1//===- MachineBlockFrequencyInfo.cpp - MBB Frequency Analysis -------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Loops should be simplified before this analysis.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
14#include "llvm/ADT/DenseMap.h"
15#include "llvm/ADT/iterator.h"
16#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
17#include "llvm/CodeGen/MachineBasicBlock.h"
18#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineLoopInfo.h"
21#include "llvm/InitializePasses.h"
22#include "llvm/Pass.h"
23#include "llvm/Support/CommandLine.h"
24#include "llvm/Support/GraphWriter.h"
25#include <optional>
26#include <string>
27
28using namespace llvm;
29
30#define DEBUG_TYPE "machine-block-freq"
31
32namespace llvm {
33static cl::opt<GVDAGType> ViewMachineBlockFreqPropagationDAG(
34 "view-machine-block-freq-propagation-dags", cl::Hidden,
35 cl::desc("Pop up a window to show a dag displaying how machine block "
36 "frequencies propagate through the CFG."),
37 cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
38 clEnumValN(GVDT_Fraction, "fraction",
39 "display a graph using the "
40 "fractional block frequency representation."),
41 clEnumValN(GVDT_Integer, "integer",
42 "display a graph using the raw "
43 "integer fractional block frequency representation."),
44 clEnumValN(GVDT_Count, "count", "display a graph using the real "
45 "profile count if available.")));
46
47// Similar option above, but used to control BFI display only after MBP pass
48cl::opt<GVDAGType> ViewBlockLayoutWithBFI(
49 "view-block-layout-with-bfi", cl::Hidden,
50 cl::desc(
51 "Pop up a window to show a dag displaying MBP layout and associated "
52 "block frequencies of the CFG."),
53 cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."),
54 clEnumValN(GVDT_Fraction, "fraction",
55 "display a graph using the "
56 "fractional block frequency representation."),
57 clEnumValN(GVDT_Integer, "integer",
58 "display a graph using the raw "
59 "integer fractional block frequency representation."),
60 clEnumValN(GVDT_Count, "count",
61 "display a graph using the real "
62 "profile count if available.")));
63
64// Command line option to specify the name of the function for CFG dump
65// Defined in Analysis/BlockFrequencyInfo.cpp: -view-bfi-func-name=
66extern cl::opt<std::string> ViewBlockFreqFuncName;
67
68// Command line option to specify hot frequency threshold.
69// Defined in Analysis/BlockFrequencyInfo.cpp: -view-hot-freq-perc=
70extern cl::opt<unsigned> ViewHotFreqPercent;
71
72static cl::opt<bool> PrintMachineBlockFreq(
73 "print-machine-bfi", cl::init(Val: false), cl::Hidden,
74 cl::desc("Print the machine block frequency info."));
75
76// Command line option to specify the name of the function for block frequency
77// dump. Defined in Analysis/BlockFrequencyInfo.cpp.
78extern cl::opt<std::string> PrintBFIFuncName;
79} // namespace llvm
80
81static GVDAGType getGVDT() {
82 if (ViewBlockLayoutWithBFI != GVDT_None)
83 return ViewBlockLayoutWithBFI;
84
85 return ViewMachineBlockFreqPropagationDAG;
86}
87
88namespace llvm {
89
90template <> struct GraphTraits<MachineBlockFrequencyInfo *> {
91 using NodeRef = const MachineBasicBlock *;
92 using ChildIteratorType = MachineBasicBlock::const_succ_iterator;
93 using nodes_iterator = pointer_iterator<MachineFunction::const_iterator>;
94
95 static NodeRef getEntryNode(const MachineBlockFrequencyInfo *G) {
96 return &G->getFunction()->front();
97 }
98
99 static ChildIteratorType child_begin(const NodeRef N) {
100 return N->succ_begin();
101 }
102
103 static ChildIteratorType child_end(const NodeRef N) { return N->succ_end(); }
104
105 static nodes_iterator nodes_begin(const MachineBlockFrequencyInfo *G) {
106 return nodes_iterator(G->getFunction()->begin());
107 }
108
109 static nodes_iterator nodes_end(const MachineBlockFrequencyInfo *G) {
110 return nodes_iterator(G->getFunction()->end());
111 }
112};
113
114using MBFIDOTGraphTraitsBase =
115 BFIDOTGraphTraitsBase<MachineBlockFrequencyInfo,
116 MachineBranchProbabilityInfo>;
117
118template <>
119struct DOTGraphTraits<MachineBlockFrequencyInfo *>
120 : public MBFIDOTGraphTraitsBase {
121 const MachineFunction *CurFunc = nullptr;
122 DenseMap<const MachineBasicBlock *, int> LayoutOrderMap;
123
124 explicit DOTGraphTraits(bool isSimple = false)
125 : MBFIDOTGraphTraitsBase(isSimple) {}
126
127 std::string getNodeLabel(const MachineBasicBlock *Node,
128 const MachineBlockFrequencyInfo *Graph) {
129 int layout_order = -1;
130 // Attach additional ordering information if 'isSimple' is false.
