUG=panicnil=1

Or add a directive to your go.mod (Go 1.23+) or source file:

//go:debug panicnil=1

The compiler automatically handles argument passing, register usage, and stack layout based on your target architecture (GOARCH) and OS (GOOS).

Go's calling convention is the set of rules the compiler uses to pass data between functions, which happens automatically behind the scenes. You don't need to write assembly or configure registers manually; the toolchain handles this based on your operating system and processor. Think of it like a standardized handshake protocol that ensures every function knows exactly where to find its inputs and where to put its outputs.