threadentry_noasm.go RawHistoryFolder

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2026 The Ebitengine Authors
3
4//go:build !cgo && !amd64 && (darwin || freebsd || linux || netbsd)
5
6package fakecgo
7
8import "unsafe"
9
10// callThreadEntryFn calls fn (runtime.mstart). On architectures without the
11// amd64 frame-pointer epilogue issue this is a plain indirect call. It must be
12// nosplit and norace like the threadentry callers so it neither inserts a
13// morestack preamble nor runs race instrumentation during the fragile
14// thread-bootstrap window.
15//
16//go:nosplit
17//go:norace
18func callThreadEntryFn(fn uintptr) {
19	// fn is the code pointer. Build a func value whose first word is fn by
20	// pointing the closure at &fn, then call it (same trick fakecgo has always
21	// used to call a raw PC from Go).
22	fnPtr := uintptr(unsafe.Pointer(&fn))
23	(*(*func())(unsafe.Pointer(&fnPtr)))()
24}