1 files changed, 64 insertions, 51 deletions

diff --git a/Python/compile.c b/Python/compile.c
index 3f620be..2f1130e 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -9704,56 +9704,77 @@ instructions_to_cfg(PyObject *instructions, cfg_builder *g)
 {
     assert(PyList_Check(instructions));
 
-    Py_ssize_t instr_size = PyList_GET_SIZE(instructions);
-    for (Py_ssize_t i = 0; i < instr_size; i++) {
+    Py_ssize_t num_insts = PyList_GET_SIZE(instructions);
+    bool *is_target = PyMem_Calloc(num_insts, sizeof(bool));
+    if (is_target == NULL) {
+        return ERROR;
+    }
+    for (Py_ssize_t i = 0; i < num_insts; i++) {
         PyObject *item = PyList_GET_ITEM(instructions, i);
-        if (PyLong_Check(item)) {
-            int lbl_id = PyLong_AsLong(item);
+        if (!PyTuple_Check(item) || PyTuple_GET_SIZE(item) != 6) {
+            PyErr_SetString(PyExc_ValueError, "expected a 6-tuple");
+            goto error;
+        }
+        int opcode = PyLong_AsLong(PyTuple_GET_ITEM(item, 0));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        if (HAS_TARGET(opcode)) {
+            int oparg = PyLong_AsLong(PyTuple_GET_ITEM(item, 1));
             if (PyErr_Occurred()) {
-                return ERROR;
+                goto error;
             }
-            if (lbl_id <= 0 || lbl_id > instr_size) {
-                /* expect label in a reasonable range */
+            if (oparg < 0 || oparg >= num_insts) {
                 PyErr_SetString(PyExc_ValueError, "label out of range");
-                return ERROR;
+                goto error;
             }
-            jump_target_label lbl = {lbl_id};
+            is_target[oparg] = true;
+        }
+    }
+
+    for (int i = 0; i < num_insts; i++) {
+        if (is_target[i]) {
+            jump_target_label lbl = {i};
             RETURN_IF_ERROR(cfg_builder_use_label(g, lbl));
         }
-        else {
-            if (!PyTuple_Check(item) || PyTuple_GET_SIZE(item) != 6) {
-                PyErr_SetString(PyExc_ValueError, "expected a 6-tuple");
-                return ERROR;
-            }
-            int opcode = PyLong_AsLong(PyTuple_GET_ITEM(item, 0));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            int oparg = PyLong_AsLong(PyTuple_GET_ITEM(item, 1));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            location loc;
-            loc.lineno = PyLong_AsLong(PyTuple_GET_ITEM(item, 2));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            loc.end_lineno = PyLong_AsLong(PyTuple_GET_ITEM(item, 3));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            loc.col_offset = PyLong_AsLong(PyTuple_GET_ITEM(item, 4));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            loc.end_col_offset = PyLong_AsLong(PyTuple_GET_ITEM(item, 5));
-            if (PyErr_Occurred()) {
-                return ERROR;
-            }
-            RETURN_IF_ERROR(cfg_builder_addop(g, opcode, oparg, loc));
+        PyObject *item = PyList_GET_ITEM(instructions, i);
+        if (!PyTuple_Check(item) || PyTuple_GET_SIZE(item) != 6) {
+            PyErr_SetString(PyExc_ValueError, "expected a 6-tuple");
+            goto error;
+        }
+        int opcode = PyLong_AsLong(PyTuple_GET_ITEM(item, 0));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        int oparg = PyLong_AsLong(PyTuple_GET_ITEM(item, 1));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        location loc;
+        loc.lineno = PyLong_AsLong(PyTuple_GET_ITEM(item, 2));
+        if (PyErr_Occurred()) {
+            goto error;
         }
+        loc.end_lineno = PyLong_AsLong(PyTuple_GET_ITEM(item, 3));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        loc.col_offset = PyLong_AsLong(PyTuple_GET_ITEM(item, 4));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        loc.end_col_offset = PyLong_AsLong(PyTuple_GET_ITEM(item, 5));
+        if (PyErr_Occurred()) {
+            goto error;
+        }
+        RETURN_IF_ERROR(cfg_builder_addop(g, opcode, oparg, loc));
     }
+
+    PyMem_Free(is_target);
     return SUCCESS;
+error:
+    PyMem_Free(is_target);
+    return ERROR;
 }
 
 static PyObject *
@@ -9763,20 +9784,12 @@ cfg_to_instructions(cfg_builder *g)
     if (instructions == NULL) {
         return NULL;
     }
-    int lbl = 1;
+    int lbl = 0;
     for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
-        b->b_label = lbl++;
+        b->b_label = lbl;
+        lbl += b->b_iused;
     }
     for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
-        PyObject *lbl = PyLong_FromLong(b->b_label);
-        if (lbl == NULL) {
-            goto error;
-        }
-        if (PyList_Append(instructions, lbl) != 0) {
-            Py_DECREF(lbl);
-            goto error;
-        }
-        Py_DECREF(lbl);
         for (int i = 0; i < b->b_iused; i++) {
             struct instr *instr = &b->b_instr[i];
             location loc = instr->i_loc;