Virtual iterators. Work in progress

Author: markshannon

Include/internal/pycore_magic_number.h

@@ -274,6 +274,7 @@ Known values:
     Python 3.14a6 3619 (Renumber RESUME opcode from 149 to 128)
     Python 3.14a6 3620 (Optimize bytecode for all/any/tuple called on a genexp)
     Python 3.14a7 3621 (Optimize LOAD_FAST opcodes into LOAD_FAST_BORROW)
+    Python 3.14a8 3622 (Virtual iterators)
 
     Python 3.15 will start with 3650
 
@@ -286,7 +287,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3621
+#define PYC_MAGIC_NUMBER 3622
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

Include/internal/pycore_opcode_metadata.h

@@ -405,7 +405,12 @@ dummy_func(
             PyStackRef_CLOSE(value);
         }
 
-        macro(POP_ITER) = POP_TOP;
+
+        inst(POP_ITER, (iter, index_or_null -- )) {
+            (void)index_or_null;
+            DEAD(index_or_null);
+            PyStackRef_CLOSE(iter);
+        }
 
         no_save_ip tier1 inst(INSTRUMENTED_END_FOR, (receiver, value -- receiver)) {
             /* Need to create a fake StopIteration error here,
@@ -419,7 +424,9 @@ dummy_func(
             PyStackRef_CLOSE(value);
         }
 
-        tier1 inst(INSTRUMENTED_POP_ITER, (iter -- )) {
+        tier1 inst(INSTRUMENTED_POP_ITER, (iter, index_or_null -- )) {
+            (void)index_or_null;
+            DEAD(index_or_null);
             INSTRUMENTED_JUMP(prev_instr, this_instr+1, PY_MONITORING_EVENT_BRANCH_RIGHT);
             PyStackRef_CLOSE(iter);
         }
@@ -2972,12 +2979,13 @@ dummy_func(
             values_or_none = PyStackRef_FromPyObjectSteal(values_or_none_o);
         }
 
-        inst(GET_ITER, (iterable -- iter)) {
+        inst(GET_ITER, (iterable -- iter, null)) {
             /* before: [obj]; after [getiter(obj)] */
             PyObject *iter_o = PyObject_GetIter(PyStackRef_AsPyObjectBorrow(iterable));
             PyStackRef_CLOSE(iterable);
             ERROR_IF(iter_o == NULL, error);
             iter = PyStackRef_FromPyObjectSteal(iter_o);
+            null = PyStackRef_NULL;
         }
 
         inst(GET_YIELD_FROM_ITER, (iterable -- iter)) {
@@ -3024,7 +3032,7 @@ dummy_func(
             FOR_ITER_GEN,
         };
 
-        specializing op(_SPECIALIZE_FOR_ITER, (counter/1, iter -- iter)) {
+        specializing op(_SPECIALIZE_FOR_ITER, (counter/1, iter, null_or_index -- iter, null_or_index)) {
             #if ENABLE_SPECIALIZATION_FT
             if (ADAPTIVE_COUNTER_TRIGGERS(counter)) {
                 next_instr = this_instr;
@@ -3036,7 +3044,7 @@ dummy_func(
             #endif  /* ENABLE_SPECIALIZATION_FT */
         }
 
-        replaced op(_FOR_ITER, (iter -- iter, next)) {
+        replaced op(_FOR_ITER, (iter, null_or_index -- iter, null_or_index, next)) {
             /* before: [iter]; after: [iter, iter()] *or* [] (and jump over END_FOR.) */
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             PyObject *next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
@@ -3060,7 +3068,7 @@ dummy_func(
             // Common case: no jump, leave it to the code generator
         }
 
-        op(_FOR_ITER_TIER_TWO, (iter -- iter, next)) {
+        op(_FOR_ITER_TIER_TWO, (iter, null_or_index -- iter, null_or_index, next)) {
             /* before: [iter]; after: [iter, iter()] *or* [] (and jump over END_FOR.) */
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             PyObject *next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
@@ -3084,7 +3092,7 @@ dummy_func(
         macro(FOR_ITER) = _SPECIALIZE_FOR_ITER + _FOR_ITER;
 
