1//===- llvm/Pass.h - Base class for Passes ----------------------*- C++ -*-===//
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 defines a base class that indicates that a specified class is a
10// transformation pass implementation.
11//
12// Passes are designed this way so that it is possible to run passes in a cache
13// and organizationally optimal order without having to specify it at the front
14// end. This allows arbitrary passes to be strung together and have them
15// executed as efficiently as possible.
16//
17// Passes should extend one of the classes below, depending on the guarantees
18// that it can make about what will be modified as it is run. For example, most
19// global optimizations should derive from FunctionPass, because they do not add
20// or delete functions, they operate on the internals of the function.
21//
22// Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the
23// bottom), so the APIs exposed by these files are also automatically available
24// to all users of this file.
25//
26//===----------------------------------------------------------------------===//
27
28#ifndef LLVM_PASS_H
29#define LLVM_PASS_H
30
31#include <string>
32
33namespace llvm {
34
35class AnalysisResolver;
36class AnalysisUsage;
37class Function;
38class ImmutablePass;
39class Module;
40class PassInfo;
41class PMDataManager;
42class PMStack;
43class raw_ostream;
44class StringRef;
45
46// AnalysisID - Use the PassInfo to identify a pass...
47using AnalysisID = const void *;
48
49/// Different types of internal pass managers. External pass managers
50/// (PassManager and FunctionPassManager) are not represented here.
51/// Ordering of pass manager types is important here.
52enum PassManagerType {
53 PMT_Unknown = 0,
54 PMT_ModulePassManager = 1, ///< MPPassManager
55 PMT_CallGraphPassManager, ///< CGPassManager
56 PMT_FunctionPassManager, ///< FPPassManager
57 PMT_LoopPassManager, ///< LPPassManager
58 PMT_RegionPassManager, ///< RGPassManager
59 PMT_Last
60};
61
62// Different types of passes.
63enum PassKind {
64 PT_Region,
65 PT_Loop,
66 PT_Function,
67 PT_CallGraphSCC,
68 PT_Module,
69 PT_PassManager
70};
71
72/// This enumerates the LLVM full LTO or ThinLTO optimization phases.
73enum class ThinOrFullLTOPhase {
74 /// No LTO/ThinLTO behavior needed.
75 None,
76 /// ThinLTO prelink (summary) phase.
77 ThinLTOPreLink,
78 /// ThinLTO postlink (backend compile) phase.
79 ThinLTOPostLink,
80 /// Full LTO prelink phase.
81 FullLTOPreLink,
82 /// Full LTO postlink (backend compile) phase.
83 FullLTOPostLink
84};
85
86//===----------------------------------------------------------------------===//
87/// Pass interface - Implemented by all 'passes'. Subclass this if you are an
88/// interprocedural optimization or you do not fit into any of the more
89/// constrained passes described below.
90///
91class Pass {
92 AnalysisResolver *Resolver = nullptr; // Used to resolve analysis
93 const void *PassID;
94 PassKind Kind;
95
96public:
97 explicit Pass(PassKind K, char &pid) : PassID(&pid), Kind(K) {}
98 Pass(const Pass &) = delete;
99 Pass &operator=(const Pass &) = delete;
100 virtual ~Pass();
101
102 PassKind getPassKind() const { return Kind; }
103
104 /// getPassName - Return a nice clean name for a pass. This usually
105 /// implemented in terms of the name that is registered by one of the
106 /// Registration templates, but can be overloaded directly.
107 virtual StringRef getPassName() const;
108
109 /// getPassID - Return the PassID number that corresponds to this pass.
110 AnalysisID getPassID() const {
111 return PassID;
112 }
113
114 /// doInitialization - Virtual method overridden by subclasses to do
115 /// any necessary initialization before any pass is run.
116 virtual bool doInitialization(Module &) { return false; }
117
118 /// doFinalization - Virtual method overriden by subclasses to do any
119 /// necessary clean up after all passes have run.
120 virtual bool doFinalization(Module &) { return false; }
121
122 /// print - Print out the internal state of the pass. This is called by
123 /// Analyze to print out the contents of an analysis. Otherwise it is not
124 /// necessary to implement this method. Beware that the module pointer MAY be
125 /// null. This automatically forwards to a virtual function that does not
126 /// provide the Module* in case the analysis doesn't need it it can just be
127 /// ignored.
128 virtual void print(raw_ostream &OS, const Module *M) const;
129
130 void dump() const; // dump - Print to stderr.
