Split generated casts test for more coverage (#7543)

Split the automatically generated optimize-instructions-all-casts.wast
into two tests: one that tests casts to exact types and another that
tests casts to inexact types. For the test file that does not cast to
exact types, additionally test with custom descriptors disabled to
ensure that the results validate.

Author: tlively

scripts/test/fuzzing.py

@@ -114,7 +114,7 @@
     'exact-references-lowering.wast',
     'exact-casts.wast',
     'exact-casts-trivial.wast',
-    'optimize-instructions-all-casts.wast',
+    'optimize-instructions-all-casts-exact.wast',
     'local-subtyping-exact.wast',
     'remove-unused-types-exact.wast',
     'coalesce-locals-exact.wast',

scripts/test/gen-cast-test.py

@@ -1,10 +1,10 @@
 #! /usr/bin/python3
 
 '''
-This script is used to generate
-test/lit/passes/optimize-instructions-all-casts.wast
+Generate test modules with all interesting casts
 '''
 
+import argparse
 import itertools
 
 interesting_pairs = [('$super', '$super', 'cast-to-self-nonfinal'),
@@ -16,14 +16,16 @@
                      ('none', '$super', 'cast-from-bottom')]
 
 
-def gen_test_configs():
+def gen_test_configs(args):
     for src_heap, cast_heap, heap_name in interesting_pairs:
         for src_nullable, src_exact, cast_nullable, cast_exact in \
                 itertools.product([True, False], repeat=4):
             if src_exact and src_heap == 'none':
                 continue
             if cast_exact and cast_heap == 'none':
                 continue
+            if args.enable_descs != cast_exact:
+                continue
             yield heap_name, src_heap, cast_heap, src_nullable, cast_nullable, \
                 src_exact, cast_exact
 
@@ -62,23 +64,37 @@ def print_test(config):
     print(test)
 
 
-def print_tests():
-    for config in gen_test_configs():
+def print_tests(args):
+    for config in gen_test_configs(args):
         print_test(config)
 
 
-def print_header():
-    header = ''';; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
-;; NOTE: Test has been generated by scripts/test/gen-cast-test.py. Do not edit manually.
+def print_header(args):
+    flags = ''
+    if args.enable_descs:
+        flags = ' --enable-custom-descs'
+    header = f''';; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+;; NOTE: Test has been generated by scripts/test/gen-cast-test.py{flags}. Do not edit manually.
 
 ;; Exhaustively test optimization of all interesting casts.
+'''
 
+    if args.enable_descs:
+        header += '''
 ;; RUN: wasm-opt %s -all --optimize-instructions -S -o - | filecheck %s
+'''
+    else:
+        header += '''
+;; RUN: wasm-opt %s -all                              --optimize-instructions -S -o - | filecheck %s
+;; RUN: wasm-opt %s -all --disable-custom-descriptors --optimize-instructions -S -o - | filecheck %s --check-prefix=NO_CD
+'''
 
+    header += '''
 (module
   (type $super (sub (struct)))
   (type $sub (sub $super (struct)))
   (type $sub-final (sub final $super (struct)))'''
+
     print(header)
 
 
@@ -87,8 +103,11 @@ def print_footer():
 
 
 def main():
-    print_header()
-    print_tests()
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--enable-custom-descs', action='store_true', dest='enable_descs')
+    args = parser.parse_args()
+    print_header(args)
+    print_tests(args)
     print_footer()