lib/Analysis/IPA/CallGraphSCCPass.cpp

   1 //===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the CallGraphSCCPass class, which is used for passes
  11 // which are implemented as bottom-up traversals on the call graph.  Because
  12 // there may be cycles in the call graph, passes of this type operate on the
  13 // call-graph in SCC order: that is, they process function bottom-up, except for
  14 // recursive functions, which they process all at once.
  15 //
  16 //===----------------------------------------------------------------------===//
  17
  18 #include "llvm/CallGraphSCCPass.h"
  19 #include "llvm/Analysis/CallGraph.h"
  20 #include "llvm/ADT/SCCIterator.h"
  21 #include "llvm/PassManagers.h"
  22 #include "llvm/Function.h"
  23 using namespace llvm;
  24
  25 //===----------------------------------------------------------------------===//
  26 // CGPassManager
  27 //
  28 /// CGPassManager manages FPPassManagers and CalLGraphSCCPasses.
  29
  30 namespace {
  31
  32 class CGPassManager : public ModulePass, public PMDataManager {
  33
  34 public:
  35   static char ID;
  36   explicit CGPassManager(int Depth)
  37     : ModulePass(&ID), PMDataManager(Depth) { }
  38
  39   /// run - Execute all of the passes scheduled for execution.  Keep track of
  40   /// whether any of the passes modifies the module, and if so, return true.
  41   bool runOnModule(Module &M);
  42
  43   bool doInitialization(CallGraph &CG);
  44   bool doFinalization(CallGraph &CG);
  45
  46   /// Pass Manager itself does not invalidate any analysis info.
  47   void getAnalysisUsage(AnalysisUsage &Info) const {
  48     // CGPassManager walks SCC and it needs CallGraph.
  49     Info.addRequired<CallGraph>();
  50     Info.setPreservesAll();
  51   }
  52
  53   virtual const char *getPassName() const {
  54     return "CallGraph Pass Manager";
  55   }
  56
  57   // Print passes managed by this manager
  58   void dumpPassStructure(unsigned Offset) {
  59     llvm::cerr << std::string(Offset*2, ' ') << "Call Graph SCC Pass Manager\n";
  60     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
  61       Pass *P = getContainedPass(Index);
  62       P->dumpPassStructure(Offset + 1);
  63       dumpLastUses(P, Offset+1);
  64     }
  65   }
  66
  67   Pass *getContainedPass(unsigned N) {
  68     assert ( N < PassVector.size() && "Pass number out of range!");
  69     Pass *FP = static_cast<Pass *>(PassVector[N]);
  70     return FP;
  71   }
  72
  73   virtual PassManagerType getPassManagerType() const {
  74     return PMT_CallGraphPassManager;
  75   }
  76 };
  77
  78 }
  79
  80 char CGPassManager::ID = 0;
  81 /// run - Execute all of the passes scheduled for execution.  Keep track of
  82 /// whether any of the passes modifies the module, and if so, return true.
  83 bool CGPassManager::runOnModule(Module &M) {
  84   CallGraph &CG = getAnalysis<CallGraph>();
  85   bool Changed = doInitialization(CG);
  86
  87   // Walk SCC
  88   for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG);
  89        I != E; ++I) {
  90
  91     // Run all passes on current SCC
  92     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
  93       Pass *P = getContainedPass(Index);
  94
  95       dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, "");
  96       dumpRequiredSet(P);
  97
  98       initializeAnalysisImpl(P);
  99
 100       StartPassTimer(P);
 101       if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P))
 102         Changed |= CGSP->runOnSCC(*I);   // TODO : What if CG is changed ?
 103       else {
 104         FPPassManager *FPP = dynamic_cast<FPPassManager *>(P);
 105         assert (FPP && "Invalid CGPassManager member");
 106
 107         // Run pass P on all functions current SCC
 108         std::vector<CallGraphNode*> &SCC = *I;
 109         for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
 110           Function *F = SCC[i]->getFunction();
 111           if (F) {
 112             dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getNameStart());
 113             Changed |= FPP->runOnFunction(*F);
 114           }
 115         }
 116       }
 117       StopPassTimer(P);
 118
 119       if (Changed)
 120         dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
 121       dumpPreservedSet(P);
 122
 123       verifyPreservedAnalysis(P);
 124       removeNotPreservedAnalysis(P);
 125       recordAvailableAnalysis(P);
 126       removeDeadPasses(P, "", ON_CG_MSG);
 127     }
 128   }
 129   Changed |= doFinalization(CG);
 130   return Changed;
 131 }
 132
 133 /// Initialize CG
 134 bool CGPassManager::doInitialization(CallGraph &CG) {
 135   bool Changed = false;
 136   for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
 137     Pass *P = getContainedPass(Index);
 138     if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
 139       Changed |= CGSP->doInitialization(CG);
 140     } else {
 141       FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
 142       assert (FP && "Invalid CGPassManager member");
 143       Changed |= FP->doInitialization(CG.getModule());
 144     }
 145   }
 146   return Changed;
 147 }
 148
 149 /// Finalize CG
 150 bool CGPassManager::doFinalization(CallGraph &CG) {
 151   bool Changed = false;
 152   for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
 153     Pass *P = getContainedPass(Index);
 154     if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
 155       Changed |= CGSP->doFinalization(CG);
 156     } else {
 157       FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
 158       assert (FP && "Invalid CGPassManager member");
 159       Changed |= FP->doFinalization(CG.getModule());
 160     }
 161   }
 162   return Changed;
 163 }
 164
 165 /// Assign pass manager to manage this pass.
 166 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
 167                                          PassManagerType PreferredType) {
 168   // Find CGPassManager
 169   while (!PMS.empty() &&
 170          PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
 171     PMS.pop();
 172
 173   assert (!PMS.empty() && "Unable to handle Call Graph Pass");
 174   CGPassManager *CGP = dynamic_cast<CGPassManager *>(PMS.top());
 175
 176   // Create new Call Graph SCC Pass Manager if it does not exist.
 177   if (!CGP) {
 178
 179     assert (!PMS.empty() && "Unable to create Call Graph Pass Manager");
 180     PMDataManager *PMD = PMS.top();
 181
 182     // [1] Create new Call Graph Pass Manager
 183     CGP = new CGPassManager(PMD->getDepth() + 1);
 184
 185     // [2] Set up new manager's top level manager
 186     PMTopLevelManager *TPM = PMD->getTopLevelManager();
 187     TPM->addIndirectPassManager(CGP);
 188
 189     // [3] Assign manager to manage this new manager. This may create
 190     // and push new managers into PMS
 191     Pass *P = dynamic_cast<Pass *>(CGP);
 192     TPM->schedulePass(P);
 193
 194     // [4] Push new manager into PMS
 195     PMS.push(CGP);
 196   }
 197
 198   CGP->add(this);
 199 }
 200
 201 /// getAnalysisUsage - For this class, we declare that we require and preserve
 202 /// the call graph.  If the derived class implements this method, it should
 203 /// always explicitly call the implementation here.
 204 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
 205   AU.addRequired<CallGraph>();
 206   AU.addPreserved<CallGraph>();
 207 }