On Fri, Jan 29, 2021 at 4:30 PM Andrew MacLeod via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Ranger spends a lot of time tracking pointer type ssa_names which are > initialized to non-null, ie (a_2 = &foo). This turns out to be a waste > of effort. > > Pointers can effectively have one of 3 values we care about: VARYING, > [0,0], or [1, +INF]. If an ssa_name is globally [0,0] or [1, +INF], > the only "refinement" that can be made on an outgoing edge is to > evaluate to UNDEFINED. There is no need to track UNDEFINED on the > un-taken edge as the branch will be folded and the edge removed. The > range will remain the same on the other edge. > > Initializing to [0,0] produces a singleton range, and constants like > this tend to be propagated away anyway, so their usage patterns are less > of an issue. [1, +INF] however looks like a range which can be > modified, and we spend a lot of pointless time in this PR processing it. > > This patch extends current invariant tracking to also include pointers > which evaluate to [1, +INF] at their definition, and thus will not be > included in the on-entry cache, and resolves the compilation time issue. > > I also renamed the local member name as it now has a more specific > definition. > > Bootstrapped on x86_64-pc-linux-gnu with no regressions. > I'm not sure the current protocol for checking things in, so I will ask > for blessing from the release managers:-) OK for trunk?
OK. Richard. > Andrew >
