lib/Analysis/PruneUnprofitable.cpp

   1 //===- PruneUnprofitable.cpp ----------------------------------------------===//
   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 // Mark a SCoP as unfeasible if not deemed profitable to optimize.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "polly/PruneUnprofitable.h"
  15 #include "polly/ScopDetection.h"
  16 #include "polly/ScopInfo.h"
  17 #include "polly/ScopPass.h"
  18 #include "llvm/ADT/Statistic.h"
  19 #include "llvm/IR/DebugLoc.h"
  20 #include "llvm/Pass.h"
  21 #include "llvm/Support/Debug.h"
  22 #include "llvm/Support/raw_ostream.h"
  23
  24 using namespace llvm;
  25 using namespace polly;
  26
  27 #define DEBUG_TYPE "polly-prune-unprofitable"
  28
  29 namespace {
  30
  31 STATISTIC(ScopsProcessed,
  32           "Number of SCoPs considered for unprofitability pruning");
  33 STATISTIC(ScopsPruned, "Number of pruned SCoPs because it they cannot be "
  34                        "optimized in a significant way");
  35 STATISTIC(ScopsSurvived, "Number of SCoPs after pruning");
  36
  37 STATISTIC(NumPrunedLoops, "Number of pruned loops");
  38 STATISTIC(NumPrunedBoxedLoops, "Number of pruned boxed loops");
  39 STATISTIC(NumPrunedAffineLoops, "Number of pruned affine loops");
  40
  41 STATISTIC(NumLoopsInScop, "Number of loops in scops after pruning");
  42 STATISTIC(NumBoxedLoops, "Number of boxed loops in SCoPs after pruning");
  43 STATISTIC(NumAffineLoops, "Number of affine loops in SCoPs after pruning");
  44
  45 class PruneUnprofitable : public ScopPass {
  46 private:
  47   void updateStatistics(Scop &S, bool Pruned) {
  48     auto ScopStats = S.getStatistics();
  49     if (Pruned) {
  50       ScopsPruned++;
  51       NumPrunedLoops += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  52       NumPrunedBoxedLoops += ScopStats.NumBoxedLoops;
  53       NumPrunedAffineLoops += ScopStats.NumAffineLoops;
  54     } else {
  55       ScopsSurvived++;
  56       NumLoopsInScop += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  57       NumBoxedLoops += ScopStats.NumBoxedLoops;
  58       NumAffineLoops += ScopStats.NumAffineLoops;
  59     }
  60   }
  61
  62 public:
  63   static char ID;
  64
  65   explicit PruneUnprofitable() : ScopPass(ID) {}
  66   PruneUnprofitable(const PruneUnprofitable &) = delete;
  67   PruneUnprofitable &operator=(const PruneUnprofitable &) = delete;
  68
  69   void getAnalysisUsage(AnalysisUsage &AU) const override {
  70     AU.addRequired<ScopInfoRegionPass>();
  71     AU.setPreservesAll();
  72   }
  73
  74   bool runOnScop(Scop &S) override {
  75     if (PollyProcessUnprofitable) {
  76       LLVM_DEBUG(
  77           dbgs() << "NOTE: -polly-process-unprofitable active, won't prune "
  78                     "anything\n");
  79       return false;
  80     }
  81
  82     ScopsProcessed++;
  83
  84     if (!S.isProfitable(true)) {
  85       LLVM_DEBUG(
  86           dbgs() << "SCoP pruned because it probably cannot be optimized in "
  87                     "a significant way\n");
  88       S.invalidate(PROFITABLE, DebugLoc());
  89       updateStatistics(S, true);
  90     } else {
  91       updateStatistics(S, false);
  92     }
  93
  94     return false;
  95   }
  96 };
  97 } // namespace
  98
  99 char PruneUnprofitable::ID;
 100
 101 Pass *polly::createPruneUnprofitablePass() { return new PruneUnprofitable(); }
 102
 103 INITIALIZE_PASS_BEGIN(PruneUnprofitable, "polly-prune-unprofitable",
 104                       "Polly - Prune unprofitable SCoPs", false, false)
 105 INITIALIZE_PASS_END(PruneUnprofitable, "polly-prune-unprofitable",
 106                     "Polly - Prune unprofitable SCoPs", false, false)