GH-93516: Speedup line number checks when tracing. (GH-93763)

* Use a lookup table to reduce overhead of getting line numbers during tracing.

1 files changed, 29 insertions, 0 deletions

diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
index 805c82483e..bb82d9fb9c 100644
--- a/Include/internal/pycore_code.h
+++ b/Include/internal/pycore_code.h
@@ -461,6 +461,35 @@ adaptive_counter_backoff(uint16_t counter) {
 }
 
 
+/* Line array cache for tracing */
+
+extern int _PyCode_CreateLineArray(PyCodeObject *co);
+
+static inline int
+_PyCode_InitLineArray(PyCodeObject *co)
+{
+    if (co->_co_linearray) {
+        return 0;
+    }
+    return _PyCode_CreateLineArray(co);
+}
+
+static inline int
+_PyCode_LineNumberFromArray(PyCodeObject *co, int index)
+{
+    assert(co->_co_linearray != NULL);
+    assert(index >= 0);
+    assert(index < Py_SIZE(co));
+    if (co->_co_linearray_entry_size == 2) {
+        return ((int16_t *)co->_co_linearray)[index];
+    }
+    else {
+        assert(co->_co_linearray_entry_size == 4);
+        return ((int32_t *)co->_co_linearray)[index];
+    }
+}
+
+
 #ifdef __cplusplus
 }
 #endif