movabsq $0x1F, %r9
This is an ATT version instruction so $0x1F is sorce and %r9 is dest.
I think this instruction is correct.
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Janez Kuhar
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平沢唯
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1Yes, that's correct. You could have just tried it by assembling it into an executable and single-stepping it in a debugger. (Yes, that line by itself in a `.s` will work with `gcc -nostdlib -static foo.s`, to get that instruction as the first one executed in user-space where you can single-step it. And then crash if you let it step farther, but that's fine.) – Peter Cordes Apr 13 '21 at 06:35
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If you mean efficient, though, in terms of how to set R9 = 0x1F, it's worse code-size than `mov $0x1F, %r9d`. So it's correct but not efficient. – Peter Cordes Apr 13 '21 at 06:38