112 lines
3.9 KiB
C++
112 lines
3.9 KiB
C++
//===- PrintSCC.cpp - Enumerate SCCs in some key graphs -------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file provides passes to print out SCCs in a CFG or a CallGraph.
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// Normally, you would not use these passes; instead, you would use the
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// scc_iterator directly to enumerate SCCs and process them in some way. These
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// passes serve three purposes:
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//
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// (1) As a reference for how to use the scc_iterator.
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// (2) To print out the SCCs for a CFG or a CallGraph:
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// analyze -print-cfg-sccs to print the SCCs in each CFG of a module.
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// analyze -print-cfg-sccs -stats to print the #SCCs and the maximum SCC size.
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// analyze -print-cfg-sccs -debug > /dev/null to watch the algorithm in action.
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//
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// and similarly:
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// analyze -print-callgraph-sccs [-stats] [-debug] to print SCCs in the CallGraph
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//
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// (3) To test the scc_iterator.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/SCCIterator.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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struct CFGSCC : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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CFGSCC() : FunctionPass(ID) {}
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bool runOnFunction(Function& func) override;
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void print(raw_ostream &O, const Module* = nullptr) const override { }
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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}
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};
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struct CallGraphSCC : public ModulePass {
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static char ID; // Pass identification, replacement for typeid
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CallGraphSCC() : ModulePass(ID) {}
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// run - Print out SCCs in the call graph for the specified module.
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bool runOnModule(Module &M) override;
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void print(raw_ostream &O, const Module* = nullptr) const override { }
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// getAnalysisUsage - This pass requires the CallGraph.
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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AU.addRequired<CallGraphWrapperPass>();
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}
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};
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}
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char CFGSCC::ID = 0;
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static RegisterPass<CFGSCC>
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Y("print-cfg-sccs", "Print SCCs of each function CFG");
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char CallGraphSCC::ID = 0;
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static RegisterPass<CallGraphSCC>
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Z("print-callgraph-sccs", "Print SCCs of the Call Graph");
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bool CFGSCC::runOnFunction(Function &F) {
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unsigned sccNum = 0;
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errs() << "SCCs for Function " << F.getName() << " in PostOrder:";
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for (scc_iterator<Function*> SCCI = scc_begin(&F); !SCCI.isAtEnd(); ++SCCI) {
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const std::vector<BasicBlock *> &nextSCC = *SCCI;
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errs() << "\nSCC #" << ++sccNum << " : ";
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for (std::vector<BasicBlock*>::const_iterator I = nextSCC.begin(),
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E = nextSCC.end(); I != E; ++I)
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errs() << (*I)->getName() << ", ";
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if (nextSCC.size() == 1 && SCCI.hasLoop())
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errs() << " (Has self-loop).";
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}
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errs() << "\n";
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return true;
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}
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// run - Print out SCCs in the call graph for the specified module.
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bool CallGraphSCC::runOnModule(Module &M) {
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CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
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unsigned sccNum = 0;
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errs() << "SCCs for the program in PostOrder:";
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for (scc_iterator<CallGraph*> SCCI = scc_begin(&CG); !SCCI.isAtEnd();
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++SCCI) {
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const std::vector<CallGraphNode*> &nextSCC = *SCCI;
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errs() << "\nSCC #" << ++sccNum << " : ";
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for (std::vector<CallGraphNode*>::const_iterator I = nextSCC.begin(),
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E = nextSCC.end(); I != E; ++I)
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errs() << ((*I)->getFunction() ? (*I)->getFunction()->getName()
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: "external node") << ", ";
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if (nextSCC.size() == 1 && SCCI.hasLoop())
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errs() << " (Has self-loop).";
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}
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errs() << "\n";
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return true;
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}
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