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 5 package runtime 6 7 import "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 20 var ( 21 _cgo_init unsafe.Pointer 22 _cgo_thread_start unsafe.Pointer 23 _cgo_sys_thread_create unsafe.Pointer 24 _cgo_notify_runtime_init_done unsafe.Pointer 25 _cgo_callers unsafe.Pointer 26 _cgo_set_context_function unsafe.Pointer 27 ) 28 29 // iscgo is set to true by the runtime/cgo package 30 var iscgo bool 31 32 // cgoHasExtraM is set on startup when an extra M is created for cgo. 33 // The extra M must be created before any C/C++ code calls cgocallback. 34 var cgoHasExtraM bool 35 36 // cgoUse is called by cgo-generated code (using go:linkname to get at 37 // an unexported name). The calls serve two purposes: 38 // 1) they are opaque to escape analysis, so the argument is considered to 39 // escape to the heap. 40 // 2) they keep the argument alive until the call site; the call is emitted after 41 // the end of the (presumed) use of the argument by C. 42 // cgoUse should not actually be called (see cgoAlwaysFalse). 43 func cgoUse(interface{}) { throw("cgoUse should not be called") } 44 45 // cgoAlwaysFalse is a boolean value that is always false. 46 // The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }. 47 // The compiler cannot see that cgoAlwaysFalse is always false, 48 // so it emits the test and keeps the call, giving the desired 49 // escape analysis result. The test is cheaper than the call. 50 var cgoAlwaysFalse bool 51
