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) {
29 unsigned long sccNum = 0;
30 std::cout << "SCCs for Function " << func.getName() << " in PostOrder:";
31 for (TarjanSCC_iterator<Function*> I = tarj_begin(&func),
32 E = tarj_end(&func); I != E; ++I) {
33 SCC<Function*> &nextSCC = **I;
34 std::cout << "\nSCC #" << ++sccNum << " : ";
35 for (SCC<Function*>::const_iterator I = nextSCC.begin(),E = nextSCC.end();
37 std::cout << (*I)->getName() << ", ";
38 if (nextSCC.size() == 1 && nextSCC.HasLoop())
39 std::cout << " (Has self-loop).";
45 void print(std::ostream &O) const { }
49 struct CallGraphSCC : public Pass {
50 // run - Print out SCCs in the call graph for the specified module.
52 CallGraphNode* rootNode = getAnalysis<CallGraph>().getRoot();
53 unsigned long sccNum = 0;
54 std::cout << "SCCs for the program in PostOrder:";
55 for (TarjanSCC_iterator<CallGraphNode*> SCCI = tarj_begin(rootNode),
56 E = tarj_end(rootNode); SCCI != E; ++SCCI) {
57 const SCC<CallGraphNode*> &nextSCC = **SCCI;
58 std::cout << "\nSCC #" << ++sccNum << " : ";
59 for (SCC<CallGraphNode*>::const_iterator I = nextSCC.begin(),
60 E = nextSCC.end(); I != E; ++I)
61 std::cout << ((*I)->getFunction() ? (*I)->getFunction()->getName()
62 : std::string("Indirect CallGraph node")) << ", ";
63 if (nextSCC.size() == 1 && nextSCC.HasLoop())
64 std::cout << " (Has self-loop).";
71 void print(std::ostream &O) const { }
73 // getAnalysisUsage - This pass requires the CallGraph.
74 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
76 AU.addRequired<CallGraph>();
80 RegisterAnalysis<CFGSCC>
81 Y("cfgscc", "Print SCCs of each function CFG");
83 RegisterAnalysis<CallGraphSCC>
84 Z("callscc", "Print SCCs of the Call Graph");