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                clEnumValEnd));
48 
49 extern cl::opt<std::string> ViewBlockFreqFuncName;
50 extern cl::opt<unsigned> ViewHotFreqPercent;
51 
52 namespace llvm {
53 
54 template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
55   typedef const MachineBasicBlock *NodeRef;
56   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
57   typedef pointer_iterator<MachineFunction::const_iterator> nodes_iterator;
58 
59   static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
60     return &G->getFunction()->front();
61   }
62 
63   static ChildIteratorType child_begin(const NodeRef N) {
64     return N->succ_begin();
65   }
66 
67   static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
68 
69   static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
70     return nodes_iterator(G->getFunction()->begin());
71   }
72 
73   static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
74     return nodes_iterator(G->getFunction()->end());
75   }
76 };
77 
78 typedef BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
79                               MachineBranchProbabilityInfo>
80     MBFIDOTGraphTraitsBase;
81 template <>
82 struct DOTGraphTraits<MachineBlockFrequencyInfo *>
83     : public MBFIDOTGraphTraitsBase {
84   explicit DOTGraphTraits(bool isSimple = false)
85       : MBFIDOTGraphTraitsBase(isSimple) {}
86 
87   std::string getNodeLabel(const MachineBasicBlock *Node,
88                            const MachineBlockFrequencyInfo *Graph) {
89     return MBFIDOTGraphTraitsBase::getNodeLabel(
90         Node, Graph, ViewMachineBlockFreqPropagationDAG);
91   }
92 
93   std::string getNodeAttributes(const MachineBasicBlock *Node,
94                                 const MachineBlockFrequencyInfo *Graph) {
95     return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
96                                                      ViewHotFreqPercent);
97   }
98 
99   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
100                                 const MachineBlockFrequencyInfo *MBFI) {
101     return MBFIDOTGraphTraitsBase::getEdgeAttributes(
102         Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
103   }
104 };
105 
106 } // end namespace llvm
107 #endif
108 
109 INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfo, "machine-block-freq",
110                       "Machine Block Frequency Analysis", true, true)
111 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
112 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
113 INITIALIZE_PASS_END(MachineBlockFrequencyInfo, "machine-block-freq",
114                     "Machine Block Frequency Analysis", true, true)
115 
116 char MachineBlockFrequencyInfo::ID = 0;
117 
118 MachineBlockFrequencyInfo::MachineBlockFrequencyInfo()
119     : MachineFunctionPass(ID) {
120   initializeMachineBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
121 }
122 
123 MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() {}
124 
125 void MachineBlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
126   AU.addRequired<MachineBranchProbabilityInfo>();
127   AU.addRequired<MachineLoopInfo>();
128   AU.setPreservesAll();
129   MachineFunctionPass::getAnalysisUsage(AU);
130 }
131 
132 bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) {
133   MachineBranchProbabilityInfo &MBPI =
134       getAnalysis<MachineBranchProbabilityInfo>();
135   MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
136   if (!MBFI)
137     MBFI.reset(new ImplType);
138   MBFI->calculate(F, MBPI, MLI);
139 #ifndef NDEBUG
140   if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
141       (ViewBlockFreqFuncName.empty() ||
142        F.getName().equals(ViewBlockFreqFuncName))) {
143     view();
144   }
145 #endif
146   return false;
147 }
148 
149 void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
150 
151 /// Pop up a ghostview window with the current block frequency propagation
152 /// rendered using dot.
153 void MachineBlockFrequencyInfo::view() const {
154 // This code is only for debugging.
155 #ifndef NDEBUG
156   ViewGraph(const_cast<MachineBlockFrequencyInfo *>(this),
157             "MachineBlockFrequencyDAGs");
158 #else
159   errs() << "MachineBlockFrequencyInfo::view is only available in debug builds "
160             "on systems with Graphviz or gv!\n";
161 #endif // NDEBUG
162 }
163 
164 BlockFrequency
165 MachineBlockFrequencyInfo::getBlockFreq(const MachineBasicBlock *MBB) const {
166   return MBFI ? MBFI->getBlockFreq(MBB) : 0;
167 }
168 
169 Optional<uint64_t> MachineBlockFrequencyInfo::getBlockProfileCount(
170     const MachineBasicBlock *MBB) const {
171   const Function *F = MBFI->getFunction()->getFunction();
172   return MBFI ? MBFI->getBlockProfileCount(*F, MBB) : None;
173 }
174 
175 Optional<uint64_t>
176 MachineBlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const {
177   const Function *F = MBFI->getFunction()->getFunction();
178   return MBFI ? MBFI->getProfileCountFromFreq(*F, Freq) : None;
179 }
180 
181 const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
182   return MBFI ? MBFI->getFunction() : nullptr;
183 }
184 
185 const MachineBranchProbabilityInfo *MachineBlockFrequencyInfo::getMBPI() const {
186   return MBFI ? &MBFI->getBPI() : nullptr;
187 }
188 
189 raw_ostream &
190 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
191                                           const BlockFrequency Freq) const {
192   return MBFI ? MBFI->printBlockFreq(OS, Freq) : OS;
193 }
194 
195 raw_ostream &
196 MachineBlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
197                                           const MachineBasicBlock *MBB) const {
198   return MBFI ? MBFI->printBlockFreq(OS, MBB) : OS;
199 }
200 
201 uint64_t MachineBlockFrequencyInfo::getEntryFreq() const {
202   return MBFI ? MBFI->getEntryFreq() : 0;
203 }
204