LLVM  6.0.0svn
BlockFrequencyInfo.cpp
Go to the documentation of this file.
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 or text dump after profile annotation.
66  "pgo-view-counts", cl::Hidden,
67  cl::desc("A boolean option to show CFG dag or text 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  cl::values(clEnumValN(PGOVCT_None, "none", "do not show."),
78  clEnumValN(PGOVCT_Graph, "graph", "show a graph."),
79  clEnumValN(PGOVCT_Text, "text", "show in text.")));
80 
82  "print-bfi", cl::init(false), cl::Hidden,
83  cl::desc("Print the block frequency info."));
84 
86  "print-bfi-func-name", cl::Hidden,
87  cl::desc("The option to specify the name of the function "
88  "whose block frequency info is printed."));
89 
90 namespace llvm {
91 
92 static GVDAGType getGVDT() {
94  return GVDT_Count;
96 }
97 
98 template <>
100  using NodeRef = const BasicBlock *;
103 
105  return &G->getFunction()->front();
106  }
107 
109  return succ_begin(N);
110  }
111 
112  static ChildIteratorType child_end(const NodeRef N) { return succ_end(N); }
113 
115  return nodes_iterator(G->getFunction()->begin());
116  }
117 
119  return nodes_iterator(G->getFunction()->end());
120  }
121 };
122 
123 using BFIDOTGTraitsBase =
125 
126 template <>
128  explicit DOTGraphTraits(bool isSimple = false)
130 
131  std::string getNodeLabel(const BasicBlock *Node,
132  const BlockFrequencyInfo *Graph) {
133 
134  return BFIDOTGTraitsBase::getNodeLabel(Node, Graph, getGVDT());
135  }
136 
137  std::string getNodeAttributes(const BasicBlock *Node,
138  const BlockFrequencyInfo *Graph) {
139  return BFIDOTGTraitsBase::getNodeAttributes(Node, Graph,
141  }
142 
143  std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI,
144  const BlockFrequencyInfo *BFI) {
145  return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI, BFI->getBPI(),
147  }
148 };
149 
150 } // end namespace llvm
151 
153 
155  const BranchProbabilityInfo &BPI,
156  const LoopInfo &LI) {
157  calculate(F, BPI, LI);
158 }
159 
161  : BFI(std::move(Arg.BFI)) {}
162 
164  releaseMemory();
165  BFI = std::move(RHS.BFI);
166  return *this;
167 }
168 
169 // Explicitly define the default constructor otherwise it would be implicitly
170 // defined at the first ODR-use which is the BFI member in the
171 // LazyBlockFrequencyInfo header. The dtor needs the BlockFrequencyInfoImpl
172 // template instantiated which is not available in the header.
174 
177  // Check whether the analysis, all analyses on functions, or the function's
178  // CFG have been preserved.
179  auto PAC = PA.getChecker<BlockFrequencyAnalysis>();
180  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
181  PAC.preservedSet<CFGAnalyses>());
182 }
183 
185  const BranchProbabilityInfo &BPI,
186  const LoopInfo &LI) {
187  if (!BFI)
188  BFI.reset(new ImplType);
189  BFI->calculate(F, BPI, LI);
191  (ViewBlockFreqFuncName.empty() ||
193  view();
194  }
195  if (PrintBlockFreq &&
196  (PrintBlockFreqFuncName.empty() ||
198  print(dbgs());
199  }
200 }
201 
203  return BFI ? BFI->getBlockFreq(BB) : 0;
204 }
205 
208  if (!BFI)
209  return None;
210 
211  return BFI->getBlockProfileCount(*getFunction(), BB);
212 }
213 
216  if (!BFI)
217  return None;
218  return BFI->getProfileCountFromFreq(*getFunction(), Freq);
219 }
220 
221 void BlockFrequencyInfo::setBlockFreq(const BasicBlock *BB, uint64_t Freq) {
222  assert(BFI && "Expected analysis to be available");
223  BFI->setBlockFreq(BB, Freq);
224 }
225 
227  const BasicBlock *ReferenceBB, uint64_t Freq,
228  SmallPtrSetImpl<BasicBlock *> &BlocksToScale) {
229  assert(BFI && "Expected analysis to be available");
230  // Use 128 bits APInt to avoid overflow.
