[CallGraphUpdater] Remove some legacy pass manager support (#98362)

aeubanks · web-flow · commit 58bc98cd3abd · 2024-07-12T10:02:50.000-07:00
We don't have any legacy pass manager CGSCC passes that modify the call
graph (we only use it in the codegen pipeline to run function passes in
call graph order). This is the beginning of removing CallGraphUpdater
and making all the relevant CGSCC passes directly use the new pass
manager APIs.
diff --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -1828,14 +1828,6 @@ struct Attributor {
       Configuration.InitializationCallback(*this, F);
   }
 
-  /// Helper function to remove callsite.
-  void removeCallSite(CallInst *CI) {
-    if (!CI)
-      return;
-
-    Configuration.CGUpdater.removeCallSite(*CI);
-  }
-
   /// Record that \p U is to be replaces with \p NV after information was
   /// manifested. This also triggers deletion of trivially dead istructions.
   bool changeUseAfterManifest(Use &U, Value &NV) {
diff --git a/llvm/include/llvm/Transforms/Utils/CallGraphUpdater.h b/llvm/include/llvm/Transforms/Utils/CallGraphUpdater.h
@@ -38,12 +38,6 @@ class CallGraphUpdater {
   SmallVector<Function *, 16> DeadFunctionsInComdats;
   ///}
 
-  /// Old PM variables
-  ///{
-  CallGraph *CG = nullptr;
-  CallGraphSCC *CGSCC = nullptr;
-  ///}
-
   /// New PM variables
   ///{
   LazyCallGraph *LCG = nullptr;
@@ -60,10 +54,6 @@ class CallGraphUpdater {
   /// Initializers for usage outside of a CGSCC pass, inside a CGSCC pass in
   /// the old and new pass manager (PM).
   ///{
-  void initialize(CallGraph &CG, CallGraphSCC &SCC) {
-    this->CG = &CG;
-    this->CGSCC = &SCC;
-  }
   void initialize(LazyCallGraph &LCG, LazyCallGraph::SCC &SCC,
                   CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR) {
     this->LCG = &LCG;
@@ -95,14 +85,6 @@ class CallGraphUpdater {
   /// Note that \p OldFn is also removed from the call graph
   /// (\see removeFunction).
   void replaceFunctionWith(Function &OldFn, Function &NewFn);
-
-  /// Remove the call site \p CS from the call graph.
-  void removeCallSite(CallBase &CS);
-
-  /// Replace \p OldCS with the new call site \p NewCS.
-  /// \return True if the replacement was successful, otherwise False. In the
-  /// latter case the parent function of \p OldCB needs to be re-analyzed.
-  bool replaceCallSite(CallBase &OldCS, CallBase &NewCS);
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -2557,8 +2557,6 @@ ChangeStatus Attributor::cleanupIR() {
       if (auto *CB = dyn_cast<CallBase>(I)) {
         assert((isa<IntrinsicInst>(CB) || isRunOn(*I->getFunction())) &&
                "Cannot delete an instruction outside the current SCC!");
-        if (!isa<IntrinsicInst>(CB))
-          Configuration.CGUpdater.removeCallSite(*CB);
       }
       I->dropDroppableUses();
       CGModifiedFunctions.insert(I->getFunction());
@@ -3186,7 +3184,6 @@ ChangeStatus Attributor::rewriteFunctionSignatures(
       assert(OldCB.getType() == NewCB.getType() &&
              "Cannot handle call sites with different types!");
       ModifiedFns.insert(OldCB.getFunction());
-      Configuration.CGUpdater.replaceCallSite(OldCB, NewCB);
       OldCB.replaceAllUsesWith(&NewCB);
       OldCB.eraseFromParent();
     }
diff --git a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
@@ -1453,7 +1453,6 @@ struct OpenMPOpt {
       };
       emitRemark<OptimizationRemark>(CI, "OMP160", Remark);
 
