gh-98831: rewrite UNPACK_EX, UNPACK_SEQUENCE, UNPACK_SEQUENCE_TWO_TUPLE in the instruction definition DSL (#101641)

3 files changed, 40 insertions, 54 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index ec0439a..b43625f 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -859,13 +859,11 @@ dummy_func(
             }
         }
 
-        // stack effect: (__0 -- __array[oparg])
-        inst(UNPACK_SEQUENCE) {
+        inst(UNPACK_SEQUENCE, (unused/1, seq -- unused[oparg])) {
             #if ENABLE_SPECIALIZATION
             _PyUnpackSequenceCache *cache = (_PyUnpackSequenceCache *)next_instr;
             if (ADAPTIVE_COUNTER_IS_ZERO(cache->counter)) {
                 assert(cframe.use_tracing == 0);
-                PyObject *seq = TOP();
                 next_instr--;
                 _Py_Specialize_UnpackSequence(seq, next_instr, oparg);
                 DISPATCH_SAME_OPARG();
@@ -873,27 +871,19 @@ dummy_func(
             STAT_INC(UNPACK_SEQUENCE, deferred);
             DECREMENT_ADAPTIVE_COUNTER(cache->counter);
             #endif  /* ENABLE_SPECIALIZATION */
-            PyObject *seq = POP();
-            PyObject **top = stack_pointer + oparg;
-            if (!unpack_iterable(tstate, seq, oparg, -1, top)) {
-                Py_DECREF(seq);
-                goto error;
-            }
-            STACK_GROW(oparg);
+            PyObject **top = stack_pointer + oparg - 1;
+            int res = unpack_iterable(tstate, seq, oparg, -1, top);
             Py_DECREF(seq);
-            JUMPBY(INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
+            ERROR_IF(res == 0, error);
         }
 
-        // stack effect: (__0 -- __array[oparg])
-        inst(UNPACK_SEQUENCE_TWO_TUPLE) {
-            PyObject *seq = TOP();
+        inst(UNPACK_SEQUENCE_TWO_TUPLE, (unused/1, seq -- v1, v0)) {
             DEOPT_IF(!PyTuple_CheckExact(seq), UNPACK_SEQUENCE);
             DEOPT_IF(PyTuple_GET_SIZE(seq) != 2, UNPACK_SEQUENCE);
             STAT_INC(UNPACK_SEQUENCE, hit);
-            SET_TOP(Py_NewRef(PyTuple_GET_ITEM(seq, 1)));
-            PUSH(Py_NewRef(PyTuple_GET_ITEM(seq, 0)));
+            v1 = Py_NewRef(PyTuple_GET_ITEM(seq, 1));
+            v0 = Py_NewRef(PyTuple_GET_ITEM(seq, 0));
             Py_DECREF(seq);
-            JUMPBY(INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
         }
 
         // stack effect: (__0 -- __array[oparg])
@@ -926,17 +916,12 @@ dummy_func(
             JUMPBY(INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
         }
 
-        // error: UNPACK_EX has irregular stack effect
-        inst(UNPACK_EX) {
+        inst(UNPACK_EX, (seq -- unused[oparg & 0xFF], unused, unused[oparg >> 8])) {
             int totalargs = 1 + (oparg & 0xFF) + (oparg >> 8);
-            PyObject *seq = POP();
-            PyObject **top = stack_pointer + totalargs;
-            if (!unpack_iterable(tstate, seq, oparg & 0xFF, oparg >> 8, top)) {
-                Py_DECREF(seq);
-                goto error;
-            }
-            STACK_GROW(totalargs);
+            PyObject **top = stack_pointer + totalargs - 1;
+            int res = unpack_iterable(tstate, seq, oparg & 0xFF, oparg >> 8, top);
             Py_DECREF(seq);
+            ERROR_IF(res == 0, error);
         }
 
         family(store_attr, INLINE_CACHE_ENTRIES_STORE_ATTR) = {
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 4e511f4..ab19f43 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -1108,11 +1108,11 @@
 
         TARGET(UNPACK_SEQUENCE) {
             PREDICTED(UNPACK_SEQUENCE);
+            PyObject *seq = PEEK(1);
             #if ENABLE_SPECIALIZATION
             _PyUnpackSequenceCache *cache = (_PyUnpackSequenceCache *)next_instr;
             if (ADAPTIVE_COUNTER_IS_ZERO(cache->counter)) {
                 assert(cframe.use_tracing == 0);
-                PyObject *seq = TOP();
                 next_instr--;
                 _Py_Specialize_UnpackSequence(seq, next_instr, oparg);
                 DISPATCH_SAME_OPARG();
@@ -1120,27 +1120,30 @@
             STAT_INC(UNPACK_SEQUENCE, deferred);
             DECREMENT_ADAPTIVE_COUNTER(cache->counter);
             #endif  /* ENABLE_SPECIALIZATION */
-            PyObject *seq = POP();
-            PyObject **top = stack_pointer + oparg;
-            if (!unpack_iterable(tstate, seq, oparg, -1, top)) {
-                Py_DECREF(seq);
-                goto error;
-            }
-            STACK_GROW(oparg);
+            PyObject **top = stack_pointer + oparg - 1;
+            int res = unpack_iterable(tstate, seq, oparg, -1, top);
             Py_DECREF(seq);
-            JUMPBY(INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
+            if (res == 0) goto pop_1_error;
+            STACK_SHRINK(1);
+            STACK_GROW(oparg);
+            JUMPBY(1);
             DISPATCH();
         }
 
