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
updateStatistics(Scop & S,bool Pruned)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
runPruneUnprofitable(Scop & S)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 : public ScopPass {
82 public:
83 static char ID;
84
PruneUnprofitableWrapperPass()85 explicit PruneUnprofitableWrapperPass() : ScopPass(ID) {}
86 PruneUnprofitableWrapperPass(const PruneUnprofitableWrapperPass &) = delete;
87 PruneUnprofitableWrapperPass &
88 operator=(const PruneUnprofitableWrapperPass &) = delete;
89
getAnalysisUsage(AnalysisUsage & AU) const90 void getAnalysisUsage(AnalysisUsage &AU) const override {
91 AU.addRequired<ScopInfoRegionPass>();
92 AU.setPreservesAll();
93 }
94
runOnScop(Scop & S)95 bool runOnScop(Scop &S) override { return runPruneUnprofitable(S); }
96 };
97 } // namespace
98
99 char PruneUnprofitableWrapperPass::ID;
100
createPruneUnprofitableWrapperPass()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
run(Scop & S,ScopAnalysisManager & SAM,ScopStandardAnalysisResults & SAR,SPMUpdater & U)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 }
124