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

5 files changed, 107 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.
diff --git a/misc/cgo/test/callback_c_gc.c b/misc/cgo/test/callback_c_gc.c
index 8953b74a6..32bfed0c0 100644
--- a/misc/cgo/test/callback_c_gc.c
+++ b/misc/cgo/test/callback_c_gc.c
@@ -5,11 +5,15 @@
 // +build gc
 
 #include "_cgo_export.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 /* Test calling panic from C.  This is what SWIG does.  */
 
 extern void crosscall2(void (*fn)(void *, int), void *, int);
 extern void _cgo_panic(void *, int);
+extern void _cgo_allocate(void *, int);
 
 void
 callPanic(void)
@@ -19,3 +23,48 @@ callPanic(void)
 	crosscall2(_cgo_panic, &a, sizeof a);
 	*(int*)1 = 1;
 }
+
+/* Test calling cgo_allocate from C. This is what SWIG does. */
+
+typedef struct List List;
+struct List
+{
+	List *next;
+	int x;
+};
+
+void
+callCgoAllocate(void)
+{
+	int i;
+	struct { size_t n; void *ret; } a;
+	List *l, *head, **tail;
+	
+	head = 0;
+	tail = &head;
+	for(i=0; i<100; i++) {
+		a.n = sizeof *l;
+		crosscall2(_cgo_allocate, &a, sizeof a);
+		l = a.ret;
+		l->x = i;
+		l->next = 0;
+		*tail = l;
+		tail = &l->next;
+	}
+	
+	gc();
+	
+	l = head;
+	for(i=0; i<100; i++) {
+		if(l->x != i) {
+			fprintf(stderr, "callCgoAllocate: lost memory\n");
+			exit(2);
+		}
+		l = l->next;
+	}
+	if(l != 0) {
+		fprintf(stderr, "callCgoAllocate: lost memory\n");
+		exit(2);
+	}
+}
+
diff --git a/misc/cgo/test/callback_c_gccgo.c b/misc/cgo/test/callback_c_gccgo.c
index 0ea7296c6..d92dca009 100644
--- a/misc/cgo/test/callback_c_gccgo.c
+++ b/misc/cgo/test/callback_c_gccgo.c
@@ -5,13 +5,59 @@
 // +build gccgo
 
 #include "_cgo_export.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 /* Test calling panic from C.  This is what SWIG does.  */
 
 extern void _cgo_panic(const char *);
+extern void *_cgo_allocate(size_t);
 
 void
 callPanic(void)
 {
 	_cgo_panic("panic from C");
 }
+
+/* Test calling cgo_allocate from C. This is what SWIG does. */
+
+typedef struct List List;
+struct List
+{
+	List *next;
+	int x;
+};
+
+void
+callCgoAllocate(void)
+{
+	int i;
+	List *l, *head, **tail;
+	
+	head = 0;
+	tail = &head;
+	for(i=0; i<100; i++) {
+		l = _cgo_allocate(sizeof *l);
+		l->x = i;
+		l->next = 0;
+		*tail = l;
+		tail = &l->next;
+	}
+	
+	gc();
+	
+	l = head;
+	for(i=0; i<100; i++) {
+		if(l->x != i) {
+			fprintf(stderr, "callCgoAllocate: lost memory\n");
+			exit(2);
+		}
+		l = l->next;
+	}
+	if(l != 0) {
+		fprintf(stderr, "callCgoAllocate: lost memory\n");
+		exit(2);
+	}
+}
+
diff --git a/misc/cgo/test/cgo_test.go b/misc/cgo/test/cgo_test.go
index 3cc83060f..3783af061 100644
--- a/misc/cgo/test/cgo_test.go
+++ b/misc/cgo/test/cgo_test.go
@@ -23,6 +23,7 @@ func TestCallbackPanic(t *testing.T)       { testCallbackPanic(t) }
 func TestCallbackPanicLoop(t *testing.T)   { testCallbackPanicLoop(t) }
 func TestCallbackPanicLocked(t *testing.T) { testCallbackPanicLocked(t) }
 func TestPanicFromC(t *testing.T)          { testPanicFromC(t) }
+func TestAllocateFromC(t *testing.T)       { testAllocateFromC(t) }
 func TestZeroArgCallback(t *testing.T)     { testZeroArgCallback(t) }
 func TestBlocking(t *testing.T)            { testBlocking(t) }
 func Test1328(t *testing.T)                { test1328(t) }
diff --git a/misc/cgo/test/exports.go b/misc/cgo/test/exports.go
index f96c60b00..4fe1703a6 100644
--- a/misc/cgo/test/exports.go
+++ b/misc/cgo/test/exports.go
@@ -5,8 +5,14 @@
 package cgotest
 
 import "C"
+import "runtime"
 
 //export ReturnIntLong
 func ReturnIntLong() (int, C.long) {
 	return 1, 2
 }
+
+//export gc
+func gc() {
+	runtime.GC()
+}