1 //===- Pass.cpp - LLVM Pass Infrastructure Implementation -----------------===//
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 the LLVM Pass infrastructure.  It is primarily
10 // responsible with ensuring that passes are executed and batched together
11 // optimally.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Pass.h"
16 #include "llvm/Config/llvm-config.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/IRPrintingPasses.h"
19 #include "llvm/IR/LLVMContext.h"
20 #include "llvm/IR/LegacyPassNameParser.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/IR/OptBisect.h"
23 #include "llvm/PassInfo.h"
24 #include "llvm/PassRegistry.h"
25 #include "llvm/Support/Compiler.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include <cassert>
29 
30 #ifdef EXPENSIVE_CHECKS
31 #include "llvm/IR/StructuralHash.h"
32 #endif
33 
34 using namespace llvm;
35 
36 #define DEBUG_TYPE "ir"
37 
38 //===----------------------------------------------------------------------===//
39 // Pass Implementation
40 //
41 
42 // Force out-of-line virtual method.
43 Pass::~Pass() {
44   delete Resolver;
45 }
46 
47 // Force out-of-line virtual method.
48 ModulePass::~ModulePass() = default;
49 
50 Pass *ModulePass::createPrinterPass(raw_ostream &OS,
51                                     const std::string &Banner) const {
52   return createPrintModulePass(OS, Banner);
53 }
54 
55 PassManagerType ModulePass::getPotentialPassManagerType() const {
56   return PMT_ModulePassManager;
57 }
58 
59 static std::string getDescription(const Module &M) {
60   return "module (" + M.getName().str() + ")";
61 }
62 
63 bool ModulePass::skipModule(Module &M) const {
64   OptPassGate &Gate = M.getContext().getOptPassGate();
65   return Gate.isEnabled() && !Gate.shouldRunPass(this, getDescription(M));
66 }
67 
68 bool Pass::mustPreserveAnalysisID(char &AID) const {
69   return Resolver->getAnalysisIfAvailable(&AID) != nullptr;
70 }
71 
72 // dumpPassStructure - Implement the -debug-pass=Structure option
73 void Pass::dumpPassStructure(unsigned Offset) {
74   dbgs().indent(Offset*2) << getPassName() << "\n";
75 }
76 
77 /// getPassName - Return a nice clean name for a pass.  This usually
78 /// implemented in terms of the name that is registered by one of the
79 /// Registration templates, but can be overloaded directly.
80 StringRef Pass::getPassName() const {
81   AnalysisID AID =  getPassID();
82   const PassInfo *PI = PassRegistry::getPassRegistry()->getPassInfo(AID);
83   if (PI)
84     return PI->getPassName();
85   return "Unnamed pass: implement Pass::getPassName()";
86 }
87 
88 void Pass::preparePassManager(PMStack &) {
89   // By default, don't do anything.
90 }
91 
92 PassManagerType Pass::getPotentialPassManagerType() const {
93   // Default implementation.
94   return PMT_Unknown;
95 }
96 
97 void Pass::getAnalysisUsage(AnalysisUsage &) const {
98   // By default, no analysis results are used, all are invalidated.
99 }
100 
101 void Pass::releaseMemory() {
102   // By default, don't do anything.
103 }
104 
105 void Pass::verifyAnalysis() const {
106   // By default, don't do anything.
107 }
108 
109 void *Pass::getAdjustedAnalysisPointer(AnalysisID AID) {
110   return this;
111 }
112 
113 ImmutablePass *Pass::getAsImmutablePass() {
114   return nullptr;
115 }
116 
117 PMDataManager *Pass::getAsPMDataManager() {
118   return nullptr;
119 }
120 
121 void Pass::setResolver(AnalysisResolver *AR) {
122   assert(!Resolver && "Resolver is already set");
123   Resolver = AR;
124 }
125 
126 // print - Print out the internal state of the pass.  This is called by Analyze
127 // to print out the contents of an analysis.  Otherwise it is not necessary to
128 // implement this method.
129 void Pass::print(raw_ostream &OS, const Module *) const {
130   OS << "Pass::print not implemented for pass: '" << getPassName() << "'!\n";
131 }
132 
133 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
134 // dump - call print(cerr);
135 LLVM_DUMP_METHOD void Pass::dump() const {
136   print(dbgs(), nullptr);
137 }
138 #endif
139 
140 #ifdef EXPENSIVE_CHECKS
141 uint64_t Pass::structuralHash(Module &M) const { return StructuralHash(M); }
142 
143 uint64_t Pass::structuralHash(Function &F) const { return StructuralHash(F); }
144 #endif
145 
146 //===----------------------------------------------------------------------===//
147 // ImmutablePass Implementation
148 //
149 // Force out-of-line virtual method.
150 ImmutablePass::~ImmutablePass() = default;
151 
152 void ImmutablePass::initializePass() {
153   // By default, don't do anything.
