[dev.typeparams] runtime: make deferproc take a func() argument

Previously it takes a *funcval, as it can be any function types.
Now it must be func(). Make it so.

Change-Id: I04273047b024386f55dbbd5fbda4767cbee7ac93
Reviewed-on: https://go-review.googlesource.com/c/go/+/325918
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

src/runtime/heapdump.go

@@ -381,12 +381,13 @@ func dumpgoroutine(gp *g) {
 		dumpint(uint64(uintptr(unsafe.Pointer(gp))))
 		dumpint(uint64(d.sp))
 		dumpint(uint64(d.pc))
-		dumpint(uint64(uintptr(unsafe.Pointer(d.fn))))
+		fn := *(**funcval)(unsafe.Pointer(&d.fn))
-		if d.fn == nil {
+		dumpint(uint64(uintptr(unsafe.Pointer(fn))))
+		if fn == nil {
 			// d.fn can be nil for open-coded defers
 			dumpint(uint64(0))
 		} else {
-			dumpint(uint64(uintptr(unsafe.Pointer(d.fn.fn))))
+			dumpint(uint64(uintptr(unsafe.Pointer(fn.fn))))
 		}
 		dumpint(uint64(uintptr(unsafe.Pointer(d.link))))
 	}

src/runtime/panic.go

@@ -227,7 +227,7 @@ func panicmemAddr(addr uintptr) {
 // Create a new deferred function fn, which has no arguments and results.
 // The compiler turns a defer statement into a call to this.
 //go:nosplit
-func deferproc(fn *funcval) { // TODO: Make deferproc just take a func().
+func deferproc(fn func()) {
 	gp := getg()
 	if gp.m.curg != gp {
 		// go code on the system stack can't defer
@@ -363,16 +363,6 @@ func testdefersizes() {
 	}
 }
 
-// deferFunc returns d's deferred function. This is temporary while we
-// support both modes of GOEXPERIMENT=regabidefer. Once we commit to
-// that experiment, we should change the type of d.fn.
-//go:nosplit
-func deferFunc(d *_defer) func() {
-	var fn func()
-	*(**funcval)(unsafe.Pointer(&fn)) = d.fn
-	return fn
-}
-
 var deferType *_type // type of _defer struct
 
 func init() {
@@ -555,7 +545,9 @@ func deferreturn() {
 	// called with a callback on an LR architecture and jmpdefer is on the
 	// stack, because the stack trace can be incorrect in that case - see
 	// issue #8153).
-	_ = fn.fn
+	if fn == nil {
+		fn()
+	}
 	jmpdefer(fn, argp)
 }
 
@@ -619,7 +611,7 @@ func Goexit() {
 		} else {
 			// Save the pc/sp in deferCallSave(), so we can "recover" back to this
 			// loop if necessary.
-			deferCallSave(&p, deferFunc(d))
+			deferCallSave(&p, d.fn)
 		}
 		if p.aborted {
 			// We had a recursive panic in the defer d we started, and
@@ -824,12 +816,12 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
 			}
 			continue
 		}
-		closure := *(**funcval)(unsafe.Pointer(d.varp - uintptr(closureOffset)))
+		closure := *(*func())(unsafe.Pointer(d.varp - uintptr(closureOffset)))
 		d.fn = closure
 		deferBits = deferBits &^ (1 << i)
 		*(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset))) = deferBits
 		p := d._panic
-		deferCallSave(p, deferFunc(d))
+		deferCallSave(p, d.fn)
 		if p != nil && p.aborted {
 			break
 		}
@@ -950,8 +942,7 @@ func gopanic(e interface{}) {
 			}
 		} else {
 			p.argp = unsafe.Pointer(getargp())
-			fn := deferFunc(d)
+			d.fn()
-			fn()
 		}
 		p.argp = nil
 

src/runtime/runtime2.go

@@ -956,7 +956,7 @@ type _defer struct {
 	openDefer bool
 	sp        uintptr // sp at time of defer
 	pc        uintptr // pc at time of defer
-	fn        *funcval // can be nil for open-coded defers
+	fn        func()  // can be nil for open-coded defers
 	_panic    *_panic // panic that is running defer
 	link      *_defer
 

src/runtime/stubs.go

@@ -177,7 +177,7 @@ func cgocallback(fn, frame, ctxt uintptr)
 func gogo(buf *gobuf)
 
 //go:noescape
-func jmpdefer(fv *funcval, argp uintptr)
+func jmpdefer(fv func(), argp uintptr)
 func asminit()
 func setg(gg *g)
 func breakpoint()