[PATCH] D59620: [llvm-pdbutil] Add -type-ref-stats to help find unused type info

Thu Mar 21 05:45:15 PDT 2019

aganea added a comment.

In D59620#1437234 <https://reviews.llvm.org/D59620#1437234>, @zturner wrote:

> If we ever wanted more aggressive pruning of dead type information, it probably makes sense to do that as a post-processing step where we re-write the PDB, something like an `llvm-pdbutil gc` subcommand.

@zturner You mean in terms of execution time, or in terms of code complexity in LLD?

@rnk At a later stage, would it be possible to add an option to only print the referenced/unreferenced types? ie. `llvm-pdbutil dump -types=[all(default),ref,unref]`

Just wanted to mention that we've just hit the 2 GB bar for PDBs in some of our production builds. So even if it's a 20% reduction for PDBs, it would make a difference for us.
The other related issue is the symbol servers, which use CAB as a compressed file format. Unfortunately, CAB has a uncompressed file size limit of 2 GB, so we can't store them compressed anymore, which is a bit annoying to say the least.
I'll run your patch on some PDBs to see what numbers I come with.

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