1 files changed, 34 insertions, 1 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index ea33578502b..14546c0fe4c 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1092,6 +1092,28 @@ uint64_t BitcodeReader::decodeSignRotatedValue(uint64_t V) {
   return 1ULL << 63;
 }
 
+// FIXME: Delete this in LLVM 4.0 and just assert that the aliasee is a
+// GlobalObject.
+static GlobalObject &
+getGlobalObjectInExpr(const DenseMap<GlobalAlias *, Constant *> &Map,
+                      Constant &C) {
+  auto *GO = dyn_cast<GlobalObject>(&C);
+  if (GO)
+    return *GO;
+
+  auto *GA = dyn_cast<GlobalAlias>(&C);
+  if (GA)
+    return getGlobalObjectInExpr(Map, *Map.find(GA)->second);
+
+  auto &CE = cast<ConstantExpr>(C);
+  assert(CE.getOpcode() == Instruction::BitCast ||
+         CE.getOpcode() == Instruction::GetElementPtr ||
+         CE.getOpcode() == Instruction::AddrSpaceCast);
+  if (CE.getOpcode() == Instruction::GetElementPtr)
+    assert(cast<GEPOperator>(CE).hasAllZeroIndices());
+  return getGlobalObjectInExpr(Map, *CE.getOperand(0));
+}
+
 /// ResolveGlobalAndAliasInits - Resolve all of the initializers for global
 /// values and aliases that we can.
 error_code BitcodeReader::ResolveGlobalAndAliasInits() {
@@ -1117,19 +1139,30 @@ error_code BitcodeReader::ResolveGlobalAndAliasInits() {
     GlobalInitWorklist.pop_back();
   }
 
+  // FIXME: Delete this in LLVM 4.0
+  // Older versions of llvm could write an alias pointing to another. We cannot
+  // construct those aliases, so we first collect an alias to aliasee expression
+  // and then compute the actual aliasee.
+  DenseMap<GlobalAlias *, Constant *> AliasInit;
+
   while (!AliasInitWorklist.empty()) {
     unsigned ValID = AliasInitWorklist.back().second;
     if (ValID >= ValueList.size()) {
       AliasInits.push_back(AliasInitWorklist.back());
     } else {
       if (Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]))
-        AliasInitWorklist.back().first->setAliasee(C);
+        AliasInit.insert(std::make_pair(AliasInitWorklist.back().first, C));
       else
         return Error(ExpectedConstant);
     }
     AliasInitWorklist.pop_back();
   }
 
+  for (auto &Pair : AliasInit) {
+    auto &GO = getGlobalObjectInExpr(AliasInit, *Pair.second);
+    Pair.first->setAliasee(&GO);
+  }
+
   while (!FunctionPrefixWorklist.empty()) {
     unsigned ValID = FunctionPrefixWorklist.back().second;
     if (ValID >= ValueList.size()) {