Option 2: Add bool& Devirt parameter to runSCC

[GorNishanov]

Summary

• very in your face
• breaks out-of-tree projects (but easy to fix)

+now any SCCPass has an ability to indicate that is has devirtualized something or for some other reason pipeline need to be run one more time for the current SCC.

include/llvm/Analysis/CallGraphSCCPass.h

public:
   /// runOnSCC - This method should be implemented by the subclass to perform
   /// whatever action is necessary for the specified SCC.  Note that
   /// non-recursive (or only self-recursive) functions will have an SCC size of
   /// 1, where recursive portions of the call graph will have SCC size > 1.
   ///
   /// SCC passes that add or delete functions to the SCC are required to update
   /// the SCC list, otherwise stale pointers may be dereferenced.
   ///
-  virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
+  /// If the SCC pass requires the entire CGSCC pipeline to rerun on 
+  /// the current SCC. Set Devirt to true.
+  virtual bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) = 0;
 
   /// doFinalization - This method is called after the SCC's of the program has
   /// been processed, allowing the pass to do final cleanup as necessary.
   virtual bool doFinalization(CallGraph &CG) {
     return false;
   }
 
   /// Assign pass manager to manager this pass

include/llvm/Transforms/IPO/InlinerPass.h

struct Inliner : public CallGraphSCCPass {
 
   /// getAnalysisUsage - For this class, we declare that we require and preserve
   /// the call graph.  If the derived class implements this method, it should
   /// always explicitly call the implementation here.
   void getAnalysisUsage(AnalysisUsage &Info) const override;
 
   // Main run interface method, this implements the interface required by the
   // Pass class.
-  bool runOnSCC(CallGraphSCC &SCC) override;
+  bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override;
 
   using llvm::Pass::doFinalization;
   // doFinalization - Remove now-dead linkonce functions at the end of
   // processing to avoid breaking the SCC traversal.
   bool doFinalization(CallGraph &CG) override;
 
   /// getInlineCost - This method must be implemented by the subclass to
   /// determine the cost of inlining the specified call site.  If the cost

lib/Analysis/CallGraphSCCPass.cpp

if (!PM) {
     CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
     if (!CallGraphUpToDate) {
       DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false);
       CallGraphUpToDate = true;
     }
 
     {
       TimeRegion PassTimer(getPassTimer(CGSP));
-      Changed = CGSP->runOnSCC(CurSCC);
+      Changed = CGSP->runOnSCC(CurSCC, DevirtualizedCall);
     }
     
     // After the CGSCCPass is done, when assertions are enabled, use
     // RefreshCallGraph to verify that the callgraph was correctly updated.
 #ifndef NDEBUG
     if (Changed)
       RefreshCallGraph(CurSCC, CG, true);
 #endif
public:
     static char ID;
     PrintCallGraphPass(const std::string &B, raw_ostream &o)
       : CallGraphSCCPass(ID), Banner(B), Out(o) {}
 
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.setPreservesAll();
     }
 
-    bool runOnSCC(CallGraphSCC &SCC) override {
+    bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override {
       Out << Banner;
       for (CallGraphNode *CGN : SCC) {
         if (CGN->getFunction()) {
           if (isFunctionInPrintList(CGN->getFunction()->getName()))
             CGN->getFunction()->print(Out);
         } else
           Out << "\nPrinting <null> Function\n";
       }

lib/Transforms/Coroutines/CoroInline.cpp

 
 /// \brief Inline outlined coroutine parts.
 class CoroInline : public CallGraphSCCPass {
 public:
   CoroInline() : CallGraphSCCPass(ID) {}
 
   static char ID; // Pass identification, replacement for typeid
 
-  bool runOnSCC(CallGraphSCC &SCC) override {
+  bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override {
     bool changed = false;
 
     for (CallGraphNode *CGN : SCC)
       if (auto F = CGN->getFunction())
         if (auto CI = CoroCommon::findCoroInit(F, Phase::ReadyForSplit))
           changed |= processParts(CI->meta().getParts());
 
     return changed;

lib/Transforms/Coroutines/CoroSplit.cpp

 #if 0
     bool doInitialization(CallGraph &CG) override {
       bool changed = preSplitCoroutines(CG);
       changed |= CallGraphSCCPass::doInitialization(CG);
       return changed;
     }
 #endif
 
