runtime: implement Goexit

This is needed for full support for the testing package

compiler/testdata/defer-cortex-m-qemu.ll

@@ -3,7 +3,7 @@ source_filename = "defer.go"
 target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv7m-unknown-unknown-eabi"
 
-%runtime.deferFrame = type { ptr, ptr, [0 x ptr], ptr, i1, %runtime._interface }
+%runtime.deferFrame = type { ptr, ptr, [0 x ptr], ptr, i8, %runtime._interface }
 %runtime._interface = type { ptr, ptr }
 %runtime._defer = type { i32, ptr }
 

src/runtime/panic.go

@@ -38,12 +38,24 @@ type deferFrame struct {
 	JumpPC     unsafe.Pointer                 // pc to return to
 	ExtraRegs  [deferExtraRegs]unsafe.Pointer // extra registers (depending on the architecture)
 	Previous   *deferFrame                    // previous recover buffer pointer
-	Panicking  bool                           // true iff this defer frame is panicking
+	Panicking  panicState                     // not panicking, panicking, or in Goexit
 	PanicValue interface{}                    // panic value, might be nil for panic(nil) for example
 }
 
+type panicState uint8
+
+const (
+	panicFalse panicState = iota
+	panicTrue
+	panicGoexit
+)
+
 // Builtin function panic(msg), used as a compiler intrinsic.
 func _panic(message interface{}) {
+	panicOrGoexit(message, panicTrue)
+}
+
+func panicOrGoexit(message interface{}, panicking panicState) {
 	if panicStrategy() == tinygo.PanicStrategyTrap {
 		trap()
 	}
@@ -53,11 +65,16 @@ func _panic(message interface{}) {
 		frame := (*deferFrame)(task.Current().DeferFrame)
 		if frame != nil {
 			frame.PanicValue = message
-			frame.Panicking = true
+			frame.Panicking = panicking
 			tinygo_longjmp(frame)
 			// unreachable
 		}
 	}
+	if panicking == panicGoexit {
+		// Call to Goexit() instead of a panic.
+		// Exit the goroutine instead of printing a panic message.
+		deadlock()
+	}
 	printstring("panic: ")
 	printitf(message)
 	printnl()
@@ -103,7 +120,7 @@ func setupDeferFrame(frame *deferFrame, jumpSP unsafe.Pointer) {
 	currentTask := task.Current()
 	frame.Previous = (*deferFrame)(currentTask.DeferFrame)
 	frame.JumpSP = jumpSP
-	frame.Panicking = false
+	frame.Panicking = panicFalse
 	currentTask.DeferFrame = unsafe.Pointer(frame)
 }
 
@@ -115,10 +132,10 @@ func setupDeferFrame(frame *deferFrame, jumpSP unsafe.Pointer) {
 //go:nobounds
 func destroyDeferFrame(frame *deferFrame) {
 	task.Current().DeferFrame = unsafe.Pointer(frame.Previous)
-	if frame.Panicking {
+	if frame.Panicking != panicFalse {
 		// We're still panicking!
 		// Re-raise the panic now.
-		_panic(frame.PanicValue)
+		panicOrGoexit(frame.PanicValue, frame.Panicking)
 	}
 }
 
@@ -143,10 +160,15 @@ func _recover(useParentFrame bool) interface{} {
 		// already), but instead from the previous frame.
 		frame = frame.Previous
 	}
-	if frame != nil && frame.Panicking {
+	if frame != nil && frame.Panicking != panicFalse {
+		if frame.Panicking == panicGoexit {
+			// Special value that indicates we're exiting the goroutine using
+			// Goexit(). Therefore, make this recover call a no-op.
+			return nil
+		}
 		// Only the first call to recover returns the panic value. It also stops
 		// the panicking sequence, hence setting panicking to false.
-		frame.Panicking = false
+		frame.Panicking = panicFalse
 		return frame.PanicValue
 	}
 	// Not panicking, so return a nil interface.

src/runtime/scheduler.go

@@ -28,11 +28,6 @@ func scheduleLogChan(msg string, ch *channel, t *task.Task) {
 }
 
 // Goexit terminates the currently running goroutine. No other goroutines are affected.
-//
-// Unlike the main Go implementation, no deferred calls will be run.
-//
-//go:inline
 func Goexit() {
-	// TODO: run deferred functions
-	deadlock()
+	panicOrGoexit(nil, panicGoexit)
 }

testdata/recover.go

@@ -1,5 +1,10 @@
 package main
 
+import (
+	"runtime"
+	"time"
+)
+
 func main() {
 	println("# simple recover")
 	recoverSimple()
@@ -22,6 +27,9 @@ func main() {
 
 	println("\n# defer panic")
 	deferPanic()
+
+	println("\n# runtime.Goexit")
+	runtimeGoexit()
 }
 
 func recoverSimple() {
@@ -104,6 +112,17 @@ func deferPanic() {
 	println("defer panic")
 }
 
+func runtimeGoexit() {
+	go func() {
+		defer func() {
+			println("Goexit deferred function, recover is nil:", recover() == nil)
+		}()
+
+		runtime.Goexit()
+	}()
+	time.Sleep(time.Millisecond)
+}
+
 func printitf(msg string, itf interface{}) {
 	switch itf := itf.(type) {
 	case string:

testdata/recover.txt

@@ -27,3 +27,6 @@ recovered: panic 2
 # defer panic
 defer panic
 recovered from deferred call: deferred panic
+
+# runtime.Goexit
+Goexit deferred function, recover is nil: true