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[3.10] bpo-46724: Use JUMP_ABSOLUTE for all backward jumps. #31352

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markshannon wants to merge 1 commit into from
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[3.10] bpo-46724: Use JUMP_ABSOLUTE for all backward jumps. #31352

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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-02-14-14-44-06.bpo-46724.jym_K6.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Make sure that all backwards jumps use the ``JUMP_ABSOLUTE`` instruction, rather
than ``JUMP_FORWARD`` with an argument of ``(2**32)+offset``.
5 changes: 5 additions & 0 deletions Python/compile.c
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Expand Up @@ -6702,6 +6702,11 @@ assemble_emit(struct assembler *a, struct instr *i)
}

static void
if (last->i_opcode == JUMP_FORWARD) {
if (last->i_target->b_visited == 1) {
last->i_opcode = JUMP_ABSOLUTE;
}
}
assemble_jump_offsets(struct assembler *a, struct compiler *c)
{
basicblock *b;
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