Extend number of flat parameters in async lower from 1 to 4

Author: lukewagner

design/mvp/canonical-abi/definitions.py

@@ -1522,6 +1522,7 @@ def lower_async_value(ReadableEndT, cx, v, t):
 
 MAX_FLAT_PARAMS = 16
 MAX_FLAT_RESULTS = 1
+MAX_FLAT_ASYNC_PARAMS = 4
 
 def flatten_functype(opts, ft, context):
   flat_params = flatten_types(ft.param_types())
@@ -1545,7 +1546,7 @@ def flatten_functype(opts, ft, context):
         else:
           flat_results = []
       case 'lower':
-        if len(flat_params) > 1:
+        if len(flat_params) > MAX_FLAT_ASYNC_PARAMS:
           flat_params = ['i32']
         if len(flat_results) > 0:
           flat_params += ['i32']
@@ -1932,7 +1933,7 @@ def on_resolve(results):
 
   def on_start():
     on_progress()
-    return lift_flat_values(cx, 1, flat_args, ft.param_types())
+    return lift_flat_values(cx, MAX_FLAT_ASYNC_PARAMS, flat_args, ft.param_types())
 
   def on_resolve(results):
     on_progress()

design/mvp/canonical-abi/run_tests.py

@@ -2231,6 +2231,25 @@ async def core_func(task, args):
 
   await canon_lift(sync_opts, inst, ft, core_func, None, lambda:[], lambda _:(), host_on_block)
 
+async def test_async_abi():
+  heap = Heap(1000)
+  opts = mk_opts(heap.memory, 'utf8', heap.realloc)
+  inst = ComponentInstance()
+  caller = Task(opts, inst, FuncType([],[]), None, None, None)
+
+  ft1 = FuncType([F32Type(), F64Type(), U32Type(), S64Type()],[])
+  async def f1(task, on_start, on_resolve, on_block):
+    args = on_start()
+    assert(len(args) == 4)
+    assert(args[0] == 1.1)
+    assert(args[1] == 2.2)
+    assert(args[2] == 3)
+    assert(args[3] == 4)
+    on_resolve([])
+  [] = await canon_lower(opts, ft1, f1, caller, [1.1, 2.2, 3, 4])
+
+  TODO
+
 async def run_async_tests():
   await test_roundtrips()
   await test_handles()
@@ -2250,6 +2269,7 @@ async def run_async_tests():
   await test_futures()
   await test_cancel_subtask()
   await test_self_empty()
+  await test_async_abi()
 
 asyncio.run(run_async_tests())