1// Copyright 2014 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 runtime
6
7import "unsafe"
8
9//go:cgo_export_static main
10
11// Filled in by runtime/cgo when linked into binary.
12
13//go:linkname _cgo_init _cgo_init
14//go:linkname _cgo_thread_start _cgo_thread_start
15//go:linkname _cgo_sys_thread_create _cgo_sys_thread_create
16//go:linkname _cgo_notify_runtime_init_done _cgo_notify_runtime_init_done
17//go:linkname _cgo_callers _cgo_callers
18//go:linkname _cgo_set_context_function _cgo_set_context_function
19//go:linkname _cgo_yield _cgo_yield
20//go:linkname _cgo_pthread_key_created _cgo_pthread_key_created
21//go:linkname _cgo_bindm _cgo_bindm
22//go:linkname _cgo_getstackbound _cgo_getstackbound
23
24var (
25	_cgo_init                     unsafe.Pointer
26	_cgo_thread_start             unsafe.Pointer
27	_cgo_sys_thread_create        unsafe.Pointer
28	_cgo_notify_runtime_init_done unsafe.Pointer
29	_cgo_callers                  unsafe.Pointer
30	_cgo_set_context_function     unsafe.Pointer
31	_cgo_yield                    unsafe.Pointer
32	_cgo_pthread_key_created      unsafe.Pointer
33	_cgo_bindm                    unsafe.Pointer
34	_cgo_getstackbound            unsafe.Pointer
35)
36
37// iscgo is set to true by the runtime/cgo package
38//
39// iscgo should be an internal detail,
40// but widely used packages access it using linkname.
41// Notable members of the hall of shame include:
42//   - github.com/ebitengine/purego
43//
44// Do not remove or change the type signature.
45// See go.dev/issue/67401.
46//
47//go:linkname iscgo
48var iscgo bool
49
50// set_crosscall2 is set by the runtime/cgo package
51// set_crosscall2 should be an internal detail,
52// but widely used packages access it using linkname.
53// Notable members of the hall of shame include:
54//   - github.com/ebitengine/purego
55//
56// Do not remove or change the type signature.
57// See go.dev/issue/67401.
58//
59//go:linkname set_crosscall2
60var set_crosscall2 func()
61
62// cgoHasExtraM is set on startup when an extra M is created for cgo.
63// The extra M must be created before any C/C++ code calls cgocallback.
64var cgoHasExtraM bool
65
66// cgoUse is called by cgo-generated code (using go:linkname to get at
67// an unexported name). The calls serve two purposes:
68// 1) they are opaque to escape analysis, so the argument is considered to
69// escape to the heap.
70// 2) they keep the argument alive until the call site; the call is emitted after
71// the end of the (presumed) use of the argument by C.
72// cgoUse should not actually be called (see cgoAlwaysFalse).
73func cgoUse(any) { throw("cgoUse should not be called") }
74
75// cgoAlwaysFalse is a boolean value that is always false.
76// The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }.
77// The compiler cannot see that cgoAlwaysFalse is always false,
78// so it emits the test and keeps the call, giving the desired
79// escape analysis result. The test is cheaper than the call.
80var cgoAlwaysFalse bool
81
82var cgo_yield = &_cgo_yield
83
84func cgoNoCallback(v bool) {
85	g := getg()
86	if g.nocgocallback && v {
87		panic("runtime: unexpected setting cgoNoCallback")
88	}
89	g.nocgocallback = v
90}
91