[Python-Dev] Unexpected bytecode difference (original) (raw)
Alexander Belopolsky alexander.belopolsky at gmail.com
Mon Jan 22 13:09:36 EST 2018
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On Fri, Jan 19, 2018 at 7:18 PM, Victor Stinner <victor.stinner at gmail.com> wrote:
It seems like the EXTENDEDARG doc wasn't updated.
I've opened <https://bugs.python.org/issue32625> to update the dis module documentation.
I have also found a patch (mkfu4.patch) attached to issue 27095 where EXTENDED_ARG is described as
.. opcode:: EXTENDED_ARG (ext)
EXTENDED_ARG adds *ext* * 256 to the next instruction's argument.
This is used for arguments exceeding a byte in size, and can be chained
to create 4-byte arguments.
I am not sure this is correct. First, multiple EXTENDED_ARG codes seem to add ext * 256 ** i or bit-append ext to arg. Second, it looks like this mechanism allows forming arguments of arbitrary bit length, not just 4-byte arguments.
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