-    bool runOnSCC(CallGraphSCC &SCC) override {
+    bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override {
       // find coroutines for processing
       SmallVector<CoroInitInst*, 4> CIs;
       for (CallGraphNode *CGN : SCC)
         if (auto F = CGN->getFunction())
           if (auto CoroInit =
                   CoroCommon::findCoroInit(F, Phase::PostSplit, false))
             CIs.push_back(CoroInit);
 
       if (CIs.empty())
         return false;
 
       CoroutineShape Shape;
 
       for (CoroInitInst* CoroInit : CIs)
-        if (CoroInit->meta().getPhase() == Phase::NotReadyForSplit)
+        if (CoroInit->meta().getPhase() == Phase::NotReadyForSplit) {
           preSplitPass(CoroInit, SCC);
+          Devirt = true;
+        }
         else
           splitCoroutine(CoroInit, Shape);
 
       return true;
     }
   };
 }
 

lib/Transforms/IPO/ArgumentPromotion.cpp

namespace {
   struct ArgPromotion : public CallGraphSCCPass {
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.addRequired<AssumptionCacheTracker>();
       AU.addRequired<TargetLibraryInfoWrapperPass>();
       getAAResultsAnalysisUsage(AU);
       CallGraphSCCPass::getAnalysisUsage(AU);
     }
 
-    bool runOnSCC(CallGraphSCC &SCC) override;
+    bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override;
     static char ID; // Pass identification, replacement for typeid
     explicit ArgPromotion(unsigned maxElements = 3)
         : CallGraphSCCPass(ID), maxElements(maxElements) {
       initializeArgPromotionPass(*PassRegistry::getPassRegistry());
     }
 
     /// A vector used to hold the indices of a single GEP instruction
     typedef std::vector<uint64_t> IndicesVector;

 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_END(ArgPromotion, "argpromotion",
                 "Promote 'by reference' arguments to scalars", false, false)
 
 Pass *llvm::createArgumentPromotionPass(unsigned maxElements) {
   return new ArgPromotion(maxElements);
 }
 
-bool ArgPromotion::runOnSCC(CallGraphSCC &SCC) {
+bool ArgPromotion::runOnSCC(CallGraphSCC &SCC, bool& Devirt) {
   bool Changed = false, LocalChange;
 
   do {  // Iterate until we stop promoting from this SCC.
     LocalChange = false;
     // Attempt to promote arguments from all functions in this SCC.
     for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
       if (CallGraphNode *CGN = PromoteArguments(*I)) {
         LocalChange = true;

lib/Transforms/IPO/FunctionAttrs.cpp

 
 namespace {
 struct PostOrderFunctionAttrsLegacyPass : public CallGraphSCCPass {
   static char ID; // Pass identification, replacement for typeid
   PostOrderFunctionAttrsLegacyPass() : CallGraphSCCPass(ID) {
     initializePostOrderFunctionAttrsLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
-  bool runOnSCC(CallGraphSCC &SCC) override;
+  bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override;
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesCFG();
     AU.addRequired<AssumptionCacheTracker>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
     getAAResultsAnalysisUsage(AU);
     CallGraphSCCPass::getAnalysisUsage(AU);
   }

 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
 INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_END(PostOrderFunctionAttrsLegacyPass, "functionattrs",
                     "Deduce function attributes", false, false)
 
 Pass *llvm::createPostOrderFunctionAttrsLegacyPass() { return new PostOrderFunctionAttrsLegacyPass(); }
 
-bool PostOrderFunctionAttrsLegacyPass::runOnSCC(CallGraphSCC &SCC) {
+bool PostOrderFunctionAttrsLegacyPass::runOnSCC(CallGraphSCC &SCC,
+                                                bool &Devirt) {
   TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
   bool Changed = false;
 
   // We compute dedicated AA results for each function in the SCC as needed. We
   // use a lambda referencing external objects so that they live long enough to
   // be queried, but we re-use them each time.
   Optional<BasicAAResult> BAR;
   Optional<AAResults> AAR;

lib/Transforms/IPO/InlineSimple.cpp

public:
   static char ID; // Pass identification, replacement for typeid
 
   InlineCost getInlineCost(CallSite CS) override {
     Function *Callee = CS.getCalledFunction();
     TargetTransformInfo &TTI = TTIWP->getTTI(*Callee);
     return llvm::getInlineCost(CS, DefaultThreshold, TTI, ACT);
   }
 
