1// Copyright 2024 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package abi
6
7import "unsafe"
8
9// NoEscape hides the pointer p from escape analysis, preventing it
10// from escaping to the heap. It compiles down to nothing.
11//
12// WARNING: This is very subtle to use correctly. The caller must
13// ensure that it's truly safe for p to not escape to the heap by
14// maintaining runtime pointer invariants (for example, that globals
15// and the heap may not generally point into a stack).
16//
17//go:nosplit
18//go:nocheckptr
19func NoEscape(p unsafe.Pointer) unsafe.Pointer {
20	x := uintptr(p)
21	return unsafe.Pointer(x ^ 0)
22}
23
24var alwaysFalse bool
25var escapeSink any
26
27// Escape forces any pointers in x to escape to the heap.
28func Escape[T any](x T) T {
29	if alwaysFalse {
30		escapeSink = x
31	}
32	return x
33}
34