diff options
Diffstat (limited to 'libgo/go/runtime/cgo_gccgo.go')
| -rw-r--r-- | libgo/go/runtime/cgo_gccgo.go | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/libgo/go/runtime/cgo_gccgo.go b/libgo/go/runtime/cgo_gccgo.go index c3bf9552ea8..05be4964500 100644 --- a/libgo/go/runtime/cgo_gccgo.go +++ b/libgo/go/runtime/cgo_gccgo.go @@ -27,6 +27,13 @@ var iscgo bool // The extra M must be created before any C/C++ code calls cgocallback. var cgoHasExtraM bool +// 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 + // Cgocall prepares to call from code written in Go to code written in // C/C++. This takes the current goroutine out of the Go scheduler, as // though it were making a system call. Otherwise the program can @@ -37,12 +44,11 @@ var cgoHasExtraM bool // defer syscall.Cgocalldone() // cfunction() func Cgocall() { - lockOSThread() mp := getg().m mp.ncgocall++ mp.ncgo++ - mp.incgo = true entersyscall(0) + mp.incgo = true } // CgocallDone prepares to return to Go code from C/C++ code. @@ -59,8 +65,6 @@ func CgocallDone() { if readgstatus(gp)&^_Gscan == _Gsyscall { exitsyscall(0) } - - unlockOSThread() } // CgocallBack is used when calling from C/C++ code into Go code. @@ -78,6 +82,8 @@ func CgocallBack() { mp.dropextram = true } + lockOSThread() + exitsyscall(0) gp.m.incgo = false @@ -100,6 +106,8 @@ func CgocallBack() { // CgocallBackDone prepares to return to C/C++ code that has called // into Go code. func CgocallBackDone() { + unlockOSThread() + // If we are the top level Go function called from C/C++, then // we need to release the m. But don't release it if we are // panicing; since this is the top level, we are going to |