all: allow -O0 optimization level

src/runtime/runtime.go

@@ -10,14 +10,18 @@ const Compiler = "tgo"
 // package.
 func initAll()
 
-// These signatures are used to call the correct main function: with scheduling
-// or without scheduling.
-func main_main()
-func main_mainAsync(parent *coroutine) *coroutine
-
-// The compiler will change this to true if there are 'go' statements in the
-// compiled program and turn it into a const.
-var hasScheduler bool
+// The compiler will insert the call to main.main() here, depending on whether
+// the scheduler is necessary.
+//
+// Without scheduler:
+//
+//     main.main()
+//
+// With scheduler:
+//
+//     coroutine := main.main(nil)
+//     scheduler(coroutine)
+func mainWrapper()
 
 // Entry point for Go. Initialize all packages and call main.main().
 //go:export main
@@ -31,18 +35,11 @@ func main() int {
 	// Enable interrupts etc.
 	postinit()
 
-	// This branch must be optimized away. Only one of the targets must remain,
-	// or there will be link errors.
-	if hasScheduler {
-		// Initialize main and run the scheduler.
-		coro := main_mainAsync(nil)
-		scheduler(coro)
-		return 0
-	} else {
-		// No scheduler is necessary. Call main directly.
-		main_main()
-		return 0
-	}
+	// Compiler-generated wrapper to main.main().
+	mainWrapper()
+
+	// For libc compatibility.
+	return 0
 }
 
 func GOMAXPROCS(n int) int {