1 //===- PassManager internal APIs and implementation details -----*- C++ -*-===//
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 /// \file
10 ///
11 /// This header provides internal APIs and implementation details used by the
12 /// pass management interfaces exposed in PassManager.h. To understand more
13 /// context of why these particular interfaces are needed, see that header
14 /// file. None of these APIs should be used elsewhere.
15 ///
16 //===----------------------------------------------------------------------===//
17 
18 #ifndef LLVM_IR_PASSMANAGERINTERNAL_H
19 #define LLVM_IR_PASSMANAGERINTERNAL_H
20 
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/StringRef.h"
23 
24 namespace llvm {
25 
26 template <typename IRUnitT> class AnalysisManager;
27 class PreservedAnalyses;
28 
29 /// \brief Implementation details of the pass manager interfaces.
30 namespace detail {
31 
32 /// \brief Template for the abstract base class used to dispatch
33 /// polymorphically over pass objects.
34 template <typename IRUnitT> struct PassConcept {
35   // Boiler plate necessary for the container of derived classes.
~PassConceptPassConcept36   virtual ~PassConcept() {}
37 
38   /// \brief The polymorphic API which runs the pass over a given IR entity.
39   ///
40   /// Note that actual pass object can omit the analysis manager argument if
41   /// desired. Also that the analysis manager may be null if there is no
42   /// analysis manager in the pass pipeline.
43   virtual PreservedAnalyses run(IRUnitT &IR, AnalysisManager<IRUnitT> &AM) = 0;
44 
45   /// \brief Polymorphic method to access the name of a pass.
46   virtual StringRef name() = 0;
47 };
48 
49 /// \brief A template wrapper used to implement the polymorphic API.
50 ///
51 /// Can be instantiated for any object which provides a \c run method accepting
52 /// an \c IRUnitT& and an \c AnalysisManager<IRUnit>&. It requires the pass to
53 /// be a copyable object. When the
54 template <typename IRUnitT, typename PassT,
55           typename PreservedAnalysesT = PreservedAnalyses>
56 struct PassModel : PassConcept<IRUnitT> {
PassModelPassModel57   explicit PassModel(PassT Pass) : Pass(std::move(Pass)) {}
58   // We have to explicitly define all the special member functions because MSVC
59   // refuses to generate them.
PassModelPassModel60   PassModel(const PassModel &Arg) : Pass(Arg.Pass) {}
PassModelPassModel61   PassModel(PassModel &&Arg) : Pass(std::move(Arg.Pass)) {}
swapPassModel62   friend void swap(PassModel &LHS, PassModel &RHS) {
63     using std::swap;
64     swap(LHS.Pass, RHS.Pass);
65   }
66   PassModel &operator=(PassModel RHS) {
67     swap(*this, RHS);
68     return *this;
69   }
70 
runPassModel71   PreservedAnalysesT run(IRUnitT &IR, AnalysisManager<IRUnitT> &AM) override {
72     return Pass.run(IR, AM);
73   }
namePassModel74   StringRef name() override { return PassT::name(); }
75   PassT Pass;
76 };
77 
78 /// \brief Abstract concept of an analysis result.
79 ///
80 /// This concept is parameterized over the IR unit that this result pertains
81 /// to.
82 template <typename IRUnitT> struct AnalysisResultConcept {
~AnalysisResultConceptAnalysisResultConcept83   virtual ~AnalysisResultConcept() {}
84 
85   /// \brief Method to try and mark a result as invalid.
86   ///
87   /// When the outer analysis manager detects a change in some underlying
88   /// unit of the IR, it will call this method on all of the results cached.
89   ///
90   /// This method also receives a set of preserved analyses which can be used
91   /// to avoid invalidation because the pass which changed the underlying IR
92   /// took care to update or preserve the analysis result in some way.
93   ///
94   /// \returns true if the result is indeed invalid (the default).
95   virtual bool invalidate(IRUnitT &IR, const PreservedAnalyses &PA) = 0;
96 };
97 
98 /// \brief SFINAE metafunction for computing whether \c ResultT provides an
99 /// \c invalidate member function.
100 template <typename IRUnitT, typename ResultT> class ResultHasInvalidateMethod {
101   typedef char SmallType;
102   struct BigType {
103     char a, b;
104   };
105 
106   template <typename T, bool (T::*)(IRUnitT &, const PreservedAnalyses &)>
107   struct Checker;
108 
109   template <typename T> static SmallType f(Checker<T, &T::invalidate> *);
110   template <typename T> static BigType f(...);
111 
112 public:
113   enum { Value = sizeof(f<ResultT>(nullptr)) == sizeof(SmallType) };
114 };
115 
116 /// \brief Wrapper to model the analysis result concept.
117 ///
118 /// By default, this will implement the invalidate method with a trivial
119 /// implementation so that the actual analysis result doesn't need to provide
120 /// an invalidation handler. It is only selected when the invalidation handler
121 /// is not part of the ResultT's interface.
122 template <typename IRUnitT, typename PassT, typename ResultT,
123           typename PreservedAnalysesT = PreservedAnalyses,
124           bool HasInvalidateHandler =
125               ResultHasInvalidateMethod<IRUnitT, ResultT>::Value>
126 struct AnalysisResultModel;
127 
128 /// \brief Specialization of \c AnalysisResultModel which provides the default
129 /// invalidate functionality.