154 }
155 
156 //===----------------------------------------------------------------------===//
157 // FunctionPass Implementation
158 //
159 
160 Pass *FunctionPass::createPrinterPass(raw_ostream &OS,
161                                       const std::string &Banner) const {
162   return createPrintFunctionPass(OS, Banner);
163 }
164 
165 PassManagerType FunctionPass::getPotentialPassManagerType() const {
166   return PMT_FunctionPassManager;
167 }
168 
169 static std::string getDescription(const Function &F) {
170   return "function (" + F.getName().str() + ")";
171 }
172 
173 bool FunctionPass::skipFunction(const Function &F) const {
174   OptPassGate &Gate = F.getContext().getOptPassGate();
175   if (Gate.isEnabled() && !Gate.shouldRunPass(this, getDescription(F)))
176     return true;
177 
178   if (F.hasOptNone()) {
179     LLVM_DEBUG(dbgs() << "Skipping pass '" << getPassName() << "' on function "
180                       << F.getName() << "\n");
181     return true;
182   }
183   return false;
184 }
185 
186 const PassInfo *Pass::lookupPassInfo(const void *TI) {
187   return PassRegistry::getPassRegistry()->getPassInfo(TI);
188 }
189 
190 const PassInfo *Pass::lookupPassInfo(StringRef Arg) {
191   return PassRegistry::getPassRegistry()->getPassInfo(Arg);
192 }
193 
194 Pass *Pass::createPass(AnalysisID ID) {
195   const PassInfo *PI = PassRegistry::getPassRegistry()->getPassInfo(ID);
196   if (!PI)
197     return nullptr;
198   return PI->createPass();
199 }
200 
201 //===----------------------------------------------------------------------===//
202 //                  Analysis Group Implementation Code
203 //===----------------------------------------------------------------------===//
204 
205 // RegisterAGBase implementation
206 
207 RegisterAGBase::RegisterAGBase(StringRef Name, const void *InterfaceID,
208                                const void *PassID, bool isDefault)
209     : PassInfo(Name, InterfaceID) {
210   PassRegistry::getPassRegistry()->registerAnalysisGroup(InterfaceID, PassID,
211                                                          *this, isDefault);
212 }
213 
214 //===----------------------------------------------------------------------===//
215 // PassRegistrationListener implementation
216 //
217 
218 // enumeratePasses - Iterate over the registered passes, calling the
219 // passEnumerate callback on each PassInfo object.
220 void PassRegistrationListener::enumeratePasses() {
221   PassRegistry::getPassRegistry()->enumerateWith(this);
222 }
223 
224 PassNameParser::PassNameParser(cl::Option &O)
225     : cl::parser<const PassInfo *>(O) {
226   PassRegistry::getPassRegistry()->addRegistrationListener(this);
227 }
228 
229 // This only gets called during static destruction, in which case the
230 // PassRegistry will have already been destroyed by llvm_shutdown().  So
231 // attempting to remove the registration listener is an error.
232 PassNameParser::~PassNameParser() = default;
233 
234 //===----------------------------------------------------------------------===//
235 //   AnalysisUsage Class Implementation
236 //
237 
238 namespace {
239 
240 struct GetCFGOnlyPasses : public PassRegistrationListener {
241   using VectorType = AnalysisUsage::VectorType;
242 
243   VectorType &CFGOnlyList;
244 
245   GetCFGOnlyPasses(VectorType &L) : CFGOnlyList(L) {}
246 
247   void passEnumerate(const PassInfo *P) override {
248     if (P->isCFGOnlyPass())
249       CFGOnlyList.push_back(P->getTypeInfo());
250   }
251 };
252 
253 } // end anonymous namespace
254 
255 // setPreservesCFG - This function should be called to by the pass, iff they do
256 // not:
257 //
258 //  1. Add or remove basic blocks from the function
259 //  2. Modify terminator instructions in any way.
260 //
261 // This function annotates the AnalysisUsage info object to say that analyses
262 // that only depend on the CFG are preserved by this pass.
263 void AnalysisUsage::setPreservesCFG() {
264   // Since this transformation doesn't modify the CFG, it preserves all analyses
265   // that only depend on the CFG (like dominators, loop info, etc...)
266   GetCFGOnlyPasses(Preserved).enumeratePasses();
267 }
268 
269 AnalysisUsage &AnalysisUsage::addPreserved(StringRef Arg) {
270   const PassInfo *PI = Pass::lookupPassInfo(Arg);
271   // If the pass exists, preserve it. Otherwise silently do nothing.
272   if (PI)
273     pushUnique(Preserved, PI->getTypeInfo());
274   return *this;
275 }
276 
277 AnalysisUsage &AnalysisUsage::addRequiredID(const void *ID) {
278   pushUnique(Required, ID);
279   return *this;
280 }
281 
282 AnalysisUsage &AnalysisUsage::addRequiredID(char &ID) {
283   pushUnique(Required, &ID);
284   return *this;
285 }
286 
287 AnalysisUsage &AnalysisUsage::addRequiredTransitiveID(char &ID) {
288   pushUnique(Required, &ID);
289   pushUnique(RequiredTransitive, &ID);
290   return *this;
291 }
292