[PATCH] D27790: Pass sample pgo flags to thinlto.

Teresa Johnson via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Dec 15 16:35:31 PST 2016

tejohnson accepted this revision.
tejohnson added inline comments.

Comment at: lib/LTO/LTO.cpp:135
+    if (FileOrErr)
+      Hasher.update(FileOrErr.get()->getBuffer());
+  }
mehdi_amini wrote:
> tejohnson wrote:
> > Will this be expensive, for large apps with large profiles? Since this is the same for each backend, can we compute once and pass down?
> If we go this route (and we should), then I rather do it as a separate patch and do as I suggested originally when the config was added there: have a `hash` method on the config itself where we would hash early the whole config part and do it once early.
Agreed, all the module-independent stuff should be hashed early and passed down. I suppose this is the best approach for now - maybe slow, but safe and enables this change to go in.

We can pull it out as part of the config early hashing implementation in a separate patch.


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