bpo-26219: per opcode cache for LOAD_GLOBAL (GH-12884)
This patch implements per opcode cache mechanism, and use it in
only LOAD_GLOBAL opcode.
Based on Yury's opcache3.patch in bpo-26219.
diff --git a/Include/code.h b/Include/code.h
index 933de97..b79d977 100644
--- a/Include/code.h
+++ b/Include/code.h
@@ -17,6 +17,8 @@
# define _Py_OPARG(word) ((word) >> 8)
#endif
+typedef struct _PyOpcache _PyOpcache;
+
/* Bytecode object */
typedef struct {
PyObject_HEAD
@@ -49,6 +51,21 @@
Type is a void* to keep the format private in codeobject.c to force
people to go through the proper APIs. */
void *co_extra;
+
+ /* Per opcodes just-in-time cache
+ *
+ * To reduce cache size, we use indirect mapping from opcode index to
+ * cache object:
+ * cache = co_opcache[co_opcache_map[next_instr - first_instr] - 1]
+ */
+
+ // co_opcache_map is indexed by (next_instr - first_instr).
+ // * 0 means there is no cache for this opcode.
+ // * n > 0 means there is cache in co_opcache[n-1].
+ unsigned char *co_opcache_map;
+ _PyOpcache *co_opcache;
+ int co_opcache_flag; // used to determine when create a cache.
+ unsigned char co_opcache_size; // length of co_opcache.
} PyCodeObject;
/* Masks for co_flags above */