bpo-43693: Turn localspluskinds into an object (GH-26749)

Managing it as a bare pointer to malloc'ed bytes is just too awkward in a few places.

2 files changed, 18 insertions, 27 deletions

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
index 5bf4c8c..77801dc 100644
--- a/Include/cpython/code.h
+++ b/Include/cpython/code.h
@@ -26,9 +26,6 @@ typedef uint16_t _Py_CODEUNIT;
 typedef struct _PyOpcache _PyOpcache;
 
 
-typedef unsigned char _PyLocalsPlusKind;
-typedef _PyLocalsPlusKind *_PyLocalsPlusKinds;
-
 /* Bytecode object */
 struct PyCodeObject {
     PyObject_HEAD
@@ -75,7 +72,7 @@ struct PyCodeObject {
     int co_firstlineno;         /* first source line number */
     PyObject *co_code;          /* instruction opcodes */
     PyObject *co_localsplusnames;  /* tuple mapping offsets to names */
-    _PyLocalsPlusKinds co_localspluskinds; /* array mapping to local kinds */
+    PyObject *co_localspluskinds; /* Bytes mapping to local kinds (one byte per variable) */
     PyObject *co_filename;      /* unicode (where it was loaded from) */
     PyObject *co_name;          /* unicode (name, for reference) */
     PyObject *co_linetable;     /* string (encoding addr<->lineno mapping) See
@@ -222,4 +219,3 @@ void PyLineTable_InitAddressRange(const char *linetable, Py_ssize_t length, int
 int PyLineTable_NextAddressRange(PyCodeAddressRange *range);
 int PyLineTable_PreviousAddressRange(PyCodeAddressRange *range);
 
-
diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
index 1e78b92..78969df 100644
--- a/Include/internal/pycore_code.h
+++ b/Include/internal/pycore_code.h
@@ -180,39 +180,34 @@ extern Py_ssize_t _Py_QuickenedCount;
  * "free" kind is mutually exclusive with both.
  */
 
-// For now _PyLocalsPlusKind and _PyLocalsPlusKinds are defined
-// in Include/cpython/code.h.
-/* Note that these all fit within _PyLocalsPlusKind, as do combinations. */
+// Note that these all fit within a byte, as do combinations.
 // Later, we will use the smaller numbers to differentiate the different
 // kinds of locals (e.g. pos-only arg, varkwargs, local-only).
 #define CO_FAST_LOCAL   0x20
 #define CO_FAST_CELL    0x40
 #define CO_FAST_FREE    0x80
 
-static inline int
-_PyCode_InitLocalsPlusKinds(int num, _PyLocalsPlusKinds *pkinds)
+typedef unsigned char _PyLocals_Kind;
+
+static inline _PyLocals_Kind
+_PyLocals_GetKind(PyObject *kinds, int i)
 {
-    if (num == 0) {
-        *pkinds = NULL;
-        return 0;
-    }
-    _PyLocalsPlusKinds kinds = PyMem_NEW(_PyLocalsPlusKind, num);
-    if (kinds == NULL) {
-        PyErr_NoMemory();
-        return -1;
-    }
-    *pkinds = kinds;
-    return 0;
+    assert(PyBytes_Check(kinds));
+    assert(0 <= i && i < PyBytes_GET_SIZE(kinds));
+    char *ptr = PyBytes_AS_STRING(kinds);
+    return (_PyLocals_Kind)(ptr[i]);
 }
 
 static inline void
-_PyCode_ClearLocalsPlusKinds(_PyLocalsPlusKinds kinds)
+_PyLocals_SetKind(PyObject *kinds, int i, _PyLocals_Kind kind)
 {
-    if (kinds != NULL) {
-        PyMem_Free(kinds);
-    }
+    assert(PyBytes_Check(kinds));
+    assert(0 <= i && i < PyBytes_GET_SIZE(kinds));
+    char *ptr = PyBytes_AS_STRING(kinds);
+    ptr[i] = (char) kind;
 }
 
+
 struct _PyCodeConstructor {
     /* metadata */
     PyObject *filename;
@@ -229,8 +224,8 @@ struct _PyCodeConstructor {
     PyObject *names;
 
     /* mapping frame offsets to information */
-    PyObject *localsplusnames;
-    _PyLocalsPlusKinds localspluskinds;
+    PyObject *localsplusnames;  // Tuple of strings
+    PyObject *localspluskinds;  // Bytes object, one byte per variable
 
     /* args (within varnames) */
     int argcount;