youknowone · youknowone · Aug 20, 2026 · Aug 21, 2026 · Aug 20, 2026 · Aug 20, 2026
diff --git a/pyre/bench/synth/README.md b/pyre/bench/synth/README.md
@@ -27,8 +27,21 @@ opt into the same directory's self-checking mode:
 # pyre-check: selfcheck
 ```
 
-Such a fixture must exit successfully and print `PASS`. It is still discovered
-by both runners; `check_synthetic.py` runs it only when `--pyre` is supplied.
-A backend lacking a required mechanism can be scoped out in `check.py` with
-`# pyre-check: skip-backends=wasm` followed by a comment explaining the missing
-mechanism.
+Such a fixture must exit successfully, print `PASS`, and have compiled at
+least one loop. The last of those is what stops an interpreted run from
+satisfying a guard written about compiled code: the assertion holds either way,
+so without it the fixture would keep passing if the shape it guards stopped
+reaching the JIT. A fixture whose invariant is not about compiled code says so
+with
+
+```python
+# pyre-check: selfcheck-interpreted
+```
+
+followed by a comment saying why, and is then graded on the exit status and the
+marker alone.
+
+A selfcheck fixture is still discovered by both runners; `check_synthetic.py`
+runs it only when `--pyre` is supplied. A backend lacking a required mechanism
+can be scoped out in `check.py` with `# pyre-check: skip-backends=wasm`
+followed by a comment explaining the missing mechanism.
diff --git a/pyre/bench/synth/foriter_operator_index_replay_regression.py b/pyre/bench/synth/foriter_operator_index_replay_regression.py
@@ -0,0 +1,40 @@
+# pyre-check: selfcheck
+# `operator.index(x)` reaches `space.index`, whose first test is
+# `is_int_or_long`: an int is returned as-is, before any `__index__` lookup, so
+# that call runs no user code and is replay-safe.  Every other argument
+# dispatches through `__index__`, which IS user code — so the replay-safe class
+# must observe the argument, not merely pin the callable.
+#
+# `helper` is admitted into the surrounding FOR_ITER body.  The trailing opaque
+# `id` call makes the first inline sub-walk abort and replay `helper`.  The int
+# call is the arm being admitted; the object call must stay opaque.  Admitting
+# the object call too would let the replay run `__index__` a second time, and
+# `hits` would read N + 1.
+
+from operator import index as _index
+
+N = 5000
+hits = [0]
+
+
+class C:
+    def __index__(self) -> int:
+        hits[0] += 1
+        return 3
+
+
+def helper(obj, n):
+    a = _index(n)
+    b = _index(obj)
+    id(obj)
+    return a + b
+
+
+obj = C()
+total = 0
+for _ in range(N):
+    total += helper(obj, 1)
+
+assert hits[0] == N, f"__index__ ran {hits[0]} times, expected {N}"
+assert total == 4 * N, f"total {total}, expected {4 * N}"
+print("PASS")
diff --git a/pyre/bench/synth/global_store_plain_dict_globals.wasm.jitstats b/pyre/bench/synth/global_store_plain_dict_globals.wasm.jitstats
@@ -8,8 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=1
+guard_failures=18
 internal_compile_panics=0
-loops_aborted=0
-loops_compiled=4
+loops_aborted=1
+loops_compiled=5
 retraces_compiled=0
diff --git a/pyre/bench/synth/list_append_virtual_payload.cranelift.jitstats b/pyre/bench/synth/list_append_virtual_payload.cranelift.jitstats
@@ -1,4 +1,4 @@
-bridges_compiled=4
+bridges_compiled=7
 descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
@@ -8,7 +8,7 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=1001
+guard_failures=1403
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=2

diff --git a/pyre/bench/synth/list_append_virtual_payload.dynasm.jitstats b/pyre/bench/synth/list_append_virtual_payload.dynasm.jitstats
@@ -1,4 +1,4 @@
-bridges_compiled=4
+bridges_compiled=7
 descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
@@ -8,7 +8,7 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=1001
+guard_failures=1403
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=2

diff --git a/pyre/bench/synth/list_append_virtual_payload.wasm.jitstats b/pyre/bench/synth/list_append_virtual_payload.wasm.jitstats
@@ -1,4 +1,4 @@
-bridges_compiled=4
+bridges_compiled=7
 descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
@@ -8,7 +8,7 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=1001
+guard_failures=1403
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=2

diff --git a/pyre/bench/synth/list_to_tuple_star.cranelift.jitstats b/pyre/bench/synth/list_to_tuple_star.cranelift.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=1
 internal_compile_panics=0
 loops_aborted=0
-loops_compiled=0
+loops_compiled=1
+retraces_compiled=0
diff --git a/pyre/bench/synth/list_to_tuple_star.dynasm.jitstats b/pyre/bench/synth/list_to_tuple_star.dynasm.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=1
 internal_compile_panics=0
 loops_aborted=0
-loops_compiled=0
+loops_compiled=1
+retraces_compiled=0
diff --git a/pyre/bench/synth/list_to_tuple_star.wasm.jitstats b/pyre/bench/synth/list_to_tuple_star.wasm.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=1
 internal_compile_panics=0
 loops_aborted=0
-loops_compiled=0
+loops_compiled=1
+retraces_compiled=0
diff --git a/pyre/bench/synth/mapdict_frozen_unboxing_fold.cranelift.jitstats b/pyre/bench/synth/mapdict_frozen_unboxing_fold.cranelift.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=2
+guard_failures=13
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=3
+retraces_compiled=0
diff --git a/pyre/bench/synth/mapdict_frozen_unboxing_fold.dynasm.jitstats b/pyre/bench/synth/mapdict_frozen_unboxing_fold.dynasm.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=2
+guard_failures=13
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=3
+retraces_compiled=0
diff --git a/pyre/bench/synth/mapdict_frozen_unboxing_fold.wasm.jitstats b/pyre/bench/synth/mapdict_frozen_unboxing_fold.wasm.jitstats
@@ -8,7 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=2
+guard_failures=13
 internal_compile_panics=0
 loops_aborted=0
 loops_compiled=3
+retraces_compiled=0
diff --git a/pyre/bench/synth/oserror_errno_fields_regression.py b/pyre/bench/synth/oserror_errno_fields_regression.py
@@ -1,4 +1,6 @@
 # pyre-check: selfcheck
+# pyre-check: selfcheck-interpreted
+# The invariant is interpreter-level, so the run compiles no loop.
