[Wasm GC] Implement closed-world flag (#5303)

With this change we default to an open world, that is, we do the safe thing
by default: we no longer assume a closed world. Users that want a closed
world must pass --closed-world.

Atm we just do not run passes that assume a closed world. (We might later
refine them to find which types don't escape and only optimize those.) The
RemoveUnusedModuleElements is an exception in that the closed-world
flag influences one part of its operation, but not the rest.

Fixes #5292

1 files changed, 49 insertions, 0 deletions

diff --git a/test/unit/test_passes.py b/test/unit/test_passes.py
new file mode 100644
index 000000000..2fe7f6263
--- /dev/null
+++ b/test/unit/test_passes.py
@@ -0,0 +1,49 @@
+import os
+import re
+import subprocess
+from scripts.test import shared
+from . import utils
+
+
+class PassesTest(utils.BinaryenTestCase):
+    # Given some arguments, return the passes that were run.
+    def get_passes_run(self, args):
+        os.environ['BINARYEN_PASS_DEBUG'] = '1'
+        try:
+            hello_wat = self.input_path('hello_world.wat')
+            log = shared.run_process(shared.WASM_OPT + [hello_wat] + args,
+                                     stderr=subprocess.PIPE).stderr
+            print(log)
+            passes = re.findall(r'running pass: ([\w-]+)\.\.\.', log)
+            return passes
+        finally:
+            del os.environ['BINARYEN_PASS_DEBUG']
+
+    def test_O2(self):
+        args = ['-O2', '-all']
+        for nominal in ['--nominal', False]:
+            for closed_world in ['--closed-world', False]:
+                curr_args = args[:]
+                if nominal:
+                    curr_args.append(nominal)
+                if closed_world:
+                    curr_args.append(closed_world)
+                passes = self.get_passes_run(curr_args)
+
+                # dce always runs
+                self.assertIn('dce', passes)
+
+                # some passes only run in closed world
+                CLOSED_WORLD_PASSES = [
+                    'type-refining',
+                    'signature-pruning',
+                    'signature-refining',
+                    'gto',
+                    'cfp',
+                    'gsi',
+                ]
+                for pass_ in CLOSED_WORLD_PASSES:
+                    if closed_world:
+                        self.assertIn(pass_, passes)
+                    else:
+                        self.assertNotIn(pass_, passes)