[ORC] Fix transfer to unknown ResourceTrackers (#114063)

When transferring resources, the destination tracker key may not be in
the internal map, invalidating iterators and value references. The added
test creates such situation and would fail before with "Finalized
allocation was not deallocated."

For good measure, fix the same pattern in RTDyldObjectLinkingLayer
which is harder to test because it "only" results in memory managers
being deleted in the wrong order.

Author: hahnjo

llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp

@@ -701,16 +701,15 @@ Error ObjectLinkingLayer::handleRemoveResources(JITDylib &JD, ResourceKey K) {
 void ObjectLinkingLayer::handleTransferResources(JITDylib &JD,
                                                  ResourceKey DstKey,
                                                  ResourceKey SrcKey) {
-  auto I = Allocs.find(SrcKey);
-  if (I != Allocs.end()) {
-    auto &SrcAllocs = I->second;
+  if (Allocs.contains(SrcKey)) {
+    // DstKey may not be in the DenseMap yet, so the following line may resize
+    // the container and invalidate iterators and value references.
     auto &DstAllocs = Allocs[DstKey];
+    auto &SrcAllocs = Allocs[SrcKey];
     DstAllocs.reserve(DstAllocs.size() + SrcAllocs.size());
     for (auto &Alloc : SrcAllocs)
       DstAllocs.push_back(std::move(Alloc));
 
-    // Erase SrcKey entry using value rather than iterator I: I may have been
-    // invalidated when we looked up DstKey.
     Allocs.erase(SrcKey);
   }
 

llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp

@@ -430,16 +430,15 @@ Error RTDyldObjectLinkingLayer::handleRemoveResources(JITDylib &JD,
 void RTDyldObjectLinkingLayer::handleTransferResources(JITDylib &JD,
                                                        ResourceKey DstKey,
                                                        ResourceKey SrcKey) {
-  auto I = MemMgrs.find(SrcKey);
-  if (I != MemMgrs.end()) {
-    auto &SrcMemMgrs = I->second;
+  if (MemMgrs.contains(SrcKey)) {
+    // DstKey may not be in the DenseMap yet, so the following line may resize
+    // the container and invalidate iterators and value references.
     auto &DstMemMgrs = MemMgrs[DstKey];
+    auto &SrcMemMgrs = MemMgrs[SrcKey];
     DstMemMgrs.reserve(DstMemMgrs.size() + SrcMemMgrs.size());
     for (auto &MemMgr : SrcMemMgrs)
       DstMemMgrs.push_back(std::move(MemMgr));
 
-    // Erase SrcKey entry using value rather than iterator I: I may have been
-    // invalidated when we looked up DstKey.
     MemMgrs.erase(SrcKey);
   }
 }

llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp

@@ -65,6 +65,36 @@ TEST_F(ObjectLinkingLayerTest, AddLinkGraph) {
   EXPECT_THAT_EXPECTED(ES.lookup(&JD, "_X"), Succeeded());
 }
 
+TEST_F(ObjectLinkingLayerTest, ResourceTracker) {
+  // This test transfers allocations to previously unknown ResourceTrackers,
+  // while increasing the number of trackers in the ObjectLinkingLayer, which
+  // may invalidate some iterators internally.
+  std::vector<ResourceTrackerSP> Trackers;
+  for (unsigned I = 0; I < 64; I++) {
+    auto G = std::make_unique<LinkGraph>("foo", Triple("x86_64-apple-darwin"),
+                                         8, llvm::endianness::little,
+                                         x86_64::getEdgeKindName);
+
+    auto &Sec1 = G->createSection("__data", MemProt::Read | MemProt::Write);
+    auto &B1 = G->createContentBlock(Sec1, BlockContent,
+                                     orc::ExecutorAddr(0x1000), 8, 0);
+    llvm::SmallString<0> SymbolName;
+    SymbolName += "_X";
+    SymbolName += std::to_string(I);
+    G->addDefinedSymbol(B1, 4, SymbolName, 4, Linkage::Strong, Scope::Default,
+                        false, false);
+
+    auto RT1 = JD.createResourceTracker();
+    EXPECT_THAT_ERROR(ObjLinkingLayer.add(RT1, std::move(G)), Succeeded());
+    EXPECT_THAT_EXPECTED(ES.lookup(&JD, SymbolName), Succeeded());
+
+    auto RT2 = JD.createResourceTracker();
+    RT1->transferTo(*RT2);
+
+    Trackers.push_back(RT2);
+  }
+}
+
 TEST_F(ObjectLinkingLayerTest, ClaimLateDefinedWeakSymbols) {
   // Check that claiming weak symbols works as expected.
   //