-  bool runOnSCC(CallGraphSCC &SCC) override;
+  bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override;
   void getAnalysisUsage(AnalysisUsage &AU) const override;
 
 private:
   TargetTransformInfoWrapperPass *TTIWP;
 };
 
 } // end anonymous namespace
 

 }
 
 Pass *llvm::createFunctionInliningPass(unsigned OptLevel,
                                        unsigned SizeOptLevel) {
   return new SimpleInliner(
       llvm::computeThresholdFromOptLevels(OptLevel, SizeOptLevel));
 }
 
-bool SimpleInliner::runOnSCC(CallGraphSCC &SCC) {
+bool SimpleInliner::runOnSCC(CallGraphSCC &SCC, bool& Devirt) {
   TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
-  return Inliner::runOnSCC(SCC);
+  return Inliner::runOnSCC(SCC, Devirt);
 }
 
 void SimpleInliner::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<TargetTransformInfoWrapperPass>();
   Inliner::getAnalysisUsage(AU);
 }

lib/Transforms/IPO/Inliner.cpp

assert(unsigned(InlineHistoryID) < InlineHistory.size() &&
            "Invalid inline history ID");
     if (InlineHistory[InlineHistoryID].first == F)
       return true;
     InlineHistoryID = InlineHistory[InlineHistoryID].second;
   }
   return false;
 }
 
-bool Inliner::runOnSCC(CallGraphSCC &SCC) {
+bool Inliner::runOnSCC(CallGraphSCC &SCC, bool& Devirt) {
   CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
   ACT = &getAnalysis<AssumptionCacheTracker>();
   auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
 
   SmallPtrSet<Function*, 8> SCCFunctions;
   DEBUG(dbgs() << "Inliner visiting SCC:");
   for (CallGraphNode *Node : SCC) {
     Function *F = Node->getFunction();

lib/Transforms/IPO/PruneEH.cpp

 namespace {
   struct PruneEH : public CallGraphSCCPass {
     static char ID; // Pass identification, replacement for typeid
     PruneEH() : CallGraphSCCPass(ID) {
       initializePruneEHPass(*PassRegistry::getPassRegistry());
     }
 
     // runOnSCC - Analyze the SCC, performing the transformation if possible.
-    bool runOnSCC(CallGraphSCC &SCC) override;
+    bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override;
 
     bool SimplifyFunction(Function *F);
     void DeleteBasicBlock(BasicBlock *BB);
   };
 }
 
 char PruneEH::ID = 0;
 INITIALIZE_PASS_BEGIN(PruneEH, "prune-eh",
                 "Remove unused exception handling info", false, false)
 INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
 INITIALIZE_PASS_END(PruneEH, "prune-eh",
                 "Remove unused exception handling info", false, false)
 
 Pass *llvm::createPruneEHPass() { return new PruneEH(); }
 
 
-bool PruneEH::runOnSCC(CallGraphSCC &SCC) {
+bool PruneEH::runOnSCC(CallGraphSCC &SCC, bool& Devirt) {
   SmallPtrSet<CallGraphNode *, 8> SCCNodes;
   CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
   bool MadeChange = false;
 
   // Fill SCCNodes with the elements of the SCC.  Used for quickly
   // looking up whether a given CallGraphNode is in this SCC.
   for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
     SCCNodes.insert(*I);

tools/opt/PassPrinters.cpp

struct CallGraphSCCPassPrinter : public CallGraphSCCPass {
   bool QuietPass;
 
   CallGraphSCCPassPrinter(const PassInfo *PI, raw_ostream &out, bool Quiet)
       : CallGraphSCCPass(ID), PassToPrint(PI), Out(out), QuietPass(Quiet) {
     std::string PassToPrintName = PassToPrint->getPassName();
     PassName = "CallGraphSCCPass Printer: " + PassToPrintName;
   }
 
-  bool runOnSCC(CallGraphSCC &SCC) override {
+  bool runOnSCC(CallGraphSCC &SCC, bool& Devirt) override {
     if (!QuietPass)
       Out << "Printing analysis '" << PassToPrint->getPassName() << "':\n";
 
     // Get and print pass...
     for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
       Function *F = (*I)->getFunction();
       if (F)
         getAnalysisID<Pass>(PassToPrint->getTypeInfo())