231  APInt NewFreq(128, Freq);
232  APInt OldFreq(128, BFI->getBlockFreq(ReferenceBB).getFrequency());
233  APInt BBFreq(128, 0);
234  for (auto *BB : BlocksToScale) {
235  BBFreq = BFI->getBlockFreq(BB).getFrequency();
236  // Multiply first by NewFreq and then divide by OldFreq
237  // to minimize loss of precision.
238  BBFreq *= NewFreq;
239  // udiv is an expensive operation in the general case. If this ends up being
240  // a hot spot, one of the options proposed in
241  // https://reviews.llvm.org/D28535#650071 could be used to avoid this.
242  BBFreq = BBFreq.udiv(OldFreq);
243  BFI->setBlockFreq(BB, BBFreq.getLimitedValue());
244  }
245  BFI->setBlockFreq(ReferenceBB, Freq);
246 }
247 
248 /// Pop up a ghostview window with the current block frequency propagation
249 /// rendered using dot.
251  ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs");
252 }
253 
255  return BFI ? BFI->getFunction() : nullptr;
256 }
257 
259  return BFI ? &BFI->getBPI() : nullptr;
260 }
261 
263 printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const {
264  return BFI ? BFI->printBlockFreq(OS, Freq) : OS;
265 }
266 
267 raw_ostream &
269  const BasicBlock *BB) const {
270  return BFI ? BFI->printBlockFreq(OS, BB) : OS;
271 }
272 
274  return BFI ? BFI->getEntryFreq() : 0;
275 }
276 
278 
280  if (BFI)
281  BFI->print(OS);
282 }
283 
285  "Block Frequency Analysis", true, true)
289  "Block Frequency Analysis", true, true)
290 
291 char BlockFrequencyInfoWrapperPass::ID = 0;
292 
293 BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass()
294  : FunctionPass(ID) {
296 }
297 
299 
301  const Module *) const {
302  BFI.print(OS);
303 }
304 
308  AU.setPreservesAll();
309 }
310 
312 
314  BranchProbabilityInfo &BPI =
315  getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
316  LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
317  BFI.calculate(F, BPI, LI);
318  return false;
319 }
320 
321 AnalysisKey BlockFrequencyAnalysis::Key;
326  AM.getResult<LoopAnalysis>(F));
327  return BFI;
328 }
329 
332  OS << "Printing analysis results of BFI for function "
333  << "'" << F.getName() << "':"
334  << "\n";
336  return PreservedAnalyses::all();
337 }
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:590
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...
cl::opt< PGOViewCountsType > PGOViewCounts("pgo-view-counts", cl::Hidden, cl::desc("A boolean option to show CFG dag or text 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."), cl::values(clEnumValN(PGOVCT_None, "none", "do not show."), clEnumValN(PGOVCT_Graph, "graph", "show a graph."), clEnumValN(PGOVCT_Text, "text", "show in text.")))
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
F(f)
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:336
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:871
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:103
static bool isSimple(Instruction *I)
Analysis pass which computes BranchProbabilityInfo.
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:588
Legacy analysis pass which computes BranchProbabilityInfo.
Interval::succ_iterator succ_end(Interval *I)
Definition: Interval.h:106
BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to estimate IR basic block frequen...
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:406
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
static cl::opt< bool > PrintBlockFreq("print-bfi", cl::init(false), cl::Hidden, cl::desc("Print the block frequency info."))
ValuesClass values(OptsTy... Options)
Helper to build a ValuesClass by forwarding a variable number of arguments as an initializer list to ...
Definition: CommandLine.h:626
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:285
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:211
void setBlockFreq(const BasicBlock *BB, uint64_t Freq)
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.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
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.
cl::opt< std::string > PrintBlockFreqFuncName("print-bfi-func-name", cl::Hidden, cl::desc("The option to specify the name of the function " "whose block frequency info is printed."))
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:601
amdgpu Simplify well known AMD library false Value Value * Arg
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
#define N
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:595
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:896
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)