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 //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 24 var ( 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 var iscgo bool 39 40 // set_crosscall2 is set by the runtime/cgo package 41 var set_crosscall2 func() 42 43 // cgoHasExtraM is set on startup when an extra M is created for cgo. 44 // The extra M must be created before any C/C++ code calls cgocallback. 45 var cgoHasExtraM bool 46 47 // cgoUse is called by cgo-generated code (using go:linkname to get at 48 // an unexported name). The calls serve two purposes: 49 // 1) they are opaque to escape analysis, so the argument is considered to 50 // escape to the heap. 51 // 2) they keep the argument alive until the call site; the call is emitted after 52 // the end of the (presumed) use of the argument by C. 53 // cgoUse should not actually be called (see cgoAlwaysFalse). 54 func cgoUse(any) { throw("cgoUse should not be called") } 55 56 // cgoAlwaysFalse is a boolean value that is always false. 57 // The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }. 58 // The compiler cannot see that cgoAlwaysFalse is always false, 59 // so it emits the test and keeps the call, giving the desired 60 // escape analysis result. The test is cheaper than the call. 61 var cgoAlwaysFalse bool 62 63 var cgo_yield = &_cgo_yield 64 65 func cgoNoCallback(v bool) { 66 g := getg() 67 if g.nocgocallback && v { 68 panic("runtime: unexpected setting cgoNoCallback") 69 } 70 g.nocgocallback = v 71 } 72