131
132 /// createPrinterPass - Get a Pass appropriate to print the IR this
133 /// pass operates on (Module, Function or MachineFunction).
134 virtual Pass *createPrinterPass(raw_ostream &OS,
135 const std::string &Banner) const = 0;
136
137 /// Each pass is responsible for assigning a pass manager to itself.
138 /// PMS is the stack of available pass manager.
139 virtual void assignPassManager(PMStack &,
140 PassManagerType) {}
141
142 /// Check if available pass managers are suitable for this pass or not.
143 virtual void preparePassManager(PMStack &);
144
145 /// Return what kind of Pass Manager can manage this pass.
146 virtual PassManagerType getPotentialPassManagerType() const;
147
148 // Access AnalysisResolver
149 void setResolver(AnalysisResolver *AR);
150 AnalysisResolver *getResolver() const { return Resolver; }
151
152 /// getAnalysisUsage - This function should be overriden by passes that need
153 /// analysis information to do their job. If a pass specifies that it uses a
154 /// particular analysis result to this function, it can then use the
155 /// getAnalysis<AnalysisType>() function, below.
156 virtual void getAnalysisUsage(AnalysisUsage &) const;
157
158 /// releaseMemory() - This member can be implemented by a pass if it wants to
159 /// be able to release its memory when it is no longer needed. The default
160 /// behavior of passes is to hold onto memory for the entire duration of their
161 /// lifetime (which is the entire compile time). For pipelined passes, this
162 /// is not a big deal because that memory gets recycled every time the pass is
163 /// invoked on another program unit. For IP passes, it is more important to
164 /// free memory when it is unused.
165 ///
166 /// Optionally implement this function to release pass memory when it is no
167 /// longer used.
168 virtual void releaseMemory();
169
170 /// getAdjustedAnalysisPointer - This method is used when a pass implements
171 /// an analysis interface through multiple inheritance. If needed, it should
172 /// override this to adjust the this pointer as needed for the specified pass
173 /// info.
174 virtual void *getAdjustedAnalysisPointer(AnalysisID ID);
175 virtual ImmutablePass *getAsImmutablePass();
176 virtual PMDataManager *getAsPMDataManager();
177
178 /// verifyAnalysis() - This member can be implemented by a analysis pass to
179 /// check state of analysis information.
180 virtual void verifyAnalysis() const;
181
182 // dumpPassStructure - Implement the -debug-passes=PassStructure option
183 virtual void dumpPassStructure(unsigned Offset = 0);
184
185 // lookupPassInfo - Return the pass info object for the specified pass class,
186 // or null if it is not known.
187 static const PassInfo *lookupPassInfo(const void *TI);
188
189 // lookupPassInfo - Return the pass info object for the pass with the given
190 // argument string, or null if it is not known.
191 static const PassInfo *lookupPassInfo(StringRef Arg);
192
193 // createPass - Create a object for the specified pass class,
194 // or null if it is not known.
195 static Pass *createPass(AnalysisID ID);
196
197 /// getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to
198 /// get analysis information that might be around, for example to update it.
199 /// This is different than getAnalysis in that it can fail (if the analysis
200 /// results haven't been computed), so should only be used if you can handle
201 /// the case when the analysis is not available. This method is often used by
202 /// transformation APIs to update analysis results for a pass automatically as
203 /// the transform is performed.
204 template<typename AnalysisType> AnalysisType *
205 getAnalysisIfAvailable() const; // Defined in PassAnalysisSupport.h
206
207 /// mustPreserveAnalysisID - This method serves the same function as
208 /// getAnalysisIfAvailable, but works if you just have an AnalysisID. This
209 /// obviously cannot give you a properly typed instance of the class if you
210 /// don't have the class name available (use getAnalysisIfAvailable if you
211 /// do), but it can tell you if you need to preserve the pass at least.
212 bool mustPreserveAnalysisID(char &AID) const;
213
214 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
215 /// to the analysis information that they claim to use by overriding the
216 /// getAnalysisUsage function.
