diff options
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/cgo.go | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/runtime/cgo.go b/src/runtime/cgo.go index d8ae6ec94b..169a31d4c6 100644 --- a/src/runtime/cgo.go +++ b/src/runtime/cgo.go @@ -32,3 +32,19 @@ var iscgo bool // cgoHasExtraM is set on startup when an extra M is created for cgo. // The extra M must be created before any C/C++ code calls cgocallback. var cgoHasExtraM bool + +// cgoUse is called by cgo-generated code (using go:linkname to get at +// an unexported name). The calls serve two purposes: +// 1) they are opaque to escape analysis, so the argument is considered to +// escape to the heap. +// 2) they keep the argument alive until the call site; the call is emitted after +// the end of the (presumed) use of the argument by C. +// cgoUse should not actually be called (see cgoAlwaysFalse). +func cgoUse(interface{}) { throw("cgoUse should not be called") } + +// cgoAlwaysFalse is a boolean value that is always false. +// The cgo-generated code says if cgoAlwaysFalse { cgoUse(p) }. +// The compiler cannot see that cgoAlwaysFalse is always false, +// so it emits the test and keeps the call, giving the desired +// escape analysis result. The test is cheaper than the call. +var cgoAlwaysFalse bool |