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/ADT/PostOrderIterator.h"
14 #include "llvm/ADT/Statistic.h"
15 #include "llvm/Analysis/LoopInfo.h"
16 #include "llvm/Analysis/RegionInfoImpl.h"
17 #include "llvm/Analysis/RegionIterator.h"
18 #include "llvm/IR/PassManager.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #ifndef NDEBUG
23 #include "llvm/Analysis/RegionPrinter.h"
24 #endif
25 
26 using namespace llvm;
27 
28 #define DEBUG_TYPE "region"
29 
30 namespace llvm {
31 template class RegionBase<RegionTraits<Function>>;
32 template class RegionNodeBase<RegionTraits<Function>>;
33 template class RegionInfoBase<RegionTraits<Function>>;
34 }
35 
36 STATISTIC(numRegions,       "The # of regions");
37 STATISTIC(numSimpleRegions, "The # of simple regions");
38 
39 // Always verify if expensive checking is enabled.
40 
41 static cl::opt<bool,true>
42 VerifyRegionInfoX(
43   "verify-region-info",
44   cl::location(RegionInfoBase<RegionTraits<Function>>::VerifyRegionInfo),
45   cl::desc("Verify region info (time consuming)"));
46 
47 
48 static cl::opt<Region::PrintStyle, true> printStyleX("print-region-style",
49   cl::location(RegionInfo::printStyle),
50   cl::Hidden,
51   cl::desc("style of printing regions"),
52   cl::values(
53     clEnumValN(Region::PrintNone, "none",  "print no details"),
54     clEnumValN(Region::PrintBB, "bb",
55                "print regions in detail with block_iterator"),
56     clEnumValN(Region::PrintRN, "rn",
57                "print regions in detail with element_iterator")));
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 #ifndef NDEBUG
107 void RegionInfo::view() { viewRegion(this); }
108 
109 void RegionInfo::viewOnly() { viewRegionOnly(this); }
110 #endif
111 
112 //===----------------------------------------------------------------------===//
113 // RegionInfoPass implementation
114 //
115 
116 RegionInfoPass::RegionInfoPass() : FunctionPass(ID) {
117   initializeRegionInfoPassPass(*PassRegistry::getPassRegistry());
118 }
119 
120 RegionInfoPass::~RegionInfoPass() {
121 
122 }
123 
124 bool RegionInfoPass::runOnFunction(Function &F) {
125   releaseMemory();
126 
127   auto DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
128   auto PDT = &getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
129   auto DF = &getAnalysis<DominanceFrontierWrapperPass>().getDominanceFrontier();
130 
131   RI.recalculate(F, DT, PDT, DF);
132   return false;
133 }
134 
135 void RegionInfoPass::releaseMemory() {
136   RI.releaseMemory();
137 }
138 
139 void RegionInfoPass::verifyAnalysis() const {
140     RI.verifyAnalysis();
141 }
142 
143 void RegionInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
144   AU.setPreservesAll();
145   AU.addRequiredTransitive<DominatorTreeWrapperPass>();
146   AU.addRequired<PostDominatorTreeWrapperPass>();
147   AU.addRequired<DominanceFrontierWrapperPass>();
148 }
149 
150 void RegionInfoPass::print(raw_ostream &OS, const Module *) const {
151   RI.print(OS);
152 }
153 
154 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
155 LLVM_DUMP_METHOD void RegionInfoPass::dump() const {
156   RI.dump();
157 }
158 #endif
159 
160 char RegionInfoPass::ID = 0;
161 
162 INITIALIZE_PASS_BEGIN(RegionInfoPass, "regions",
163                 "Detect single entry single exit regions", true, true)
164 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
165 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
166 INITIALIZE_PASS_DEPENDENCY(DominanceFrontierWrapperPass)
167 INITIALIZE_PASS_END(RegionInfoPass, "regions",
168                 "Detect single entry single exit regions", true, true)
169 
170 // Create methods available outside of this file, to use them
171 // "include/llvm/LinkAllPasses.h". Otherwise the pass would be deleted by
172 // the link time optimization.
173 
174 namespace llvm {
175   FunctionPass *createRegionInfoPass() {
176     return new RegionInfoPass();
177   }
178 }
179 
180 //===----------------------------------------------------------------------===//
181 // RegionInfoAnalysis implementation
182 //
183 
184 char RegionInfoAnalysis::PassID;
185 
186 RegionInfo RegionInfoAnalysis::run(Function &F, FunctionAnalysisManager &AM) {
187   RegionInfo RI;
188   auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
189   auto *PDT = &AM.getResult<PostDominatorTreeAnalysis>(F);
190   auto *DF = &AM.getResult<DominanceFrontierAnalysis>(F);
191 
192   RI.recalculate(F, DT, PDT, DF);
193   return RI;
194 }
195 
196 RegionInfoPrinterPass::RegionInfoPrinterPass(raw_ostream &OS)
197   : OS(OS) {}
198 
199 PreservedAnalyses RegionInfoPrinterPass::run(Function &F,
200                                              FunctionAnalysisManager &AM) {
201   OS << "Region Tree for function: " << F.getName() << "\n";
202   AM.getResult<RegionInfoAnalysis>(F).print(OS);
203 
204   return PreservedAnalyses::all();
205 }
206 
207 PreservedAnalyses RegionInfoVerifierPass::run(Function &F,
208                                               FunctionAnalysisManager &AM) {
209   AM.getResult<RegionInfoAnalysis>(F).verifyAnalysis();
210 
211   return PreservedAnalyses::all();
212 }
213