compiler, runtime: Use runtime functions to pass closure value.

This changes the compiler and runtime to not pass a closure
value as the last argument, but to instead pass it via
__go_set_closure and retrieve it via __go_get_closure.  This
eliminates the need for function descriptor wrapper functions.
It will make it possible to retrieve the closure value in a
reflect.MakeFunc function.

From-SVN: r202233

6 files changed, 36 insertions, 27 deletions

diff --git a/libgo/go/reflect/value.go b/libgo/go/reflect/value.go
index 6bf66c8..45a0858 100644
--- a/libgo/go/reflect/value.go
+++ b/libgo/go/reflect/value.go
@@ -434,9 +434,6 @@ func (v Value) call(op string, in []Value) []Value {
 		nin++
 	}
 	firstPointer := len(in) > 0 && Kind(t.In(0).(*rtype).kind) != Ptr && v.flag&flagMethod == 0 && isMethod(v.typ)
-	if v.flag&flagMethod == 0 && !firstPointer {
-		nin++
-	}
 	params := make([]unsafe.Pointer, nin)
 	off := 0
 	if v.flag&flagMethod != 0 {
@@ -464,10 +461,6 @@ func (v Value) call(op string, in []Value) []Value {
 		}
 		off++
 	}
-	if v.flag&flagMethod == 0 && !firstPointer {
-		// Closure argument.
-		params[off] = unsafe.Pointer(&fn)
-	}
 
 	ret := make([]Value, nout)
 	results := make([]unsafe.Pointer, nout)
diff --git a/libgo/runtime/go-reflect-call.c b/libgo/runtime/go-reflect-call.c
index 83b9eba..5cf3707 100644
--- a/libgo/runtime/go-reflect-call.c
+++ b/libgo/runtime/go-reflect-call.c
@@ -302,9 +302,7 @@ go_func_to_cif (const struct __go_func_type *func, _Bool is_interface,
   in_types = ((const struct __go_type_descriptor **)
 	      func->__in.__values);
 
-  num_args = (num_params
-	      + (is_interface ? 1 : 0)
-	      + (!is_interface && !is_method ? 1 : 0));
+  num_args = num_params + (is_interface ? 1 : 0);
   args = (ffi_type **) __go_alloc (num_args * sizeof (ffi_type *));
   i = 0;
   off = 0;
@@ -321,12 +319,6 @@ go_func_to_cif (const struct __go_func_type *func, _Bool is_interface,
   for (; i < num_params; ++i)
     args[i + off] = go_type_to_ffi (in_types[i]);
 
-  if (!is_interface && !is_method)
-    {
-      // There is a closure argument, a pointer.
-      args[i + off] = &ffi_type_pointer;
-    }
-
   rettype = go_func_return_ffi (func);
 
   status = ffi_prep_cif (cif, FFI_DEFAULT_ABI, num_args, rettype, args);
@@ -511,9 +503,8 @@ go_set_results (const struct __go_func_type *func, unsigned char *call_result,
    regardless of FUNC_TYPE, it is passed as a pointer.
 
    If neither IS_INTERFACE nor IS_METHOD is true then we are calling a
-   function indirectly, and the caller is responsible for passing a
-   trailing closure argument, a pointer, which is not described in
-   FUNC_TYPE.  */
+   function indirectly, and we must pass a closure pointer via
+   __go_set_closure.  The pointer to pass is simply FUNC_VAL.  */
 
 void
 reflect_call (const struct __go_func_type *func_type, FuncVal *func_val,
@@ -528,6 +519,8 @@ reflect_call (const struct __go_func_type *func_type, FuncVal *func_val,
 
   call_result = (unsigned char *) malloc (go_results_size (func_type));
 
+  if (!is_interface && !is_method)
+    __go_set_closure (func_val);
   ffi_call (&cif, func_val->fn, call_result, params);
 
   /* Some day we may need to free result values if RESULTS is
diff --git a/libgo/runtime/mgc0.c b/libgo/runtime/mgc0.c
index 36afd2b..c3b3211 100644
--- a/libgo/runtime/mgc0.c
+++ b/libgo/runtime/mgc0.c
@@ -2263,12 +2263,11 @@ runfinq(void* dummy __attribute__ ((unused)))
 		for(; fb; fb=next) {
 			next = fb->next;
 			for(i=0; i<(uint32)fb->cnt; i++) {
-				void *params[2];
+				void *param;
 
 				f = &fb->fin[i];
-				params[0] = &f->arg;
-				params[1] = f;
-				reflect_call(f->ft, f->fn, 0, 0, params, nil);
+				param = &f->arg;
+				reflect_call(f->ft, f->fn, 0, 0, &param, nil);
 				f->fn = nil;
 				f->arg = nil;
 			}
diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index d42ff33..0e77a3e 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -2832,3 +2832,23 @@ runtime_proc_scan(void (*addroot)(Obj))
 {
 	addroot((Obj){(byte*)&runtime_sched, sizeof runtime_sched, 0});
 }
+
+// When a function calls a closure, it passes the closure value to
+// __go_set_closure immediately before the function call.  When a
+// function uses a closure, it calls __go_get_closure immediately on
+// function entry.  This is a hack, but it will work on any system.
+// It would be better to use the static chain register when there is
+// one.  It is also worth considering expanding these functions
+// directly in the compiler.
+
+void
+__go_set_closure(void* v)
+{
+	g->closure = v;
+}
+
+void *
+__go_get_closure(void)
+{
+	return g->closure;
+}
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index 78fd388..d2e7d4c 100644
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -190,6 +190,7 @@ struct	Location
 
 struct	G
 {
+	void*	closure;	// Closure value.
 	Defer*	defer;
 	Panic*	panic;
 	void*	exception;	// current exception being thrown
@@ -759,3 +760,6 @@ extern void runtime_main(void*);
 int32 getproccount(void);
 
 #define PREFETCH(p) __builtin_prefetch(p)
+
+void	__go_set_closure(void*);
+void*	__go_get_closure(void);
diff --git a/libgo/runtime/time.goc b/libgo/runtime/time.goc
index e06b75c..8d12fe0 100644
--- a/libgo/runtime/time.goc
+++ b/libgo/runtime/time.goc
@@ -46,10 +46,9 @@ static void siftdown(int32);
 
 // Ready the goroutine e.data.
 static void
-ready(int64 now, Eface e, void *closure)
+ready(int64 now, Eface e)
 {
 	USED(now);
-	USED(closure);
 
 	runtime_ready(e.__object);
 }
@@ -166,7 +165,7 @@ timerproc(void* dummy __attribute__ ((unused)))
 {
 	int64 delta, now;
 	Timer *t;
-	void (*f)(int64, Eface, void *);
+	void (*f)(int64, Eface);
 	Eface arg;
 
 	for(;;) {
@@ -197,7 +196,8 @@ timerproc(void* dummy __attribute__ ((unused)))
 			runtime_unlock(&timers);
 			if(raceenabled)
 				runtime_raceacquire(t);
-			f(now, arg, &t->fv);
+			__go_set_closure(t->fv);
+			f(now, arg);
 			runtime_lock(&timers);
 		}
 		if(delta < 0) {