1 //===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the CallGraphSCCPass class, which is used for passes
11 // which are implemented as bottom-up traversals on the call graph. Because
12 // there may be cycles in the call graph, passes of this type operate on the
13 // call-graph in SCC order: that is, they process function bottom-up, except for
14 // recursive functions, which they process all at once.
16 //===----------------------------------------------------------------------===//
18 #define DEBUG_TYPE "cgscc-passmgr"
19 #include "llvm/CallGraphSCCPass.h"
20 #include "llvm/Analysis/CallGraph.h"
21 #include "llvm/ADT/SCCIterator.h"
22 #include "llvm/PassManagers.h"
23 #include "llvm/Function.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/raw_ostream.h"
28 //===----------------------------------------------------------------------===//
31 /// CGPassManager manages FPPassManagers and CalLGraphSCCPasses.
35 class CGPassManager : public ModulePass, public PMDataManager {
38 explicit CGPassManager(int Depth)
39 : ModulePass(&ID), PMDataManager(Depth) { }
41 /// run - Execute all of the passes scheduled for execution. Keep track of
42 /// whether any of the passes modifies the module, and if so, return true.
43 bool runOnModule(Module &M);
45 bool doInitialization(CallGraph &CG);
46 bool doFinalization(CallGraph &CG);
48 /// Pass Manager itself does not invalidate any analysis info.
49 void getAnalysisUsage(AnalysisUsage &Info) const {
50 // CGPassManager walks SCC and it needs CallGraph.
51 Info.addRequired<CallGraph>();
52 Info.setPreservesAll();
55 virtual const char *getPassName() const {
56 return "CallGraph Pass Manager";
59 // Print passes managed by this manager
60 void dumpPassStructure(unsigned Offset) {
61 errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
62 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
63 Pass *P = getContainedPass(Index);
64 P->dumpPassStructure(Offset + 1);
65 dumpLastUses(P, Offset+1);
69 Pass *getContainedPass(unsigned N) {
70 assert(N < PassVector.size() && "Pass number out of range!");
71 return static_cast<Pass *>(PassVector[N]);
74 virtual PassManagerType getPassManagerType() const {
75 return PMT_CallGraphPassManager;
79 bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
80 CallGraph &CG, bool &CallGraphUpToDate);
81 void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
85 } // end anonymous namespace.
87 char CGPassManager::ID = 0;
89 bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
90 CallGraph &CG, bool &CallGraphUpToDate) {
92 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass*>(P)) {
93 if (!CallGraphUpToDate) {
94 RefreshCallGraph(CurSCC, CG, false);
95 CallGraphUpToDate = true;
99 Changed = CGSP->runOnSCC(CurSCC);
102 // After the CGSCCPass is done, when assertions are enabled, use
103 // RefreshCallGraph to verify that the callgraph was correctly updated.
106 RefreshCallGraph(CurSCC, CG, true);
113 FPPassManager *FPP = dynamic_cast<FPPassManager *>(P);
114 assert(FPP && "Invalid CGPassManager member");
116 // Run pass P on all functions in the current SCC.
117 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
118 if (Function *F = CurSCC[i]->getFunction()) {
119 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
120 Changed |= FPP->runOnFunction(*F);
125 // The function pass(es) modified the IR, they may have clobbered the
127 if (Changed && CallGraphUpToDate) {
128 DEBUG(errs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
129 << P->getPassName() << '\n');
130 CallGraphUpToDate = false;
136 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
137 /// callgraph with the call sites found in it. This is used after
138 /// FunctionPasses have potentially munged the callgraph, and can be used after
139 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
141 void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
142 CallGraph &CG, bool CheckingMode) {
143 DenseMap<Value*, CallGraphNode*> CallSites;
145 DEBUG(errs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
147 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
151 bool MadeChange = false;
153 // Scan all functions in the SCC.
154 for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
155 CallGraphNode *CGN = CurSCC[sccidx];
156 Function *F = CGN->getFunction();
157 if (F == 0 || F->isDeclaration()) continue;
159 // Walk the function body looking for call sites. Sync up the call sites in
160 // CGN with those actually in the function.
162 // Get the set of call sites currently in the function.
163 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ){
164 // If this call site is null, then the function pass deleted the call
165 // entirely and the WeakVH nulled it out.
167 // If we've already seen this call site, then the FunctionPass RAUW'd
168 // one call with another, which resulted in two "uses" in the edge
169 // list of the same call.
170 CallSites.count(I->first) ||
172 // If the call edge is not from a call or invoke, then the function
173 // pass RAUW'd a call with another value. This can happen when
174 // constant folding happens of well known functions etc.
175 CallSite::get(I->first).getInstruction() == 0) {
176 assert(!CheckingMode &&
177 "CallGraphSCCPass did not update the CallGraph correctly!");
179 // Just remove the edge from the set of callees.
180 CGN->removeCallEdge(I);
185 assert(!CallSites.count(I->first) &&
186 "Call site occurs in node multiple times");
187 CallSites.insert(std::make_pair(I->first, I->second));
191 // Loop over all of the instructions in the function, getting the callsites.
192 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
193 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
194 CallSite CS = CallSite::get(I);
195 if (!CS.getInstruction()) continue;
197 // If this call site already existed in the callgraph, just verify it
198 // matches up to expectations and remove it from CallSites.
199 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
200 CallSites.find(CS.getInstruction());
201 if (ExistingIt != CallSites.end()) {
202 CallGraphNode *ExistingNode = ExistingIt->second;
204 // Remove from CallSites since we have now seen it.
205 CallSites.erase(ExistingIt);
207 // Verify that the callee is right.
