1//===- RegionPass.cpp - Region Pass and Region Pass Manager ---------------===//
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// This file implements RegionPass and RGPassManager. All region optimization
10// and transformation passes are derived from RegionPass. RGPassManager is
11// responsible for managing RegionPasses.
12// Most of this code has been COPIED from LoopPass.cpp
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Analysis/RegionPass.h"
17#include "llvm/Analysis/RegionInfo.h"
18#include "llvm/IR/OptBisect.h"
19#include "llvm/IR/PassTimingInfo.h"
20#include "llvm/IR/PrintPasses.h"
21#include "llvm/Support/Debug.h"
22#include "llvm/Support/Timer.h"
23#include "llvm/Support/raw_ostream.h"
24
25using namespace llvm;
26
27#define DEBUG_TYPE "regionpassmgr"
28
29//===----------------------------------------------------------------------===//
30// RGPassManager
31//
32
33char RGPassManager::ID = 0;
34
35RGPassManager::RGPassManager() : FunctionPass(ID) {
36 RI = nullptr;
37 CurrentRegion = nullptr;
38}
39
40// Recurse through all subregions and all regions into RQ.
41static void addRegionIntoQueue(Region &R, std::deque<Region *> &RQ) {
42 RQ.push_back(x: &R);
43 for (const auto &E : R)
44 addRegionIntoQueue(R&: *E, RQ);
45}
46
47/// Pass Manager itself does not invalidate any analysis info.
48void RGPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
49 Info.addRequired<RegionInfoPass>();
50 Info.setPreservesAll();
51}
52
53/// run - Execute all of the passes scheduled for execution. Keep track of
54/// whether any of the passes modifies the function, and if so, return true.
55bool RGPassManager::runOnFunction(Function &F) {
56 RI = &getAnalysis<RegionInfoPass>().getRegionInfo();
57 bool Changed = false;
58
59 // Collect inherited analysis from Module level pass manager.
60 populateInheritedAnalysis(PMS&: TPM->activeStack);
61
62 addRegionIntoQueue(R&: *RI->getTopLevelRegion(), RQ);
63
64 if (RQ.empty()) // No regions, skip calling finalizers
65 return false;
66
67 // Initialization
68 for (Region *R : RQ) {
69 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
70 RegionPass *RP = (RegionPass *)getContainedPass(N: Index);
71 Changed |= RP->doInitialization(R, RGM&: *this);
72 }
73 }
74
75 // Walk Regions
76 while (!RQ.empty()) {
77
78 CurrentRegion = RQ.back();
79
80 // Run all passes on the current Region.
81 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
82 RegionPass *P = (RegionPass*)getContainedPass(N: Index);
83
84 if (isPassDebuggingExecutionsOrMore()) {
85 dumpPassInfo(P, S1: EXECUTION_MSG, S2: ON_REGION_MSG,
86 Msg: CurrentRegion->getNameStr());
87 dumpRequiredSet(P);
88 }
89
90 initializeAnalysisImpl(P);
91
92 bool LocalChanged = false;
93 {
94 PassManagerPrettyStackEntry X(P, *CurrentRegion->getEntry());
95
96 TimeRegion PassTimer(getPassTimer(P));
97#ifdef EXPENSIVE_CHECKS
98 uint64_t RefHash = P->structuralHash(F);
99#endif
100 LocalChanged = P->runOnRegion(R: CurrentRegion, RGM&: *this);
101
102#ifdef EXPENSIVE_CHECKS
103 if (!LocalChanged && (RefHash != P->structuralHash(F))) {
104 llvm::errs() << "Pass modifies its input and doesn't report it: "
105 << P->getPassName() << "\n";
106 llvm_unreachable("Pass modifies its input and doesn't report it");
107 }
108#endif
109
110 Changed |= LocalChanged;
111 }
112
113 if (isPassDebuggingExecutionsOrMore()) {
114 if (LocalChanged)
115 dumpPassInfo(P, S1: MODIFICATION_MSG, S2: ON_REGION_MSG,
116 Msg: CurrentRegion->getNameStr());
117 dumpPreservedSet(P);
118 }
119
120 // Manually check that this region is still healthy. This is done
121 // instead of relying on RegionInfo::verifyRegion since RegionInfo
122 // is a function pass and it's really expensive to verify every
123 // Region in the function every time. That level of checking can be
124 // enabled with the -verify-region-info option.
125 {
126 TimeRegion PassTimer(getPassTimer(P));
127 CurrentRegion->verifyRegion();
128 }
129
130 // Then call the regular verifyAnalysis functions.
131 verifyPreservedAnalysis(P);
132
133 if (LocalChanged)
134 removeNotPreservedAnalysis(P);
135 recordAvailableAnalysis(P);
136 removeDeadPasses(P,
137 Msg: (!isPassDebuggingExecutionsOrMore())
138 ? "<deleted>"
139 : CurrentRegion->getNameStr(),
140 ON_REGION_MSG);
141 }
142
143 // Pop the region from queue after running all passes.
144 RQ.pop_back();
145
146 // Free all region nodes created in region passes.
