src/llvm/lib/Analysis/RegionPass.cpp

   1 //===- RegionPass.cpp - Region Pass and Region Pass Manager ---------------===//
   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 RegionPass and RGPassManager. All region optimization
  11 // and transformation passes are derived from RegionPass. RGPassManager is
  12 // responsible for managing RegionPasses.
  13 // most of these codes are COPY from LoopPass.cpp
  14 //
  15 //===----------------------------------------------------------------------===//
  16 #include "llvm/Analysis/RegionPass.h"
  17 #include "llvm/Analysis/RegionIterator.h"
  18 #include "llvm/Support/Debug.h"
  19 #include "llvm/Support/Timer.h"
  20 using namespace llvm;
  21
  22 #define DEBUG_TYPE "regionpassmgr"
  23
  24 //===----------------------------------------------------------------------===//
  25 // RGPassManager
  26 //
  27
  28 char RGPassManager::ID = 0;
  29
  30 RGPassManager::RGPassManager()
  31   : FunctionPass(ID), PMDataManager() {
  32   skipThisRegion = false;
  33   redoThisRegion = false;
  34   RI = nullptr;
  35   CurrentRegion = nullptr;
  36 }
  37
  38 // Recurse through all subregions and all regions  into RQ.
  39 static void addRegionIntoQueue(Region &R, std::deque<Region *> &RQ) {
  40   RQ.push_back(&R);
  41   for (const auto &E : R)
  42     addRegionIntoQueue(*E, RQ);
  43 }
  44
  45 /// Pass Manager itself does not invalidate any analysis info.
  46 void RGPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
  47   Info.addRequired<RegionInfoPass>();
  48   Info.setPreservesAll();
  49 }
  50
  51 /// run - Execute all of the passes scheduled for execution.  Keep track of
  52 /// whether any of the passes modifies the function, and if so, return true.
  53 bool RGPassManager::runOnFunction(Function &F) {
  54   RI = &getAnalysis<RegionInfoPass>().getRegionInfo();
  55   bool Changed = false;
  56
  57   // Collect inherited analysis from Module level pass manager.
  58   populateInheritedAnalysis(TPM->activeStack);
  59
  60   addRegionIntoQueue(*RI->getTopLevelRegion(), RQ);
  61
  62   if (RQ.empty()) // No regions, skip calling finalizers
  63     return false;
  64
  65   // Initialization
  66   for (std::deque<Region *>::const_iterator I = RQ.begin(), E = RQ.end();
  67        I != E; ++I) {
  68     Region *R = *I;
  69     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
  70       RegionPass *RP = (RegionPass *)getContainedPass(Index);
  71       Changed |= RP->doInitialization(R, *this);
  72     }
  73   }
  74
  75   // Walk Regions
  76   while (!RQ.empty()) {
  77
  78     CurrentRegion  = RQ.back();
  79     skipThisRegion = false;
  80     redoThisRegion = false;
  81
  82     // Run all passes on the current Region.
  83     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
  84       RegionPass *P = (RegionPass*)getContainedPass(Index);
  85
  86       dumpPassInfo(P, EXECUTION_MSG, ON_REGION_MSG,
  87                    CurrentRegion->getNameStr());
  88       dumpRequiredSet(P);
  89
  90       initializeAnalysisImpl(P);
  91
  92       {
  93         PassManagerPrettyStackEntry X(P, *CurrentRegion->getEntry());
  94
  95         TimeRegion PassTimer(getPassTimer(P));
  96         Changed |= P->runOnRegion(CurrentRegion, *this);
  97       }
  98
  99       if (Changed)
 100         dumpPassInfo(P, MODIFICATION_MSG, ON_REGION_MSG,
 101                      skipThisRegion ? "<deleted>" :
 102                                     CurrentRegion->getNameStr());
 103       dumpPreservedSet(P);
 104
 105       if (!skipThisRegion) {
 106         // Manually check that this region is still healthy. This is done
 107         // instead of relying on RegionInfo::verifyRegion since RegionInfo
 108         // is a function pass and it's really expensive to verify every
 109         // Region in the function every time. That level of checking can be
 110         // enabled with the -verify-region-info option.
 111         {
 112           TimeRegion PassTimer(getPassTimer(P));
 113           CurrentRegion->verifyRegion();
 114         }
 115
 116         // Then call the regular verifyAnalysis functions.
 117         verifyPreservedAnalysis(P);
 118       }
 119
 120       removeNotPreservedAnalysis(P);
 121       recordAvailableAnalysis(P);
 122       removeDeadPasses(P,
 123                        skipThisRegion ? "<deleted>" :
 124                                       CurrentRegion->getNameStr(),
 125                        ON_REGION_MSG);
 126
 127       if (skipThisRegion)
 128         // Do not run other passes on this region.
 129         break;
 130     }
 131
 132     // If the region was deleted, release all the region passes. This frees up
 133     // some memory, and avoids trouble with the pass manager trying to call
 134     // verifyAnalysis on them.
