LLVM  6.0.0svn
BlockFrequencyInfo.cpp
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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 
15 #include "llvm/ADT/APInt.h"
16 #include "llvm/ADT/None.h"
17 #include "llvm/ADT/iterator.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/IR/CFG.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/PassManager.h"
24 #include "llvm/Pass.h"
28 #include <algorithm>
29 #include <cassert>
30 #include <string>
31 
32 using namespace llvm;
33 
34 #define DEBUG_TYPE "block-freq"
35 
37  "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(clEnumValN(GVDT_None, "none", "do not display graphs."),
41  clEnumValN(GVDT_Fraction, "fraction",
42  "display a graph using the "
43  "fractional block frequency representation."),
44  clEnumValN(GVDT_Integer, "integer",
45  "display a graph using the raw "
46  "integer fractional block frequency representation."),
47  clEnumValN(GVDT_Count, "count", "display a graph using the real "
48  "profile count if available.")));
49 
51  ViewBlockFreqFuncName("view-bfi-func-name", cl::Hidden,
52  cl::desc("The option to specify "
53  "the name of the function "
54  "whose CFG will be displayed."));
55 
57  ViewHotFreqPercent("view-hot-freq-percent", cl::init(10), cl::Hidden,
58  cl::desc("An integer in percent used to specify "
59  "the hot blocks/edges to be displayed "
60  "in red: a block or edge whose frequency "
61  "is no less than the max frequency of the "
62  "function multiplied by this percent."));
63 
64 // Command line option to turn on CFG dot dump after profile annotation.
66  PGOViewCounts("pgo-view-counts", cl::init(false), cl::Hidden,
67  cl::desc("A boolean option to show CFG dag with "
68  "block profile counts and branch probabilities "
69  "right after PGO profile annotation step. The "
70  "profile counts are computed using branch "
71  "probabilities from the runtime profile data and "
72  "block frequency propagation algorithm. To view "
73  "the raw counts from the profile, use option "
74  "-pgo-view-raw-counts instead. To limit graph "
75  "display to only one function, use filtering option "
76  "-view-bfi-func-name."));
77 
78 namespace llvm {
79 
80 static GVDAGType getGVDT() {
81  if (PGOViewCounts)
82  return GVDT_Count;
84 }
85 
86 template <>
88  using NodeRef = const BasicBlock *;
91 
93  return &G->getFunction()->front();
94  }
95 
97  return succ_begin(N);
98  }
99 
100  static ChildIteratorType child_end(const NodeRef N) { return succ_end(N); }
101 
103  return nodes_iterator(G->getFunction()->begin());
104  }
105 
107  return nodes_iterator(G->getFunction()->end());
108  }
109 };
110 
111 using BFIDOTGTraitsBase =
113 
114 template <>
116  explicit DOTGraphTraits(bool isSimple = false)
118 
119  std::string getNodeLabel(const BasicBlock *Node,
120  const BlockFrequencyInfo *Graph) {
121 
122  return BFIDOTGTraitsBase::getNodeLabel(Node, Graph, getGVDT());
123  }
124 
125  std::string getNodeAttributes(const BasicBlock *Node,
126  const BlockFrequencyInfo *Graph) {
127  return BFIDOTGTraitsBase::getNodeAttributes(Node, Graph,
129  }
130 
131  std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI,
132  const BlockFrequencyInfo *BFI) {
133  return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI, BFI->getBPI(),
135  }
136 };
137 
138 } // end namespace llvm
139 
141 
143  const BranchProbabilityInfo &BPI,
144  const LoopInfo &LI) {
145  calculate(F, BPI, LI);
146 }
147 
149  : BFI(std::move(Arg.BFI)) {}
150 
152  releaseMemory();
153  BFI = std::move(RHS.BFI);
154  return *this;
155 }
156 
157 // Explicitly define the default constructor otherwise it would be implicitly
158 // defined at the first ODR-use which is the BFI member in the
159 // LazyBlockFrequencyInfo header. The dtor needs the BlockFrequencyInfoImpl
160 // template instantiated which is not available in the header.
