[PATCH] D14677: [LegacyPassManager] Reduce memory usage for AnalysisUsage

[Chandler Carruth via llvm-commits]

chandlerc added a comment.

This is a really nice improvement. Minor adjustment below is my only real suggestion.


================
Comment at: lib/IR/LegacyPassManager.cpp:582-587
@@ +581,8 @@
+    // of dependencies.
+    AnalysisUsage AU;
+    P->getAnalysisUsage(AU);
+
+    auto *Node = [&]() {
+      FoldingSetNodeID ID;
+      AUFoldingSetNode::Profile(ID, AU);
+      void *IP = nullptr;
----------------
Since we build this completely each time, the folding set machinery isn't really hepling much. Maybe just provide a hash_value overload and use a SmallSet? Should be able to either delegate to the vector's hash_value or use hash_combine_range.

(This isn't because they're that much simpler, I'd just rather move everything away from folding sets where reasonable.)

================
Comment at: lib/IR/LegacyPassManager.cpp:594
@@ +593,3 @@
+      return Temp;
+    }();
+
----------------
As sympathetic as I am to using multiple returns like this in an immediately called lamda, I find it quite confusing. Especially with the auto type on the variable.

Fortunately, I think with a set, the code to do this without a lambda shouldn't be onerous at all.


http://reviews.llvm.org/D14677