 135     if (skipThisRegion)
 136       for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
 137         Pass *P = getContainedPass(Index);
 138         freePass(P, "<deleted>", ON_REGION_MSG);
 139       }
 140
 141     // Pop the region from queue after running all passes.
 142     RQ.pop_back();
 143
 144     if (redoThisRegion)
 145       RQ.push_back(CurrentRegion);
 146
 147     // Free all region nodes created in region passes.
 148     RI->clearNodeCache();
 149   }
 150
 151   // Finalization
 152   for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
 153     RegionPass *P = (RegionPass*)getContainedPass(Index);
 154     Changed |= P->doFinalization();
 155   }
 156
 157   // Print the region tree after all pass.
 158   DEBUG(
 159     dbgs() << "\nRegion tree of function " << F.getName()
 160            << " after all region Pass:\n";
 161     RI->dump();
 162     dbgs() << "\n";
 163     );
 164
 165   return Changed;
 166 }
 167
 168 /// Print passes managed by this manager
 169 void RGPassManager::dumpPassStructure(unsigned Offset) {
 170   errs().indent(Offset*2) << "Region Pass Manager\n";
 171   for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
 172     Pass *P = getContainedPass(Index);
 173     P->dumpPassStructure(Offset + 1);
 174     dumpLastUses(P, Offset+1);
 175   }
 176 }
 177
 178 namespace {
 179 //===----------------------------------------------------------------------===//
 180 // PrintRegionPass
 181 class PrintRegionPass : public RegionPass {
 182 private:
 183   std::string Banner;
 184   raw_ostream &Out;       // raw_ostream to print on.
 185
 186 public:
 187   static char ID;
 188   PrintRegionPass(const std::string &B, raw_ostream &o)
 189       : RegionPass(ID), Banner(B), Out(o) {}
 190
 191   void getAnalysisUsage(AnalysisUsage &AU) const override {
 192     AU.setPreservesAll();
 193   }
 194
 195   bool runOnRegion(Region *R, RGPassManager &RGM) override {
 196     Out << Banner;
 197     for (const auto &BB : R->blocks()) {
 198       if (BB)
 199         BB->print(Out);
 200       else
 201         Out << "Printing <null> Block";
 202     }
 203
 204     return false;
 205   }
 206 };
 207
 208 char PrintRegionPass::ID = 0;
 209 }  //end anonymous namespace
 210
 211 //===----------------------------------------------------------------------===//
 212 // RegionPass
 213
 214 // Check if this pass is suitable for the current RGPassManager, if
 215 // available. This pass P is not suitable for a RGPassManager if P
 216 // is not preserving higher level analysis info used by other
 217 // RGPassManager passes. In such case, pop RGPassManager from the
 218 // stack. This will force assignPassManager() to create new
 219 // LPPassManger as expected.
 220 void RegionPass::preparePassManager(PMStack &PMS) {
 221
 222   // Find RGPassManager
 223   while (!PMS.empty() &&
 224          PMS.top()->getPassManagerType() > PMT_RegionPassManager)
 225     PMS.pop();
 226
 227
 228   // If this pass is destroying high level information that is used
 229   // by other passes that are managed by LPM then do not insert
 230   // this pass in current LPM. Use new RGPassManager.
 231   if (PMS.top()->getPassManagerType() == PMT_RegionPassManager &&
 232     !PMS.top()->preserveHigherLevelAnalysis(this))
 233     PMS.pop();
 234 }
 235
 236 /// Assign pass manager to manage this pass.
 237 void RegionPass::assignPassManager(PMStack &PMS,
 238                                  PassManagerType PreferredType) {
 239   // Find RGPassManager
 240   while (!PMS.empty() &&
 241          PMS.top()->getPassManagerType() > PMT_RegionPassManager)
 242     PMS.pop();
 243
 244   RGPassManager *RGPM;
 245
 246   // Create new Region Pass Manager if it does not exist.
 247   if (PMS.top()->getPassManagerType() == PMT_RegionPassManager)
 248     RGPM = (RGPassManager*)PMS.top();
 249   else {
 250
 251     assert (!PMS.empty() && "Unable to create Region Pass Manager");
 252     PMDataManager *PMD = PMS.top();
 253
 254     // [1] Create new Region Pass Manager
 255     RGPM = new RGPassManager();
 256     RGPM->populateInheritedAnalysis(PMS);
 257
 258     // [2] Set up new manager's top level manager
 259     PMTopLevelManager *TPM = PMD->getTopLevelManager();
 260     TPM->addIndirectPassManager(RGPM);
 261
 262     // [3] Assign manager to manage this new manager. This may create
 263     // and push new managers into PMS
 264     TPM->schedulePass(RGPM);
 265
 266     // [4] Push new manager into PMS
 267     PMS.push(RGPM);
 268   }
 269
 270   RGPM->add(this);
 271 }
 272
 273 /// Get the printer pass
 274 Pass *RegionPass::createPrinterPass(raw_ostream &O,
 275                                   const std::string &Banner) const {
 276   return new PrintRegionPass(Banner, O);
 277 }