polly/lib/Analysis/PruneUnprofitable.cpp

   1 //===- PruneUnprofitable.cpp ----------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Mark a SCoP as unfeasible if not deemed profitable to optimize.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "polly/PruneUnprofitable.h"
  14 #include "polly/ScopDetection.h"
  15 #include "polly/ScopInfo.h"
  16 #include "polly/ScopPass.h"
  17 #include "llvm/ADT/Statistic.h"
  18 #include "llvm/IR/DebugLoc.h"
  19 #include "llvm/Support/Debug.h"
  20 #include "llvm/Support/raw_ostream.h"
  21
  22 using namespace llvm;
  23 using namespace polly;
  24
  25 #include "polly/Support/PollyDebug.h"
  26 #define DEBUG_TYPE "polly-prune-unprofitable"
  27
  28 namespace {
  29
  30 STATISTIC(ScopsProcessed,
  31           "Number of SCoPs considered for unprofitability pruning");
  32 STATISTIC(ScopsPruned, "Number of pruned SCoPs because it they cannot be "
  33                        "optimized in a significant way");
  34 STATISTIC(ScopsSurvived, "Number of SCoPs after pruning");
  35
  36 STATISTIC(NumPrunedLoops, "Number of pruned loops");
  37 STATISTIC(NumPrunedBoxedLoops, "Number of pruned boxed loops");
  38 STATISTIC(NumPrunedAffineLoops, "Number of pruned affine loops");
  39
  40 STATISTIC(NumLoopsInScop, "Number of loops in scops after pruning");
  41 STATISTIC(NumBoxedLoops, "Number of boxed loops in SCoPs after pruning");
  42 STATISTIC(NumAffineLoops, "Number of affine loops in SCoPs after pruning");
  43
  44 static void updateStatistics(Scop &S, bool Pruned) {
  45   Scop::ScopStatistics ScopStats = S.getStatistics();
  46   if (Pruned) {
  47     ScopsPruned++;
  48     NumPrunedLoops += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  49     NumPrunedBoxedLoops += ScopStats.NumBoxedLoops;
  50     NumPrunedAffineLoops += ScopStats.NumAffineLoops;
  51   } else {
  52     ScopsSurvived++;
  53     NumLoopsInScop += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  54     NumBoxedLoops += ScopStats.NumBoxedLoops;
  55     NumAffineLoops += ScopStats.NumAffineLoops;
  56   }
  57 }
  58
  59 static bool runPruneUnprofitable(Scop &S) {
  60   if (PollyProcessUnprofitable) {
  61     POLLY_DEBUG(
  62         dbgs() << "NOTE: -polly-process-unprofitable active, won't prune "
  63                   "anything\n");
  64     return false;
  65   }
  66
  67   ScopsProcessed++;
  68
  69   if (!S.isProfitable(true)) {
  70     POLLY_DEBUG(
  71         dbgs() << "SCoP pruned because it probably cannot be optimized in "
  72                   "a significant way\n");
  73     S.invalidate(PROFITABLE, DebugLoc());
  74     updateStatistics(S, true);
  75   } else {
  76     updateStatistics(S, false);
  77   }
  78
  79   return false;
  80 }
  81
  82 class PruneUnprofitableWrapperPass final : public ScopPass {
  83 public:
  84   static char ID;
  85
  86   explicit PruneUnprofitableWrapperPass() : ScopPass(ID) {}
  87   PruneUnprofitableWrapperPass(const PruneUnprofitableWrapperPass &) = delete;
  88   PruneUnprofitableWrapperPass &
  89   operator=(const PruneUnprofitableWrapperPass &) = delete;
  90
  91   void getAnalysisUsage(AnalysisUsage &AU) const override {
  92     AU.addRequired<ScopInfoRegionPass>();
  93     AU.setPreservesAll();
  94   }
  95
  96   bool runOnScop(Scop &S) override { return runPruneUnprofitable(S); }
  97 };
  98 } // namespace
  99
 100 char PruneUnprofitableWrapperPass::ID;
 101
 102 Pass *polly::createPruneUnprofitableWrapperPass() {
 103   return new PruneUnprofitableWrapperPass();
 104 }
 105
 106 INITIALIZE_PASS_BEGIN(PruneUnprofitableWrapperPass, "polly-prune-unprofitable",
 107                       "Polly - Prune unprofitable SCoPs", false, false)
 108 INITIALIZE_PASS_END(PruneUnprofitableWrapperPass, "polly-prune-unprofitable",
 109                     "Polly - Prune unprofitable SCoPs", false, false)
 110
 111 llvm::PreservedAnalyses
 112 PruneUnprofitablePass::run(Scop &S, ScopAnalysisManager &SAM,
 113                            ScopStandardAnalysisResults &SAR, SPMUpdater &U) {
 114   bool Changed = runPruneUnprofitable(S);
 115
 116   if (!Changed)
 117     return PreservedAnalyses::all();
 118
 119   PreservedAnalyses PA;
 120   PA.preserveSet<AllAnalysesOn<Module>>();
 121   PA.preserveSet<AllAnalysesOn<Function>>();
 122   PA.preserveSet<AllAnalysesOn<Loop>>();
 123   return PA;
 124 }