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check.py: correct the jit-stats docstring, and re-record eight dynasm baselines #1019

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Merged
youknowone merged 2 commits into from
Aug 4, 2026
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check.py: correct the jit-stats docstring, and re-record eight dynasm baselines #1019

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6149ae8
check.py: drop the stale wasm claim from the jit-stats docstring
youknowone Aug 3, 2026
c419046
bench: re-record eight dynasm jit-stats baselines
youknowone Aug 3, 2026
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6 changes: 3 additions & 3 deletions pyre/bench/synth/exception_bridge_traceback_head.dynasm.jitstats
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
bridges_compiled=6
bridges_compiled=4
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
guard_failures=1203
guard_failures=802
internal_compile_panics=0
loops_aborted=1
loops_aborted=0
loops_compiled=2
4 changes: 2 additions & 2 deletions pyre/bench/synth/exception_escape_caller_frame_tb_node.dynasm.jitstats
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Expand Up @@ -2,7 +2,7 @@ bridges_compiled=0
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
guard_failures=8
guard_failures=5
internal_compile_panics=0
loops_aborted=1
loops_aborted=0
loops_compiled=8
2 changes: 1 addition & 1 deletion pyre/bench/synth/exception_raise_caught_same_frame_tb.dynasm.jitstats
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bridges_compiled=2
bridges_compiled=4
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
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2 changes: 1 addition & 1 deletion pyre/bench/synth/exception_residual_raise_caught_in_frame.dynasm.jitstats
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bridges_compiled=0
bridges_compiled=1
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
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2 changes: 1 addition & 1 deletion pyre/bench/synth/exception_traceback_frame_lineno.dynasm.jitstats
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bridges_compiled=3
bridges_compiled=5
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
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6 changes: 3 additions & 3 deletions pyre/bench/synth/gc_bug_bridge_flavor_traceback_names.dynasm.jitstats
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bridges_compiled=10
bridges_compiled=7
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
guard_failures=2018
guard_failures=1655
internal_compile_panics=0
loops_aborted=1
loops_aborted=0
loops_compiled=4
4 changes: 2 additions & 2 deletions pyre/bench/synth/list_length_hint_validate.dynasm.jitstats
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bridges_compiled=4
bridges_compiled=0
descr_set_absent=0
descr_set_ambiguous=0
descr_set_stale_absent=0
guard_failures=828
guard_failures=1
internal_compile_panics=0
loops_aborted=10
loops_compiled=2
4 changes: 2 additions & 2 deletions pyre/bench/synth/slots_class_var_conflict.dynasm.jitstats
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Expand Up @@ -4,5 +4,5 @@ descr_set_ambiguous=0
descr_set_stale_absent=0
guard_failures=1
internal_compile_panics=0
loops_aborted=5
loops_compiled=3
loops_aborted=0
loops_compiled=5
9 changes: 6 additions & 3 deletions pyre/check.py
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Expand Up @@ -676,9 +676,12 @@ def _jit_stats_change(saved, current):

A field missing from either side reads as "0", so a baseline recorded before
a counter existed still matches a run that reports it as 0, and adding an
invariant counter costs no re-record. The wasm [jit-stats] line reports only
the badness fields, so its baselines carry only those and stay equal on the
three it never prints."""
invariant counter costs no re-record. The cost of that convenience is that a
field absent from BOTH sides compares equal forever: a backend whose
[jit-stats] line stops naming a counter disarms that counter's gate on every
one of its baselines, silently. Whenever a backend's line changes shape,
re-record its whole baseline surface rather than trusting the run that
follows."""
Comment on lines +679 to +684

@coderabbitai coderabbitai Bot Aug 4, 2026

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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Qualify the missing-counter warning.

When current omits a field but saved contains a non-zero value, _jit_stats_change compares that value with "0" and reports a change. The gate is silently disabled only when both snapshots omit the field, or when the saved value is already zero.

Replace “disarms that counter’s gate on every one of its baselines” with wording that reflects this behavior.

Suggested wording 
-    field absent from BOTH sides compares equal forever: a backend whose
-    [jit-stats] line stops naming a counter disarms that counter's gate on every
-    one of its baselines, silently.
+    field absent from BOTH sides compares equal forever. If a backend stops
+    naming a counter, only baselines with a saved value of zero are silently
+    disabled; a non-zero saved value still compares against zero and fails.
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
invariant counter costs no re-record. The cost of that convenience is that a
field absent from BOTH sides compares equal forever: a backend whose
[jit-stats] line stops naming a counter disarms that counter's gate on every
one of its baselines, silently. Whenever a backend's line changes shape,
re-record its whole baseline surface rather than trusting the run that
follows."""
invariant counter costs no re-record. The cost of that convenience is that a
field absent from BOTH sides compares equal forever. If a backend stops
naming a counter, only baselines with a saved value of zero are silently
disabled; a non-zero saved value still compares against zero and fails.
Whenever a backend's line changes shape, re-record its whole baseline surface
rather than trusting the run that follows."""
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@pyre/check.py` around lines 679 - 684, Update the explanatory comment near
_jit_stats_change to qualify that a missing field in current disables the gate
only when the corresponding field is also absent from saved or saved already has
a zero value; retain the existing behavior for non-zero saved values, which are
reported as changes.

Comment on lines +682 to +684

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 4, 2026

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P2 Badge Do not re-record after an emitted counter disappears

When a backend stops emitting a counter whose saved value is nonzero, _jit_stats_change does not silently disarm the gate: the missing current value defaults to 0, so the comparison fails. Following this new advice with --snapshot is what actually disarms it, because record mode bypasses the comparison and rewrites the baseline without the field; subsequent runs then compare missing against missing. A disappearing counter should therefore be fixed or explicitly removed from the gated surface, not handled by re-recording.

Useful? React with 👍 / 👎.

old_fields = _parse_jit_stats(saved)
new_fields = _parse_jit_stats(current)
changes = [
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