On Sat, Nov 11, 2023 at 05:05:57PM -0800, Andrii Nakryiko wrote:
> Generalize bounds adjustment logic of reg_set_min_max() to handle not
> just register vs constant case, but in general any register vs any
> register cases. For most of the operations it's trivial extension based
> on range vs range comparison logic, we just need to properly pick
> min/max of a range to compare against min/max of the other range.
>
> For BPF_JSET we keep the original capabilities, just make sure JSET is
> integrated in the common framework. This is manifested in the
> internal-only BPF_JSET + BPF_X "opcode" to allow for simpler and more
> uniform rev_opcode() handling. See the code for details. This allows to
> reuse the same code exactly both for TRUE and FALSE branches without
> explicitly handling both conditions with custom code.
>
> Note also that now we don't need a special handling of BPF_JEQ/BPF_JNE
> case none of the registers are constants. This is now just a normal
^
missing a word here? ("when" perhaps)
> generic case handled by reg_set_min_max().
>
> To make tnum handling cleaner, tnum_with_subreg() helper is added, as
> that's a common operator when dealing with 32-bit subregister bounds.
> This keeps the overall logic much less noisy when it comes to tnums.
>
> Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
