fix miscompile of static goroutine calls to closures

compiler/compiler.go

@@ -1080,28 +1080,34 @@ func (c *Compiler) parseInstr(frame *Frame, instr ssa.Instruction) {
 			// Static callee is known. This makes it easier to start a new
 			// goroutine.
 			calleeFn := c.ir.GetFunction(callee)
-			if !calleeFn.IsExported() && c.selectScheduler() != "tasks" {
-				// For coroutine scheduling, this is only required when calling
-				// an external function.
-				// For tasks, because all params are stored in a single object,
-				// no unnecessary parameters should be stored anyway.
-				params = append(params, llvm.Undef(c.i8ptrType))            // context parameter
-				params = append(params, llvm.ConstPointerNull(c.i8ptrType)) // parent coroutine handle
+			var context llvm.Value
+			switch value := instr.Call.Value.(type) {
+			case *ssa.Function:
+				// Goroutine call is regular function call. No context is necessary.
+				context = llvm.Undef(c.i8ptrType)
+			case *ssa.MakeClosure:
+				// A goroutine call on a func value, but the callee is trivial to find. For
+				// example: immediately applied functions.
+				funcValue := c.getValue(frame, value)
+				context = c.extractFuncContext(funcValue)
+			default:
+				panic("StaticCallee returned an unexpected value")
 			}
+			params = append(params, context) // context parameter
 			c.emitStartGoroutine(calleeFn.LLVMFn, params)
 		} else if !instr.Call.IsInvoke() {
 			// This is a function pointer.
 			// At the moment, two extra params are passed to the newly started
 			// goroutine:
 			//   * The function context, for closures.
-			//   * The parent handle (for coroutines) or the function pointer
-			//     itself (for tasks).
+			//   * The function pointer (for tasks).
 			funcPtr, context := c.decodeFuncValue(c.getValue(frame, instr.Call.Value), instr.Call.Value.Type().(*types.Signature))
 			params = append(params, context) // context parameter
 			switch c.selectScheduler() {
 			case "coroutines":
-				params = append(params, llvm.ConstPointerNull(c.i8ptrType)) // parent coroutine handle
+				// There are no additional parameters needed for the goroutine start operation.
 			case "tasks":
+				// Add the function pointer as a parameter to start the goroutine.
 				params = append(params, funcPtr)
 			default:
 				panic("unknown scheduler type")

compiler/func-lowering.go

@@ -98,6 +98,10 @@ func (c *Compiler) LowerFuncValues() {
 					continue
 				}
 				for _, funcValueWithSignatureConstant := range getUses(ptrtoint) {
+					if !funcValueWithSignatureConstant.IsACallInst().IsNil() && funcValueWithSignatureConstant.CalledValue().Name() == "runtime.makeGoroutine" {
+						// makeGoroutine calls are handled seperately
+						continue
+					}
 					for _, funcValueWithSignatureGlobal := range getUses(funcValueWithSignatureConstant) {
 						for _, use := range getUses(funcValueWithSignatureGlobal) {
 							if ptrtoint.IsAConstantExpr().IsNil() || ptrtoint.Opcode() != llvm.PtrToInt {
@@ -182,7 +186,11 @@ func (c *Compiler) LowerFuncValues() {
 								panic("expected a inttoptr")
 							}
 							for _, use := range getUses(inttoptr) {
-								c.addFuncLoweringSwitch(funcID, use, c.emitStartGoroutine, functions)
+								c.addFuncLoweringSwitch(funcID, use, func(funcPtr llvm.Value, params []llvm.Value) llvm.Value {
+									// The function lowering switch code passes in a parent handle value.
+									// Strip the parent handle off here because it is irrelevant to goroutine starts.
+									return c.emitStartGoroutine(funcPtr, params[:len(params)-1])
+								}, functions)
 								use.EraseFromParentAsInstruction()
 							}
 							inttoptr.EraseFromParentAsInstruction()

compiler/goroutine.go

@@ -7,6 +7,9 @@ import "tinygo.org/x/go-llvm"
 
 // emitStartGoroutine starts a new goroutine with the provided function pointer
 // and parameters.
+// In general, you should pass all regular parameters plus the context parameter.
+// There is one exception: the task-based scheduler needs to have the function
+// pointer passed in as a parameter too in addition to the context.
 //
 // Because a go statement doesn't return anything, return undef.
 func (c *Compiler) emitStartGoroutine(funcPtr llvm.Value, params []llvm.Value) llvm.Value {
@@ -24,7 +27,7 @@ func (c *Compiler) emitStartGoroutine(funcPtr llvm.Value, params []llvm.Value) l
 		calleeValue := c.builder.CreatePtrToInt(funcPtr, c.uintptrType, "")
 		calleeValue = c.createRuntimeCall("makeGoroutine", []llvm.Value{calleeValue}, "")
 		calleeValue = c.builder.CreateIntToPtr(calleeValue, funcPtr.Type(), "")
-		c.createCall(calleeValue, params, "")
+		c.createCall(calleeValue, append(params, llvm.ConstPointerNull(c.i8ptrType)), "")
 	default:
 		panic("unreachable")
 	}
@@ -74,8 +77,8 @@ func (c *Compiler) createGoroutineStartWrapper(fn llvm.Value) llvm.Value {
 
 		// Create the list of params for the call.
 		paramTypes := fn.Type().ElementType().ParamTypes()
-		params := c.emitPointerUnpack(wrapper.Param(0), paramTypes[:len(paramTypes)-2])
-		params = append(params, llvm.Undef(c.i8ptrType), llvm.ConstPointerNull(c.i8ptrType))
+		params := c.emitPointerUnpack(wrapper.Param(0), paramTypes[:len(paramTypes)-1])
+		params = append(params, llvm.Undef(c.i8ptrType))
 
 		// Create the call.
 		c.builder.CreateCall(fn, params, "")

testdata/coroutines.go

@@ -41,6 +41,16 @@ func main() {
 	})
 
 	time.Sleep(2 * time.Millisecond)
+
+	var x int
+	go func() {
+		time.Sleep(2 * time.Millisecond)
+		x = 1
+	}()
+	time.Sleep(time.Second/2)
+	println("closure go call result:", x)
+
+	time.Sleep(2 * time.Millisecond)
 }
 
 func sub() {

testdata/coroutines.txt

@@ -13,3 +13,4 @@ done with non-blocking goroutine
 async interface method call
 slept inside func pointer 8
 slept inside closure, with value: 20 8
+closure go call result: 1