[3.11] GH-93516: Backport GH-93769: Speedup line number checks when tracing (GH-94127)

Co-authored-by: Pablo Galindo <pablogsal@gmail.com>

2 files changed, 32 insertions, 1 deletions

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
index ba7324b..d7c9aee 100644
--- a/Include/cpython/code.h
+++ b/Include/cpython/code.h
@@ -62,7 +62,8 @@ typedef uint16_t _Py_CODEUNIT;
     PyObject *co_exceptiontable;   /* Byte string encoding exception handling  \
                                       table */                                 \
     int co_flags;                  /* CO_..., see below */                     \
-    int co_warmup;                 /* Warmup counter for quickening */         \
+    short co_warmup;                 /* Warmup counter for quickening */       \
+    short _co_linearray_entry_size;  /* Size of each entry in _co_linearray */ \
                                                                                \
     /* The rest are not so impactful on performance. */                        \
     int co_argcount;              /* #arguments, except *args */               \
@@ -88,6 +89,7 @@ typedef uint16_t _Py_CODEUNIT;
     PyObject *co_qualname;        /* unicode (qualname, for reference) */      \
     PyObject *co_linetable;       /* bytes object that holds location info */  \
     PyObject *co_weakreflist;     /* to support weakrefs to code objects */    \
+    char *_co_linearray;          /* array of line offsets */                  \
     /* Scratch space for extra data relating to the code object.               \
        Type is a void* to keep the format private in codeobject.c to force     \
        people to go through the proper APIs. */                                \
diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
index e11d1f0..551b9c0 100644
--- a/Include/internal/pycore_code.h
+++ b/Include/internal/pycore_code.h
@@ -475,6 +475,35 @@ write_location_entry_start(uint8_t *ptr, int code, int length)
 }
 
 
+/* 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