escape.go

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package abi

import "unsafe"

// NoEscape hides the pointer p from escape analysis, preventing it
// from escaping to the heap. It compiles down to nothing.
//
// WARNING: This is very subtle to use correctly. The caller must
// ensure that it's truly safe for p to not escape to the heap by
// maintaining runtime pointer invariants (for example, that globals
// and the heap may not generally point into a stack).
//
//go:nosplit
//go:nocheckptr
func NoEscape(p unsafe.Pointer) unsafe.Pointer {
	x := uintptr(p)
	return unsafe.Pointer(x ^ 0)
}

var alwaysFalse bool
var escapeSink any

// Escape forces any pointers in x to escape to the heap.
func Escape[T any](x T) T {
	if alwaysFalse {
		escapeSink = x
	}
	return x
}