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 #define DEBUG_TYPE "polly-prune-unprofitable"
  26
  27 namespace {
  28
  29 STATISTIC(ScopsProcessed,
  30           "Number of SCoPs considered for unprofitability pruning");
  31 STATISTIC(ScopsPruned, "Number of pruned SCoPs because it they cannot be "
  32                        "optimized in a significant way");
  33 STATISTIC(ScopsSurvived, "Number of SCoPs after pruning");
  34
  35 STATISTIC(NumPrunedLoops, "Number of pruned loops");
  36 STATISTIC(NumPrunedBoxedLoops, "Number of pruned boxed loops");
  37 STATISTIC(NumPrunedAffineLoops, "Number of pruned affine loops");
  38
  39 STATISTIC(NumLoopsInScop, "Number of loops in scops after pruning");
  40 STATISTIC(NumBoxedLoops, "Number of boxed loops in SCoPs after pruning");
  41 STATISTIC(NumAffineLoops, "Number of affine loops in SCoPs after pruning");
  42
  43 static void updateStatistics(Scop &S, bool Pruned) {
  44   Scop::ScopStatistics ScopStats = S.getStatistics();
  45   if (Pruned) {
  46     ScopsPruned++;
  47     NumPrunedLoops += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  48     NumPrunedBoxedLoops += ScopStats.NumBoxedLoops;
  49     NumPrunedAffineLoops += ScopStats.NumAffineLoops;
  50   } else {
  51     ScopsSurvived++;
  52     NumLoopsInScop += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
  53     NumBoxedLoops += ScopStats.NumBoxedLoops;
  54     NumAffineLoops += ScopStats.NumAffineLoops;
  55   }
  56 }
  57
  58 static bool runPruneUnprofitable(Scop &S) {
  59   if (PollyProcessUnprofitable) {
  60     LLVM_DEBUG(
  61         dbgs() << "NOTE: -polly-process-unprofitable active, won't prune "
  62                   "anything\n");
  63     return false;
  64   }
  65
  66   ScopsProcessed++;
  67
  68   if (!S.isProfitable(true)) {
  69     LLVM_DEBUG(
  70         dbgs() << "SCoP pruned because it probably cannot be optimized in "
  71                   "a significant way\n");
  72     S.invalidate(PROFITABLE, DebugLoc());
  73     updateStatistics(S, true);
  74   } else {
  75     updateStatistics(S, false);
  76   }
  77
  78   return false;
  79 }
  80
  81 class PruneUnprofitableWrapperPass final : public ScopPass {
  82 public:
  83   static char ID;
  84
  85   explicit PruneUnprofitableWrapperPass() : ScopPass(ID) {}
  86   PruneUnprofitableWrapperPass(const PruneUnprofitableWrapperPass &) = delete;
  87   PruneUnprofitableWrapperPass &
  88   operator=(const PruneUnprofitableWrapperPass &) = delete;
  89
  90   void getAnalysisUsage(AnalysisUsage &AU) const override {
  91     AU.addRequired<ScopInfoRegionPass>();
  92     AU.setPreservesAll();
  93   }
  94
  95   bool runOnScop(Scop &S) override { return runPruneUnprofitable(S); }
  96 };
  97 } // namespace
  98
  99 char PruneUnprofitableWrapperPass::ID;
 100
 101 Pass *polly::createPruneUnprofitableWrapperPass() {
 102   return new PruneUnprofitableWrapperPass();
 103 }
 104
 105 INITIALIZE_PASS_BEGIN(PruneUnprofitableWrapperPass, "polly-prune-unprofitable",
 106                       "Polly - Prune unprofitable SCoPs", false, false)
 107 INITIALIZE_PASS_END(PruneUnprofitableWrapperPass, "polly-prune-unprofitable",
 108                     "Polly - Prune unprofitable SCoPs", false, false)
 109
 110 llvm::PreservedAnalyses
 111 PruneUnprofitablePass::run(Scop &S, ScopAnalysisManager &SAM,
 112                            ScopStandardAnalysisResults &SAR, SPMUpdater &U) {
 113   bool Changed = runPruneUnprofitable(S);
 114
 115   if (!Changed)
 116     return PreservedAnalyses::all();
 117
 118   PreservedAnalyses PA;
 119   PA.preserveSet<AllAnalysesOn<Module>>();
 120   PA.preserveSet<AllAnalysesOn<Function>>();
 121   PA.preserveSet<AllAnalysesOn<Loop>>();
 122   return PA;
 123 }