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[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 bde06e1b83
)
Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
This commit is contained in:
parent
3517c138a8
commit
74c953d396
5 changed files with 34 additions and 10 deletions
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@ -366,14 +366,12 @@ dis_traceback = """\
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LOAD_CONST 2 (0)
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--> BINARY_OP 11 (/)
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POP_TOP
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%3d LOAD_FAST 1 (tb)
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RETURN_VALUE
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JUMP_FORWARD 30 (to 76)
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>> PUSH_EXC_INFO
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%3d LOAD_GLOBAL 0 (Exception)
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CHECK_EXC_MATCH
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POP_JUMP_FORWARD_IF_FALSE 18 (to 72)
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POP_JUMP_FORWARD_IF_FALSE 17 (to 68)
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STORE_FAST 0 (e)
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%3d LOAD_FAST 0 (e)
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@ -383,9 +381,7 @@ dis_traceback = """\
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LOAD_CONST 0 (None)
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STORE_FAST 0 (e)
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DELETE_FAST 0 (e)
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%3d LOAD_FAST 1 (tb)
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RETURN_VALUE
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JUMP_FORWARD 8 (to 76)
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>> LOAD_CONST 0 (None)
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STORE_FAST 0 (e)
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DELETE_FAST 0 (e)
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@ -395,15 +391,17 @@ dis_traceback = """\
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>> COPY 3
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POP_EXCEPT
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RERAISE 1
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%3d >> LOAD_FAST 1 (tb)
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RETURN_VALUE
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ExceptionTable:
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""" % (TRACEBACK_CODE.co_firstlineno,
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TRACEBACK_CODE.co_firstlineno + 1,
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TRACEBACK_CODE.co_firstlineno + 2,
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TRACEBACK_CODE.co_firstlineno + 5,
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TRACEBACK_CODE.co_firstlineno + 3,
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TRACEBACK_CODE.co_firstlineno + 4,
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TRACEBACK_CODE.co_firstlineno + 5,
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TRACEBACK_CODE.co_firstlineno + 3)
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TRACEBACK_CODE.co_firstlineno + 3,
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TRACEBACK_CODE.co_firstlineno + 5)
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def _fstring(a, b, c, d):
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return f'{a} {b:4} {c!r} {d!r:4}'
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@ -344,6 +344,8 @@ class TestTranforms(BytecodeTestCase):
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self.assertEqual(len(returns), 1)
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self.check_lnotab(f)
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@unittest.skip("Following gh-92228 the return has two predecessors "
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"and that prevents jump elimination.")
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def test_elim_jump_to_return(self):
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# JUMP_FORWARD to RETURN --> RETURN
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def f(cond, true_value, false_value):
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@ -2042,6 +2042,15 @@ class JumpTestCase(unittest.TestCase):
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output.append(6)
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output.append(7)
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@jump_test(6, 1, [1, 5, 1, 5])
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def test_jump_over_try_except(output):
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output.append(1)
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try:
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1 / 0
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except ZeroDivisionError as e:
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output.append(5)
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x = 42 # has to be a two-instruction block
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@jump_test(2, 4, [1, 4, 5, -4])
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def test_jump_across_with(output):
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output.append(1)
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@ -0,0 +1 @@
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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.
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@ -8976,6 +8976,16 @@ error:
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return -1;
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}
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static bool
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basicblock_has_lineno(const basicblock *bb) {
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for (int i = 0; i < bb->b_iused; i++) {
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if (bb->b_instr[i].i_lineno > 0) {
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return true;
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}
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}
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return false;
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}
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/* If this block ends with an unconditional jump to an exit block,
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* then remove the jump and extend this block with the target.
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*/
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@ -8992,6 +9002,10 @@ extend_block(basicblock *bb) {
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}
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if (last->i_target->b_exit && last->i_target->b_iused <= MAX_COPY_SIZE) {
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basicblock *to_copy = last->i_target;
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if (basicblock_has_lineno(to_copy)) {
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/* copy only blocks without line number (like implicit 'return None's) */
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return 0;
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}
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last->i_opcode = NOP;
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for (int i = 0; i < to_copy->b_iused; i++) {
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int index = compiler_next_instr(bb);
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