go_util.go RawHistoryFolder

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build !cgo && (darwin || freebsd || linux || netbsd)
5
6package fakecgo
7
8import "unsafe"
9
10// _cgo_thread_start is split into three parts in cgo since only one part is system dependent (keep it here for easier handling)
11
12// _cgo_thread_start(ThreadStart *arg) (runtime/cgo/gcc_util.c)
13// This get's called instead of the go code for creating new threads
14// -> pthread_* stuff is used, so threads are setup correctly for C
15// If this is missing, TLS is only setup correctly on thread 1!
16// This function should be go:systemstack instead of go:nosplit (but that requires runtime)
17//
18//go:nosplit
19//go:norace
20func x_cgo_thread_start(arg *ThreadStart) {
21	var ts *ThreadStart
22	// Make our own copy that can persist after we return.
23	//	_cgo_tsan_acquire();
24	ts = (*ThreadStart)(malloc(unsafe.Sizeof(*ts)))
25	//	_cgo_tsan_release();
26	if ts == nil {
27		println("fakecgo: out of memory in thread_start")
28		abort()
29	}
30	// *ts = *arg would cause a writebarrier so copy using slices
31	const ptrSize = unsafe.Sizeof(uintptr(0))
32	s1 := unsafe.Slice((*uintptr)(unsafe.Pointer(ts)), unsafe.Sizeof(*ts)/ptrSize)
33	s2 := unsafe.Slice((*uintptr)(unsafe.Pointer(arg)), unsafe.Sizeof(*arg)/ptrSize)
34	for i := range s2 {
35		s1[i] = s2[i]
36	}
37	_cgo_sys_thread_start(ts) // OS-dependent half
38}