https://github.com/python/cpython/commit/004f9fd1f22643100aa8163cc9f7bcde7df... commit: 004f9fd1f22643100aa8163cc9f7bcde7df54973 branch: main author: Brandt Bucher <brandtbucher@microsoft.com> committer: brandtbucher <brandtbucher@gmail.com> date: 2025-01-08T09:00:11-08:00 summary: Remove unnecessary LIST_TO_TUPLE conversions (GH-126558) files: M Lib/test/test_peepholer.py M Python/flowgraph.c diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py index c7da151dce3b37..b5b2b350e77a3b 100644 --- a/Lib/test/test_peepholer.py +++ b/Lib/test/test_peepholer.py @@ -1193,5 +1193,56 @@ def get_insts(lno1, lno2, op1, op2): ] self.cfg_optimization_test(insts, expected_insts, consts=list(range(5))) + def test_list_to_tuple_get_iter(self): + # for _ in (*foo, *bar) -> for _ in [*foo, *bar] + INTRINSIC_LIST_TO_TUPLE = 6 + insts = [ + ("BUILD_LIST", 0, 1), + ("LOAD_FAST", 0, 2), + ("LIST_EXTEND", 1, 3), + ("LOAD_FAST", 1, 4), + ("LIST_EXTEND", 1, 5), + ("CALL_INTRINSIC_1", INTRINSIC_LIST_TO_TUPLE, 6), + ("GET_ITER", None, 7), + top := self.Label(), + ("FOR_ITER", end := self.Label(), 8), + ("STORE_FAST", 2, 9), + ("JUMP", top, 10), + end, + ("END_FOR", None, 11), + ("POP_TOP", None, 12), + ("LOAD_CONST", 0, 13), + ("RETURN_VALUE", None, 14), + ] + expected_insts = [ + ("BUILD_LIST", 0, 1), + ("LOAD_FAST", 0, 2), + ("LIST_EXTEND", 1, 3), + ("LOAD_FAST", 1, 4), + ("LIST_EXTEND", 1, 5), + ("NOP", None, 6), # ("CALL_INTRINSIC_1", INTRINSIC_LIST_TO_TUPLE, 6), + ("GET_ITER", None, 7), + top := self.Label(), + ("FOR_ITER", end := self.Label(), 8), + ("STORE_FAST", 2, 9), + ("JUMP", top, 10), + end, + ("END_FOR", None, 11), + ("POP_TOP", None, 12), + ("LOAD_CONST", 0, 13), + ("RETURN_VALUE", None, 14), + ] + self.cfg_optimization_test(insts, expected_insts, consts=[None]) + + def test_list_to_tuple_get_iter_is_safe(self): + a, b = [], [] + for item in (*(items := [0, 1, 2, 3]),): + a.append(item) + b.append(items.pop()) + self.assertEqual(a, [0, 1, 2, 3]) + self.assertEqual(b, [3, 2, 1, 0]) + self.assertEqual(items, []) + + if __name__ == "__main__": unittest.main() diff --git a/Python/flowgraph.c b/Python/flowgraph.c index 017216aadd1f01..24561c1ee04db9 100644 --- a/Python/flowgraph.c +++ b/Python/flowgraph.c @@ -4,6 +4,7 @@ #include "Python.h" #include "pycore_flowgraph.h" #include "pycore_compile.h" +#include "pycore_intrinsics.h" #include "pycore_pymem.h" // _PyMem_IsPtrFreed() #include "pycore_opcode_utils.h" @@ -1874,6 +1875,12 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts) continue; } break; + case CALL_INTRINSIC_1: + // for _ in (*foo, *bar) -> for _ in [*foo, *bar] + if (oparg == INTRINSIC_LIST_TO_TUPLE && nextop == GET_ITER) { + INSTR_SET_OP0(inst, NOP); + } + break; } }