transforms.interleaver: handle function calls (as atomic so far).

This commit solves issue #2 described in 50e7b44; a function call
is now a valid decomposition for a delay instruction, and this
metadata is propagated when the interleaver converts delays.

However, the interleaver does not yet detect that a called function
is compound, i.e. it is not correct.

artiq/compiler/transforms/interleaver.py

@@ -104,7 +104,7 @@ class Interleaver:
                         new_decomp.loc = old_decomp.loc
                         source_terminator.basic_block.insert(source_terminator, new_decomp)
                     else:
-                        assert False # TODO
+                        old_decomp, new_decomp = None, old_decomp
 
                     source_terminator.replace_with(ir.Delay(iodelay.Const(target_time_delta), {},
                                                             new_decomp, source_terminator.target()))

lit-test/test/interleaving/indirect.py

@@ -0,0 +1,28 @@
+# RUN: %python -m artiq.compiler.testbench.jit %s >%t
+# RUN: OutputCheck %s --file-to-check=%t
+
+def f():
+    delay_mu(2)
+
+def g():
+    with parallel:
+        with sequential:
+            print("A", now_mu())
+            f()
+            #
+            print("B", now_mu())
+        with sequential:
+            print("C", now_mu())
+            f()
+            #
+            print("D", now_mu())
+            f()
+            #
+            print("E", now_mu())
+
+# CHECK-L: A 0
+# CHECK-L: C 0
+# CHECK-L: B 2
+# CHECK-L: D 2
+# CHECK-L: E 4
+g()

lit-test/test/interleaving/indirect_arg.py

@@ -0,0 +1,28 @@
+# RUN: %python -m artiq.compiler.testbench.jit %s >%t
+# RUN: OutputCheck %s --file-to-check=%t
+
+def f(n):
+    delay_mu(n)
+
+def g():
+    with parallel:
+        with sequential:
+            print("A", now_mu())
+            f(2)
+            #
+            print("B", now_mu())
+        with sequential:
+            print("C", now_mu())
+            f(2)
+            #
+            print("D", now_mu())
+            f(2)
+            #
+            print("E", now_mu())
+
+# CHECK-L: A 0
+# CHECK-L: C 0
+# CHECK-L: B 2
+# CHECK-L: D 2
+# CHECK-L: E 4
+g()