GH-98686: Get rid of "adaptive" and "quick" instructions (GH-99182)

Author: brandtbucher

Include/internal/pycore_code.h

@@ -91,8 +91,6 @@ typedef struct {
 
 #define INLINE_CACHE_ENTRIES_FOR_ITER CACHE_ENTRIES(_PyForIterCache)
 
-extern uint8_t _PyOpcode_Adaptive[256];
-
 // Borrowed references to common callables:
 struct callable_cache {
     PyObject *isinstance;
@@ -219,11 +217,14 @@ extern int _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr,
                                    PyObject *name);
 extern int _Py_Specialize_StoreAttr(PyObject *owner, _Py_CODEUNIT *instr,
                                     PyObject *name);
-extern int _Py_Specialize_LoadGlobal(PyObject *globals, PyObject *builtins, _Py_CODEUNIT *instr, PyObject *name);
-extern int _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container, _Py_CODEUNIT *instr);
-extern int _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub, _Py_CODEUNIT *instr);
-extern int _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr,
-                               int nargs, PyObject *kwnames);
+extern void _Py_Specialize_LoadGlobal(PyObject *globals, PyObject *builtins,
+                                      _Py_CODEUNIT *instr, PyObject *name);
+extern void _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container,
+                                        _Py_CODEUNIT *instr);
+extern void _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub,
+                                       _Py_CODEUNIT *instr);
+extern void _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr,
+                                int nargs, PyObject *kwnames);
 extern void _Py_Specialize_BinaryOp(PyObject *lhs, PyObject *rhs, _Py_CODEUNIT *instr,
                                     int oparg, PyObject **locals);
 extern void _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs,
@@ -377,8 +378,22 @@ write_location_entry_start(uint8_t *ptr, int code, int length)
 
 /* With a 16-bit counter, we have 12 bits for the counter value, and 4 bits for the backoff */
 #define ADAPTIVE_BACKOFF_BITS 4
-/* The initial counter value is 1 == 2**ADAPTIVE_BACKOFF_START - 1 */
-#define ADAPTIVE_BACKOFF_START 1
+
+// A value of 1 means that we attempt to specialize the *second* time each
+// instruction is executed. Executing twice is a much better indicator of
+// "hotness" than executing once, but additional warmup delays only prevent
+// specialization. Most types stabilize by the second execution, too:
+#define ADAPTIVE_WARMUP_VALUE 1
+#define ADAPTIVE_WARMUP_BACKOFF 1
+
+// A value of 52 means that we attempt to re-specialize after 53 misses (a prime
+// number, useful for avoiding artifacts if every nth value is a different type
+// or something). Setting the backoff to 0 means that the counter is reset to
+// the same state as a warming-up instruction (value == 1, backoff == 1) after
+// deoptimization. This isn't strictly necessary, but it is bit easier to reason
+// about when thinking about the opcode transitions as a state machine:
+#define ADAPTIVE_COOLDOWN_VALUE 52
+#define ADAPTIVE_COOLDOWN_BACKOFF 0
 
 #define MAX_BACKOFF_VALUE (16 - ADAPTIVE_BACKOFF_BITS)
 
@@ -390,9 +405,15 @@ adaptive_counter_bits(int value, int backoff) {
 }
 
 static inline uint16_t
-adaptive_counter_start(void) {
-    unsigned int value = (1 << ADAPTIVE_BACKOFF_START) - 1;
-    return adaptive_counter_bits(value, ADAPTIVE_BACKOFF_START);
+adaptive_counter_warmup(void) {
+    return adaptive_counter_bits(ADAPTIVE_WARMUP_VALUE,
+                                 ADAPTIVE_WARMUP_BACKOFF);
+}
+
+static inline uint16_t
+adaptive_counter_cooldown(void) {
+    return adaptive_counter_bits(ADAPTIVE_COOLDOWN_VALUE,
+                                 ADAPTIVE_COOLDOWN_BACKOFF);
 }
 
 static inline uint16_t