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 27namespace llvm { 28 29class CallGraph; 30class CallGraphNode; 31class CallGraphSCC; 32class PMStack; 33 34class CallGraphSCCPass : public Pass { 35public: 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. 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. 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. 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 80protected: 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. 87class 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 92public: 93 CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {} 94 95 void initialize(ArrayRef<CallGraphNode *> NewNodes) { 96 Nodes.assign(NewNodes.begin(), NewNodes.end()); 97 } 98 99 bool isSingular() const { return Nodes.size() == 1; } 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; 107 108 iterator begin() const { return Nodes.begin(); } 109 iterator end() const { return Nodes.end(); } 110 111 const CallGraph &getCallGraph() { return CG; } 112}; 113 114void initializeDummyCGSCCPassPass(PassRegistry &); 115 116/// This pass is required by interprocedural register allocation. It forces 117/// codegen to follow bottom up order on call graph. 118class DummyCGSCCPass : public CallGraphSCCPass { 119public: 120 static char ID; 121 122 DummyCGSCCPass() : CallGraphSCCPass(ID) { 123 PassRegistry &Registry = *PassRegistry::getPassRegistry(); 124 initializeDummyCGSCCPassPass(Registry); 125 } 126 127 bool runOnSCC(CallGraphSCC &SCC) override { return false; } 128 129 void getAnalysisUsage(AnalysisUsage &AU) const override { 130 AU.setPreservesAll(); 131 } 132}; 133 134} // end namespace llvm 135 136#endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H 137