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 <vector> 26 27 namespace llvm { 28 29 class CallGraph; 30 class CallGraphNode; 31 class CallGraphSCC; 32 class PMStack; 33 34 class CallGraphSCCPass : public Pass { 35 public: CallGraphSCCPass(char & pid)36 explicit CallGraphSCCPass(char &pid) : Pass(PT_CallGraphSCC, pid) {} 37 38 /// createPrinterPass - Get a pass that prints the Module 39 /// corresponding to a CallGraph. 40 Pass *createPrinterPass(raw_ostream &OS, 41 const std::string &Banner) const override; 42 43 using llvm::Pass::doInitialization; 44 using llvm::Pass::doFinalization; 45 46 /// doInitialization - This method is called before the SCC's of the program 47 /// has been processed, allowing the pass to do initialization as necessary. doInitialization(CallGraph & CG)48 virtual bool doInitialization(CallGraph &CG) { 49 return false; 50 } 51 52 /// runOnSCC - This method should be implemented by the subclass to perform 53 /// whatever action is necessary for the specified SCC. Note that 54 /// non-recursive (or only self-recursive) functions will have an SCC size of 55 /// 1, where recursive portions of the call graph will have SCC size > 1. 56 /// 57 /// SCC passes that add or delete functions to the SCC are required to update 58 /// the SCC list, otherwise stale pointers may be dereferenced. 59 virtual bool runOnSCC(CallGraphSCC &SCC) = 0; 60 61 /// doFinalization - This method is called after the SCC's of the program has 62 /// been processed, allowing the pass to do final cleanup as necessary. doFinalization(CallGraph & CG)63 virtual bool doFinalization(CallGraph &CG) { 64 return false; 65 } 66 67 /// Assign pass manager to manager this pass 68 void assignPassManager(PMStack &PMS, PassManagerType PMT) override; 69 70 /// Return what kind of Pass Manager can manage this pass. getPotentialPassManagerType()71 PassManagerType getPotentialPassManagerType() const override { 72 return PMT_CallGraphPassManager; 73 } 74 75 /// getAnalysisUsage - For this class, we declare that we require and preserve 76 /// the call graph. If the derived class implements this method, it should 77 /// always explicitly call the implementation here. 78 void getAnalysisUsage(AnalysisUsage &Info) const override; 79 80 protected: 81 /// Optional passes call this function to check whether the pass should be 82 /// skipped. This is the case when optimization bisect is over the limit. 83 bool skipSCC(CallGraphSCC &SCC) const; 84 }; 85 86 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on. 87 class CallGraphSCC { 88 const CallGraph &CG; // The call graph for this SCC. 89 void *Context; // The CGPassManager object that is vending this. 90 std::vector<CallGraphNode *> Nodes; 91 92 public: CallGraphSCC(CallGraph & cg,void * context)93 CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {} 94 initialize(ArrayRef<CallGraphNode * > NewNodes)95 void initialize(ArrayRef<CallGraphNode *> NewNodes) { 96 Nodes.assign(NewNodes.begin(), NewNodes.end()); 97 } 98 isSingular()99 bool isSingular() const { return Nodes.size() == 1; } size()100 unsigned size() const { return Nodes.size(); } 101 102 /// ReplaceNode - This informs the SCC and the pass manager that the specified 103 /// Old node has been deleted, and New is to be used in its place. 104 void ReplaceNode(CallGraphNode *Old, CallGraphNode *New); 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 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 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