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 class PruneUnprofitable : public ScopPass {
44 private:
updateStatistics(Scop & S,bool Pruned)45 void updateStatistics(Scop &S, bool Pruned) {
46 auto ScopStats = S.getStatistics();
47 if (Pruned) {
48 ScopsPruned++;
49 NumPrunedLoops += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
50 NumPrunedBoxedLoops += ScopStats.NumBoxedLoops;
51 NumPrunedAffineLoops += ScopStats.NumAffineLoops;
52 } else {
53 ScopsSurvived++;
54 NumLoopsInScop += ScopStats.NumAffineLoops + ScopStats.NumBoxedLoops;
55 NumBoxedLoops += ScopStats.NumBoxedLoops;
56 NumAffineLoops += ScopStats.NumAffineLoops;
57 }
58 }
59
60 public:
61 static char ID;
62
PruneUnprofitable()63 explicit PruneUnprofitable() : ScopPass(ID) {}
64 PruneUnprofitable(const PruneUnprofitable &) = delete;
65 PruneUnprofitable &operator=(const PruneUnprofitable &) = delete;
66
getAnalysisUsage(AnalysisUsage & AU) const67 void getAnalysisUsage(AnalysisUsage &AU) const override {
68 AU.addRequired<ScopInfoRegionPass>();
69 AU.setPreservesAll();
70 }
71
runOnScop(Scop & S)72 bool runOnScop(Scop &S) override {
73 if (PollyProcessUnprofitable) {
74 LLVM_DEBUG(
75 dbgs() << "NOTE: -polly-process-unprofitable active, won't prune "
76 "anything\n");
77 return false;
78 }
79
80 ScopsProcessed++;
81
82 if (!S.isProfitable(true)) {
83 LLVM_DEBUG(
84 dbgs() << "SCoP pruned because it probably cannot be optimized in "
85 "a significant way\n");
86 S.invalidate(PROFITABLE, DebugLoc());
87 updateStatistics(S, true);
88 } else {
89 updateStatistics(S, false);
90 }
91
92 return false;
93 }
94 };
95 } // namespace
96
97 char PruneUnprofitable::ID;
98
createPruneUnprofitablePass()99 Pass *polly::createPruneUnprofitablePass() { return new PruneUnprofitable(); }
100
101 INITIALIZE_PASS_BEGIN(PruneUnprofitable, "polly-prune-unprofitable",
102 "Polly - Prune unprofitable SCoPs", false, false)
103 INITIALIZE_PASS_END(PruneUnprofitable, "polly-prune-unprofitable",
104 "Polly - Prune unprofitable SCoPs", false, false)
105