bpo-42246: Don't eliminate jumps to jump, if it will break PEP 626. - #23896
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markshannon merged 4 commits intoDec 23, 2020
Merged
bpo-42246: Don't eliminate jumps to jump, if it will break PEP 626.#23896markshannon merged 4 commits into
markshannon merged 4 commits into
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Consider the following weird function:
On master this produces the code:
1 >> 0 NOP 2 2 LOAD_FAST 0 (x) 4 POP_JUMP_IF_FALSE 0 3 6 LOAD_CONST 0 (None) 8 RETURN_VALUEwhich, when x is False will generate the trace 1, 2, 1, 2, 1, 2, ...
with this PR it produces the following correct, if slightly less efficient code:
1 >> 0 NOP 2 2 LOAD_FAST 0 (x) 4 POP_JUMP_IF_FALSE 10 3 6 LOAD_CONST 0 (None) 8 RETURN_VALUE 4 >> 10 JUMP_ABSOLUTE 0which generates the correct trace 1, 2, 4, 1, 2, 4, 1, 2, 4, ...
When https://bugs.python.org/issue42719 is addressed we should be able to produce more efficient code.
https://bugs.python.org/issue42246