Line data Source code
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/ADT/APInt.h"
16 : #include "llvm/ADT/None.h"
17 : #include "llvm/ADT/iterator.h"
18 : #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
19 : #include "llvm/Analysis/BranchProbabilityInfo.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"
25 : #include "llvm/Support/CommandLine.h"
26 : #include "llvm/Support/GraphWriter.h"
27 : #include "llvm/Support/raw_ostream.h"
28 : #include <algorithm>
29 : #include <cassert>
30 : #include <string>
31 :
32 : using namespace llvm;
33 :
34 : #define DEBUG_TYPE "block-freq"
35 :
36 : static cl::opt<GVDAGType> ViewBlockFreqPropagationDAG(
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 :
50 : cl::opt<std::string>
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 :
56 : cl::opt<unsigned>
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.
65 : cl::opt<PGOViewCountsType> PGOViewCounts(
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 :
81 : static cl::opt<bool> PrintBlockFreq(
82 : "print-bfi", cl::init(false), cl::Hidden,
83 : cl::desc("Print the block frequency info."));
84 :
85 : cl::opt<std::string> PrintBlockFreqFuncName(
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() {
93 0 : if (PGOViewCounts == PGOVCT_Graph)
94 : return GVDT_Count;
95 : return ViewBlockFreqPropagationDAG;
96 : }
97 :
98 : template <>
99 : struct GraphTraits<BlockFrequencyInfo *> {
100 : using NodeRef = const BasicBlock *;
101 : using ChildIteratorType = succ_const_iterator;
102 : using nodes_iterator = pointer_iterator<Function::const_iterator>;
103 :
104 : static NodeRef getEntryNode(const BlockFrequencyInfo *G) {
105 : return &G->getFunction()->front();
106 : }
107 :
108 : static ChildIteratorType child_begin(const NodeRef N) {
109 : return succ_begin(N);
110 : }
111 :
112 0 : static ChildIteratorType child_end(const NodeRef N) { return succ_end(N); }
113 :
114 : static nodes_iterator nodes_begin(const BlockFrequencyInfo *G) {
115 0 : return nodes_iterator(G->getFunction()->begin());
116 : }
117 :
118 : static nodes_iterator nodes_end(const BlockFrequencyInfo *G) {
119 0 : return nodes_iterator(G->getFunction()->end());
120 : }
121 : };
122 :
123 : using BFIDOTGTraitsBase =
124 : BFIDOTGraphTraitsBase<BlockFrequencyInfo, BranchProbabilityInfo>;
125 :
126 : template <>
127 : struct DOTGraphTraits<BlockFrequencyInfo *> : public BFIDOTGTraitsBase {
128 : explicit DOTGraphTraits(bool isSimple = false)
129 : : BFIDOTGTraitsBase(isSimple) {}
130 :
131 : std::string getNodeLabel(const BasicBlock *Node,
132 : const BlockFrequencyInfo *Graph) {
133 :
134 0 : 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,
140 0 : ViewHotFreqPercent);
141 : }
142 :
143 0 : std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI,
144 : const BlockFrequencyInfo *BFI) {
145 : return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI, BFI->getBPI(),
146 0 : ViewHotFreqPercent);
147 : }
148 : };
149 :
150 : } // end namespace llvm
151 :
152 : BlockFrequencyInfo::BlockFrequencyInfo() = default;
153 :
154 198880 : BlockFrequencyInfo::BlockFrequencyInfo(const Function &F,
155 : const BranchProbabilityInfo &BPI,
156 : const LoopInfo &LI) {
157 198880 : calculate(F, BPI, LI);
158 198880 : }
159 :
160 1838 : BlockFrequencyInfo::BlockFrequencyInfo(BlockFrequencyInfo &&Arg)
161 1838 : : BFI(std::move(Arg.BFI)) {}
162 :
163 0 : BlockFrequencyInfo &BlockFrequencyInfo::operator=(BlockFrequencyInfo &&RHS) {
164 0 : releaseMemory();
165 : BFI = std::move(RHS.BFI);
166 0 : 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.