162 
165  // Check whether the analysis, all analyses on functions, or the function's
166  // CFG have been preserved.
167  auto PAC = PA.getChecker<BlockFrequencyAnalysis>();
168  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
169  PAC.preservedSet<CFGAnalyses>());
170 }
171 
173  const BranchProbabilityInfo &BPI,
174  const LoopInfo &LI) {
175  if (!BFI)
176  BFI.reset(new ImplType);
177  BFI->calculate(F, BPI, LI);
179  (ViewBlockFreqFuncName.empty() ||
181  view();
182  }
183 }
184 
186  return BFI ? BFI->getBlockFreq(BB) : 0;
187 }
188 
191  if (!BFI)
192  return None;
193 
194  return BFI->getBlockProfileCount(*getFunction(), BB);
195 }
196 
199  if (!BFI)
200  return None;
201  return BFI->getProfileCountFromFreq(*getFunction(), Freq);
202 }
203 
204 void BlockFrequencyInfo::setBlockFreq(const BasicBlock *BB, uint64_t Freq) {
205  assert(BFI && "Expected analysis to be available");
206  BFI->setBlockFreq(BB, Freq);
207 }
208 
210  const BasicBlock *ReferenceBB, uint64_t Freq,
211  SmallPtrSetImpl<BasicBlock *> &BlocksToScale) {
212  assert(BFI && "Expected analysis to be available");
213  // Use 128 bits APInt to avoid overflow.
214  APInt NewFreq(128, Freq);
215  APInt OldFreq(128, BFI->getBlockFreq(ReferenceBB).getFrequency());
216  APInt BBFreq(128, 0);
217  for (auto *BB : BlocksToScale) {
218  BBFreq = BFI->getBlockFreq(BB).getFrequency();
219  // Multiply first by NewFreq and then divide by OldFreq
220  // to minimize loss of precision.
221  BBFreq *= NewFreq;
222  // udiv is an expensive operation in the general case. If this ends up being
223  // a hot spot, one of the options proposed in
224  // https://reviews.llvm.org/D28535#650071 could be used to avoid this.
225  BBFreq = BBFreq.udiv(OldFreq);
226  BFI->setBlockFreq(BB, BBFreq.getLimitedValue());
227  }
228  BFI->setBlockFreq(ReferenceBB, Freq);
229 }
230 
231 /// Pop up a ghostview window with the current block frequency propagation
232 /// rendered using dot.
234  ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs");
235 }
236 
238  return BFI ? BFI->getFunction() : nullptr;
239 }
240 
242  return BFI ? &BFI->getBPI() : nullptr;
243 }
244 
246 printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const {
247  return BFI ? BFI->printBlockFreq(OS, Freq) : OS;
248 }
249 
250 raw_ostream &
252  const BasicBlock *BB) const {
253  return BFI ? BFI->printBlockFreq(OS, BB) : OS;
254 }
255 
257  return BFI ? BFI->getEntryFreq() : 0;
258 }
259 
261 
263  if (BFI)
264  BFI->print(OS);
265 }
266 
268  "Block Frequency Analysis", true, true)
272  "Block Frequency Analysis", true, true)
273 
274 char BlockFrequencyInfoWrapperPass::ID = 0;
275 
276 BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass()
277  : FunctionPass(ID) {
279 }
280 
282 
284  const Module *) const {
285  BFI.print(OS);
286 }
287 
291  AU.setPreservesAll();
292 }
293 
295 
297  BranchProbabilityInfo &BPI =
298  getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
299  LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
300  BFI.calculate(F, BPI, LI);
301  return false;
302 }
303 
304 AnalysisKey BlockFrequencyAnalysis::Key;
309  AM.getResult<LoopAnalysis>(F));
310  return BFI;
311 }
312 
315  OS << "Printing analysis results of BFI for function "
316  << "'" << F.getName() << "':"
317  << "\n";
319  return PreservedAnalyses::all();
320 }
static NodeRef getEntryNode(const BlockFrequencyInfo *G)
Result run(Function &F, FunctionAnalysisManager &AM)
Run the analysis pass over a function and produce BFI.
