LLVM API Documentation

PassAnalysisSupport.h

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00001 //===- llvm/PassAnalysisSupport.h - Analysis Pass Support code --*- C++ -*-===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file defines stuff that is used to define and "use" Analysis Passes.
00011 // This file is automatically #included by Pass.h, so:
00012 //
00013 //           NO .CPP FILES SHOULD INCLUDE THIS FILE DIRECTLY
00014 //
00015 // Instead, #include Pass.h
00016 //
00017 //===----------------------------------------------------------------------===//
00018 
00019 #ifndef LLVM_PASS_ANALYSIS_SUPPORT_H
00020 #define LLVM_PASS_ANALYSIS_SUPPORT_H
00021 
00022 #include <vector>
00023 
00024 namespace llvm {
00025 
00026 // No need to include Pass.h, we are being included by it!
00027 
00028 //===----------------------------------------------------------------------===//
00029 // AnalysisUsage - Represent the analysis usage information of a pass.  This
00030 // tracks analyses that the pass REQUIRES (must be available when the pass
00031 // runs), REQUIRES TRANSITIVE (must be available throughout the lifetime of the
00032 // pass), and analyses that the pass PRESERVES (the pass does not invalidate the
00033 // results of these analyses).  This information is provided by a pass to the
00034 // Pass infrastructure through the getAnalysisUsage virtual function.
00035 //
00036 class AnalysisUsage {
00037   // Sets of analyses required and preserved by a pass
00038   std::vector<AnalysisID> Required, RequiredTransitive, Preserved;
00039   bool PreservesAll;
00040 public:
00041   AnalysisUsage() : PreservesAll(false) {}
00042 
00043   // addRequired - Add the specified ID to the required set of the usage info
00044   // for a pass.
00045   //
00046   AnalysisUsage &addRequiredID(AnalysisID ID) {
00047     Required.push_back(ID);
00048     return *this;
00049   }
00050   template<class PassClass>
00051   AnalysisUsage &addRequired() {
00052     assert(Pass::getClassPassInfo<PassClass>() && "Pass class not registered!");
00053     Required.push_back(Pass::getClassPassInfo<PassClass>());
00054     return *this;
00055   }
00056 
00057   template<class PassClass>
00058   AnalysisUsage &addRequiredTransitive() {
00059     AnalysisID ID = Pass::getClassPassInfo<PassClass>();
00060     assert(ID && "Pass class not registered!");
00061     Required.push_back(ID);
00062     RequiredTransitive.push_back(ID);
00063     return *this;
00064   }
00065 
00066   // addPreserved - Add the specified ID to the set of analyses preserved by
00067   // this pass
00068   //
00069   AnalysisUsage &addPreservedID(AnalysisID ID) {
00070     Preserved.push_back(ID);
00071     return *this;
00072   }
00073 
00074   template<class PassClass>
00075   AnalysisUsage &addPreserved() {
00076     assert(Pass::getClassPassInfo<PassClass>() && "Pass class not registered!");
00077     Preserved.push_back(Pass::getClassPassInfo<PassClass>());
00078     return *this;
00079   }
00080 
00081   // setPreservesAll - Set by analyses that do not transform their input at all
00082   void setPreservesAll() { PreservesAll = true; }
00083   bool getPreservesAll() const { return PreservesAll; }
00084 
00085   /// setPreservesCFG - This function should be called by the pass, iff they do
00086   /// not:
00087   ///
00088   ///  1. Add or remove basic blocks from the function
00089   ///  2. Modify terminator instructions in any way.
00090   ///
00091   /// This function annotates the AnalysisUsage info object to say that analyses
00092   /// that only depend on the CFG are preserved by this pass.
00093   ///
00094   void setPreservesCFG();
00095 
00096   const std::vector<AnalysisID> &getRequiredSet() const { return Required; }
00097   const std::vector<AnalysisID> &getRequiredTransitiveSet() const {
00098     return RequiredTransitive;
00099   }
00100   const std::vector<AnalysisID> &getPreservedSet() const { return Preserved; }
00101 };
00102 
00103 
00104 
00105 //===----------------------------------------------------------------------===//
00106 // AnalysisResolver - Simple interface implemented by PassManager objects that
00107 // is used to pull analysis information out of them.
00108 //
00109 struct AnalysisResolver {
00110   virtual ~AnalysisResolver();
00111   virtual Pass *getAnalysisOrNullUp(AnalysisID ID) const = 0;
00112   virtual Pass *getAnalysisOrNullDown(AnalysisID ID) const = 0;
00113   virtual void addPass(ImmutablePass *IP, AnalysisUsage &AU) = 0;
00114   Pass *getAnalysis(AnalysisID ID) const {
00115     Pass *Result = getAnalysisOrNullUp(ID);
00116     assert(Result && "Pass has an incorrect analysis uses set!");
00117     return Result;
00118   }
00119 
00120   // getAnalysisToUpdate - Return an analysis result or null if it doesn't exist
00121   Pass *getAnalysisToUpdate(AnalysisID ID) const {
00122     return getAnalysisOrNullUp(ID);
00123   }
00124 
00125   // Methods for introspecting into pass manager objects...
00126   virtual unsigned getDepth() const = 0;
00127   virtual unsigned getNumContainedPasses() const = 0;
00128   virtual const Pass *getContainedPass(unsigned N) const = 0;
00129 
00130   virtual void markPassUsed(AnalysisID P, Pass *User) = 0;
00131 
00132   void startPass(Pass *P) {}
00133   void endPass(Pass *P) {}
00134 protected:
00135   void setAnalysisResolver(Pass *P, AnalysisResolver *AR);
00136 };
00137 
00138 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
00139 /// to get to the analysis information that might be around that needs to be
00140 /// updated.  This is different than getAnalysis in that it can fail (ie the
00141 /// analysis results haven't been computed), so should only be used if you
00142 /// provide the capability to update an analysis that exists.  This method is
00143 /// often used by transformation APIs to update analysis results for a pass
00144 /// automatically as the transform is performed.
00145 ///
00146 template<typename AnalysisType>
00147 AnalysisType *Pass::getAnalysisToUpdate() const {
00148   assert(Resolver && "Pass not resident in a PassManager object!");
00149   const PassInfo *PI = getClassPassInfo<AnalysisType>();
00150   if (PI == 0) return 0;
00151   return dynamic_cast<AnalysisType*>(Resolver->getAnalysisToUpdate(PI));
00152 }
00153 
00154 } // End llvm namespace
00155 
00156 #endif