 
-        inst(INSTRUMENTED_FOR_ITER, (unused/1, iter -- iter, next)) {
+        inst(INSTRUMENTED_FOR_ITER, (unused/1, iter, null_or_index -- iter, null_or_index, next)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             PyObject *next_o = (*Py_TYPE(iter_o)->tp_iternext)(iter_o);
             if (next_o != NULL) {
@@ -3110,7 +3118,7 @@ dummy_func(
         }
 
 
-        op(_ITER_CHECK_LIST, (iter -- iter)) {
+        op(_ITER_CHECK_LIST, (iter, null_or_index -- iter, null_or_index)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             EXIT_IF(Py_TYPE(iter_o) != &PyListIter_Type);
 #ifdef Py_GIL_DISABLED
@@ -3121,7 +3129,7 @@ dummy_func(
 #endif
         }
 
-        replaced op(_ITER_JUMP_LIST, (iter -- iter)) {
+        replaced op(_ITER_JUMP_LIST, (iter, null_or_index -- iter, null_or_index)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             assert(Py_TYPE(iter_o) == &PyListIter_Type);
 // For free-threaded Python, the loop exit can happen at any point during
@@ -3149,7 +3157,7 @@ dummy_func(
         }
 
         // Only used by Tier 2
-        op(_GUARD_NOT_EXHAUSTED_LIST, (iter -- iter)) {
+        op(_GUARD_NOT_EXHAUSTED_LIST, (iter, null_or_index -- iter, null_or_index)) {
 #ifndef Py_GIL_DISABLED
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             _PyListIterObject *it = (_PyListIterObject *)iter_o;
@@ -3163,7 +3171,7 @@ dummy_func(
 #endif
         }
 
-        replaced op(_ITER_NEXT_LIST, (iter -- iter, next)) {
+        replaced op(_ITER_NEXT_LIST, (iter, null_or_index -- iter, null_or_index, next)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             _PyListIterObject *it = (_PyListIterObject *)iter_o;
             assert(Py_TYPE(iter_o) == &PyListIter_Type);
@@ -3192,7 +3200,7 @@ dummy_func(
         }
 
         // Only used by Tier 2
-        op(_ITER_NEXT_LIST_TIER_TWO, (iter -- iter, next)) {
+        op(_ITER_NEXT_LIST_TIER_TWO, (iter, null_or_index -- iter, null_or_index, next)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             _PyListIterObject *it = (_PyListIterObject *)iter_o;
             assert(Py_TYPE(iter_o) == &PyListIter_Type);
@@ -3224,15 +3232,15 @@ dummy_func(
             _ITER_JUMP_LIST +
             _ITER_NEXT_LIST;
 
-        op(_ITER_CHECK_TUPLE, (iter -- iter)) {
+        op(_ITER_CHECK_TUPLE, (iter, null_or_index -- iter, null_or_index)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             EXIT_IF(Py_TYPE(iter_o) != &PyTupleIter_Type);
 #ifdef Py_GIL_DISABLED
             EXIT_IF(!_PyObject_IsUniquelyReferenced(iter_o));
 #endif
         }
 
-        replaced op(_ITER_JUMP_TUPLE, (iter -- iter)) {
+        replaced op(_ITER_JUMP_TUPLE, (iter, null_or_index -- iter, null_or_index)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             (void)iter_o;
             assert(Py_TYPE(iter_o) == &PyTupleIter_Type);
@@ -3256,7 +3264,7 @@ dummy_func(
         }
 