block Block Frequency true
std::string getNodeLabel(const BasicBlock *Node, const BlockFrequencyInfo *Graph)
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:687
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BlockFrequencyInfo & operator=(const BlockFrequencyInfo &)=delete
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
iterator end()
Definition: Function.h:582
cl::opt< unsigned > ViewHotFreqPercent("view-hot-freq-percent", cl::init(10), cl::Hidden, cl::desc("An integer in percent used to specify " "the hot blocks/edges to be displayed " "in red: a block or edge whose frequency " "is no less than the max frequency of the " "function multiplied by this percent."))
APInt udiv(const APInt &RHS) const
Unsigned division operation.
Definition: APInt.cpp:1519
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
cl::opt< bool > PGOViewCounts("pgo-view-counts", cl::init(false), cl::Hidden, cl::desc("A boolean option to show CFG dag with " "block profile counts and branch probabilities " "right after PGO profile annotation step. The " "profile counts are computed using branch " "probabilities from the runtime profile data and " "block frequency propagation algorithm. To view " "the raw counts from the profile, use option " "-pgo-view-raw-counts instead. To limit graph " "display to only one function, use filtering option " "-view-bfi-func-name."))
static GVDAGType getGVDT()
raw_ostream & printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:345
PreservedAnalysisChecker getChecker() const
Build a checker for this PreservedAnalyses and the specified analysis type.
Definition: PassManager.h:304
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
void initializeBlockFrequencyInfoWrapperPassPass(PassRegistry &)
Definition: BitVector.h:920
Legacy analysis pass which computes BlockFrequencyInfo.
std::string getNodeLabel(NodeRef Node, const BlockFrequencyInfoT *Graph, GVDAGType GType, int layout_order=-1)
void setBlockFreqAndScale(const BasicBlock *ReferenceBB, uint64_t Freq, SmallPtrSetImpl< BasicBlock *> &BlocksToScale)
Set the frequency of ReferenceBB to Freq and scale the frequencies of the blocks in BlocksToScale suc...
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:820
This file implements a class to represent arbitrary precision integral constant values and operations...
std::string getNodeAttributes(const BasicBlock *Node, const BlockFrequencyInfo *Graph)
Interval::succ_iterator succ_begin(Interval *I)
succ_begin/succ_end - define methods so that Intervals may be used just like BasicBlocks can with the...
Definition: Interval.h:106
static bool isSimple(Instruction *I)
Analysis pass which computes BranchProbabilityInfo.
#define F(x, y, z)
Definition: MD5.cpp:55
static nodes_iterator nodes_begin(const BlockFrequencyInfo *G)
INITIALIZE_PASS_BEGIN(BlockFrequencyInfoWrapperPass, "block-freq", "Block Frequency Analysis", true, true) INITIALIZE_PASS_END(BlockFrequencyInfoWrapperPass
static ChildIteratorType child_end(const NodeRef N)
iterator begin()
Definition: Function.h:580
Legacy analysis pass which computes BranchProbabilityInfo.
Interval::succ_iterator succ_end(Interval *I)
Definition: Interval.h:109
BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to estimate IR basic block frequen...
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:404
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
ValuesClass values(OptsTy... Options)
Helper to build a ValuesClass by forwarding a variable number of arguments as an initializer list to ...
Definition: CommandLine.h:624
block freq
static ChildIteratorType child_begin(const NodeRef N)
void calculate(const Function &F, const BranchProbabilityInfo &BPI, const LoopInfo &LI)
calculate - compute block frequency info for the given function.
