[PATCH] D76977: [lld-macho] Implement basic export trie

[Shoaib Meenai via Phabricator via llvm-commits]

smeenai added inline comments.


================
Comment at: lld/MachO/ExportTrie.cpp:192-195
+  std::vector<TrieNode *> orderedNodes;
+  orderedNodes.reserve(allNodes.size());
+  for (const Symbol *sym : exported)
+    rootNode->orderNodes(*sym, orderedNodes);
----------------
int3 wrote:
> This is basically a topological sort. It's unclear to me though why this approach (of finding every element starting from the root) was chosen vs doing a single preorder traversal of the trie...
Not having looked at this in detail yet, would they give comparable results?


================
Comment at: lld/MachO/ExportTrie.cpp:75
+
+void TrieNode::addSymbol(const Symbol &entry,
+                         std::vector<TrieNode *> &allNodes) {
----------------
ruiu wrote:
> ruiu wrote:
> > int3 wrote:
> > > ruiu wrote:
> > > > `addSymbol` seem to keep the internal trie consistent all the time, but I don't think we need to split the work between `addSymbol` and `build`. We can make `addSymbol` just to store an argument to an array, and move the code for trie construction to `build`.
> > > Not sure I understand what you're going for. Do you mean to have TrieBuilder::addSymbol collect the symbols to export in a vector, and then have `build()` call `TrieNode::addSymbol()` for all the symbols right before serializing the trie?
> > Yes, that's what I meant.
> What I wanted to say is that it looks like the trie implemented in this file is designed with the generic Map use cases in mind. You can add a new string one at a time to an existing trie, and you can also look it up as if it were a map (it is actually a map). In order to that, we create a trie in memory. But I think we can avoid that. We can just accumulate added strings to a vector, and in build() we sort the strings and directly emit a serialized trie from the sorted strings.
+1 – we should only need the trie for output purposes here.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76977/new/

https://reviews.llvm.org/D76977