From 74c953d396816c0ef3de80276c00d29f79cbf8bf Mon Sep 17 00:00:00 2001 From: Christian Heimes Date: Thu, 7 Jul 2022 12:10:32 +0200 Subject: [3.11] gh-92228: disable the compiler's 'small exit block inlining' optimization for blocks that have a line number (GH-94592) (GH-94643) Inlining of code that corresponds to source code lines, can make it hard to distinguish later between code which is only reachable from except handlers, and that which is reachable in normal control flow. This caused problems with the debugger's jump feature. This PR turns off the inlining optimisation for code which has line numbers. We still inline things like the implicit "return None".. (cherry picked from commit bde06e1b8381f140b296a397ddd1deb1c784ff8e) Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com> --- Lib/test/test_dis.py | 18 ++++++++---------- Lib/test/test_peepholer.py | 2 ++ Lib/test/test_sys_settrace.py | 9 +++++++++ .../2022-07-06-14-02-26.gh-issue-92228.44Cbly.rst | 1 + Python/compile.c | 14 ++++++++++++++ 5 files changed, 34 insertions(+), 10 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2022-07-06-14-02-26.gh-issue-92228.44Cbly.rst diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py index 4283c30..b00f329 100644 --- a/Lib/test/test_dis.py +++ b/Lib/test/test_dis.py @@ -366,14 +366,12 @@ dis_traceback = """\ LOAD_CONST 2 (0) --> BINARY_OP 11 (/) POP_TOP - -%3d LOAD_FAST 1 (tb) - RETURN_VALUE + JUMP_FORWARD 30 (to 76) >> PUSH_EXC_INFO %3d LOAD_GLOBAL 0 (Exception) CHECK_EXC_MATCH - POP_JUMP_FORWARD_IF_FALSE 18 (to 72) + POP_JUMP_FORWARD_IF_FALSE 17 (to 68) STORE_FAST 0 (e) %3d LOAD_FAST 0 (e) @@ -383,9 +381,7 @@ dis_traceback = """\ LOAD_CONST 0 (None) STORE_FAST 0 (e) DELETE_FAST 0 (e) - -%3d LOAD_FAST 1 (tb) - RETURN_VALUE + JUMP_FORWARD 8 (to 76) >> LOAD_CONST 0 (None) STORE_FAST 0 (e) DELETE_FAST 0 (e) @@ -395,15 +391,17 @@ dis_traceback = """\ >> COPY 3 POP_EXCEPT RERAISE 1 + +%3d >> LOAD_FAST 1 (tb) + RETURN_VALUE ExceptionTable: """ % (TRACEBACK_CODE.co_firstlineno, TRACEBACK_CODE.co_firstlineno + 1, TRACEBACK_CODE.co_firstlineno + 2, - TRACEBACK_CODE.co_firstlineno + 5, TRACEBACK_CODE.co_firstlineno + 3, TRACEBACK_CODE.co_firstlineno + 4, - TRACEBACK_CODE.co_firstlineno + 5, - TRACEBACK_CODE.co_firstlineno + 3) + TRACEBACK_CODE.co_firstlineno + 3, + TRACEBACK_CODE.co_firstlineno + 5) def _fstring(a, b, c, d): return f'{a} {b:4} {c!r} {d!r:4}' diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py index 6a2f550..241644a 100644 --- a/Lib/test/test_peepholer.py +++ b/Lib/test/test_peepholer.py @@ -344,6 +344,8 @@ class TestTranforms(BytecodeTestCase): self.assertEqual(len(returns), 1) self.check_lnotab(f) + @unittest.skip("Following gh-92228 the return has two predecessors " + "and that prevents jump elimination.") def test_elim_jump_to_return(self): # JUMP_FORWARD to RETURN --> RETURN def f(cond, true_value, false_value): diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py index 7ec290d..f03b03e 100644 --- a/Lib/test/test_sys_settrace.py +++ b/Lib/test/test_sys_settrace.py @@ -2042,6 +2042,15 @@ class JumpTestCase(unittest.TestCase): output.append(6) output.append(7) + @jump_test(6, 1, [1, 5, 1, 5]) + def test_jump_over_try_except(output): + output.append(1) + try: + 1 / 0 + except ZeroDivisionError as e: + output.append(5) + x = 42 # has to be a two-instruction block + @jump_test(2, 4, [1, 4, 5, -4]) def test_jump_across_with(output): output.append(1) diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-07-06-14-02-26.gh-issue-92228.44Cbly.rst b/Misc/NEWS.d/next/Core and Builtins/2022-07-06-14-02-26.gh-issue-92228.44Cbly.rst new file mode 100644 index 0000000..458ad89 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2022-07-06-14-02-26.gh-issue-92228.44Cbly.rst @@ -0,0 +1 @@ +Disable the compiler's inline-small-exit-blocks optimization for exit blocks that are associated with source code lines. This fixes a bug where the debugger cannot tell where an exception handler ends and the following code block begins. diff --git a/Python/compile.c b/Python/compile.c index cfe4b6e..a71e7d3 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -8976,6 +8976,16 @@ error: return -1; } +static bool +basicblock_has_lineno(const basicblock *bb) { + for (int i = 0; i < bb->b_iused; i++) { + if (bb->b_instr[i].i_lineno > 0) { + return true; + } + } + return false; +} + /* If this block ends with an unconditional jump to an exit block, * then remove the jump and extend this block with the target. */ @@ -8992,6 +9002,10 @@ extend_block(basicblock *bb) { } if (last->i_target->b_exit && last->i_target->b_iused <= MAX_COPY_SIZE) { basicblock *to_copy = last->i_target; + if (basicblock_has_lineno(to_copy)) { + /* copy only blocks without line number (like implicit 'return None's) */ + return 0; + } last->i_opcode = NOP; for (int i = 0; i < to_copy->b_iused; i++) { int index = compiler_next_instr(bb); -- cgit v0.12