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 "machine-block-freq"
30 
31 
32 static cl::opt<GVDAGType> ViewMachineBlockFreqPropagationDAG(
33     "view-machine-block-freq-propagation-dags", cl::Hidden,
34     cl::desc("Pop up a window to show a dag displaying how machine block "
35              "frequencies propagate through the CFG."),
36     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
37                clEnumValN(GVDT_Fraction, "fraction",
38                           "display a graph using the "
39                           "fractional block frequency representation."),
40                clEnumValN(GVDT_Integer, "integer",
41                           "display a graph using the raw "
42                           "integer fractional block frequency representation."),
43                clEnumValN(GVDT_Count, "count", "display a graph using the real "
44                                                "profile count if available.")));
45 // Similar option above, but used to control BFI display only after MBP pass
46 cl::opt<GVDAGType> ViewBlockLayoutWithBFI(
47     "view-block-layout-with-bfi", cl::Hidden,
48     cl::desc(
49         "Pop up a window to show a dag displaying MBP layout and associated "
50         "block frequencies of the CFG."),
51     cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
52                clEnumValN(GVDT_Fraction, "fraction",
53                           "display a graph using the "
54                           "fractional block frequency representation."),
55                clEnumValN(GVDT_Integer, "integer",
56                           "display a graph using the raw "
57                           "integer fractional block frequency representation."),
58                clEnumValN(GVDT_Count, "count",
59                           "display a graph using the real "
60                           "profile count if available.")));
61 
62 // Command line option to specify the name of the function for CFG dump
63 // Defined in Analysis/BlockFrequencyInfo.cpp:  -view-bfi-func-name=
64 extern cl::opt<std::string> ViewBlockFreqFuncName;
65 // Command line option to specify hot frequency threshold.
66 // Defined in Analysis/BlockFrequencyInfo.cpp:  -view-hot-freq-perc=
67 extern cl::opt<unsigned> ViewHotFreqPercent;
68 
69 static GVDAGType getGVDT() {
70   if (ViewBlockLayoutWithBFI != GVDT_None)
71     return ViewBlockLayoutWithBFI;
72 
73   return ViewMachineBlockFreqPropagationDAG;
74 }
75 
76 namespace llvm {
77 
78 template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
79   typedef const MachineBasicBlock *NodeRef;
80   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
81   typedef pointer_iterator<MachineFunction::const_iterator> nodes_iterator;
82 
83   static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
84     return &G->getFunction()->front();
85   }
86 
87   static ChildIteratorType child_begin(const NodeRef N) {
88     return N->succ_begin();
89   }
90 
91   static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
92 
93   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
94     return nodes_iterator(G->getFunction()->begin());
95   }
96 
97   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
98     return nodes_iterator(G->getFunction()->end());
99   }
100 };
101 
102 typedef BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
103                               MachineBranchProbabilityInfo>
104     MBFIDOTGraphTraitsBase;
105 template <>
106 struct DOTGraphTraits<MachineBlockFrequencyInfo *>
107     : public MBFIDOTGraphTraitsBase {
108   explicit DOTGraphTraits(bool isSimple = false)
109       : MBFIDOTGraphTraitsBase(isSimple), CurFunc(nullptr), LayoutOrderMap() {}
110 
111   const MachineFunction *CurFunc;
112   DenseMap<const MachineBasicBlock *, int> LayoutOrderMap;
113 
114   std::string getNodeLabel(const MachineBasicBlock *Node,
115                            const MachineBlockFrequencyInfo *Graph) {
116 
117     int layout_order = -1;
118     // Attach additional ordering information if 'isSimple' is false.
119     if (!isSimple()) {
120       const MachineFunction *F = Node->getParent();
121       if (!CurFunc || F != CurFunc) {
122         if (CurFunc)
123           LayoutOrderMap.clear();
124 
125         CurFunc = F;
126         int O = 0;
127         for (auto MBI = F->begin(); MBI != F->end(); ++MBI, ++O) {
128           LayoutOrderMap[&*MBI] = O;
129         }
130       }
131       layout_order = LayoutOrderMap[Node];
132     }
133     return MBFIDOTGraphTraitsBase::getNodeLabel(Node, Graph, getGVDT(),
134                                                 layout_order);
135   }
136 
137   std::string getNodeAttributes(const MachineBasicBlock *Node,
138                                 const MachineBlockFrequencyInfo *Graph) {
139     return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
140                                                      ViewHotFreqPercent);
141   }
142 
143   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
144                                 const MachineBlockFrequencyInfo *MBFI) {
145     return MBFIDOTGraphTraitsBase::getEdgeAttributes(
146         Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
147   }
148 };
149 
150 } // end namespace llvm
151 
152 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, DEBUG_TYPE,
153                       "Machine Block Frequency Analysis", true, true)
154 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
155 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
156 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, DEBUG_TYPE,
157                     "Machine Block Frequency Analysis", true, true)
158 
159 char MachineBlockFrequencyInfo::ID = 0;
160 
161 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo()
162     : MachineFunctionPass(ID) {
163   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
164 }
165 
166 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {}
167 
168 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
169   AU.addRequired<MachineBranchProbabilityInfo>();
170   AU.addRequired<MachineLoopInfo>();
171   AU.setPreservesAll();
172   MachineFunctionPass::getAnalysisUsage(AU);
173 }
174 
175 void MachineBlockFrequencyInfo::calculate(
176     const MachineFunction &F, const MachineBranchProbabilityInfo &MBPI,
177     const MachineLoopInfo &MLI) {
178   if (!MBFI)
179     MBFI.reset(new ImplType);
180   MBFI->calculate(F, MBPI, MLI);
181   if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
182       (ViewBlockFreqFuncName.empty() ||
183        F.getName().equals(ViewBlockFreqFuncName))) {
184     view("MachineBlockFrequencyDAGS." + F.getName());
185   }
186 }
187 
188 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
189   MachineBranchProbabilityInfo &MBPI =
190       getAnalysis<MachineBranchProbabilityInfo>();
191   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
192   calculate(F, MBPI, MLI);
193   return false;
194 }
195 
196 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
197 
198 /// Pop up a ghostview window with the current block frequency propagation
199 /// rendered using dot.
200 void MachineBlockFrequencyInfo::view(const Twine &Name, bool isSimple) const {
201   // This code is only for debugging.
202   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this), Name, isSimple);
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