Support POP_ITER

Summary: See [GH-128445](python/cpython#128445).

Reviewed By: alexmalyshev

Differential Revision: D81142355

fbshipit-source-id: 33c7eb51bd64722229df88691619a3e9fcbede6b

Author: jbower-fb

cinderx/Common/opcode_stubs.h

@@ -75,6 +75,7 @@
   X(LOAD_SUPER_ATTR)                   \
   X(MAKE_CELL)                         \
   X(NOT_TAKEN)                         \
+  X(POP_ITER)                          \
   X(POP_JUMP_IF_NONE)                  \
   X(POP_JUMP_IF_NOT_NONE)              \
   X(PUSH_EXC_INFO)                     \
@@ -187,6 +188,7 @@ enum {
   X(LOAD_SMALL_INT)                \
   X(MAKE_OPNAME)                   \
   X(NOT_TAKEN)                     \
+  X(POP_ITER)                      \
   X(ROT_FOUR)                      \
   X(ROT_N)                         \
   X(ROT_THREE)                     \

cinderx/Jit/hir/builder.cpp

@@ -172,6 +172,7 @@ bool isSupportedOpcode(int opcode) {
     case NOT_TAKEN:
     case POP_BLOCK:
     case POP_EXCEPT:
+    case POP_ITER:
     case POP_JUMP_IF_FALSE:
     case POP_JUMP_IF_NONE:
     case POP_JUMP_IF_NONZERO:
@@ -452,6 +453,7 @@ static bool should_snapshot(
     case LOAD_FAST_CHECK:
     case LOAD_LOCAL:
     case NOP:
+    case POP_ITER:
     case POP_TOP:
     case PRIMITIVE_BOX:
     case PRIMITIVE_LOAD_CONST:
@@ -1146,6 +1148,7 @@ void HIRBuilder::translate(
           emitPopJumpIfNone(tc, bc_instr);
           break;
         }
+        case POP_ITER:
         case POP_TOP: {
           tc.frame.stack.pop();
           break;
@@ -1516,9 +1519,15 @@ void HIRBuilder::translate(
       case FOR_ITER: {
         auto condbr = static_cast<CondBranchIterNotDone*>(last_instr);
         auto new_frame = tc.frame;
-        // Pop both the sentinel value signaling iteration is complete
-        // and the iterator itself.
-        new_frame.stack.discard(2);
+        if constexpr (PY_VERSION_HEX >= 0x030E0000) {
+          // Just pop the sentinel value. The target POP_ITER will pop the
+          // iterator.
+          new_frame.stack.discard(1);
+        } else {
+          // Pop both the sentinel value signaling iteration is complete
+          // and the iterator itself.
+          new_frame.stack.discard(2);
+        }
         queue.emplace_back(condbr->true_bb(), tc.frame);
         queue.emplace_back(condbr->false_bb(), new_frame);
         break;

cinderx/PythonLib/test_cinderx/test_python314_bytecodes.py

@@ -264,6 +264,16 @@ def x(a):
         self._assertBytecodeContains(x, "TO_BOOL")
         self._assertBytecodeContains(x, "POP_JUMP_IF_FALSE")
 
+    def test_POP_ITER(self):
+        @cinder_support.fail_if_deopt
+        @cinder_support.failUnlessJITCompiled
+        def x():
+            for y in range(2):
+                return y
+
+        self.assertEqual(x(), 0)
+        self._assertBytecodeContains(x, "POP_ITER")
+
 
 if __name__ == "__main__":
     unittest.main()