1 //===- RegionInfo.cpp - SESE region detection analysis --------------------===//
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 // Detects single entry single exit regions in the control flow graph.
10 //===----------------------------------------------------------------------===//
11 
12 #include "llvm/Analysis/RegionInfo.h"
13 #include "llvm/Analysis/RegionInfoImpl.h"
14 #include "llvm/ADT/PostOrderIterator.h"
15 #include "llvm/ADT/Statistic.h"
16 #include "llvm/Analysis/LoopInfo.h"
17 #include "llvm/Analysis/RegionIterator.h"
18 #include "llvm/Support/CommandLine.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include <algorithm>
22 #include <iterator>
23 #include <set>
24 
25 using namespace llvm;
26 
27 #define DEBUG_TYPE "region"
28 
29 namespace llvm {
30 template class RegionBase<RegionTraits<Function>>;
31 template class RegionNodeBase<RegionTraits<Function>>;
32 template class RegionInfoBase<RegionTraits<Function>>;
33 }
34 
35 STATISTIC(numRegions,       "The # of regions");
36 STATISTIC(numSimpleRegions, "The # of simple regions");
37 
38 // Always verify if expensive checking is enabled.
39 
40 static cl::opt<bool,true>
41 VerifyRegionInfoX(
42   "verify-region-info",
43   cl::location(RegionInfoBase<RegionTraits<Function>>::VerifyRegionInfo),
44   cl::desc("Verify region info (time consuming)"));
45 
46 
47 static cl::opt<Region::PrintStyle, true> printStyleX("print-region-style",
48   cl::location(RegionInfo::printStyle),
49   cl::Hidden,
50   cl::desc("style of printing regions"),
51   cl::values(
52     clEnumValN(Region::PrintNone, "none",  "print no details"),
53     clEnumValN(Region::PrintBB, "bb",
54                "print regions in detail with block_iterator"),
55     clEnumValN(Region::PrintRN, "rn",
56                "print regions in detail with element_iterator"),
57     clEnumValEnd));
58 
59 
60 //===----------------------------------------------------------------------===//
61 // Region implementation
62 //
63 
64 Region::Region(BasicBlock *Entry, BasicBlock *Exit,
65                RegionInfo* RI,
66                DominatorTree *DT, Region *Parent) :
67   RegionBase<RegionTraits<Function>>(Entry, Exit, RI, DT, Parent) {
68 
69 }
70 
71 Region::~Region() { }
72 
73 //===----------------------------------------------------------------------===//
74 // RegionInfo implementation
75 //
76 
77 RegionInfo::RegionInfo() :
78   RegionInfoBase<RegionTraits<Function>>() {
79 
80 }
81 
82 RegionInfo::~RegionInfo() {
83 
84 }
85 
86 void RegionInfo::updateStatistics(Region *R) {
87   ++numRegions;
88 
89   // TODO: Slow. Should only be enabled if -stats is used.
90   if (R->isSimple())
91     ++numSimpleRegions;
92 }
93 
94 void RegionInfo::recalculate(Function &F, DominatorTree *DT_,
95                              PostDominatorTree *PDT_, DominanceFrontier *DF_) {
96   DT = DT_;
97   PDT = PDT_;
98   DF = DF_;
99 
100   TopLevelRegion = new Region(&F.getEntryBlock(), nullptr,
101                               this, DT, nullptr);
102   updateStatistics(TopLevelRegion);
103   calculate(F);
104 }
105 
106 //===----------------------------------------------------------------------===//
107 // RegionInfoPass implementation
108 //
109 
110 RegionInfoPass::RegionInfoPass() : FunctionPass(ID) {
111   initializeRegionInfoPassPass(*PassRegistry::getPassRegistry());
112 }
113 
114 RegionInfoPass::~RegionInfoPass() {
115 
116 }
117 
118 bool RegionInfoPass::runOnFunction(Function &F) {
119   releaseMemory();
120 
121   auto DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
122   auto PDT = &getAnalysis<PostDominatorTree>();
123   auto DF = &getAnalysis<DominanceFrontier>();
124 
125   RI.recalculate(F, DT, PDT, DF);
126   return false;
127 }
128 
129 void RegionInfoPass::releaseMemory() {
130   RI.releaseMemory();
131 }
132 
133 void RegionInfoPass::verifyAnalysis() const {
134     RI.verifyAnalysis();
135 }
136 
137 void RegionInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
138   AU.setPreservesAll();
139   AU.addRequiredTransitive<DominatorTreeWrapperPass>();
140   AU.addRequired<PostDominatorTree>();
141   AU.addRequired<DominanceFrontier>();
142 }
143 
144 void RegionInfoPass::print(raw_ostream &OS, const Module *) const {
145   RI.print(OS);
146 }
147 
148 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
149 void RegionInfoPass::dump() const {
150   RI.dump();
151 }
152 #endif
153 
154 char RegionInfoPass::ID = 0;
155 
156 INITIALIZE_PASS_BEGIN(RegionInfoPass, "regions",
157                 "Detect single entry single exit regions", true, true)
158 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
159 INITIALIZE_PASS_DEPENDENCY(PostDominatorTree)
160 INITIALIZE_PASS_DEPENDENCY(DominanceFrontier)
161 INITIALIZE_PASS_END(RegionInfoPass, "regions",
162                 "Detect single entry single exit regions", true, true)
163 
164 // Create methods available outside of this file, to use them
165 // "include/llvm/LinkAllPasses.h". Otherwise the pass would be deleted by
166 // the link time optimization.
167 
168 namespace llvm {
169   FunctionPass *createRegionInfoPass() {
170     return new RegionInfoPass();
171   }
172 }
173 
174