217 template<typename AnalysisType>
218 AnalysisType &getAnalysis() const; // Defined in PassAnalysisSupport.h
219
220 template <typename AnalysisType>
221 AnalysisType &
222 getAnalysis(Function &F,
223 bool *Changed = nullptr); // Defined in PassAnalysisSupport.h
224
225 template<typename AnalysisType>
226 AnalysisType &getAnalysisID(AnalysisID PI) const;
227
228 template <typename AnalysisType>
229 AnalysisType &getAnalysisID(AnalysisID PI, Function &F,
230 bool *Changed = nullptr);
231};
232
233//===----------------------------------------------------------------------===//
234/// ModulePass class - This class is used to implement unstructured
235/// interprocedural optimizations and analyses. ModulePasses may do anything
236/// they want to the program.
237///
238class ModulePass : public Pass {
239public:
240 explicit ModulePass(char &pid) : Pass(PT_Module, pid) {}
241
242 // Force out-of-line virtual method.
243 ~ModulePass() override;
244
245 /// createPrinterPass - Get a module printer pass.
246 Pass *createPrinterPass(raw_ostream &OS,
247 const std::string &Banner) const override;
248
249 /// runOnModule - Virtual method overriden by subclasses to process the module
250 /// being operated on.
251 virtual bool runOnModule(Module &M) = 0;
252
253 void assignPassManager(PMStack &PMS, PassManagerType T) override;
254
255 /// Return what kind of Pass Manager can manage this pass.
256 PassManagerType getPotentialPassManagerType() const override;
257
258protected:
259 /// Optional passes call this function to check whether the pass should be
260 /// skipped. This is the case when optimization bisect is over the limit.
261 bool skipModule(Module &M) const;
262};
263
264//===----------------------------------------------------------------------===//
265/// ImmutablePass class - This class is used to provide information that does
266/// not need to be run. This is useful for things like target information and
267/// "basic" versions of AnalysisGroups.
268///
269class ImmutablePass : public ModulePass {
270public:
271 explicit ImmutablePass(char &pid) : ModulePass(pid) {}
272
273 // Force out-of-line virtual method.
274 ~ImmutablePass() override;
275
276 /// initializePass - This method may be overriden by immutable passes to allow
277 /// them to perform various initialization actions they require. This is
278 /// primarily because an ImmutablePass can "require" another ImmutablePass,
279 /// and if it does, the overloaded version of initializePass may get access to
280 /// these passes with getAnalysis<>.
281 virtual void initializePass();
282
283 ImmutablePass *getAsImmutablePass() override { return this; }
284
285 /// ImmutablePasses are never run.
286 bool runOnModule(Module &) override { return false; }
287};
288
289//===----------------------------------------------------------------------===//
290/// FunctionPass class - This class is used to implement most global
291/// optimizations. Optimizations should subclass this class if they meet the
292/// following constraints:
293///
294/// 1. Optimizations are organized globally, i.e., a function at a time
295/// 2. Optimizing a function does not cause the addition or removal of any
296/// functions in the module
297///
298class FunctionPass : public Pass {
299public:
300 explicit FunctionPass(char &pid) : Pass(PT_Function, pid) {}
301
302 /// createPrinterPass - Get a function printer pass.
303 Pass *createPrinterPass(raw_ostream &OS,
304 const std::string &Banner) const override;
305
306 /// runOnFunction - Virtual method overriden by subclasses to do the
307 /// per-function processing of the pass.
308 virtual bool runOnFunction(Function &F) = 0;
309
310 void assignPassManager(PMStack &PMS, PassManagerType T) override;
311
312 /// Return what kind of Pass Manager can manage this pass.
313 PassManagerType getPotentialPassManagerType() const override;
314
315protected:
316 /// Optional passes call this function to check whether the pass should be
317 /// skipped. This is the case when Attribute::OptimizeNone is set or when
318 /// optimization bisect is over the limit.
319 bool skipFunction(const Function &F) const;
320};
321
322/// If the user specifies the -time-passes argument on an LLVM tool command line
323/// then the value of this boolean will be true, otherwise false.
324/// This is the storage for the -time-passes option.
325extern bool TimePassesIsEnabled;
326/// If TimePassesPerRun is true, there would be one line of report for
327/// each pass invocation.
328/// If TimePassesPerRun is false, there would be only one line of
329/// report for each pass (even there are more than one pass objects).
330/// (For new pass manager only)
331extern bool TimePassesPerRun;
332
333} // end namespace llvm
334
335// Include support files that contain important APIs commonly used by Passes,
336// but that we want to separate out to make it easier to read the header files.
337#include "llvm/PassAnalysisSupport.h"
338#include "llvm/PassSupport.h"
339
340#endif // LLVM_PASS_H
341