         // Only used by Tier 2
-        op(_GUARD_NOT_EXHAUSTED_TUPLE, (iter -- iter)) {
+        op(_GUARD_NOT_EXHAUSTED_TUPLE, (iter, null_or_index -- iter, null_or_index)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             _PyTupleIterObject *it = (_PyTupleIterObject *)iter_o;
             assert(Py_TYPE(iter_o) == &PyTupleIter_Type);
@@ -3268,7 +3276,7 @@ dummy_func(
             EXIT_IF(it->it_index >= PyTuple_GET_SIZE(seq));
         }
 
-        op(_ITER_NEXT_TUPLE, (iter -- iter, next)) {
+        op(_ITER_NEXT_TUPLE, (iter, null_or_index -- iter, null_or_index, next)) {
             PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
             _PyTupleIterObject *it = (_PyTupleIterObject *)iter_o;
             assert(Py_TYPE(iter_o) == &PyTupleIter_Type);
@@ -3295,7 +3303,7 @@ dummy_func(
 #endif
         }
 
-        replaced op(_ITER_JUMP_RANGE, (iter -- iter)) {
+        replaced op(_ITER_JUMP_RANGE, (iter, null_or_index -- iter, null_or_index)) {
             _PyRangeIterObject *r = (_PyRangeIterObject *)PyStackRef_AsPyObjectBorrow(iter);
             assert(Py_TYPE(r) == &PyRangeIter_Type);
 #ifdef Py_GIL_DISABLED
@@ -3310,13 +3318,13 @@ dummy_func(
         }
 
         // Only used by Tier 2
-        op(_GUARD_NOT_EXHAUSTED_RANGE, (iter -- iter)) {
+        op(_GUARD_NOT_EXHAUSTED_RANGE, (iter, null_or_index -- iter, null_or_index)) {
             _PyRangeIterObject *r = (_PyRangeIterObject *)PyStackRef_AsPyObjectBorrow(iter);
             assert(Py_TYPE(r) == &PyRangeIter_Type);
             EXIT_IF(r->len <= 0);
         }
 
-        op(_ITER_NEXT_RANGE, (iter -- iter, next)) {
+        op(_ITER_NEXT_RANGE, (iter, null_or_index -- iter, null_or_index, next)) {
             _PyRangeIterObject *r = (_PyRangeIterObject *)PyStackRef_AsPyObjectBorrow(iter);
             assert(Py_TYPE(r) == &PyRangeIter_Type);
 #ifdef Py_GIL_DISABLED
@@ -3337,7 +3345,7 @@ dummy_func(
             _ITER_JUMP_RANGE +
             _ITER_NEXT_RANGE;
 
-        op(_FOR_ITER_GEN_FRAME, (iter -- iter, gen_frame: _PyInterpreterFrame*)) {
+        op(_FOR_ITER_GEN_FRAME, (iter, null -- iter, null, gen_frame: _PyInterpreterFrame*)) {
             PyGenObject *gen = (PyGenObject *)PyStackRef_AsPyObjectBorrow(iter);
             DEOPT_IF(Py_TYPE(gen) != &PyGen_Type);
 #ifdef Py_GIL_DISABLED

Include/internal/pycore_uop_ids.h

@@ -267,6 +267,7 @@ maybe_lltrace_resume_frame(_PyInterpreterFrame *frame, PyObject *globals)
             lltrace = *python_lltrace - '0';  // TODO: Parse an int and all that
         }
     }
+    lltrace = 5;
     if (lltrace >= 5) {
         lltrace_resume_frame(frame);
     }

Include/internal/pycore_uop_metadata.h

@@ -527,9 +527,10 @@ codegen_unwind_fblock(compiler *c, location *ploc,
         case COMPILE_FBLOCK_FOR_LOOP:
             /* Pop the iterator */
             if (preserve_tos) {
-                ADDOP_I(c, *ploc, SWAP, 2);
+                ADDOP_I(c, *ploc, SWAP, 3);
             }
             ADDOP(c, *ploc, POP_TOP);
+            ADDOP(c, *ploc, POP_TOP);
             return SUCCESS;
 
         case COMPILE_FBLOCK_TRY_EXCEPT: