Follow-up for masks on shift operations #105
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Add tests to make sure we handle the masking of the value (in the source register or as an immediate) telling by how many bits the value in the destination register should be shifted. The context is that we used to do no masking on this value, but the BPF ISA specification does require one, and the kernel implements it when the value is passed in the source register (and rejects immediates that it deems invalid). Signed-off-by: Quentin Monnet <qmo@qmon.net>
We recently fixed the 64-bit arithmetic shift-right operations by adding a mask to the number of bits (as immediates or from the source register) by which to shift, as per the eBPF ISA specification. The 32-bit operations must use the same mask, but .wrapping_shr() already takes care of it for us. Let's add a comment to make it explicit. As it turns out, masking is just as well unnecessary for the non-arithmetic left-right shift operations that we tried to fix recently. Let's also remove the mask there. Signed-off-by: Quentin Monnet <qmo@qmon.net>
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Many thanks for the follow-up! |
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Cc: @pcy190