1 //===- MachineBlockFrequencyInfo.cpp - MBB Frequency 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 //
10 // Loops should be simplified before this analysis.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
15 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
16 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
17 #include "llvm/CodeGen/MachineFunction.h"
18 #include "llvm/CodeGen/MachineLoopInfo.h"
19 #include "llvm/CodeGen/Passes.h"
20 #include "llvm/InitializePasses.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/Format.h"
24 #include "llvm/Support/GraphWriter.h"
25 #include "llvm/Support/raw_ostream.h"
26 
27 using namespace llvm;
28 
29 #define DEBUG_TYPE "block-freq"
30 
31 #ifndef NDEBUG
32 
33 static cl::opt<GVDAGType> ViewMachineBlockFreqPropagationDAG(
34     "view-machine-block-freq-propagation-dags", cl::Hidden,
35     cl::desc("Pop up a window to show a dag displaying how machine block "
36              "frequencies propagate through the CFG."),
37     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
38                clEnumValN(GVDT_Fraction, "fraction",
39                           "display a graph using the "
40                           "fractional block frequency representation."),
41                clEnumValN(GVDT_Integer, "integer",
42                           "display a graph using the raw "
43                           "integer fractional block frequency representation."),
44                clEnumValN(GVDT_Count, "count", "display a graph using the real "
45                                                "profile count if available.")));
46 // Similar option above, but used to control BFI display only after MBP pass
47 cl::opt<GVDAGType> ViewBlockLayoutWithBFI(
48     "view-block-layout-with-bfi", cl::Hidden,
49     cl::desc(
50         "Pop up a window to show a dag displaying MBP layout and associated "
51         "block frequencies of the CFG."),
52     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
53                clEnumValN(GVDT_Fraction, "fraction",
54                           "display a graph using the "
55                           "fractional block frequency representation."),
56                clEnumValN(GVDT_Integer, "integer",
57                           "display a graph using the raw "
58                           "integer fractional block frequency representation."),
59                clEnumValN(GVDT_Count, "count",
60                           "display a graph using the real "
61                           "profile count if available.")));
62 
63 extern cl::opt<std::string> ViewBlockFreqFuncName;
64 extern cl::opt<unsigned> ViewHotFreqPercent;
65 
66 static GVDAGType getGVDT() {
67   if (ViewBlockLayoutWithBFI != GVDT_None)
68     return ViewBlockLayoutWithBFI;
69 
70   return ViewMachineBlockFreqPropagationDAG;
71 }
72 
73 namespace llvm {
74 
75 template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
76   typedef const MachineBasicBlock *NodeRef;
77   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
78   typedef pointer_iterator<MachineFunction::const_iterator> nodes_iterator;
79 
80   static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
81     return &G->getFunction()->front();
82   }
83 
84   static ChildIteratorType child_begin(const NodeRef N) {
85     return N->succ_begin();
86   }
87 
88   static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
89 
90   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
91     return nodes_iterator(G->getFunction()->begin());
92   }
93 
94   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
95     return nodes_iterator(G->getFunction()->end());
96   }
97 };
98 
99 typedef BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
100                               MachineBranchProbabilityInfo>
101     MBFIDOTGraphTraitsBase;
102 template <>
103 struct DOTGraphTraits<MachineBlockFrequencyInfo *>
104     : public MBFIDOTGraphTraitsBase {
105   explicit DOTGraphTraits(bool isSimple = false)
106       : MBFIDOTGraphTraitsBase(isSimple), CurFunc(nullptr), LayoutOrderMap() {}
107 
108   const MachineFunction *CurFunc;
109   DenseMap<const MachineBasicBlock *, int> LayoutOrderMap;
110 
111   std::string getNodeLabel(const MachineBasicBlock *Node,
112                            const MachineBlockFrequencyInfo *Graph) {
113 
114     int layout_order = -1;
115     // Attach additional ordering information if 'isSimple' is false.
