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//===- PrintSCC.cpp - Enumerate SCCs in some key graphs -------------------===//
//
// This file provides passes to print out SCCs in a CFG or a CallGraph.
// Normally, you would not use these passes; instead, you would use the
// TarjanSCCIterator directly to enumerate SCCs and process them in some way.
// These passes serve three purposes:
// (1) As a reference for how to use the TarjanSCCIterator.
// (2) To print out the SCCs for a CFG or a CallGraph:
// analyze -cfgscc to print the SCCs in each CFG of a module.
// analyze -cfgscc -stats to print the #SCCs and the maximum SCC size.
// analyze -cfgscc -debug > /dev/null to watch the algorithm in action.
//
// and similarly:
// analyze -callscc [-stats] [-debug] to print SCCs in the CallGraph
//
// (3) To test the TarjanSCCIterator.
//
//===----------------------------------------------------------------------===//
#include "llvm/Pass.h"
#include "llvm/Module.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Support/CFG.h"
#include "Support/TarjanSCCIterator.h"
namespace {
struct CFGSCC: public FunctionPass {
bool runOnFunction(Function& func) {
unsigned long sccNum = 0;
std::cout << "SCCs for Function " << func.getName() << " in PostOrder:";
for (TarjanSCC_iterator<Function*> I = tarj_begin(&func),
E = tarj_end(&func); I != E; ++I) {
SCC<Function*> &nextSCC = **I;
std::cout << "\nSCC #" << ++sccNum << " : ";
for (SCC<Function*>::const_iterator I = nextSCC.begin(),E = nextSCC.end();
I != E; ++I)
std::cout << (*I)->getName() << ", ";
if (nextSCC.size() == 1 && nextSCC.HasLoop())
std::cout << " (Has self-loop).";
}
std::cout << "\n";
return true;
}
void print(std::ostream &O) const { }
};
struct CallGraphSCC : public Pass {
// run - Print out SCCs in the call graph for the specified module.
bool run(Module &M) {
CallGraphNode* rootNode = getAnalysis<CallGraph>().getRoot();
unsigned long sccNum = 0;
std::cout << "SCCs for the program in PostOrder:";
for (TarjanSCC_iterator<CallGraphNode*> SCCI = tarj_begin(rootNode),
E = tarj_end(rootNode); SCCI != E; ++SCCI) {
const SCC<CallGraphNode*> &nextSCC = **SCCI;
std::cout << "\nSCC #" << ++sccNum << " : ";
for (SCC<CallGraphNode*>::const_iterator I = nextSCC.begin(),
E = nextSCC.end(); I != E; ++I)
std::cout << ((*I)->getFunction() ? (*I)->getFunction()->getName()
: std::string("Indirect CallGraph node")) << ", ";
if (nextSCC.size() == 1 && nextSCC.HasLoop())
std::cout << " (Has self-loop).";
}
std::cout << "\n";
return true;
}
void print(std::ostream &O) const { }
// getAnalysisUsage - This pass requires the CallGraph.
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<CallGraph>();
}
};
RegisterAnalysis<CFGSCC>
Y("cfgscc", "Print SCCs of each function CFG");
RegisterAnalysis<CallGraphSCC>
Z("callscc", "Print SCCs of the Call Graph");
}
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