-      CGUpdater.removeCallSite(*CI);
       CI->eraseFromParent();
       Changed = true;
       ++NumOpenMPParallelRegionsDeleted;
@@ -1895,7 +1894,6 @@ struct OpenMPOpt {
       else
         emitRemark<OptimizationRemark>(&F, "OMP170", Remark);
 
-      CGUpdater.removeCallSite(*CI);
       CI->replaceAllUsesWith(ReplVal);
       CI->eraseFromParent();
       ++NumOpenMPRuntimeCallsDeduplicated;
diff --git a/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp b/llvm/lib/Transforms/Utils/CallGraphUpdater.cpp
@@ -13,9 +13,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/CallGraphUpdater.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Analysis/CallGraphSCCPass.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 
@@ -28,53 +25,33 @@ bool CallGraphUpdater::finalize() {
                          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(PoisonValue::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(PoisonValue::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);
-
-        FAM->clear(*DeadFn, DeadFn->getName());
-        AM->clear(*DeadSCC, DeadSCC->getName());
-        LCG->markDeadFunction(*DeadFn);
-
-        // Mark the relevant parts of the call graph as invalid so we don't
-        // visit them.
-        UR->InvalidatedSCCs.insert(LCG->lookupSCC(N));
-        UR->DeadFunctions.push_back(DeadFn);
-      } else {
-        // The CGSCC infrastructure batch deletes functions at the end of the
-        // call graph walk, so only erase the function if we're not using that
-        // infrastructure.
-        // The function is now really dead and de-attached from everything.
-        DeadFn->eraseFromParent();
-      }
+  // 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(PoisonValue::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);
+
+      FAM->clear(*DeadFn, DeadFn->getName());
+      AM->clear(*DeadSCC, DeadSCC->getName());
+      LCG->markDeadFunction(*DeadFn);
+
+      // Mark the relevant parts of the call graph as invalid so we don't
+      // visit them.
+      UR->InvalidatedSCCs.insert(LCG->lookupSCC(N));
+      UR->DeadFunctions.push_back(DeadFn);
+    } else {
+      // The CGSCC infrastructure batch deletes functions at the end of the
+      // call graph walk, so only erase the function if we're not using that
+      // infrastructure.
+      // The function is now really dead and de-attached from everything.
+      DeadFn->eraseFromParent();
     }
   }
 
@@ -85,11 +62,7 @@ bool CallGraphUpdater::finalize() {
 }
 
 void CallGraphUpdater::reanalyzeFunction(Function &Fn) {
-  if (CG) {
-    CallGraphNode *OldCGN = CG->getOrInsertFunction(&Fn);
-    OldCGN->removeAllCalledFunctions();
-    CG->populateCallGraphNode(OldCGN);
-  } else if (LCG) {
+  if (LCG) {
     LazyCallGraph::Node &N = LCG->get(Fn);
     LazyCallGraph::SCC *C = LCG->lookupSCC(N);
     updateCGAndAnalysisManagerForCGSCCPass(*LCG, *C, N, *AM, *UR, *FAM);
@@ -98,9 +71,7 @@ void CallGraphUpdater::reanalyzeFunction(Function &Fn) {
 
 void CallGraphUpdater::registerOutlinedFunction(Function &OriginalFn,
                                                 Function &NewFn) {
-  if (CG)
-    CG->addToCallGraph(&NewFn);
-  else if (LCG)
+  if (LCG)
     LCG->addSplitFunction(OriginalFn, NewFn);
 }
 
@@ -112,59 +83,17 @@ void CallGraphUpdater::removeFunction(Function &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);
-  }
   if (FAM)
     FAM->clear(DeadFn, DeadFn.getName());
 }
 
 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) {
+  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);
-}
diff --git a/llvm/unittests/IR/LegacyPassManagerTest.cpp b/llvm/unittests/IR/LegacyPassManagerTest.cpp
