compiler: remove parentHandle from calling convention

This removes the parentHandle argument from the internal calling convention.
It was formerly used to implment coroutines.
Now that coroutines have been removed, it is no longer necessary.

compiler/goroutine.go

@@ -90,17 +90,8 @@ func (b *builder) createGo(instr *ssa.Go) {
 		//   * The function pointer (for tasks).
 		var context llvm.Value
 		funcPtr, context = b.decodeFuncValue(b.getValue(instr.Call.Value), instr.Call.Value.Type().Underlying().(*types.Signature))
-		params = append(params, context) // context parameter
+		params = append(params, context, funcPtr)
 		hasContext = true
-		switch b.Scheduler {
-		case "none":
-			// There are no additional parameters needed for the goroutine start operation.
-		case "tasks", "asyncify":
-			// Add the function pointer as a parameter to start the goroutine.
-			params = append(params, funcPtr)
-		default:
-			panic("unknown scheduler type")
-		}
 		prefix = b.fn.RelString(nil)
 	}
 
@@ -113,7 +104,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 		// section that contains the stack size (and is modified after
 		// linking).
 		stackSizeFn := b.getFunction(b.program.ImportedPackage("internal/task").Members["getGoroutineStackSize"].(*ssa.Function))
-		stackSize = b.createCall(stackSizeFn, []llvm.Value{callee, llvm.Undef(b.i8ptrType), llvm.Undef(b.i8ptrType)}, "stacksize")
+		stackSize = b.createCall(stackSizeFn, []llvm.Value{callee, llvm.Undef(b.i8ptrType)}, "stacksize")
 	} else {
 		// The stack size is fixed at compile time. By emitting it here as a
 		// constant, it can be optimized.
@@ -123,7 +114,7 @@ func (b *builder) createGo(instr *ssa.Go) {
 		stackSize = llvm.ConstInt(b.uintptrType, b.DefaultStackSize, false)
 	}
 	start := b.getFunction(b.program.ImportedPackage("internal/task").Members["start"].(*ssa.Function))
-	b.createCall(start, []llvm.Value{callee, paramBundle, stackSize, llvm.Undef(b.i8ptrType), llvm.ConstPointerNull(b.i8ptrType)}, "")
+	b.createCall(start, []llvm.Value{callee, paramBundle, stackSize, llvm.Undef(b.i8ptrType)}, "")
 }
 
 // createGoroutineStartWrapper creates a wrapper for the task-based
@@ -202,7 +193,6 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 
 		// Create the list of params for the call.
 		paramTypes := fn.Type().ElementType().ParamTypes()
-		paramTypes = paramTypes[:len(paramTypes)-1] // strip parentHandle parameter
 		if !hasContext {
 			paramTypes = paramTypes[:len(paramTypes)-1] // strip context parameter
 		}
@@ -210,14 +200,13 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 		if !hasContext {
 			params = append(params, llvm.Undef(c.i8ptrType)) // add dummy context parameter
 		}
-		params = append(params, llvm.Undef(c.i8ptrType)) // add dummy parentHandle parameter
 
 		// Create the call.
 		builder.CreateCall(fn, params, "")
 
 		if c.Scheduler == "asyncify" {
 			builder.CreateCall(deadlock, []llvm.Value{
-				llvm.Undef(c.i8ptrType), llvm.Undef(c.i8ptrType),
+				llvm.Undef(c.i8ptrType),
 			}, "")
 		}
 
@@ -273,25 +262,19 @@ func (c *compilerContext) createGoroutineStartWrapper(fn llvm.Value, prefix stri
 
 		// Get the list of parameters, with the extra parameters at the end.
 		paramTypes := fn.Type().ElementType().ParamTypes()
-		paramTypes[len(paramTypes)-1] = fn.Type() // the last element is the function pointer
+		paramTypes = append(paramTypes, fn.Type()) // the last element is the function pointer
 		params := llvmutil.EmitPointerUnpack(builder, c.mod, wrapper.Param(0), paramTypes)
 
 		// Get the function pointer.
 		fnPtr := params[len(params)-1]
-
-		// The last parameter in the packed object has somewhat of a dual role.
-		// Inside the parameter bundle it's the function pointer, stored right
-		// after the context pointer. But in the IR call instruction, it's the
-		// parentHandle function that's always undef. Thus, make the parameter
-		// undef here.
-		params[len(params)-1] = llvm.Undef(c.i8ptrType)
+		params = params[:len(params)-1]
 
 		// Create the call.
 		builder.CreateCall(fnPtr, params, "")
 
 		if c.Scheduler == "asyncify" {
 			builder.CreateCall(deadlock, []llvm.Value{
-				llvm.Undef(c.i8ptrType), llvm.Undef(c.i8ptrType),
+				llvm.Undef(c.i8ptrType),
 			}, "")
 		}
 	}