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 /// DeleteNode - This informs the SCC and the pass manager that the specified
107 /// Old node has been deleted.
108 void DeleteNode(CallGraphNode *Old);
109
110 using iterator = std::vector<CallGraphNode *>::const_iterator;
111
112 iterator begin() const { return Nodes.begin(); }
113 iterator end() const { return Nodes.end(); }
114
115 const CallGraph &getCallGraph() { return CG; }
116};
117
118void initializeDummyCGSCCPassPass(PassRegistry &);
119
120/// This pass is required by interprocedural register allocation. It forces
121/// codegen to follow bottom up order on call graph.
122class DummyCGSCCPass : public CallGraphSCCPass {
123public:
124 static char ID;
125
126 DummyCGSCCPass() : CallGraphSCCPass(ID) {
127 PassRegistry &Registry = *PassRegistry::getPassRegistry();
128 initializeDummyCGSCCPassPass(Registry);
129 }
130
131 bool runOnSCC(CallGraphSCC &SCC) override { return false; }
132
133 void getAnalysisUsage(AnalysisUsage &AU) const override {
134 AU.setPreservesAll();
135 }
136};
137
138} // end namespace llvm
139
140#endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
141

source code of llvm/include/llvm/Analysis/CallGraphSCCPass.h