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/IntrinsicInst.h"
21 #include "llvm/Function.h"
22 #include "llvm/PassManagers.h"
23 #include "llvm/Analysis/CallGraph.h"
24 #include "llvm/ADT/SCCIterator.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/Timer.h"
27 #include "llvm/Support/raw_ostream.h"
30 //===----------------------------------------------------------------------===//
33 /// CGPassManager manages FPPassManagers and CallGraphSCCPasses.
37 class CGPassManager : public ModulePass, public PMDataManager {
40 explicit CGPassManager(int Depth)
41 : ModulePass(&ID), PMDataManager(Depth) { }
43 /// run - Execute all of the passes scheduled for execution. Keep track of
44 /// whether any of the passes modifies the module, and if so, return true.
45 bool runOnModule(Module &M);
47 bool doInitialization(CallGraph &CG);
48 bool doFinalization(CallGraph &CG);
50 /// Pass Manager itself does not invalidate any analysis info.
51 void getAnalysisUsage(AnalysisUsage &Info) const {
52 // CGPassManager walks SCC and it needs CallGraph.
53 Info.addRequired<CallGraph>();
54 Info.setPreservesAll();
57 virtual const char *getPassName() const {
58 return "CallGraph Pass Manager";
61 virtual PMDataManager *getAsPMDataManager() { return this; }
62 virtual Pass *getAsPass() { return this; }
64 // Print passes managed by this manager
65 void dumpPassStructure(unsigned Offset) {
66 errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
67 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
68 Pass *P = getContainedPass(Index);
69 P->dumpPassStructure(Offset + 1);
70 dumpLastUses(P, Offset+1);
74 Pass *getContainedPass(unsigned N) {
75 assert(N < PassVector.size() && "Pass number out of range!");
76 return static_cast<Pass *>(PassVector[N]);
79 virtual PassManagerType getPassManagerType() const {
80 return PMT_CallGraphPassManager;
84 bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
85 CallGraph &CG, bool &CallGraphUpToDate);
86 void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
90 } // end anonymous namespace.
92 char CGPassManager::ID = 0;
95 bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
96 CallGraph &CG, bool &CallGraphUpToDate) {
98 PMDataManager *PM = P->getAsPMDataManager();
101 CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
102 if (!CallGraphUpToDate) {
103 RefreshCallGraph(CurSCC, CG, false);
104 CallGraphUpToDate = true;
108 TimeRegion PassTimer(getPassTimer(CGSP));
109 Changed = CGSP->runOnSCC(CurSCC);
112 // After the CGSCCPass is done, when assertions are enabled, use
113 // RefreshCallGraph to verify that the callgraph was correctly updated.
116 RefreshCallGraph(CurSCC, CG, true);
123 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
124 "Invalid CGPassManager member");
125 FPPassManager *FPP = (FPPassManager*)P;
127 // Run pass P on all functions in the current SCC.
128 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
129 if (Function *F = CurSCC[i]->getFunction()) {
130 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
131 TimeRegion PassTimer(getPassTimer(FPP));
132 Changed |= FPP->runOnFunction(*F);
136 // The function pass(es) modified the IR, they may have clobbered the
138 if (Changed && CallGraphUpToDate) {
139 DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
140 << P->getPassName() << '\n');
141 CallGraphUpToDate = false;
147 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
148 /// callgraph with the call sites found in it. This is used after
149 /// FunctionPasses have potentially munged the callgraph, and can be used after
150 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
152 void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
153 CallGraph &CG, bool CheckingMode) {
154 DenseMap<Value*, CallGraphNode*> CallSites;
156 DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
158 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
162 bool MadeChange = false;
164 // Scan all functions in the SCC.
165 for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
166 CallGraphNode *CGN = CurSCC[sccidx];
167 Function *F = CGN->getFunction();
168 if (F == 0 || F->isDeclaration()) continue;
170 // Walk the function body looking for call sites. Sync up the call sites in
171 // CGN with those actually in the function.
173 // Get the set of call sites currently in the function.
174 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
175 // If this call site is null, then the function pass deleted the call
176 // entirely and the WeakVH nulled it out.
178 // If we've already seen this call site, then the FunctionPass RAUW'd
179 // one call with another, which resulted in two "uses" in the edge
180 // list of the same call.
181 CallSites.count(I->first) ||
183 // If the call edge is not from a call or invoke, then the function
184 // pass RAUW'd a call with another value. This can happen when
185 // constant folding happens of well known functions etc.
186 CallSite::get(I->first).getInstruction() == 0) {
187 assert(!CheckingMode &&
188 "CallGraphSCCPass did not update the CallGraph correctly!");
190 // Just remove the edge from the set of callees, keep track of whether
191 // I points to the last element of the vector.
