Another thing worth considering is just to use const char* as the map key. I believe it's safe in this case, and smaller than StringRef which is a pointer and a length.

FWIW I also tried SmallDenseMap with various inline sizes. It still seems to be the case that, once you exceed the in-situ space, you immediately grow to 64 entries.

Yeah I tested pretty much the same thing, and it was a big memory regression. The problem is that, upon first insert, the DenseMap grows to 64 entries. Even if I use a const char* key, the KV-pair is 16B, so 64 entries is 1K.

@rafael could you please review this, and maybe even commit it? Thanks.

Fix new test (added in D27217) so it covers the new behavior.

Thanks @davide, looks like I'm all set since @david2050 already did it.

Remove trailing newline.

Previous diff was a mistake. Got the revisions mixed up. Here I add the final newline to the new test.

Remove trailing whitespace