116     if (!isSimple()) {
117       const MachineFunction *F = Node->getParent();
118       if (!CurFunc || F != CurFunc) {
119         if (CurFunc)
120           LayoutOrderMap.clear();
121 
122         CurFunc = F;
123         int O = 0;
124         for (auto MBI = F->begin(); MBI != F->end(); ++MBI, ++O) {
125           LayoutOrderMap[&*MBI] = O;
126         }
127       }
128       layout_order = LayoutOrderMap[Node];
129     }
130     return MBFIDOTGraphTraitsBase::getNodeLabel(Node, Graph, getGVDT(),
131                                                 layout_order);
132   }
133 
134   std::string getNodeAttributes(const MachineBasicBlock *Node,
135                                 const MachineBlockFrequencyInfo *Graph) {
136     return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
137                                                      ViewHotFreqPercent);
138   }
139 
140   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
141                                 const MachineBlockFrequencyInfo *MBFI) {
142     return MBFIDOTGraphTraitsBase::getEdgeAttributes(
143         Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
144   }
145 };
146 
147 } // end namespace llvm
148 #endif
149 
150 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
151                       "Machine Block Frequency Analysis", true, true)
152 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
153 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
154 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
155                     "Machine Block Frequency Analysis", true, true)
156 
157 char MachineBlockFrequencyInfo::ID = 0;
158 
159 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo()
160     : MachineFunctionPass(ID) {
161   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
162 }
163 
164 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {}
165 
166 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
167   AU.addRequired<MachineBranchProbabilityInfo>();
168   AU.addRequired<MachineLoopInfo>();
169   AU.setPreservesAll();
170   MachineFunctionPass::getAnalysisUsage(AU);
171 }
172 
173 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
174   MachineBranchProbabilityInfo &MBPI =
175       getAnalysis<MachineBranchProbabilityInfo>();
176   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
177   if (!MBFI)
178     MBFI.reset(new ImplType);
179   MBFI->calculate(F, MBPI, MLI);
180 #ifndef NDEBUG
181   if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
182       (ViewBlockFreqFuncName.empty() ||
183        F.getName().equals(ViewBlockFreqFuncName))) {
184     view();
185   }
186 #endif
187   return false;
188 }
189 
190 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
191 
192 /// Pop up a ghostview window with the current block frequency propagation
193 /// rendered using dot.
194 void MachineBlockFrequencyInfo::view(bool isSimple) const {
195 // This code is only for debugging.
196 #ifndef NDEBUG
197   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this),
198             "MachineBlockFrequencyDAGs", isSimple);
199 #else
200   errs() << "MachineBlockFrequencyInfo::view is only available in debug builds "
201             "on systems with Graphviz or gv!\n";
202 #endif // NDEBUG
203 }
204 
205 BlockFrequency
206 MachineBlockFrequencyInfo::getBlockFreq(const MachineBasicBlock *MBB) const {
207   return MBFI ? MBFI->getBlockFreq(MBB) : 0;
208 }
209 
210 Optional<uint64_t> MachineBlockFrequencyInfo::getBlockProfileCount(
211     const MachineBasicBlock *MBB) const {
212   const Function *F = MBFI->getFunction()->getFunction();
213   return MBFI ? MBFI->getBlockProfileCount(*F, MBB) : None;
214 }
215 
216 Optional<uint64_t>
217 MachineBlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const {
218   const Function *F = MBFI->getFunction()->getFunction();
219   return MBFI ? MBFI->getProfileCountFromFreq(*F, Freq) : None;
220 }
221 
222 const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
223   return MBFI ? MBFI->getFunction() : nullptr;
224 }
225 
226 const MachineBranchProbabilityInfo *MachineBlockFrequencyInfo::getMBPI() const {
227   return MBFI ? &MBFI->getBPI() : nullptr;
228 }
229 
230 raw_ostream &
231 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
232                                           const BlockFrequency Freq) const {
233   return MBFI ? MBFI->printBlockFreq(OS, Freq) : OS;
234 }
235 
236 raw_ostream &
237 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
238                                           const MachineBasicBlock *MBB) const {
239   return MBFI ? MBFI->printBlockFreq(OS, MBB) : OS;
240 }
241 
242 uint64_t MachineBlockFrequencyInfo::getEntryFreq() const {
243   return MBFI ? MBFI->getEntryFreq() : 0;
244 }
245