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()->front();
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() << ":";
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
BlockFrequencyInfo()108 BlockFrequencyInfo::BlockFrequencyInfo() {}
109
BlockFrequencyInfo(const Function & F,const BranchProbabilityInfo & BPI,const LoopInfo & LI)110 BlockFrequencyInfo::BlockFrequencyInfo(const Function &F,
111 const BranchProbabilityInfo &BPI,
112 const LoopInfo &LI) {
113 calculate(F, BPI, LI);
114 }
115
calculate(const Function & F,const BranchProbabilityInfo & BPI,const LoopInfo & LI)116 void BlockFrequencyInfo::calculate(const Function &F,
117 const BranchProbabilityInfo &BPI,
118 const LoopInfo &LI) {
119 if (!BFI)
120 BFI.reset(new ImplType);
121 BFI->calculate(F, BPI, LI);
122 #ifndef NDEBUG
123 if (ViewBlockFreqPropagationDAG != GVDT_None)
124 view();
125 #endif
126 }
127
getBlockFreq(const BasicBlock * BB) const128 BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const {
129 return BFI ? BFI->getBlockFreq(BB) : 0;
130 }
131
setBlockFreq(const BasicBlock * BB,uint64_t Freq)132 void BlockFrequencyInfo::setBlockFreq(const BasicBlock *BB,
133 uint64_t Freq) {
134 assert(BFI && "Expected analysis to be available");
135 BFI->setBlockFreq(BB, Freq);
136 }
137
138 /// Pop up a ghostview window with the current block frequency propagation
139 /// rendered using dot.
view() const140 void BlockFrequencyInfo::view() const {
141 // This code is only for debugging.
142 #ifndef NDEBUG
143 ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs");
144 #else
145 errs() << "BlockFrequencyInfo::view is only available in debug builds on "
146 "systems with Graphviz or gv!\n";
147 #endif // NDEBUG
148 }
149
getFunction() const150 const Function *BlockFrequencyInfo::getFunction() const {
151 return BFI ? BFI->getFunction() : nullptr;
152 }
153
154 raw_ostream &BlockFrequencyInfo::
printBlockFreq(raw_ostream & OS,const BlockFrequency Freq) const155 printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const {
156 return BFI ? BFI->printBlockFreq(OS, Freq) : OS;
157 }
158
159 raw_ostream &
printBlockFreq(raw_ostream & OS,const BasicBlock * BB) const160 BlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
161 const BasicBlock *BB) const {
162 return BFI ? BFI->printBlockFreq(OS, BB) : OS;
163 }
164
getEntryFreq() const165 uint64_t BlockFrequencyInfo::getEntryFreq() const {
166 return BFI ? BFI->getEntryFreq() : 0;
167 }
168
releaseMemory()169 void BlockFrequencyInfo::releaseMemory() { BFI.reset(); }
170
print(raw_ostream & OS) const171 void BlockFrequencyInfo::print(raw_ostream &OS) const {
172 if (BFI)
173 BFI->print(OS);
174 }
175
176
177 INITIALIZE_PASS_BEGIN(BlockFrequencyInfoWrapperPass, "block-freq",
178 "Block Frequency Analysis", true, true)
179 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass)
180 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
181 INITIALIZE_PASS_END(BlockFrequencyInfoWrapperPass, "block-freq",
182 "Block Frequency Analysis", true, true)
183
184 char BlockFrequencyInfoWrapperPass::ID = 0;
185
186
BlockFrequencyInfoWrapperPass()187 BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass()
188 : FunctionPass(ID) {
189 initializeBlockFrequencyInfoWrapperPassPass(*PassRegistry::getPassRegistry());
190 }
191
~BlockFrequencyInfoWrapperPass()192 BlockFrequencyInfoWrapperPass::~BlockFrequencyInfoWrapperPass() {}
193
print(raw_ostream & OS,const Module *) const194 void BlockFrequencyInfoWrapperPass::print(raw_ostream &OS,
195 const Module *) const {
196 BFI.print(OS);
197 }
198
getAnalysisUsage(AnalysisUsage & AU) const199 void BlockFrequencyInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
200 AU.addRequired<BranchProbabilityInfoWrapperPass>();
201 AU.addRequired<LoopInfoWrapperPass>();
202 AU.setPreservesAll();
203 }
204
releaseMemory()205 void BlockFrequencyInfoWrapperPass::releaseMemory() { BFI.releaseMemory(); }
206
runOnFunction(Function & F)207 bool BlockFrequencyInfoWrapperPass::runOnFunction(Function &F) {
208 BranchProbabilityInfo &BPI =
209 getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
210 LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
211 BFI.calculate(F, BPI, LI);
212 return false;
213 }
214