GH-100982: Restrict `FOR_ITER_RANGE` to a single instruction to allow instrumentation. (GH-101985)

1 files changed, 8 insertions, 16 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index c5959f2f99..ad68c794fe 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -2178,35 +2178,27 @@ dummy_func(
             // Common case: no jump, leave it to the code generator
         }
 
-        // This is slightly different, when the loop isn't terminated we
-        // jump over the immediately following STORE_FAST instruction.
-        inst(FOR_ITER_RANGE, (unused/1, iter -- iter, unused)) {
+        inst(FOR_ITER_RANGE, (unused/1, iter -- iter, next)) {
             assert(cframe.use_tracing == 0);
             _PyRangeIterObject *r = (_PyRangeIterObject *)iter;
             DEOPT_IF(Py_TYPE(r) != &PyRangeIter_Type, FOR_ITER);
             STAT_INC(FOR_ITER, hit);
-            _Py_CODEUNIT next = next_instr[INLINE_CACHE_ENTRIES_FOR_ITER];
-            assert(_PyOpcode_Deopt[next.op.code] == STORE_FAST);
             if (r->len <= 0) {
                 STACK_SHRINK(1);
                 Py_DECREF(r);
                 // Jump over END_FOR instruction.
                 JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 1);
+                DISPATCH();
             }
-            else {
-                long value = r->start;
-                r->start = value + r->step;
-                r->len--;
-                if (_PyLong_AssignValue(&GETLOCAL(next.op.arg), value) < 0) {
-                    goto error;
-                }
-                // The STORE_FAST is already done.
-                JUMPBY(INLINE_CACHE_ENTRIES_FOR_ITER + 1);
+            long value = r->start;
+            r->start = value + r->step;
+            r->len--;
+            next = PyLong_FromLong(value);
+            if (next == NULL) {
+                goto error;
             }
-            DISPATCH();
         }
 
-        // This is *not* a super-instruction, unique in the family.
         inst(FOR_ITER_GEN, (unused/1, iter -- iter, unused)) {
             assert(cframe.use_tracing == 0);
             PyGenObject *gen = (PyGenObject *)iter;