[PATCH] D107533: [lld-macho] Allow encode up to 4 personality symbols.

[Vy Nguyen via Phabricator via llvm-commits]

oontvoo updated this revision to Diff 364694.
oontvoo added a comment.

Pick Defined


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107533/new/

https://reviews.llvm.org/D107533

Files:
  lld/MachO/UnwindInfoSection.cpp


Index: lld/MachO/UnwindInfoSection.cpp
===================================================================
--- lld/MachO/UnwindInfoSection.cpp
+++ lld/MachO/UnwindInfoSection.cpp
@@ -287,6 +287,10 @@
 static void
 encodePersonalities(const std::vector<CompactUnwindEntry<Ptr> *> &cuPtrVector,
                     std::vector<Ptr> &personalities) {
+  // Map of personality symbol name to (personality, personalityIndex).
+  DenseMap<StringRef, std::pair<Ptr, Ptr>> nameToPersonality;
+
+  const auto &entries = in.got->getEntries();
   for (CompactUnwindEntry<Ptr> *cu : cuPtrVector) {
     if (cu->personality == 0)
       continue;
@@ -296,13 +300,39 @@
     if (it != personalities.end()) {
       personalityIndex = std::distance(personalities.begin(), it) + 1;
     } else {
-      personalities.push_back(cu->personality);
-      personalityIndex = personalities.size();
+      const Symbol *sym = entries[cu->personality - 1]; // -1 because 1-based
+      auto it = nameToPersonality.find(sym->getName());
+
+      if (it == nameToPersonality.end()) {
+        // If we've never seen this symbol, then record it.
+        personalities.push_back(cu->personality);
+        personalityIndex = personalities.size();
+        nameToPersonality[sym->getName()] =
+            std::pair(cu->personality, personalityIndex);
+      } else {
+        auto &pair = it->second;
+        const Symbol *prev_sym = entries[pair.first - 1];
+        // Can't have both Defined with the same name and different GOT index.
+        assert(sym->kind() != Symbol::Defined ||
+               prev_sym->kind() != Symbol::Defined());
+
+        // Prioritize Defined over others, and older entries over others (just
+        // to avoid constantly updating the nameToPersonality map)
+        if (sym->kind() != Symbol::Defined ||
+            prev_sym->kind == Symbol::Defined) {
+          personalityIndex = pair.second;
+        } else {
+          personalities[pair.second] = cu->personality;
+          pair.first = cu->personality;
+          personalityIndex = pair.second;
+        }
+      }
     }
     cu->encoding |=
         personalityIndex << countTrailingZeros(
             static_cast<compact_unwind_encoding_t>(UNWIND_PERSONALITY_MASK));
   }
+
   if (personalities.size() > 3)
     error("too many personalities (" + std::to_string(personalities.size()) +
           ") for compact unwind to encode");


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