208 if (ExistingNode->getFunction() == CS.getCalledFunction())
211 // If we are in checking mode, we are not allowed to actually mutate
212 // the callgraph. If this is a case where we can infer that the
213 // callgraph is less precise than it could be (e.g. an indirect call
214 // site could be turned direct), don't reject it in checking mode, and
215 // don't tweak it to be more precise.
216 if (CheckingMode && CS.getCalledFunction() &&
217 ExistingNode->getFunction() == 0)
220 assert(!CheckingMode &&
221 "CallGraphSCCPass did not update the CallGraph correctly!");
223 // If not, we either went from a direct call to indirect, indirect to
224 // direct, or direct to different direct.
225 CallGraphNode *CalleeNode;
226 if (Function *Callee = CS.getCalledFunction())
227 CalleeNode = CG.getOrInsertFunction(Callee);
229 CalleeNode = CG.getCallsExternalNode();
231 ExistingIt->second = CalleeNode;
236 assert(!CheckingMode &&
237 "CallGraphSCCPass did not update the CallGraph correctly!");
239 // If the call site didn't exist in the CGN yet, add it. We assume that
240 // newly introduced call sites won't be indirect. This could be fixed
242 CallGraphNode *CalleeNode;
243 if (Function *Callee = CS.getCalledFunction())
244 CalleeNode = CG.getOrInsertFunction(Callee);
246 CalleeNode = CG.getCallsExternalNode();
248 CGN->addCalledFunction(CS, CalleeNode);
252 // After scanning this function, if we still have entries in callsites, then
253 // they are dangling pointers. WeakVH should save us for this, so abort if
255 assert(CallSites.empty() && "Dangling pointers found in call sites map");
257 // Periodically do an explicit clear to remove tombstones when processing
259 if ((sccidx & 15) == 0)
263 DEBUG(if (MadeChange) {
264 errs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
265 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
268 errs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
273 /// run - Execute all of the passes scheduled for execution. Keep track of
274 /// whether any of the passes modifies the module, and if so, return true.
275 bool CGPassManager::runOnModule(Module &M) {
276 CallGraph &CG = getAnalysis<CallGraph>();
277 bool Changed = doInitialization(CG);
279 std::vector<CallGraphNode*> CurSCC;
281 // Walk the callgraph in bottom-up SCC order.
282 for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
284 // Copy the current SCC and increment past it so that the pass can hack
285 // on the SCC if it wants to without invalidating our iterator.
290 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
291 // up-to-date or not. The CGSSC pass manager runs two types of passes:
292 // CallGraphSCC Passes and other random function passes. Because other
293 // random function passes are not CallGraph aware, they may clobber the
294 // call graph by introducing new calls or deleting other ones. This flag
295 // is set to false when we run a function pass so that we know to clean up
296 // the callgraph when we need to run a CGSCCPass again.
297 bool CallGraphUpToDate = true;
299 // Run all passes on current SCC.
300 for (unsigned PassNo = 0, e = getNumContainedPasses();
301 PassNo != e; ++PassNo) {
302 Pass *P = getContainedPass(PassNo);
304 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, "");
307 initializeAnalysisImpl(P);
309 // Actually run this pass on the current SCC.
310 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
313 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
316 verifyPreservedAnalysis(P);
317 removeNotPreservedAnalysis(P);
318 recordAvailableAnalysis(P);
319 removeDeadPasses(P, "", ON_CG_MSG);
322 // If the callgraph was left out of date (because the last pass run was a
323 // functionpass), refresh it before we move on to the next SCC.
324 if (!CallGraphUpToDate)
325 RefreshCallGraph(CurSCC, CG, false);
327 Changed |= doFinalization(CG);
332 bool CGPassManager::doInitialization(CallGraph &CG) {
333 bool Changed = false;
334 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
335 Pass *P = getContainedPass(Index);
336 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
337 Changed |= CGSP->doInitialization(CG);
339 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
340 assert (FP && "Invalid CGPassManager member");
341 Changed |= FP->doInitialization(CG.getModule());
348 bool CGPassManager::doFinalization(CallGraph &CG) {
349 bool Changed = false;
350 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
351 Pass *P = getContainedPass(Index);
352 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
353 Changed |= CGSP->doFinalization(CG);
355 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
356 assert (FP && "Invalid CGPassManager member");
357 Changed |= FP->doFinalization(CG.getModule());
363 /// Assign pass manager to manage this pass.
364 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
365 PassManagerType PreferredType) {
366 // Find CGPassManager
367 while (!PMS.empty() &&
368 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
371 assert (!PMS.empty() && "Unable to handle Call Graph Pass");
372 CGPassManager *CGP = dynamic_cast<CGPassManager *>(PMS.top());
374 // Create new Call Graph SCC Pass Manager if it does not exist.
377 assert (!PMS.empty() && "Unable to create Call Graph Pass Manager");
378 PMDataManager *PMD = PMS.top();
380 // [1] Create new Call Graph Pass Manager
381 CGP = new CGPassManager(PMD->getDepth() + 1);
383 // [2] Set up new manager's top level manager
384 PMTopLevelManager *TPM = PMD->getTopLevelManager();
385 TPM->addIndirectPassManager(CGP);
387 // [3] Assign manager to manage this new manager. This may create
388 // and push new managers into PMS
389 Pass *P = dynamic_cast<Pass *>(CGP);
390 TPM->schedulePass(P);
392 // [4] Push new manager into PMS
399 /// getAnalysisUsage - For this class, we declare that we require and preserve
400 /// the call graph. If the derived class implements this method, it should
401 /// always explicitly call the implementation here.
402 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
403 AU.addRequired<CallGraph>();
404 AU.addPreserved<CallGraph>();