131 if (!isSimple()) {
132 const MachineFunction *F = Node->getParent();
133 if (!CurFunc || F != CurFunc) {
134 if (CurFunc)
135 LayoutOrderMap.clear();
136
137 CurFunc = F;
138 int O = 0;
139 for (auto MBI = F->begin(); MBI != F->end(); ++MBI, ++O) {
140 LayoutOrderMap[&*MBI] = O;
141 }
142 }
143 layout_order = LayoutOrderMap[Node];
144 }
145 return MBFIDOTGraphTraitsBase::getNodeLabel(Node, Graph, GType: getGVDT(),
146 layout_order);
147 }
148
149 std::string getNodeAttributes(const MachineBasicBlock *Node,
150 const MachineBlockFrequencyInfo *Graph) {
151 return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
152 HotPercentThreshold: ViewHotFreqPercent);
153 }
154
155 std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
156 const MachineBlockFrequencyInfo *MBFI) {
157 return MBFIDOTGraphTraitsBase::getEdgeAttributes(
158 Node, EI, BFI: MBFI, BPI: MBFI->getMBPI(), HotPercentThreshold: ViewHotFreqPercent);
159 }
160};
161
162} // end namespace llvm
163
164AnalysisKey MachineBlockFrequencyAnalysis::Key;
165
166MachineBlockFrequencyAnalysis::Result
167MachineBlockFrequencyAnalysis::run(MachineFunction &MF,
168 MachineFunctionAnalysisManager &MFAM) {
169 auto &MBPI = MFAM.getResult<MachineBranchProbabilityAnalysis>(IR&: MF);
170 auto &MLI = MFAM.getResult<MachineLoopAnalysis>(IR&: MF);
171 return Result(MF, MBPI, MLI);
172}
173
174PreservedAnalyses
175MachineBlockFrequencyPrinterPass::run(MachineFunction &MF,
176 MachineFunctionAnalysisManager &MFAM) {
177 auto &MBFI = MFAM.getResult<MachineBlockFrequencyAnalysis>(IR&: MF);
178 OS << "Machine block frequency for machine function: " << MF.getName()
179 << '\n';
180 MBFI.print(OS);
181 return PreservedAnalyses::all();
182}
183
184INITIALIZE_PASS_BEGIN(MachineBlockFrequencyInfoWrapperPass, DEBUG_TYPE,
185 "Machine Block Frequency Analysis", true, true)
186INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfoWrapperPass)
187INITIALIZE_PASS_DEPENDENCY(MachineLoopInfoWrapperPass)
188INITIALIZE_PASS_END(MachineBlockFrequencyInfoWrapperPass, DEBUG_TYPE,
189 "Machine Block Frequency Analysis", true, true)
190
191char MachineBlockFrequencyInfoWrapperPass::ID = 0;
192
193MachineBlockFrequencyInfoWrapperPass::MachineBlockFrequencyInfoWrapperPass()
194 : MachineFunctionPass(ID) {
195 initializeMachineBlockFrequencyInfoWrapperPassPass(
196 Registry&: *PassRegistry::getPassRegistry());
197}
198
199MachineBlockFrequencyInfo::MachineBlockFrequencyInfo() = default;
200
201MachineBlockFrequencyInfo::MachineBlockFrequencyInfo(
202 MachineBlockFrequencyInfo &&) = default;
203
204MachineBlockFrequencyInfo::MachineBlockFrequencyInfo(
205 MachineFunction &F, MachineBranchProbabilityInfo &MBPI,
206 MachineLoopInfo &MLI) {
207 calculate(F, MBPI, MLI);
208}
209
210MachineBlockFrequencyInfo::~MachineBlockFrequencyInfo() = default;
211
212bool MachineBlockFrequencyInfo::invalidate(
213 MachineFunction &MF, const PreservedAnalyses &PA,
214 MachineFunctionAnalysisManager::Invalidator &) {
215 // Check whether the analysis, all analyses on machine functions, or the
216 // machine function's CFG have been preserved.
