Reduce abuse of default values in the GlobalAlias constructor.

[oota-llvm.git] / lib / Bitcode / Reader / BitcodeReader.cpp

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index a1ae6baff9fc8be42b02641263152229ed6ebc7f..478103f982f539e841dac701c4ae6c7a999aedb8 100644 (file)
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/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()) {
@@ -1667,8 +1700,11 @@ error_code BitcodeReader::GlobalCleanup() {
   // Look for global variables which need to be renamed.
   for (Module::global_iterator
          GI = TheModule->global_begin(), GE = TheModule->global_end();
-       GI != GE; ++GI)
-    UpgradeGlobalVariable(GI);
+       GI != GE;) {
+    GlobalVariable *GV = GI++;
+    UpgradeGlobalVariable(GV);
+  }
+
   // Force deallocation of memory for these vectors to favor the client that
   // want lazy deserialization.
   std::vector<std::pair<GlobalVariable*, unsigned> >().swap(GlobalInits);
@@ -1963,13 +1999,13 @@ error_code BitcodeReader::ParseModule(bool Resume) {
       Type *Ty = getTypeByID(Record[0]);
       if (!Ty)
         return Error(InvalidRecord);
-      if (!Ty->isPointerTy())
+      auto *PTy = dyn_cast<PointerType>(Ty);
+      if (!PTy)
         return Error(InvalidTypeForValue);
 
-      auto *PTy = cast<PointerType>(Ty);
-      GlobalAlias *NewGA =
-          new GlobalAlias(PTy->getElementType(), GetDecodedLinkage(Record[2]),
-                          "", nullptr, TheModule, PTy->getAddressSpace());
+      auto *NewGA =
+          new GlobalAlias(PTy->getElementType(), PTy->getAddressSpace(),
+                          GetDecodedLinkage(Record[2]), "", TheModule);
       // Old bitcode files didn't have visibility field.
       // Local linkage must have default visibility.
       if (Record.size() > 3 && !NewGA->hasLocalLinkage())