1 //===- BlockFrequencyInfo.cpp - Block 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/Analysis/BlockFrequencyInfo.h"
15 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
16 #include "llvm/Analysis/BranchProbabilityInfo.h"
17 #include "llvm/Analysis/LoopInfo.h"
18 #include "llvm/Analysis/Passes.h"
19 #include "llvm/IR/CFG.h"
20 #include "llvm/InitializePasses.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/GraphWriter.h"
24
25 using namespace llvm;
26
27 #define DEBUG_TYPE "block-freq"
28
29 #ifndef NDEBUG
30 enum GVDAGType {
31 GVDT_None,
32 GVDT_Fraction,
33 GVDT_Integer
34 };
35
36 static cl::opt<GVDAGType>
37 ViewBlockFreqPropagationDAG("view-block-freq-propagation-dags", cl::Hidden,
38 cl::desc("Pop up a window to show a dag displaying how block "
39 "frequencies propagation through the CFG."),
40 cl::values(
41 clEnumValN(GVDT_None, "none",
42 "do not display graphs."),
43 clEnumValN(GVDT_Fraction, "fraction", "display a graph using the "
44 "fractional block frequency representation."),
45 clEnumValN(GVDT_Integer, "integer", "display a graph using the raw "
46 "integer fractional block frequency representation."),
47 clEnumValEnd));
48
49 namespace llvm {
50
51 template <>
52 struct GraphTraits<BlockFrequencyInfo *> {
53 typedef const BasicBlock NodeType;
54 typedef succ_const_iterator ChildIteratorType;
55 typedef Function::const_iterator nodes_iterator;
56
getEntryNodellvm::GraphTraits57 static inline const NodeType *getEntryNode(const BlockFrequencyInfo *G) {
58 return G->getFunction()->begin();
59 }
child_beginllvm::GraphTraits60 static ChildIteratorType child_begin(const NodeType *N) {
61 return succ_begin(N);
62 }
child_endllvm::GraphTraits63 static ChildIteratorType child_end(const NodeType *N) {
64 return succ_end(N);
65 }
nodes_beginllvm::GraphTraits66 static nodes_iterator nodes_begin(const BlockFrequencyInfo *G) {
67 return G->getFunction()->begin();
68 }
nodes_endllvm::GraphTraits69 static nodes_iterator nodes_end(const BlockFrequencyInfo *G) {
70 return G->getFunction()->end();
71 }
72 };
73
74 template<>
75 struct DOTGraphTraits<BlockFrequencyInfo*> : public DefaultDOTGraphTraits {
DOTGraphTraitsllvm::DOTGraphTraits76 explicit DOTGraphTraits(bool isSimple=false) :
77 DefaultDOTGraphTraits(isSimple) {}
78
getGraphNamellvm::DOTGraphTraits79 static std::string getGraphName(const BlockFrequencyInfo *G) {
80 return G->getFunction()->getName();
81 }
82
getNodeLabelllvm::DOTGraphTraits83 std::string getNodeLabel(const BasicBlock *Node,
84 const BlockFrequencyInfo *Graph) {
85 std::string Result;
86 raw_string_ostream OS(Result);
87
88 OS << Node->getName().str() << ":";
89 switch (ViewBlockFreqPropagationDAG) {
90 case GVDT_Fraction:
91 Graph->printBlockFreq(OS, Node);
92 break;
93 case GVDT_Integer:
94 OS << Graph->getBlockFreq(Node).getFrequency();
95 break;
96 case GVDT_None:
97 llvm_unreachable("If we are not supposed to render a graph we should "
98 "never reach this point.");
99 }
100
101 return Result;
102 }
103 };
104
105 } // end namespace llvm
106 #endif
107
108 INITIALIZE_PASS_BEGIN(BlockFrequencyInfo, "block-freq",
109 "Block Frequency Analysis", true, true)
110 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
111 INITIALIZE_PASS_DEPENDENCY(LoopInfo)
112 INITIALIZE_PASS_END(BlockFrequencyInfo, "block-freq",
113 "Block Frequency Analysis", true, true)
114
115 char BlockFrequencyInfo::ID = 0;
116
117
BlockFrequencyInfo()118 BlockFrequencyInfo::BlockFrequencyInfo() : FunctionPass(ID) {
119 initializeBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
120 }
121
~BlockFrequencyInfo()122 BlockFrequencyInfo::~BlockFrequencyInfo() {}
123
getAnalysisUsage(AnalysisUsage & AU) const124 void BlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
125 AU.addRequired<BranchProbabilityInfo>();
126 AU.addRequired<LoopInfo>();
127 AU.setPreservesAll();
128 }
129
runOnFunction(Function & F)130 bool BlockFrequencyInfo::runOnFunction(Function &F) {
131 BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
132 LoopInfo &LI = getAnalysis<LoopInfo>();
133 if (!BFI)
134 BFI.reset(new ImplType);
135 BFI->doFunction(&F, &BPI, &LI);
136 #ifndef NDEBUG
137 if (ViewBlockFreqPropagationDAG != GVDT_None)
138 view();
139 #endif
140 return false;
141 }
142
releaseMemory()143 void BlockFrequencyInfo::releaseMemory() { BFI.reset(); }
144
print(raw_ostream & O,const Module *) const145 void BlockFrequencyInfo::print(raw_ostream &O, const Module *) const {
146 if (BFI) BFI->print(O);
147 }
148
getBlockFreq(const BasicBlock * BB) const149 BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const {
150 return BFI ? BFI->getBlockFreq(BB) : 0;
151 }
152
153 /// Pop up a ghostview window with the current block frequency propagation
154 /// rendered using dot.
view() const155 void BlockFrequencyInfo::view() const {
156 // This code is only for debugging.
157 #ifndef NDEBUG
158 ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs");
159 #else
160 errs() << "BlockFrequencyInfo::view is only available in debug builds on "
161 "systems with Graphviz or gv!\n";
162 #endif // NDEBUG
163 }
164
getFunction() const165 const Function *BlockFrequencyInfo::getFunction() const {
166 return BFI ? BFI->getFunction() : nullptr;
167 }
168
169 raw_ostream &BlockFrequencyInfo::
printBlockFreq(raw_ostream & OS,const BlockFrequency Freq) const170 printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const {
171 return BFI ? BFI->printBlockFreq(OS, Freq) : OS;
172 }
173
174 raw_ostream &
printBlockFreq(raw_ostream & OS,const BasicBlock * BB) const175 BlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
176 const BasicBlock *BB) const {
177 return BFI ? BFI->printBlockFreq(OS, BB) : OS;
178 }
179
getEntryFreq() const180 uint64_t BlockFrequencyInfo::getEntryFreq() const {
181 return BFI ? BFI->getEntryFreq() : 0;
182 }
183