1 files changed, 167 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp b/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
new file mode 100644
index 000000000000..52e859361c59
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
@@ -0,0 +1,167 @@
+//===- CallGraphUpdater.cpp - A (lazy) call graph update helper -----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file provides interfaces used to manipulate a call graph, regardless
+/// if it is a "old style" CallGraph or an "new style" LazyCallGraph.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/CallGraphUpdater.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+
+using namespace llvm;
+
+bool CallGraphUpdater::finalize() {
+  if (!DeadFunctionsInComdats.empty()) {
+    filterDeadComdatFunctions(*DeadFunctionsInComdats.front()->getParent(),
+                              DeadFunctionsInComdats);
+    DeadFunctions.append(DeadFunctionsInComdats.begin(),
+                         DeadFunctionsInComdats.end());
+  }
+
+  if (CG) {
+    // First remove all references, e.g., outgoing via called functions. This is
+    // necessary as we can delete functions that have circular references.
+    for (Function *DeadFn : DeadFunctions) {
+      DeadFn->removeDeadConstantUsers();
+      CallGraphNode *DeadCGN = (*CG)[DeadFn];
+      DeadCGN->removeAllCalledFunctions();
+      CG->getExternalCallingNode()->removeAnyCallEdgeTo(DeadCGN);
+      DeadFn->replaceAllUsesWith(UndefValue::get(DeadFn->getType()));
+    }
+
+    // Then remove the node and function from the module.
+    for (Function *DeadFn : DeadFunctions) {
+      CallGraphNode *DeadCGN = CG->getOrInsertFunction(DeadFn);
+      assert(DeadCGN->getNumReferences() == 0 &&
+             "References should have been handled by now");
+      delete CG->removeFunctionFromModule(DeadCGN);
+    }
+  } else {
+    // This is the code path for the new lazy call graph and for the case were
+    // no call graph was provided.
+    for (Function *DeadFn : DeadFunctions) {
+      DeadFn->removeDeadConstantUsers();
+      DeadFn->replaceAllUsesWith(UndefValue::get(DeadFn->getType()));
+
+      if (LCG && !ReplacedFunctions.count(DeadFn)) {
+        // Taken mostly from the inliner:
+        LazyCallGraph::Node &N = LCG->get(*DeadFn);
+        auto *DeadSCC = LCG->lookupSCC(N);
+        assert(DeadSCC && DeadSCC->size() == 1 &&
+               &DeadSCC->begin()->getFunction() == DeadFn);
+        auto &DeadRC = DeadSCC->getOuterRefSCC();
+
+        FunctionAnalysisManager &FAM =
+            AM->getResult<FunctionAnalysisManagerCGSCCProxy>(*DeadSCC, *LCG)
+                .getManager();
+
+        FAM.clear(*DeadFn, DeadFn->getName());
+        AM->clear(*DeadSCC, DeadSCC->getName());
+        LCG->removeDeadFunction(*DeadFn);
+
+        // Mark the relevant parts of the call graph as invalid so we don't
+        // visit them.
+        UR->InvalidatedSCCs.insert(DeadSCC);
+        UR->InvalidatedRefSCCs.insert(&DeadRC);
+      }
+
+      // The function is now really dead and de-attached from everything.
+      DeadFn->eraseFromParent();
+    }
+  }
+
+  bool Changed = !DeadFunctions.empty();
+  DeadFunctionsInComdats.clear();
+  DeadFunctions.clear();
+  return Changed;
+}
+
+void CallGraphUpdater::reanalyzeFunction(Function &Fn) {
+  if (CG) {
+    CallGraphNode *OldCGN = CG->getOrInsertFunction(&Fn);
+    OldCGN->removeAllCalledFunctions();
+    CG->populateCallGraphNode(OldCGN);
+  } else if (LCG) {
+    LazyCallGraph::Node &N = LCG->get(Fn);
+    LazyCallGraph::SCC *C = LCG->lookupSCC(N);
+    updateCGAndAnalysisManagerForCGSCCPass(*LCG, *C, N, *AM, *UR, *FAM);
+  }
+}
+
+void CallGraphUpdater::registerOutlinedFunction(Function &NewFn) {
+  if (CG)
+    CG->addToCallGraph(&NewFn);
+  else if (LCG)
+    LCG->addNewFunctionIntoSCC(NewFn, *SCC);
+}
+
+void CallGraphUpdater::removeFunction(Function &DeadFn) {
+  DeadFn.deleteBody();
+  DeadFn.setLinkage(GlobalValue::ExternalLinkage);
+  if (DeadFn.hasComdat())
+    DeadFunctionsInComdats.push_back(&DeadFn);
+  else
+    DeadFunctions.push_back(&DeadFn);
+
+  // For the old call graph we remove the function from the SCC right away.
+  if (CG && !ReplacedFunctions.count(&DeadFn)) {
+    CallGraphNode *DeadCGN = (*CG)[&DeadFn];
+    DeadCGN->removeAllCalledFunctions();
+    CGSCC->DeleteNode(DeadCGN);
+  }
+}
+
+void CallGraphUpdater::replaceFunctionWith(Function &OldFn, Function &NewFn) {
+  OldFn.removeDeadConstantUsers();
+  ReplacedFunctions.insert(&OldFn);
+  if (CG) {
+    // Update the call graph for the newly promoted function.
+    CallGraphNode *OldCGN = (*CG)[&OldFn];
+    CallGraphNode *NewCGN = CG->getOrInsertFunction(&NewFn);
+    NewCGN->stealCalledFunctionsFrom(OldCGN);
+    CG->ReplaceExternalCallEdge(OldCGN, NewCGN);
+
+    // And update the SCC we're iterating as well.
+    CGSCC->ReplaceNode(OldCGN, NewCGN);
+  } else if (LCG) {
+    // Directly substitute the functions in the call graph.
+    LazyCallGraph::Node &OldLCGN = LCG->get(OldFn);
+    SCC->getOuterRefSCC().replaceNodeFunction(OldLCGN, NewFn);
+  }
+  removeFunction(OldFn);
+}
+
+bool CallGraphUpdater::replaceCallSite(CallBase &OldCS, CallBase &NewCS) {
+  // This is only necessary in the (old) CG.
+  if (!CG)
+    return true;
+
+  Function *Caller = OldCS.getCaller();
+  CallGraphNode *NewCalleeNode =
+      CG->getOrInsertFunction(NewCS.getCalledFunction());
+  CallGraphNode *CallerNode = (*CG)[Caller];
+  if (llvm::none_of(*CallerNode, [&OldCS](const CallGraphNode::CallRecord &CR) {
+        return CR.first && *CR.first == &OldCS;
+      }))
+    return false;
+  CallerNode->replaceCallEdge(OldCS, NewCS, NewCalleeNode);
+  return true;
+}
+
+void CallGraphUpdater::removeCallSite(CallBase &CS) {
+  // This is only necessary in the (old) CG.
+  if (!CG)
+    return;
+
+  Function *Caller = CS.getCaller();
+  CallGraphNode *CallerNode = (*CG)[Caller];
+  CallerNode->removeCallEdgeFor(CS);
+}