1 //===- PrintSCC.cpp - Enumerate SCCs in some key graphs -------------------===//
3 // This file provides passes to print out SCCs in a CFG or a CallGraph.
4 // Normally, you would not use these passes; instead, you would use the
5 // TarjanSCCIterator directly to enumerate SCCs and process them in some way.
6 // These passes serve three purposes:
7 // (1) As a reference for how to use the TarjanSCCIterator.
8 // (2) To print out the SCCs for a CFG or a CallGraph:
9 // analyze -cfgscc to print the SCCs in each CFG of a module.
10 // analyze -cfgscc -stats to print the #SCCs and the maximum SCC size.
11 // analyze -cfgscc -debug > /dev/null to watch the algorithm in action.
14 // analyze -callscc [-stats] [-debug] to print SCCs in the CallGraph
16 // (3) To test the TarjanSCCIterator.
18 //===----------------------------------------------------------------------===//
20 #include "llvm/Pass.h"
21 #include "llvm/Module.h"
22 #include "llvm/Analysis/CallGraph.h"
23 #include "llvm/Support/CFG.h"
24 #include "Support/TarjanSCCIterator.h"
27 struct CFGSCC : public FunctionPass {
28 bool runOnFunction(Function& func);
30 void print(std::ostream &O) const { }
32 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
37 struct CallGraphSCC : public Pass {
38 // run - Print out SCCs in the call graph for the specified module.
41 void print(std::ostream &O) const { }
43 // getAnalysisUsage - This pass requires the CallGraph.
44 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
46 AU.addRequired<CallGraph>();
50 RegisterAnalysis<CFGSCC>
51 Y("cfgscc", "Print SCCs of each function CFG");
53 RegisterAnalysis<CallGraphSCC>
54 Z("callscc", "Print SCCs of the Call Graph");
57 bool CFGSCC::runOnFunction(Function &F) {
59 std::cout << "SCCs for Function " << F.getName() << " in PostOrder:";
60 for (TarjanSCC_iterator<Function*> I = tarj_begin(&F),
61 E = tarj_end(&F); I != E; ++I) {
62 SCC<Function*> &nextSCC = **I;
63 std::cout << "\nSCC #" << ++sccNum << " : ";
64 for (SCC<Function*>::const_iterator I = nextSCC.begin(),
65 E = nextSCC.end(); I != E; ++I)
66 std::cout << (*I)->getName() << ", ";
67 if (nextSCC.size() == 1 && nextSCC.HasLoop())
68 std::cout << " (Has self-loop).";
76 // run - Print out SCCs in the call graph for the specified module.
77 bool CallGraphSCC::run(Module &M) {
78 CallGraphNode* rootNode = getAnalysis<CallGraph>().getRoot();
80 std::cout << "SCCs for the program in PostOrder:";
81 for (TarjanSCC_iterator<CallGraphNode*> SCCI = tarj_begin(rootNode),
82 E = tarj_end(rootNode); SCCI != E; ++SCCI) {
83 const SCC<CallGraphNode*> &nextSCC = **SCCI;
84 std::cout << "\nSCC #" << ++sccNum << " : ";
85 for (SCC<CallGraphNode*>::const_iterator I = nextSCC.begin(),
86 E = nextSCC.end(); I != E; ++I)
87 std::cout << ((*I)->getFunction() ? (*I)->getFunction()->getName()
88 : std::string("Indirect CallGraph node")) << ", ";
89 if (nextSCC.size() == 1 && nextSCC.HasLoop())
90 std::cout << " (Has self-loop).";