Correctly handle try/catch try/finally blocks

If we have a try/catch block nested inside a try/finally, then the
finally block would not be executed in the event of the exception.
This is because the landing pad of the inner try is marked as having no
cleanup clause.

We now set has_cleanup to False only if there is no outer try block.

Signed-off-by: Jonathan Coates <jonathan.coates@oxionics.com>

artiq/compiler/transforms/artiq_ir_generator.py

@@ -696,7 +696,7 @@ class ARTIQIRGenerator(algorithm.Visitor):
                 return_action.append(ir.Return(value))
                 final_branch(return_action, return_proxy)
         else:
-            landingpad.has_cleanup = False
+            landingpad.has_cleanup = self.unwind_target is not None
 
         # we should propagate the clauses to nested try catch blocks
         # so nested try catch will jump to our clause if the inner one does not
@@ -760,7 +760,6 @@ class ARTIQIRGenerator(algorithm.Visitor):
                 self.continue_target = old_continue
             self.return_target = old_return
 
-        if any(node.finalbody):
             # create new unwind target for cleanup
             final_dispatcher = self.add_block("try.final.dispatch")
             final_landingpad = ir.LandingPad(cleanup)
@@ -769,7 +768,6 @@ class ARTIQIRGenerator(algorithm.Visitor):
             # make sure that exception clauses are unwinded to the finally block
             old_unwind, self.unwind_target = self.unwind_target, final_dispatcher
 
-        if any(node.finalbody):
             # if we have a while:try/finally continue must execute finally
             # before continuing the while
             redirect = final_branch

artiq/test/lit/exceptions/finally_catch_try.py

@@ -0,0 +1,19 @@
+# RUN: %python -m artiq.compiler.testbench.jit %s >%t
+# RUN: OutputCheck %s --file-to-check=%t
+# REQUIRES: exceptions
+
+def doit():
+    try:
+        try:
+            raise RuntimeError("Error")
+        except ValueError:
+            print("ValueError")
+    except RuntimeError:
+        print("Caught")
+    finally:
+        print("Cleanup")
+
+doit()
+
+# CHECK-L: Caught
+# CHECK-NEXT-L: Cleanup

artiq/test/lit/exceptions/finally_try.py

@@ -0,0 +1,20 @@
+# RUN: %python -m artiq.compiler.testbench.jit %s >%t
+# RUN: OutputCheck %s --file-to-check=%t
+# REQUIRES: exceptions
+
+def doit():
+    try:
+        try:
+            raise RuntimeError("Error")
+        except ValueError:
+            print("ValueError")
+    finally:
+        print("Cleanup")
+
+try:
+    doit()
+except RuntimeError:
+    print("Caught")
+
+# CHECK-L: Cleanup
+# CHECK-NEXT-L: Caught