On Sun, Oct 22, 2023 at 01:57:37PM -0700, Andrii Nakryiko wrote:
> When determining if if/else branch will always or never be taken, use
Nitpick: "... if an if/else branch will ..."
^^
> signed range knowledge in addition to currently used unsigned range knowledge.
> If either signed or unsigned range suggests that condition is
> always/never taken, return corresponding branch_taken verdict.
>
> Current use of unsigned range for this seems arbitrary and unnecessarily
> incomplete. It is possible for *signed* operations to be performed on
> register, which could "invalidate" unsigned range for that register. In
> such case branch_taken will be artificially useless, even if we can
> still tell that some constant is outside of register value range based
> on its signed bounds.
>
> veristat-based validation shows zero differences across selftests,
> Cilium, and Meta-internal BPF object files.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Otherwise,
Acked-by: Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx>
