On Wed, 2023-12-20 at 23:40 +0200, Maxim Mikityanskiy wrote: > > From: Maxim Mikityanskiy <maxim@xxxxxxxxxxxxx> > > > > Support the pattern where an unbounded scalar is spilled to the stack, > > then boundary checks are performed on the src register, after which the > > stack frame slot is refilled into a register. > > > > Before this commit, the verifier didn't treat the src register and the > > stack slot as related if the src register was an unbounded scalar. The > > register state wasn't copied, the id wasn't preserved, and the stack > > slot was marked as STACK_MISC. Subsequent boundary checks on the src > > register wouldn't result in updating the boundaries of the spilled > > variable on the stack. > > > > After this commit, the verifier will preserve the bond between src and > > dst even if src is unbounded, which permits to do boundary checks on src > > and refill dst later, still remembering its boundaries. Such a pattern > > is sometimes generated by clang when compiling complex long functions. > > > > One test is adjusted to reflect the fact that an untracked register is > > marked as precise at an earlier stage, and one more test is adjusted to > > reflect that now unbounded scalars are tracked. > > > > Signed-off-by: Maxim Mikityanskiy <maxim@xxxxxxxxxxxxx> > > --- Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
