Binary parser: Lift the limit on the number of locals (#6973)

This raises the number of locals accepted by the binary parser to the
absolute limit in the spec. A warning is now printed when writing a
binary file if the Web limit of 50,000 locals is exceeded.

Fixes #6968.

1 files changed, 16 insertions, 0 deletions

diff --git a/test/unit/test_web_limitations.py b/test/unit/test_web_limitations.py
index 6359390f9..921e02e95 100644
--- a/test/unit/test_web_limitations.py
+++ b/test/unit/test_web_limitations.py
@@ -20,3 +20,19 @@ class WebLimitations(utils.BinaryenTestCase):
                                input=module, capture_output=True)
         self.assertIn('Some VMs may not accept this binary because it has a large number of parameters in function foo.',
                       p.stderr)
+
+    def test_many_locals(self):
+        """Test that we warn on large numbers of locals, which Web VMs
+        disallow."""
+
+        params = '(local i32) ' * 50_001
+        module = '''
+        (module
+         (func $foo %s
+         )
+        )
+        ''' % params
+        p = shared.run_process(shared.WASM_OPT + ['-o', os.devnull],
+                               input=module, capture_output=True)
+        self.assertIn('Some VMs may not accept this binary because it has a large number of locals in function foo.',
+                      p.stderr)