Represent the analysis usage information of a pass.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:298
void ViewGraph(const GraphType &G, const Twine &Name, bool ShortNames=false, const Twine &Title="", GraphProgram::Name Program=GraphProgram::DOT)
ViewGraph - Emit a dot graph, run &#39;dot&#39;, run gv on the postscript file, then cleanup.
Definition: GraphWriter.h:348
void print(raw_ostream &OS) const
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
std::string getEdgeAttributes(NodeRef Node, EdgeIter EI, const BlockFrequencyInfoT *BFI, const BranchProbabilityInfoT *BPI, unsigned HotPercentThreshold=0)
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
bool invalidate(Function &F, const PreservedAnalyses &PA, FunctionAnalysisManager::Invalidator &)
Handle invalidation explicitly.
DOTGraphTraits - Template class that can be specialized to customize how graphs are converted to &#39;dot...
std::string getNodeAttributes(NodeRef Node, const BlockFrequencyInfoT *Graph, unsigned HotPercentThreshold=0)
std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI, const BlockFrequencyInfo *BFI)
Analysis pass which computes BlockFrequencyInfo.
const DataFlowGraph & G
Definition: RDFGraph.cpp:206
void setBlockFreq(const BasicBlock *BB, uint64_t Freq)
const size_t N
static cl::opt< GVDAGType > ViewBlockFreqPropagationDAG("view-block-freq-propagation-dags", cl::Hidden, cl::desc("Pop up a window to show a dag displaying how block " "frequencies propagation through the CFG."), cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."), clEnumValN(GVDT_Fraction, "fraction", "display a graph using the " "fractional block frequency representation."), clEnumValN(GVDT_Integer, "integer", "display a graph using the raw " "integer fractional block frequency representation."), clEnumValN(GVDT_Count, "count", "display a graph using the real " "profile count if available.")))
BlockFrequency getBlockFreq(const BasicBlock *BB) const
getblockFreq - Return block frequency.
Class for arbitrary precision integers.
Definition: APInt.h:69
void view() const
Pop up a ghostview window with the current block frequency propagation rendered using dot...
void setPreservesAll()
Set by analyses that do not transform their input at all.
const BranchProbabilityInfo * getBPI() const
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:114
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool equals(StringRef RHS) const
equals - Check for string equality, this is more efficient than compare() when the relative ordering ...
Definition: StringRef.h:169
#define clEnumValN(ENUMVAL, FLAGNAME, DESC)
Definition: CommandLine.h:599
cl::opt< std::string > ViewBlockFreqFuncName("view-bfi-func-name", cl::Hidden, cl::desc("The option to specify " "the name of the function " "whose CFG will be displayed."))
Analysis providing branch probability information.
block Block Frequency Analysis
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:218
typename GTraits::ChildIteratorType EdgeIter
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:559
TerminatorInst::SuccIterator< const TerminatorInst *, const BasicBlock > succ_const_iterator
Definition: CFG.h:124
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This templated class represents "all analyses that operate over <a particular IR unit>" (e...
Definition: PassManager.h:91
const BasicBlock & front() const
Definition: Function.h:587
void print(raw_ostream &OS, const Module *M) const override
print - Print out the internal state of the pass.
const Function * getFunction() const
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:44
The legacy pass manager&#39;s analysis pass to compute loop information.
Definition: LoopInfo.h:845
Shared implementation for block frequency analysis.
A container for analyses that lazily runs them and caches their results.
This header defines various interfaces for pass management in LLVM.
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:70
Optional< uint64_t > getProfileCountFromFreq(uint64_t Freq) const
Returns the estimated profile count of Freq.
Optional< uint64_t > getBlockProfileCount(const BasicBlock *BB) const
Returns the estimated profile count of BB.
static nodes_iterator nodes_end(const BlockFrequencyInfo *G)