173 : BlockFrequencyInfo::~BlockFrequencyInfo() = default;
174 :
175 551 : bool BlockFrequencyInfo::invalidate(Function &F, const PreservedAnalyses &PA,
176 : FunctionAnalysisManager::Invalidator &) {
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 1102 : return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
181 551 : PAC.preservedSet<CFGAnalyses>());
182 : }
183 :
184 487691 : void BlockFrequencyInfo::calculate(const Function &F,
185 : const BranchProbabilityInfo &BPI,
186 : const LoopInfo &LI) {
187 487691 : if (!BFI)
188 487692 : BFI.reset(new ImplType);
189 487691 : BFI->calculate(F, BPI, LI);
190 487692 : if (ViewBlockFreqPropagationDAG != GVDT_None &&
191 : (ViewBlockFreqFuncName.empty() ||
192 487692 : F.getName().equals(ViewBlockFreqFuncName))) {
193 0 : view();
194 : }
195 487692 : if (PrintBlockFreq &&
196 : (PrintBlockFreqFuncName.empty() ||
197 487692 : F.getName().equals(PrintBlockFreqFuncName))) {
198 0 : print(dbgs());
199 : }
200 487692 : }
201 :
202 14862 : BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const {
203 14862 : return BFI ? BFI->getBlockFreq(BB) : 0;
204 : }
205 :
206 : Optional<uint64_t>
207 987 : BlockFrequencyInfo::getBlockProfileCount(const BasicBlock *BB) const {
208 987 : if (!BFI)
209 : return None;
210 :
211 987 : return BFI->getBlockProfileCount(*getFunction(), BB);
212 : }
213 :
214 : Optional<uint64_t>
215 92 : BlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const {
216 92 : if (!BFI)
217 : return None;
218 92 : return BFI->getProfileCountFromFreq(*getFunction(), Freq);
219 : }
220 :
221 272 : bool BlockFrequencyInfo::isIrrLoopHeader(const BasicBlock *BB) {
222 : assert(BFI && "Expected analysis to be available");
223 272 : return BFI->isIrrLoopHeader(BB);
224 : }
225 :
226 1036 : void BlockFrequencyInfo::setBlockFreq(const BasicBlock *BB, uint64_t Freq) {
227 : assert(BFI && "Expected analysis to be available");
228 1036 : BFI->setBlockFreq(BB, Freq);
229 1036 : }
230 :
231 363 : void BlockFrequencyInfo::setBlockFreqAndScale(
232 : const BasicBlock *ReferenceBB, uint64_t Freq,
233 : SmallPtrSetImpl<BasicBlock *> &BlocksToScale) {
234 : assert(BFI && "Expected analysis to be available");
235 : // Use 128 bits APInt to avoid overflow.
236 : APInt NewFreq(128, Freq);
237 363 : APInt OldFreq(128, BFI->getBlockFreq(ReferenceBB).getFrequency());
238 : APInt BBFreq(128, 0);
239 1100 : for (auto *BB : BlocksToScale) {
240 737 : BBFreq = BFI->getBlockFreq(BB).getFrequency();
241 : // Multiply first by NewFreq and then divide by OldFreq
242 : // to minimize loss of precision.
243 737 : BBFreq *= NewFreq;
244 : // udiv is an expensive operation in the general case. If this ends up being
245 : // a hot spot, one of the options proposed in
246 : // https://reviews.llvm.org/D28535#650071 could be used to avoid this.
247 1474 : BBFreq = BBFreq.udiv(OldFreq);
248 737 : BFI->setBlockFreq(BB, BBFreq.getLimitedValue());
249 : }
250 363 : BFI->setBlockFreq(ReferenceBB, Freq);
251 363 : }
252 :
253 : /// Pop up a ghostview window with the current block frequency propagation
254 : /// rendered using dot.