217 auto PAC = PA.getChecker<MachineBlockFrequencyAnalysis>();
218 return !PAC.preserved() &&
219 !PAC.preservedSet<AllAnalysesOn<MachineFunction>>() &&
220 !PAC.preservedSet<CFGAnalyses>();
221}
222
223void MachineBlockFrequencyInfoWrapperPass::getAnalysisUsage(
224 AnalysisUsage &AU) const {
225 AU.addRequired<MachineBranchProbabilityInfoWrapperPass>();
226 AU.addRequired<MachineLoopInfoWrapperPass>();
227 AU.setPreservesAll();
228 MachineFunctionPass::getAnalysisUsage(AU);
229}
230
231void MachineBlockFrequencyInfo::calculate(
232 const MachineFunction &F, const MachineBranchProbabilityInfo &MBPI,
233 const MachineLoopInfo &MLI) {
234 if (!MBFI)
235 MBFI.reset(p: new ImplType);
236 MBFI->calculate(F, BPI: MBPI, LI: MLI);
237 if (ViewMachineBlockFreqPropagationDAG != GVDT_None &&
238 (ViewBlockFreqFuncName.empty() || F.getName() == ViewBlockFreqFuncName)) {
239 view(Name: "MachineBlockFrequencyDAGS." + F.getName());
240 }
241 if (PrintMachineBlockFreq &&
242 (PrintBFIFuncName.empty() || F.getName() == PrintBFIFuncName)) {
243 MBFI->print(OS&: dbgs());
244 }
245}
246
247bool MachineBlockFrequencyInfoWrapperPass::runOnMachineFunction(
248 MachineFunction &F) {
249 MachineBranchProbabilityInfo &MBPI =
250 getAnalysis<MachineBranchProbabilityInfoWrapperPass>().getMBPI();
251 MachineLoopInfo &MLI = getAnalysis<MachineLoopInfoWrapperPass>().getLI();
252 MBFI.calculate(F, MBPI, MLI);
253 return false;
254}
255
256void MachineBlockFrequencyInfo::print(raw_ostream &OS) { MBFI->print(OS); }
257
258void MachineBlockFrequencyInfo::releaseMemory() { MBFI.reset(); }
259
260/// Pop up a ghostview window with the current block frequency propagation
261/// rendered using dot.
262void MachineBlockFrequencyInfo::view(const Twine &Name, bool isSimple) const {
263 // This code is only for debugging.
264 ViewGraph(G: const_cast<MachineBlockFrequencyInfo *>(this), Name, ShortNames: isSimple);
265}
266
267BlockFrequency
268MachineBlockFrequencyInfo::getBlockFreq(const MachineBasicBlock *MBB) const {
269 return MBFI ? MBFI->getBlockFreq(BB: MBB) : BlockFrequency(0);
270}
271
272std::optional<uint64_t> MachineBlockFrequencyInfo::getBlockProfileCount(
273 const MachineBasicBlock *MBB) const {
274 if (!MBFI)
275 return std::nullopt;
276
277 const Function &F = MBFI->getFunction()->getFunction();
278 return MBFI->getBlockProfileCount(F, BB: MBB);
279}
280
281std::optional<uint64_t>
282MachineBlockFrequencyInfo::getProfileCountFromFreq(BlockFrequency Freq) const {
283 if (!MBFI)
284 return std::nullopt;
285
286 const Function &F = MBFI->getFunction()->getFunction();
287 return MBFI->getProfileCountFromFreq(F, Freq);
288}
289
290bool MachineBlockFrequencyInfo::isIrrLoopHeader(
291 const MachineBasicBlock *MBB) const {
292 assert(MBFI && "Expected analysis to be available");
293 return MBFI->isIrrLoopHeader(BB: MBB);
294}
295
296void MachineBlockFrequencyInfo::onEdgeSplit(
297 const MachineBasicBlock &NewPredecessor,
298 const MachineBasicBlock &NewSuccessor,
299 const MachineBranchProbabilityInfo &MBPI) {
300 assert(MBFI && "Expected analysis to be available");
301 auto NewSuccFreq = MBFI->getBlockFreq(BB: &NewPredecessor) *
302 MBPI.getEdgeProbability(Src: &NewPredecessor, Dst: &NewSuccessor);
303
304 MBFI->setBlockFreq(BB: &NewSuccessor, Freq: NewSuccFreq);
305}
306
307const MachineFunction *MachineBlockFrequencyInfo::getFunction() const {
308 return MBFI ? MBFI->getFunction() : nullptr;
309}
310
311const MachineBranchProbabilityInfo *MachineBlockFrequencyInfo::getMBPI() const {
312 return MBFI ? &MBFI->getBPI() : nullptr;
313}
314
315BlockFrequency MachineBlockFrequencyInfo::getEntryFreq() const {
316 return MBFI ? MBFI->getEntryFreq() : BlockFrequency(0);
317}
318
319Printable llvm::printBlockFreq(const MachineBlockFrequencyInfo &MBFI,
320 BlockFrequency Freq) {
321 return Printable([&MBFI, Freq](raw_ostream &OS) {
322 printRelativeBlockFreq(OS, EntryFreq: MBFI.getEntryFreq(), Freq);
323 });
324}
325
326Printable llvm::printBlockFreq(const MachineBlockFrequencyInfo &MBFI,
327 const MachineBasicBlock &MBB) {
328 return printBlockFreq(MBFI, Freq: MBFI.getBlockFreq(MBB: &MBB));
329}
330