130 template <typename IRUnitT, typename PassT, typename ResultT,
131           typename PreservedAnalysesT>
132 struct AnalysisResultModel<IRUnitT, PassT, ResultT, PreservedAnalysesT, false>
133     : AnalysisResultConcept<IRUnitT> {
134   explicit AnalysisResultModel(ResultT Result) : Result(std::move(Result)) {}
135   // We have to explicitly define all the special member functions because MSVC
136   // refuses to generate them.
137   AnalysisResultModel(const AnalysisResultModel &Arg) : Result(Arg.Result) {}
138   AnalysisResultModel(AnalysisResultModel &&Arg)
139       : Result(std::move(Arg.Result)) {}
140   friend void swap(AnalysisResultModel &LHS, AnalysisResultModel &RHS) {
141     using std::swap;
142     swap(LHS.Result, RHS.Result);
143   }
144   AnalysisResultModel &operator=(AnalysisResultModel RHS) {
145     swap(*this, RHS);
146     return *this;
147   }
148 
149   /// \brief The model bases invalidation solely on being in the preserved set.
150   //
151   // FIXME: We should actually use two different concepts for analysis results
152   // rather than two different models, and avoid the indirect function call for
153   // ones that use the trivial behavior.
154   bool invalidate(IRUnitT &, const PreservedAnalysesT &PA) override {
155     return !PA.preserved(PassT::ID());
156   }
157 
158   ResultT Result;
159 };
160 
161 /// \brief Specialization of \c AnalysisResultModel which delegates invalidate
162 /// handling to \c ResultT.
163 template <typename IRUnitT, typename PassT, typename ResultT,
164           typename PreservedAnalysesT>
165 struct AnalysisResultModel<IRUnitT, PassT, ResultT, PreservedAnalysesT, true>
166     : AnalysisResultConcept<IRUnitT> {
167   explicit AnalysisResultModel(ResultT Result) : Result(std::move(Result)) {}
168   // We have to explicitly define all the special member functions because MSVC
169   // refuses to generate them.
170   AnalysisResultModel(const AnalysisResultModel &Arg) : Result(Arg.Result) {}
171   AnalysisResultModel(AnalysisResultModel &&Arg)
172       : Result(std::move(Arg.Result)) {}
173   friend void swap(AnalysisResultModel &LHS, AnalysisResultModel &RHS) {
174     using std::swap;
175     swap(LHS.Result, RHS.Result);
176   }
177   AnalysisResultModel &operator=(AnalysisResultModel RHS) {
178     swap(*this, RHS);
179     return *this;
180   }
181 
182   /// \brief The model delegates to the \c ResultT method.
183   bool invalidate(IRUnitT &IR, const PreservedAnalysesT &PA) override {
184     return Result.invalidate(IR, PA);
185   }
186 
187   ResultT Result;
188 };
189 
190 /// \brief Abstract concept of an analysis pass.
191 ///
192 /// This concept is parameterized over the IR unit that it can run over and
193 /// produce an analysis result.
194 template <typename IRUnitT> struct AnalysisPassConcept {
195   virtual ~AnalysisPassConcept() {}
196 
197   /// \brief Method to run this analysis over a unit of IR.
198   /// \returns A unique_ptr to the analysis result object to be queried by
199   /// users.
200   virtual std::unique_ptr<AnalysisResultConcept<IRUnitT>>
201   run(IRUnitT &IR, AnalysisManager<IRUnitT> &AM) = 0;
202 
203   /// \brief Polymorphic method to access the name of a pass.
204   virtual StringRef name() = 0;
205 };
206 
207 /// \brief Wrapper to model the analysis pass concept.
208 ///
209 /// Can wrap any type which implements a suitable \c run method. The method
210 /// must accept an \c IRUnitT& and an \c AnalysisManager<IRUnitT>& as arguments
211 /// and produce an object which can be wrapped in a \c AnalysisResultModel.
212 template <typename IRUnitT, typename PassT>
213 struct AnalysisPassModel : AnalysisPassConcept<IRUnitT> {
214   explicit AnalysisPassModel(PassT Pass) : Pass(std::move(Pass)) {}
215   // We have to explicitly define all the special member functions because MSVC
216   // refuses to generate them.
217   AnalysisPassModel(const AnalysisPassModel &Arg) : Pass(Arg.Pass) {}
218   AnalysisPassModel(AnalysisPassModel &&Arg) : Pass(std::move(Arg.Pass)) {}
219   friend void swap(AnalysisPassModel &LHS, AnalysisPassModel &RHS) {
220     using std::swap;
221     swap(LHS.Pass, RHS.Pass);
222   }
223   AnalysisPassModel &operator=(AnalysisPassModel RHS) {
224     swap(*this, RHS);
225     return *this;
226   }
227 
228   // FIXME: Replace PassT::Result with type traits when we use C++11.
229   typedef AnalysisResultModel<IRUnitT, PassT, typename PassT::Result>
230       ResultModelT;
231 
232   /// \brief The model delegates to the \c PassT::run method.
233   ///
234   /// The return is wrapped in an \c AnalysisResultModel.
235   std::unique_ptr<AnalysisResultConcept<IRUnitT>>
236   run(IRUnitT &IR, AnalysisManager<IRUnitT> &AM) override {
237     return make_unique<ResultModelT>(Pass.run(IR, AM));
238   }
239 
240   /// \brief The model delegates to a static \c PassT::name method.
241   ///
242   /// The returned string ref must point to constant immutable data!
243   StringRef name() override { return PassT::name(); }
244 
245   PassT Pass;
246 };
247 
248 } // End namespace detail
249 }
250 
251 #endif
252