From 18ab892ff7e9032914ff7fdb07685d5945c84fef Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov@redhat.com>
Date: Fri, 17 Dec 2021 20:25:32 +0100
Subject: [Bitcode] Avoid setting invalid comdat pointer (NFC)

Instead track global objects with implicit comdat in a separate
set. The current approach of temporarily assigning an invalid
comdat pointer is incompatible with D115864.
---
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

(limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp')

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 909af12..d914152 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -488,6 +488,7 @@ class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
   BitcodeReaderValueList ValueList;
   Optional<MetadataLoader> MDLoader;
   std::vector<Comdat *> ComdatList;
+  DenseSet<GlobalObject *> ImplicitComdatObjects;
   SmallVector<Instruction *, 64> InstructionList;
 
   std::vector<std::pair<GlobalVariable *, unsigned>> GlobalInits;
@@ -2038,14 +2039,8 @@ Expected<Value *> BitcodeReader::recordValue(SmallVectorImpl<uint64_t> &Record,
     return error("Invalid value name");
   V->setName(NameStr);
   auto *GO = dyn_cast<GlobalObject>(V);
-  if (GO) {
-    if (GO->getComdat() == reinterpret_cast<Comdat *>(1)) {
-      if (TT.supportsCOMDAT())
-        GO->setComdat(TheModule->getOrInsertComdat(V->getName()));
-      else
-        GO->setComdat(nullptr);
-    }
-  }
+  if (GO && ImplicitComdatObjects.contains(GO) && TT.supportsCOMDAT())
+    GO->setComdat(TheModule->getOrInsertComdat(V->getName()));
   return V;
 }
 
@@ -3293,7 +3288,7 @@ Error BitcodeReader::parseGlobalVarRecord(ArrayRef<uint64_t> Record) {
       NewGV->setComdat(ComdatList[ComdatID - 1]);
     }
   } else if (hasImplicitComdat(RawLinkage)) {
-    NewGV->setComdat(reinterpret_cast<Comdat *>(1));
+    ImplicitComdatObjects.insert(NewGV);
   }
 
   if (Record.size() > 12) {
@@ -3427,7 +3422,7 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
       Func->setComdat(ComdatList[ComdatID - 1]);
     }
   } else if (hasImplicitComdat(RawLinkage)) {
-    Func->setComdat(reinterpret_cast<Comdat *>(1));
+    ImplicitComdatObjects.insert(Func);
   }
 
   if (Record.size() > 13)
-- 
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