// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package verify

import (
	"os"
	"os/exec"
	"testing"
)

// goobjAtomicMainSrc is the Go side of the LSE regression.  The kernel
// drives a counter with LDADDALD and mixes the accumulated total; main
// derives the same value in Go and panics on any divergence before
// printing the deterministic line the baseline and the gasm-linked
// binaries must agree on.
const goobjAtomicMainSrc = `package main

func caller(p *int64, addv int64, times int64) int64

func main() {
	addv, times := int64(3), int64(5)
	v := int64(0)
	got := caller(&v, addv, times)
	oldsum, cur := int64(0), int64(0)
	for i := int64(0); i < times; i++ {
		oldsum += cur
		cur += addv
	}
	k := uint64(0x9e3779b97f4a7c15)
	want := int64(uint64(oldsum+cur) * k)
	if got != want {
		panic("atomic")
	}
	println("ok", caller(&v, addv, times))
}
`

// TestGOOBJLinkAtomicKernel proves the arm64 LSE atomic families are proven
// end to end: the kernel assembles by gasm into a GOOBJ object, substitutes
// byte-wise into a real go build archive, relinks with cmd/link and the
// linked binary computes the same atomic total as the toolchain-built one
// under qemu-user, with the documented degradation on emulators without
// LSE (the baseline run fails first and the claim drops to link-only).
func TestGOOBJLinkAtomicKernel(t *testing.T) {
	if testing.Short() {
		t.Skip("builds the gasm binary and links Go programs")
	}
	if os.Getenv("GASM_LINK_PARITY") == "" {
		t.Skip("deliberate verification: set GASM_LINK_PARITY=1 (just link-parity)")
	}
	goBin, err := exec.LookPath("go")
	if err != nil {
		t.Skip("no Go toolchain available")
	}
	gasmBin := buildLinkParityGasm(t, goBin)
	t.Run("arm64", func(t *testing.T) {
		goobjLinkKernel(t, goBin, gasmBin, "arm64", "linkatomic_arm64.s", goobjAtomicMainSrc)
	})
}