Ask HN: 'Consolidated Diff' Tooling?

As a bit of background for the question: viewing and understanding diffs and patches is important for code review, and in general it's good when those diffs are small (I've heard 300 lines suggested in the past as a reasonable upper limit). But sometimes it's necessary to make changes (often find-and-replace-style) that affect thousands or more lines or even files at the same time. Does anyone know of any tools that can automatically 'summarize' those repeat changes rather than displaying them in-repeat for each affected file site? (there are some tricky challenges here, and perhaps a language/editing style that encodes search-and-replace into the diff/patch process would make this much easier.. even so, I'd figure it's worth asking. it feels like it must be a situation that a lot of programmers and reviewers encounter?)