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/IntrinsicInst.h"
26 #include "llvm/Support/raw_ostream.h"
29 //===----------------------------------------------------------------------===//
32 /// CGPassManager manages FPPassManagers and CalLGraphSCCPasses.
36 class CGPassManager : public ModulePass, public PMDataManager {
39 explicit CGPassManager(int Depth)
40 : ModulePass(&ID), PMDataManager(Depth) { }
42 /// run - Execute all of the passes scheduled for execution. Keep track of
43 /// whether any of the passes modifies the module, and if so, return true.
44 bool runOnModule(Module &M);
46 bool doInitialization(CallGraph &CG);
47 bool doFinalization(CallGraph &CG);
49 /// Pass Manager itself does not invalidate any analysis info.
50 void getAnalysisUsage(AnalysisUsage &Info) const {
51 // CGPassManager walks SCC and it needs CallGraph.
52 Info.addRequired<CallGraph>();
53 Info.setPreservesAll();
56 virtual const char *getPassName() const {
57 return "CallGraph Pass Manager";
60 // Print passes managed by this manager
61 void dumpPassStructure(unsigned Offset) {
62 errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
63 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
64 Pass *P = getContainedPass(Index);
65 P->dumpPassStructure(Offset + 1);
66 dumpLastUses(P, Offset+1);
70 Pass *getContainedPass(unsigned N) {
71 assert(N < PassVector.size() && "Pass number out of range!");
72 return static_cast<Pass *>(PassVector[N]);
75 virtual PassManagerType getPassManagerType() const {
76 return PMT_CallGraphPassManager;
80 bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
81 CallGraph &CG, bool &CallGraphUpToDate);
82 void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
86 } // end anonymous namespace.
88 char CGPassManager::ID = 0;
90 bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
91 CallGraph &CG, bool &CallGraphUpToDate) {
93 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass*>(P)) {
94 if (!CallGraphUpToDate) {
95 RefreshCallGraph(CurSCC, CG, false);
96 CallGraphUpToDate = true;
100 Changed = CGSP->runOnSCC(CurSCC);
103 // After the CGSCCPass is done, when assertions are enabled, use
104 // RefreshCallGraph to verify that the callgraph was correctly updated.
107 RefreshCallGraph(CurSCC, CG, true);
114 FPPassManager *FPP = dynamic_cast<FPPassManager *>(P);
115 assert(FPP && "Invalid CGPassManager member");
117 // Run pass P on all functions in the current SCC.
118 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
119 if (Function *F = CurSCC[i]->getFunction()) {
120 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
121 Changed |= FPP->runOnFunction(*F);
126 // The function pass(es) modified the IR, they may have clobbered the
128 if (Changed && CallGraphUpToDate) {
129 DEBUG(errs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
130 << P->getPassName() << '\n');
131 CallGraphUpToDate = false;
137 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
138 /// callgraph with the call sites found in it. This is used after
139 /// FunctionPasses have potentially munged the callgraph, and can be used after
140 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
142 void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
143 CallGraph &CG, bool CheckingMode) {
144 DenseMap<Value*, CallGraphNode*> CallSites;
146 DEBUG(errs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
148 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
152 bool MadeChange = false;
154 // Scan all functions in the SCC.
155 for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
156 CallGraphNode *CGN = CurSCC[sccidx];
157 Function *F = CGN->getFunction();
158 if (F == 0 || F->isDeclaration()) continue;
160 // Walk the function body looking for call sites. Sync up the call sites in
161 // CGN with those actually in the function.
163 // Get the set of call sites currently in the function.
164 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ){
165 // If this call site is null, then the function pass deleted the call
166 // entirely and the WeakVH nulled it out.
168 // If we've already seen this call site, then the FunctionPass RAUW'd
169 // one call with another, which resulted in two "uses" in the edge
170 // list of the same call.
171 CallSites.count(I->first) ||
173 // If the call edge is not from a call or invoke, then the function
174 // pass RAUW'd a call with another value. This can happen when
175 // constant folding happens of well known functions etc.
176 CallSite::get(I->first).getInstruction() == 0) {
177 assert(!CheckingMode &&
178 "CallGraphSCCPass did not update the CallGraph correctly!");
180 // Just remove the edge from the set of callees.
181 CGN->removeCallEdge(I);
186 assert(!CallSites.count(I->first) &&
187 "Call site occurs in node multiple times");
188 CallSites.insert(std::make_pair(I->first, I->second));
192 // Loop over all of the instructions in the function, getting the callsites.
193 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
194 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
195 CallSite CS = CallSite::get(I);
196 if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
198 // If this call site already existed in the callgraph, just verify it
199 // matches up to expectations and remove it from CallSites.
200 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
201 CallSites.find(CS.getInstruction());
202 if (ExistingIt != CallSites.end()) {
203 CallGraphNode *ExistingNode = ExistingIt->second;
205 // Remove from CallSites since we have now seen it.
206 CallSites.erase(ExistingIt);
208 // Verify that the callee is right.
209 if (ExistingNode->getFunction() == CS.getCalledFunction())
212 // If we are in checking mode, we are not allowed to actually mutate
213 // the callgraph. If this is a case where we can infer that the
214 // callgraph is less precise than it could be (e.g. an indirect call
215 // site could be turned direct), don't reject it in checking mode, and
216 // don't tweak it to be more precise.
