runtime: remove untyped allocation of ParFor

Now it's two allocations. I don't see much downside to that,
since the two pieces were in different cache lines anyway.

Rename 'conservative' to 'cgo_conservative_type' and make
clear that _cgo_allocate is the only allowed user.

This depends on CL 141490043, which removes the other
use of conservative (in defer).

LGTM=dvyukov, iant
R=khr, dvyukov, iant
CC=golang-codereviews, rlh
https://codereview.appspot.com/139610043

1 files changed, 5 insertions, 0 deletions

diff --git a/misc/cgo/test/callback.go b/misc/cgo/test/callback.go
index 281e79494..a7f1a3ecd 100644
--- a/misc/cgo/test/callback.go
+++ b/misc/cgo/test/callback.go
@@ -9,6 +9,7 @@ void callback(void *f);
 void callGoFoo(void);
 void callGoStackCheck(void);
 void callPanic(void);
+void callCgoAllocate(void);
 */
 import "C"
 
@@ -207,6 +208,10 @@ func testPanicFromC(t *testing.T) {
 	C.callPanic()
 }
 
+func testAllocateFromC(t *testing.T) {
+	C.callCgoAllocate() // crashes or exits on failure
+}
+
 func testCallbackStack(t *testing.T) {
 	// Make cgo call and callback with different amount of stack stack available.
 	// We do not do any explicit checks, just ensure that it does not crash.