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 
47 extern cl::opt<std::string> ViewBlockFreqFuncName;
48 extern cl::opt<unsigned> ViewHotFreqPercent;
49 
50 namespace llvm {
51 
52 template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
53   typedef const MachineBasicBlock *NodeRef;
54   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
55   typedef pointer_iterator<MachineFunction::const_iterator> nodes_iterator;
56 
57   static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
58     return &G->getFunction()->front();
59   }
60 
61   static ChildIteratorType child_begin(const NodeRef N) {
62     return N->succ_begin();
63   }
64 
65   static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
66 
67   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
68     return nodes_iterator(G->getFunction()->begin());
69   }
70 
71   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
72     return nodes_iterator(G->getFunction()->end());
73   }
74 };
75 
76 typedef BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
77                               MachineBranchProbabilityInfo>
78     MBFIDOTGraphTraitsBase;
79 template <>
80 struct DOTGraphTraits<MachineBlockFrequencyInfo *>
81     : public MBFIDOTGraphTraitsBase {
82   explicit DOTGraphTraits(bool isSimple = false)
83       : MBFIDOTGraphTraitsBase(isSimple) {}
84 
85   std::string getNodeLabel(const MachineBasicBlock *Node,
86                            const MachineBlockFrequencyInfo *Graph) {
87     return MBFIDOTGraphTraitsBase::getNodeLabel(
88         Node, Graph, ViewMachineBlockFreqPropagationDAG);
89   }
90 
91   std::string getNodeAttributes(const MachineBasicBlock *Node,
92                                 const MachineBlockFrequencyInfo *Graph) {
93     return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
94                                                      ViewHotFreqPercent);
95   }
96 
97   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
98                                 const MachineBlockFrequencyInfo *MBFI) {
99     return MBFIDOTGraphTraitsBase::getEdgeAttributes(
100         Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
101   }
102 };
103 
104 } // end namespace llvm
105 #endif
106 
107 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
108                       "Machine Block Frequency Analysis", true, true)
109 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
110 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
111 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
112                     "Machine Block Frequency Analysis", true, true)
113 
114 char MachineBlockFrequencyInfo::ID = 0;
115 
116 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo()
117     : MachineFunctionPass(ID) {
118   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
119 }
120 
121 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {}
122 
123 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
124   AU.addRequired<MachineBranchProbabilityInfo>();
125   AU.addRequired<MachineLoopInfo>();
126   AU.setPreservesAll();
127   MachineFunctionPass::getAnalysisUsage(AU);
128 }
129 
130 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
131   MachineBranchProbabilityInfo &MBPI =
132       getAnalysis<MachineBranchProbabilityInfo>();
133   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
134   if (!MBFI)
135     MBFI.reset(new ImplType);
136   MBFI->calculate(F, MBPI, MLI);
137 #ifndef NDEBUG
138   if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
139       (ViewBlockFreqFuncName.empty() ||
140        F.getName().equals(ViewBlockFreqFuncName))) {
141     view();
142   }
143 #endif
144   return false;
145 }
146 
147 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
148 
149 /// Pop up a ghostview window with the current block frequency propagation
150 /// rendered using dot.
151 void MachineBlockFrequencyInfo::view() const {
152 // This code is only for debugging.
153 #ifndef NDEBUG
154   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this),
155             "MachineBlockFrequencyDAGs");
156 #else
157   errs() << "MachineBlockFrequencyInfo::view is only available in debug builds "
158             "on systems with Graphviz or gv!\n";
159 #endif // NDEBUG
160 }
161 
162 BlockFrequency
163 MachineBlockFrequencyInfo::getBlockFreq(const MachineBasicBlock *MBB) const {
164   return MBFI ? MBFI->getBlockFreq(MBB) : 0;
165 }
166 
167 Optional<uint64_t> MachineBlockFrequencyInfo::getBlockProfileCount(
168     const MachineBasicBlock *MBB) const {
169   const Function *F = MBFI->getFunction()->getFunction();
170   return MBFI ? MBFI->getBlockProfileCount(*F, MBB) : None;
171 }
172 
173 Optional<uint64_t>
174 MachineBlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const {
175   const Function *F = MBFI->getFunction()->getFunction();
176   return MBFI ? MBFI->getProfileCountFromFreq(*F, Freq) : None;
177 }
178 
179 const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
180   return MBFI ? MBFI->getFunction() : nullptr;
181 }
182 
183 const MachineBranchProbabilityInfo *MachineBlockFrequencyInfo::getMBPI() const {
184   return MBFI ? &MBFI->getBPI() : nullptr;
185 }
186 
187 raw_ostream &
188 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
189                                           const BlockFrequency Freq) const {
190   return MBFI ? MBFI->printBlockFreq(OS, Freq) : OS;
191 }
192 
193 raw_ostream &
194 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
195                                           const MachineBasicBlock *MBB) const {
196   return MBFI ? MBFI->printBlockFreq(OS, MBB) : OS;
197 }
198 
199 uint64_t MachineBlockFrequencyInfo::getEntryFreq() const {
200   return MBFI ? MBFI->getEntryFreq() : 0;
201 }
202