         TARGET(UNPACK_SEQUENCE_TWO_TUPLE) {
-            PyObject *seq = TOP();
+            PyObject *seq = PEEK(1);
+            PyObject *v1;
+            PyObject *v0;
             DEOPT_IF(!PyTuple_CheckExact(seq), UNPACK_SEQUENCE);
             DEOPT_IF(PyTuple_GET_SIZE(seq) != 2, UNPACK_SEQUENCE);
             STAT_INC(UNPACK_SEQUENCE, hit);
-            SET_TOP(Py_NewRef(PyTuple_GET_ITEM(seq, 1)));
-            PUSH(Py_NewRef(PyTuple_GET_ITEM(seq, 0)));
+            v1 = Py_NewRef(PyTuple_GET_ITEM(seq, 1));
+            v0 = Py_NewRef(PyTuple_GET_ITEM(seq, 0));
             Py_DECREF(seq);
-            JUMPBY(INLINE_CACHE_ENTRIES_UNPACK_SEQUENCE);
+            STACK_GROW(1);
+            POKE(1, v0);
+            POKE(2, v1);
+            JUMPBY(1);
             DISPATCH();
         }
 
@@ -1175,15 +1178,13 @@
         }
 
         TARGET(UNPACK_EX) {
+            PyObject *seq = PEEK(1);
             int totalargs = 1 + (oparg & 0xFF) + (oparg >> 8);
-            PyObject *seq = POP();
-            PyObject **top = stack_pointer + totalargs;
-            if (!unpack_iterable(tstate, seq, oparg & 0xFF, oparg >> 8, top)) {
-                Py_DECREF(seq);
-                goto error;
-            }
-            STACK_GROW(totalargs);
+            PyObject **top = stack_pointer + totalargs - 1;
+            int res = unpack_iterable(tstate, seq, oparg & 0xFF, oparg >> 8, top);
             Py_DECREF(seq);
+            if (res == 0) goto pop_1_error;
+            STACK_GROW((oparg & 0xFF) + (oparg >> 8));
             DISPATCH();
         }
 
diff --git a/Python/opcode_metadata.h b/Python/opcode_metadata.h
index ed26ff0..d258535 100644
--- a/Python/opcode_metadata.h
+++ b/Python/opcode_metadata.h
@@ -121,15 +121,15 @@ _PyOpcode_num_popped(int opcode, int oparg, bool jump) {
         case DELETE_NAME:
             return 0;
         case UNPACK_SEQUENCE:
-            return -1;
+            return 1;
         case UNPACK_SEQUENCE_TWO_TUPLE:
-            return -1;
+            return 1;
         case UNPACK_SEQUENCE_TUPLE:
             return -1;
         case UNPACK_SEQUENCE_LIST:
             return -1;
         case UNPACK_EX:
-            return -1;
+            return 1;
         case STORE_ATTR:
             return 2;
         case DELETE_ATTR:
@@ -467,15 +467,15 @@ _PyOpcode_num_pushed(int opcode, int oparg, bool jump) {
         case DELETE_NAME:
             return 0;
         case UNPACK_SEQUENCE:
-            return -1;
+            return oparg;
         case UNPACK_SEQUENCE_TWO_TUPLE:
-            return -1;
+            return 2;
         case UNPACK_SEQUENCE_TUPLE:
             return -1;
         case UNPACK_SEQUENCE_LIST:
             return -1;
         case UNPACK_EX:
-            return -1;
+            return (oparg & 0xFF) + (oparg >> 8) + 1;
         case STORE_ATTR:
             return 0;
         case DELETE_ATTR:
@@ -759,8 +759,8 @@ struct opcode_metadata {
     [LOAD_BUILD_CLASS] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IX },
     [STORE_NAME] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },
     [DELETE_NAME] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },
-    [UNPACK_SEQUENCE] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },
-    [UNPACK_SEQUENCE_TWO_TUPLE] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IX },
+    [UNPACK_SEQUENCE] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IBC },
+    [UNPACK_SEQUENCE_TWO_TUPLE] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IXC },
     [UNPACK_SEQUENCE_TUPLE] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },
     [UNPACK_SEQUENCE_LIST] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },
     [UNPACK_EX] = { DIR_NONE, DIR_NONE, DIR_NONE, true, INSTR_FMT_IB },