[PATCH] D121368: [pseudo][WIP] Build Ambiguous forest node in the GLR Parser.

[Sam McCall via Phabricator via cfe-commits]

sammccall added a comment.

Some notes before our meeting.

It does appear that it's possible to generate duplicate forest nodes in this way, and AFAIK any method other that explicitly deduplicating creating using a map<(rule, rhsnodes), sequencenode> is going to have this problem.
The good news is:

- the cache lifetime is local to the family (outer batch), collisions necessarily happen within a family (outer batch). (We can make it a member and clear it, to reuse storage)
- I think we can form the forest nodes at the bottom of the enumerateReducePaths() call, and use them + base GSS node in place of the reduce path. (we never actually used internal gss path nodes, just the forest nodes + GSS base).
- Now reductions found by enumerateReducePaths() is identified by (base, sequence node, new state) which are cheap to compare/group in various ways

I feel like this should simplify subsequent steps, but need to think more


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https://reviews.llvm.org/D121368