255 0 : void BlockFrequencyInfo::view() const {
256 0 : ViewGraph(const_cast<BlockFrequencyInfo *>(this), "BlockFrequencyDAGs");
257 0 : }
258 :
259 1079 : const Function *BlockFrequencyInfo::getFunction() const {
260 1079 : return BFI ? BFI->getFunction() : nullptr;
261 : }
262 :
263 0 : const BranchProbabilityInfo *BlockFrequencyInfo::getBPI() const {
264 0 : return BFI ? &BFI->getBPI() : nullptr;
265 : }
266 :
267 0 : raw_ostream &BlockFrequencyInfo::
268 : printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const {
269 0 : return BFI ? BFI->printBlockFreq(OS, Freq) : OS;
270 : }
271 :
272 : raw_ostream &
273 0 : BlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
274 : const BasicBlock *BB) const {
275 0 : return BFI ? BFI->printBlockFreq(OS, BB) : OS;
276 : }
277 :
278 541 : uint64_t BlockFrequencyInfo::getEntryFreq() const {
279 541 : return BFI ? BFI->getEntryFreq() : 0;
280 : }
281 :
282 756254 : void BlockFrequencyInfo::releaseMemory() { BFI.reset(); }
283 :
284 63 : void BlockFrequencyInfo::print(raw_ostream &OS) const {
285 63 : if (BFI)
286 63 : BFI->print(OS);
287 63 : }
288 :
289 33864 : INITIALIZE_PASS_BEGIN(BlockFrequencyInfoWrapperPass, "block-freq",
290 : "Block Frequency Analysis", true, true)
291 33864 : INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass)
292 33864 : INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
293 256016 : INITIALIZE_PASS_END(BlockFrequencyInfoWrapperPass, "block-freq",
294 : "Block Frequency Analysis", true, true)
295 :
296 : char BlockFrequencyInfoWrapperPass::ID = 0;
297 :
298 34229 : BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass()
299 34229 : : FunctionPass(ID) {
300 34229 : initializeBlockFrequencyInfoWrapperPassPass(*PassRegistry::getPassRegistry());
301 34228 : }
302 :
303 : BlockFrequencyInfoWrapperPass::~BlockFrequencyInfoWrapperPass() = default;
304 :
305 29 : void BlockFrequencyInfoWrapperPass::print(raw_ostream &OS,
306 : const Module *) const {
307 29 : BFI.print(OS);
308 29 : }
309 :
310 30003 : void BlockFrequencyInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
311 : AU.addRequired<BranchProbabilityInfoWrapperPass>();
312 : AU.addRequired<LoopInfoWrapperPass>();
313 : AU.setPreservesAll();
314 30003 : }
315 :
316 287684 : void BlockFrequencyInfoWrapperPass::releaseMemory() { BFI.releaseMemory(); }
317 :
318 287684 : bool BlockFrequencyInfoWrapperPass::runOnFunction(Function &F) {
319 : BranchProbabilityInfo &BPI =
320 287684 : getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
321 287684 : LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
322 287684 : BFI.calculate(F, BPI, LI);
323 287684 : return false;
324 : }
325 :
326 : AnalysisKey BlockFrequencyAnalysis::Key;
327 919 : BlockFrequencyInfo BlockFrequencyAnalysis::run(Function &F,
328 : FunctionAnalysisManager &AM) {
329 919 : BlockFrequencyInfo BFI;
330 919 : BFI.calculate(F, AM.getResult<BranchProbabilityAnalysis>(F),
331 : AM.getResult<LoopAnalysis>(F));
332 919 : return BFI;
333 : }
334 :
335 : PreservedAnalyses
336 29 : BlockFrequencyPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
337 29 : OS << "Printing analysis results of BFI for function "
338 29 : << "'" << F.getName() << "':"
339 29 : << "\n";
340 29 : AM.getResult<BlockFrequencyAnalysis>(F).print(OS);
341 29 : return PreservedAnalyses::all();
342 : }
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