[PATCH] D54370: [codeview] Expose -gcodeview-ghash for global type hashing

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

In https://reviews.llvm.org/D54370#1294648, @aganea wrote:

> @rnk Could you possibly post build metrics for Chromium (for the whole build process, compilation and link) with and without ghash?


I think we'll put the complete analysis here: https://crbug.com/904324 You should be able to star the issue with any google account to get updates by mail.

> In my early tests, it seemed that on a large project, compilation was a bit slower overall, but linking was faster.
>  If that still holds, enabling ghash seems only useful when iterating, or if you have a good caching mecanism in your build system (which would avoid rebuilding all).

That sounds right. It effectively moves hashing work from link time to compile time, which you can mitigate by parallelizing the build with lots of cores or a fancy distributed build system. The extra object file size is crummy, though.


https://reviews.llvm.org/D54370