[PATCH] D18945: [ThinLTO] Only compute imports for current module in FunctionImport pass

[Teresa Johnson via llvm-commits]

tejohnson added a comment.

In http://reviews.llvm.org/D18945#396617, @joker.eph wrote:

> > This is particularly for the distributed build case where the importing is done in the back end processes.
>
>
> This is the part I'm not convinced yet, because of the part where I wrote "The export list is gonna be needed to drive a "smart" promotion/renaming, so I expect it to be needed at the same stage you need the import list."


Note you can still do this from libLTO where you are calling ComputeCrossModuleImport and renameModuleForThinLTO directly (a single time per link).

For the distributed back end case, I want to avoid doing redundant work in thousands of back ends, which it currently is doing unnecessarily. As mentioned, the smart promotion could be done by invoking the full ComputeCrossModuleImport in the thin link step and marking the updated linkages in the index for the backends to adjust.


http://reviews.llvm.org/D18945