147 RI->clearNodeCache();
148 }
149
150 // Finalization
151 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
152 RegionPass *P = (RegionPass*)getContainedPass(N: Index);
153 Changed |= P->doFinalization();
154 }
155
156 // Print the region tree after all pass.
157 LLVM_DEBUG(dbgs() << "\nRegion tree of function " << F.getName()
158 << " after all region Pass:\n";
159 RI->dump(); dbgs() << "\n";);
160
161 return Changed;
162}
163
164/// Print passes managed by this manager
165void RGPassManager::dumpPassStructure(unsigned Offset) {
166 errs().indent(NumSpaces: Offset*2) << "Region Pass Manager\n";
167 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
168 Pass *P = getContainedPass(N: Index);
169 P->dumpPassStructure(Offset: Offset + 1);
170 dumpLastUses(P, Offset: Offset+1);
171 }
172}
173
174namespace {
175//===----------------------------------------------------------------------===//
176// PrintRegionPass
177class PrintRegionPass : public RegionPass {
178private:
179 std::string Banner;
180 raw_ostream &Out; // raw_ostream to print on.
181
182public:
183 static char ID;
184 PrintRegionPass(const std::string &B, raw_ostream &o)
185 : RegionPass(ID), Banner(B), Out(o) {}
186
187 void getAnalysisUsage(AnalysisUsage &AU) const override {
188 AU.setPreservesAll();
189 }
190
191 bool runOnRegion(Region *R, RGPassManager &RGM) override {
192 if (!isFunctionInPrintList(FunctionName: R->getEntry()->getParent()->getName()))
193 return false;
194 Out << Banner;
195 for (const auto *BB : R->blocks()) {
196 if (BB)
197 BB->print(OS&: Out);
198 else
199 Out << "Printing <null> Block";
200 }
201
202 return false;
203 }
204
205 StringRef getPassName() const override { return "Print Region IR"; }
206};
207
208char PrintRegionPass::ID = 0;
209} //end anonymous namespace
210
211//===----------------------------------------------------------------------===//
212// RegionPass
213
214// Check if this pass is suitable for the current RGPassManager, if
215// available. This pass P is not suitable for a RGPassManager if P
216// is not preserving higher level analysis info used by other
217// RGPassManager passes. In such case, pop RGPassManager from the
218// stack. This will force assignPassManager() to create new
219// LPPassManger as expected.
220void RegionPass::preparePassManager(PMStack &PMS) {
221
222 // Find RGPassManager
223 while (!PMS.empty() &&
224 PMS.top()->getPassManagerType() > PMT_RegionPassManager)
225 PMS.pop();
226
227
228 // If this pass is destroying high level information that is used
229 // by other passes that are managed by LPM then do not insert
230 // this pass in current LPM. Use new RGPassManager.
231 if (PMS.top()->getPassManagerType() == PMT_RegionPassManager &&
232 !PMS.top()->preserveHigherLevelAnalysis(P: this))
233 PMS.pop();
234}
235
236/// Assign pass manager to manage this pass.
237void RegionPass::assignPassManager(PMStack &PMS,
238 PassManagerType PreferredType) {
239 // Find RGPassManager
240 while (!PMS.empty() &&
241 PMS.top()->getPassManagerType() > PMT_RegionPassManager)
242 PMS.pop();
243
244 RGPassManager *RGPM;
245
246 // Create new Region Pass Manager if it does not exist.
247 if (PMS.top()->getPassManagerType() == PMT_RegionPassManager)
248 RGPM = (RGPassManager*)PMS.top();
249 else {
250
251 assert (!PMS.empty() && "Unable to create Region Pass Manager");
252 PMDataManager *PMD = PMS.top();
253
254 // [1] Create new Region Pass Manager
255 RGPM = new RGPassManager();
256 RGPM->populateInheritedAnalysis(PMS);
257
258 // [2] Set up new manager's top level manager
259 PMTopLevelManager *TPM = PMD->getTopLevelManager();
260 TPM->addIndirectPassManager(Manager: RGPM);
261
262 // [3] Assign manager to manage this new manager. This may create
263 // and push new managers into PMS
264 TPM->schedulePass(P: RGPM);
265
266 // [4] Push new manager into PMS
267 PMS.push(PM: RGPM);
268 }
269
270 RGPM->add(P: this);
271}
272
273/// Get the printer pass
274Pass *RegionPass::createPrinterPass(raw_ostream &O,
275 const std::string &Banner) const {
276 return new PrintRegionPass(Banner, O);
277}
278
279static std::string getDescription(const Region &R) {
280 return "region";
281}
282
283bool RegionPass::skipRegion(Region &R) const {
284 Function &F = *R.getEntry()->getParent();
285 OptPassGate &Gate = F.getContext().getOptPassGate();
286 if (Gate.isEnabled() &&
287 !Gate.shouldRunPass(PassName: this->getPassName(), IRDescription: getDescription(R)))
288 return true;
289
290 if (F.hasOptNone()) {
291 // Report this only once per function.
292 if (R.getEntry() == &F.getEntryBlock())
293 LLVM_DEBUG(dbgs() << "Skipping pass '" << getPassName()
294 << "' on function " << F.getName() << "\n");
295 return true;
296 }
297 return false;
298}
299

source code of llvm/lib/Analysis/RegionPass.cpp