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rex.W prefix in jumps on x86_64
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From: |
Marc Nieper-Wißkirchen |
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Subject: |
rex.W prefix in jumps on x86_64 |
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Date: |
Sat, 25 Apr 2020 21:02:41 +0200 |
Hi,
I am currently using the development version of GNU lightning. When I
look at the disassembly, I see things like
rex.W jmpq *%rax
when an instruction like `jmpr R0' is jitted. I am wondering about the
REX prefix, which doesn't seem to be necessary. In 64 bit-mode, where
the operand size is fixed for jumps and calls.
Thanks!
Marc
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