217 if (CheckingMode && CS.getCalledFunction() &&
218 ExistingNode->getFunction() == 0)
221 assert(!CheckingMode &&
222 "CallGraphSCCPass did not update the CallGraph correctly!");
224 // If not, we either went from a direct call to indirect, indirect to
225 // direct, or direct to different direct.
226 CallGraphNode *CalleeNode;
227 if (Function *Callee = CS.getCalledFunction())
228 CalleeNode = CG.getOrInsertFunction(Callee);
230 CalleeNode = CG.getCallsExternalNode();
232 // Update the edge target in CGN.
233 for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
234 assert(I != CGN->end() && "Didn't find call entry");
235 if (I->first == CS.getInstruction()) {
236 I->second = CalleeNode;
244 assert(!CheckingMode &&
245 "CallGraphSCCPass did not update the CallGraph correctly!");
247 // If the call site didn't exist in the CGN yet, add it. We assume that
248 // newly introduced call sites won't be indirect. This could be fixed
250 CallGraphNode *CalleeNode;
251 if (Function *Callee = CS.getCalledFunction())
252 CalleeNode = CG.getOrInsertFunction(Callee);
254 CalleeNode = CG.getCallsExternalNode();
256 CGN->addCalledFunction(CS, CalleeNode);
260 // After scanning this function, if we still have entries in callsites, then
261 // they are dangling pointers. WeakVH should save us for this, so abort if
263 assert(CallSites.empty() && "Dangling pointers found in call sites map");
265 // Periodically do an explicit clear to remove tombstones when processing
267 if ((sccidx & 15) == 0)
271 DEBUG(if (MadeChange) {
272 errs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
273 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
276 errs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
281 /// run - Execute all of the passes scheduled for execution. Keep track of
282 /// whether any of the passes modifies the module, and if so, return true.
283 bool CGPassManager::runOnModule(Module &M) {
284 CallGraph &CG = getAnalysis<CallGraph>();
285 bool Changed = doInitialization(CG);
287 std::vector<CallGraphNode*> CurSCC;
289 // Walk the callgraph in bottom-up SCC order.
290 for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
292 // Copy the current SCC and increment past it so that the pass can hack
293 // on the SCC if it wants to without invalidating our iterator.
298 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
299 // up-to-date or not. The CGSSC pass manager runs two types of passes:
300 // CallGraphSCC Passes and other random function passes. Because other
301 // random function passes are not CallGraph aware, they may clobber the
302 // call graph by introducing new calls or deleting other ones. This flag
303 // is set to false when we run a function pass so that we know to clean up
304 // the callgraph when we need to run a CGSCCPass again.
305 bool CallGraphUpToDate = true;
307 // Run all passes on current SCC.
308 for (unsigned PassNo = 0, e = getNumContainedPasses();
309 PassNo != e; ++PassNo) {
310 Pass *P = getContainedPass(PassNo);
312 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, "");
315 initializeAnalysisImpl(P);
317 // Actually run this pass on the current SCC.
318 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
321 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
324 verifyPreservedAnalysis(P);
325 removeNotPreservedAnalysis(P);
326 recordAvailableAnalysis(P);
327 removeDeadPasses(P, "", ON_CG_MSG);
330 // If the callgraph was left out of date (because the last pass run was a
331 // functionpass), refresh it before we move on to the next SCC.
332 if (!CallGraphUpToDate)
333 RefreshCallGraph(CurSCC, CG, false);
335 Changed |= doFinalization(CG);
340 bool CGPassManager::doInitialization(CallGraph &CG) {
341 bool Changed = false;
342 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
343 Pass *P = getContainedPass(Index);
344 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
345 Changed |= CGSP->doInitialization(CG);
347 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
348 assert (FP && "Invalid CGPassManager member");
349 Changed |= FP->doInitialization(CG.getModule());
356 bool CGPassManager::doFinalization(CallGraph &CG) {
357 bool Changed = false;
358 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
359 Pass *P = getContainedPass(Index);
360 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
361 Changed |= CGSP->doFinalization(CG);
363 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
364 assert (FP && "Invalid CGPassManager member");
365 Changed |= FP->doFinalization(CG.getModule());
371 /// Assign pass manager to manage this pass.
372 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
373 PassManagerType PreferredType) {
374 // Find CGPassManager
375 while (!PMS.empty() &&
376 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
379 assert (!PMS.empty() && "Unable to handle Call Graph Pass");
380 CGPassManager *CGP = dynamic_cast<CGPassManager *>(PMS.top());
382 // Create new Call Graph SCC Pass Manager if it does not exist.
385 assert (!PMS.empty() && "Unable to create Call Graph Pass Manager");
386 PMDataManager *PMD = PMS.top();
388 // [1] Create new Call Graph Pass Manager
389 CGP = new CGPassManager(PMD->getDepth() + 1);
391 // [2] Set up new manager's top level manager
392 PMTopLevelManager *TPM = PMD->getTopLevelManager();
393 TPM->addIndirectPassManager(CGP);
395 // [3] Assign manager to manage this new manager. This may create
396 // and push new managers into PMS
397 Pass *P = dynamic_cast<Pass *>(CGP);
398 TPM->schedulePass(P);
400 // [4] Push new manager into PMS
407 /// getAnalysisUsage - For this class, we declare that we require and preserve
408 /// the call graph. If the derived class implements this method, it should
409 /// always explicitly call the implementation here.
410 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
411 AU.addRequired<CallGraph>();
412 AU.addPreserved<CallGraph>();