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
28namespace llvm {
29
30class CallGraph;
31class CallGraphNode;
32class CallGraphSCC;
33class PMStack;
34
35class LLVM_ABI CallGraphSCCPass : public Pass {
36public:
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.
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.
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.
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.
83class 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
88public:
89 CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {}
90
91 void initialize(ArrayRef<CallGraphNode *> NewNodes) {
92 Nodes.assign(first: NewNodes.begin(), last: NewNodes.end());
93 }
94
95 bool isSingular() const { return Nodes.size() == 1; }
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
108 iterator begin() const { return Nodes.begin(); }
109 iterator end() const { return Nodes.end(); }
110
111 const CallGraph &getCallGraph() { return CG; }
112};
113
114/// This pass is required by interprocedural register allocation. It forces
115/// codegen to follow bottom up order on call graph.
116class DummyCGSCCPass : public CallGraphSCCPass {
117public:
118 LLVM_ABI static char ID;
119
120 DummyCGSCCPass() : CallGraphSCCPass(ID) {}
121
122 bool runOnSCC(CallGraphSCC &SCC) override { return false; }
123
124 void getAnalysisUsage(AnalysisUsage &AU) const override {
125 AU.setPreservesAll();
126 }
127};
128
129} // end namespace llvm
130
131#endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
132