address review

Author: Fidget-Spinner

Include/cpython/pystats.h

@@ -142,6 +142,7 @@ typedef struct _optimization_stats {
     uint64_t recursive_call;
     uint64_t low_confidence;
     uint64_t unknown_callee;
+    uint64_t trace_immediately_deopts;
     uint64_t executors_invalidated;
     UOpStats opcode[PYSTATS_MAX_UOP_ID + 1];
     uint64_t unsupported_opcode[256];

Misc/NEWS.d/next/Core_and_Builtins/2025-11-26-20-01-07.gh-issue-141976.K8NDmR.rst

@@ -1 +1 @@
-Protect against specialization failures in the tracing JIT compiler.
+Protect against specialization failures in the tracing JIT compiler for performance reasons.

Python/optimizer.c

@@ -620,8 +620,11 @@ _PyJit_translate_single_bytecode_to_trace(
         // in the instruction stream, but rather the deopt.
         // It's important we check for this, as some specializations might make
         // no progress (they can immediately deopt after specializing).
+        // We do this to improve performance, as otherwise a compiled trace
+        // will just deopt immediately.
         if (backoff != adaptive_counter_cooldown().value_and_backoff &&
             backoff != trigger_backoff_counter().value_and_backoff) {
+            OPT_STAT_INC(trace_immediately_deopts);
             opcode = _PyOpcode_Deopt[opcode];
         }
     }