1 //===- CallGraphSCCPass.h - Pass that operates BU on call graph -*- 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 the CallGraphSCCPass class, which is used for passes which 10 // are implemented as bottom-up traversals on the call graph. Because there may 11 // be cycles in the call graph, passes of this type operate on the call-graph in 12 // SCC order: that is, they process function bottom-up, except for recursive 13 // functions, which they process all at once. 14 // 15 // These passes are inherently interprocedural, and are required to keep the 16 // call graph up-to-date if they do anything which could modify it. 17 // 18 //===----------------------------------------------------------------------===// 19 20 #ifndef LLVM_ANALYSIS_CALLGRAPHSCCPASS_H 21 #define LLVM_ANALYSIS_CALLGRAPHSCCPASS_H 22 23 #include "llvm/ADT/ArrayRef.h" 24 #include "llvm/Pass.h" 25 #include "llvm/Support/Compiler.h" 26 #include <vector> 27 28 namespace llvm { 29 30 class CallGraph; 31 class CallGraphNode; 32 class CallGraphSCC; 33 class PMStack; 34 35 class LLVM_ABI CallGraphSCCPass : public Pass { 36 public: CallGraphSCCPass(char & pid)37 explicit CallGraphSCCPass(char &pid) : Pass(PT_CallGraphSCC, pid) {} 38 39 /// createPrinterPass - Get a pass that prints the Module 40 /// corresponding to a CallGraph. 41 Pass *createPrinterPass(raw_ostream &OS, 42 const std::string &Banner) const override; 43 44 using llvm::Pass::doInitialization; 45 using llvm::Pass::doFinalization; 46 47 /// doInitialization - This method is called before the SCC's of the program 48 /// has been processed, allowing the pass to do initialization as necessary. doInitialization(CallGraph & CG)49 virtual bool doInitialization(CallGraph &CG) { 50 return false; 51 } 52 53 /// runOnSCC - This method should be implemented by the subclass to perform 54 /// whatever action is necessary for the specified SCC. Note that 55 /// non-recursive (or only self-recursive) functions will have an SCC size of 56 /// 1, where recursive portions of the call graph will have SCC size > 1. 57 /// 58 /// SCC passes that add or delete functions to the SCC are required to update 59 /// the SCC list, otherwise stale pointers may be dereferenced. 60 virtual bool runOnSCC(CallGraphSCC &SCC) = 0; 61 62 /// doFinalization - This method is called after the SCC's of the program has 63 /// been processed, allowing the pass to do final cleanup as necessary. doFinalization(CallGraph & CG)64 virtual bool doFinalization(CallGraph &CG) { 65 return false; 66 } 67 68 /// Assign pass manager to manager this pass 69 void assignPassManager(PMStack &PMS, PassManagerType PMT) override; 70 71 /// Return what kind of Pass Manager can manage this pass. getPotentialPassManagerType()72 PassManagerType getPotentialPassManagerType() const override { 73 return PMT_CallGraphPassManager; 74 } 75 76 /// getAnalysisUsage - For this class, we declare that we require and preserve 77 /// the call graph. If the derived class implements this method, it should 78 /// always explicitly call the implementation here. 79 void getAnalysisUsage(AnalysisUsage &Info) const override; 80 }; 81 82 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on. 83 class CallGraphSCC { 84 const CallGraph &CG; // The call graph for this SCC. 85 void *Context; // The CGPassManager object that is vending this. 86 std::vector<CallGraphNode *> Nodes; 87 88 public: CallGraphSCC(CallGraph & cg,void * context)89 CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {} 90 initialize(ArrayRef<CallGraphNode * > NewNodes)91 void initialize(ArrayRef<CallGraphNode *> NewNodes) { 92 Nodes.assign(NewNodes.begin(), NewNodes.end()); 93 } 94 isSingular()95 bool isSingular() const { return Nodes.size() == 1; } size()96 unsigned size() const { return Nodes.size(); } 97 98 /// ReplaceNode - This informs the SCC and the pass manager that the specified 99 /// Old node has been deleted, and New is to be used in its place. 100 LLVM_ABI void ReplaceNode(CallGraphNode *Old, CallGraphNode *New); 101 102 /// DeleteNode - This informs the SCC and the pass manager that the specified 103 /// Old node has been deleted. 104 LLVM_ABI void DeleteNode(CallGraphNode *Old); 105 106 using iterator = std::vector<CallGraphNode *>::const_iterator; 107 begin()108 iterator begin() const { return Nodes.begin(); } end()109 iterator end() const { return Nodes.end(); } 110 getCallGraph()111 const CallGraph &getCallGraph() { return CG; } 112 }; 113 114 LLVM_ABI void initializeDummyCGSCCPassPass(PassRegistry &); 115 116 /// This pass is required by interprocedural register allocation. It forces 117 /// codegen to follow bottom up order on call graph. 118 class DummyCGSCCPass : public CallGraphSCCPass { 119 public: 120 LLVM_ABI static char ID; 121 DummyCGSCCPass()122 DummyCGSCCPass() : CallGraphSCCPass(ID) { 123 PassRegistry &Registry = *PassRegistry::getPassRegistry(); 124 initializeDummyCGSCCPassPass(Registry); 125 } 126 runOnSCC(CallGraphSCC & SCC)127 bool runOnSCC(CallGraphSCC &SCC) override { return false; } 128 getAnalysisUsage(AnalysisUsage & AU)129 void getAnalysisUsage(AnalysisUsage &AU) const override { 130 AU.setPreservesAll(); 131 } 132 }; 133 134 } // end namespace llvm 135 136 #endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H 137