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 21var ( 22 _cgo_init unsafe.Pointer 23 _cgo_thread_start unsafe.Pointer 24 _cgo_sys_thread_create unsafe.Pointer 25 _cgo_notify_runtime_init_done unsafe.Pointer 26 _cgo_callers unsafe.Pointer 27 _cgo_set_context_function unsafe.Pointer 28 _cgo_yield unsafe.Pointer 29) 30 31// iscgo is set to true by the runtime/cgo package 32var iscgo bool 33 34// cgoHasExtraM is set on startup when an extra M is created for cgo. 35// The extra M must be created before any C/C++ code calls cgocallback. 36var cgoHasExtraM bool 37 38// cgoUse is called by cgo-generated code (using go:linkname to get at 39// an unexported name). The calls serve two purposes: 40// 1) they are opaque to escape analysis, so the argument is considered to 41// escape to the heap. 42// 2) they keep the argument alive until the call site; the call is emitted after 43// the end of the (presumed) use of the argument by C. 44// cgoUse should not actually be called (see cgoAlwaysFalse). 45func cgoUse(interface{}) { throw("cgoUse should not be called") } 46 47// cgoAlwaysFalse is a boolean value that is always false. 48// The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }. 49// The compiler cannot see that cgoAlwaysFalse is always false, 50// so it emits the test and keeps the call, giving the desired 51// escape analysis result. The test is cheaper than the call. 52var cgoAlwaysFalse bool 53 54var cgo_yield = &_cgo_yield 55