 # pyre-check: skip-backends=wasm
 # The wasm guest has no os/filesystem support used by this fixture.
 # A failed syscall raises the errno-specific OSError subclass with

diff --git a/pyre/bench/synth/pickle_terminal_raise_resume.wasm.jitstats b/pyre/bench/synth/pickle_terminal_raise_resume.wasm.jitstats
@@ -8,8 +8,8 @@ fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=318
+guard_failures=335
 internal_compile_panics=0
-loops_aborted=8
-loops_compiled=69
+loops_aborted=9
+loops_compiled=70
 retraces_compiled=0
diff --git a/pyre/bench/synth/posix_replace_regression.py b/pyre/bench/synth/posix_replace_regression.py
@@ -1,4 +1,6 @@
 # pyre-check: selfcheck
+# pyre-check: selfcheck-interpreted
+# The invariant is interpreter-level, so the run compiles no loop.
 # pyre-check: skip-backends=wasm
 # The wasm guest has no filesystem support used by this fixture.
 # os.replace(src, dst) renames over an existing destination in one step and

diff --git a/pyre/bench/synth/surrogate_class_kwargs.cranelift.jitstats b/pyre/bench/synth/surrogate_class_kwargs.cranelift.jitstats
@@ -3,12 +3,13 @@ descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=14
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=2159
 internal_compile_panics=0
-loops_aborted=0
-loops_compiled=3
+loops_aborted=14
+loops_compiled=4
+retraces_compiled=0
diff --git a/pyre/bench/synth/surrogate_class_kwargs.dynasm.jitstats b/pyre/bench/synth/surrogate_class_kwargs.dynasm.jitstats
@@ -3,12 +3,13 @@ descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=14
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=2159
 internal_compile_panics=0
-loops_aborted=0
-loops_compiled=3
+loops_aborted=14
+loops_compiled=4
+retraces_compiled=0
diff --git a/pyre/bench/synth/surrogate_class_kwargs.wasm.jitstats b/pyre/bench/synth/surrogate_class_kwargs.wasm.jitstats
@@ -3,12 +3,13 @@ descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=14
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=0
+guard_failures=2159
 internal_compile_panics=0
-loops_aborted=0
-loops_compiled=3
+loops_aborted=14
+loops_compiled=4
+retraces_compiled=0
diff --git a/pyre/bench/synth/type_name_surrogate_reject.cranelift.jitstats b/pyre/bench/synth/type_name_surrogate_reject.cranelift.jitstats
@@ -1,14 +1,15 @@
-bridges_compiled=1
+bridges_compiled=0
 descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=1
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=201
+guard_failures=17799
 internal_compile_panics=0
-loops_aborted=0
+loops_aborted=1
 loops_compiled=2
+retraces_compiled=0
diff --git a/pyre/bench/synth/type_name_surrogate_reject.dynasm.jitstats b/pyre/bench/synth/type_name_surrogate_reject.dynasm.jitstats
@@ -1,14 +1,15 @@
-bridges_compiled=1
+bridges_compiled=0
 descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=1
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
-guard_failures=201
+guard_failures=17799
 internal_compile_panics=0
-loops_aborted=0
+loops_aborted=1
 loops_compiled=2
+retraces_compiled=0
diff --git a/pyre/bench/synth/type_name_surrogate_reject.wasm.jitstats b/pyre/bench/synth/type_name_surrogate_reject.wasm.jitstats
@@ -3,12 +3,13 @@ descr_set_absent=0
 descr_set_ambiguous=0
 descr_set_stale_absent=0
 fbw_blackhole_adopted_multi_frame=0
-fbw_blackhole_adopted_single_frame=0
+fbw_blackhole_adopted_single_frame=1
 fbw_rolled_back_with_effects=0
 fbw_store_journal_rollback_failed=0
 field_pos_attached_misplaced=0
 field_pos_spec_misplaced=0
 guard_failures=201
 internal_compile_panics=0
-loops_aborted=0
+loops_aborted=1
 loops_compiled=2
+retraces_compiled=0