192 bool WasLast = I + 1 == E;
193 CGN->removeCallEdge(I);
195 // If I pointed to the last element of the vector, we have to bail out:
196 // iterator checking rejects comparisons of the resultant pointer with
204 assert(!CallSites.count(I->first) &&
205 "Call site occurs in node multiple times");
206 CallSites.insert(std::make_pair(I->first, I->second));
210 // Loop over all of the instructions in the function, getting the callsites.
211 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
212 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
213 CallSite CS = CallSite::get(I);
214 if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
216 // If this call site already existed in the callgraph, just verify it
217 // matches up to expectations and remove it from CallSites.
218 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
219 CallSites.find(CS.getInstruction());
220 if (ExistingIt != CallSites.end()) {
221 CallGraphNode *ExistingNode = ExistingIt->second;
223 // Remove from CallSites since we have now seen it.
224 CallSites.erase(ExistingIt);
226 // Verify that the callee is right.
227 if (ExistingNode->getFunction() == CS.getCalledFunction())
230 // If we are in checking mode, we are not allowed to actually mutate
231 // the callgraph. If this is a case where we can infer that the
232 // callgraph is less precise than it could be (e.g. an indirect call
233 // site could be turned direct), don't reject it in checking mode, and
234 // don't tweak it to be more precise.
235 if (CheckingMode && CS.getCalledFunction() &&
236 ExistingNode->getFunction() == 0)
239 assert(!CheckingMode &&
240 "CallGraphSCCPass did not update the CallGraph correctly!");
242 // If not, we either went from a direct call to indirect, indirect to
243 // direct, or direct to different direct.
244 CallGraphNode *CalleeNode;
245 if (Function *Callee = CS.getCalledFunction())
246 CalleeNode = CG.getOrInsertFunction(Callee);
248 CalleeNode = CG.getCallsExternalNode();
250 // Update the edge target in CGN.
251 for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
252 assert(I != CGN->end() && "Didn't find call entry");
253 if (I->first == CS.getInstruction()) {
254 I->second = CalleeNode;
262 assert(!CheckingMode &&
263 "CallGraphSCCPass did not update the CallGraph correctly!");
265 // If the call site didn't exist in the CGN yet, add it. We assume that
266 // newly introduced call sites won't be indirect. This could be fixed
268 CallGraphNode *CalleeNode;
269 if (Function *Callee = CS.getCalledFunction())
270 CalleeNode = CG.getOrInsertFunction(Callee);
272 CalleeNode = CG.getCallsExternalNode();
274 CGN->addCalledFunction(CS, CalleeNode);
278 // After scanning this function, if we still have entries in callsites, then
279 // they are dangling pointers. WeakVH should save us for this, so abort if
281 assert(CallSites.empty() && "Dangling pointers found in call sites map");
283 // Periodically do an explicit clear to remove tombstones when processing
285 if ((sccidx & 15) == 0)
289 DEBUG(if (MadeChange) {
290 dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
291 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
294 dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
299 /// run - Execute all of the passes scheduled for execution. Keep track of
300 /// whether any of the passes modifies the module, and if so, return true.
301 bool CGPassManager::runOnModule(Module &M) {
302 CallGraph &CG = getAnalysis<CallGraph>();
303 bool Changed = doInitialization(CG);
305 std::vector<CallGraphNode*> CurSCC;
307 // Walk the callgraph in bottom-up SCC order.
308 for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
310 // Copy the current SCC and increment past it so that the pass can hack
311 // on the SCC if it wants to without invalidating our iterator.
316 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
317 // up-to-date or not. The CGSSC pass manager runs two types of passes:
318 // CallGraphSCC Passes and other random function passes. Because other
319 // random function passes are not CallGraph aware, they may clobber the
320 // call graph by introducing new calls or deleting other ones. This flag
321 // is set to false when we run a function pass so that we know to clean up
322 // the callgraph when we need to run a CGSCCPass again.
323 bool CallGraphUpToDate = true;
325 // Run all passes on current SCC.
326 for (unsigned PassNo = 0, e = getNumContainedPasses();
327 PassNo != e; ++PassNo) {
328 Pass *P = getContainedPass(PassNo);
330 // If we're in -debug-pass=Executions mode, construct the SCC node list,
331 // otherwise avoid constructing this string as it is expensive.
332 if (isPassDebuggingExecutionsOrMore()) {
333 std::string Functions;
335 raw_string_ostream OS(Functions);
336 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
338 CurSCC[i]->print(OS);
342 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
346 initializeAnalysisImpl(P);
348 // Actually run this pass on the current SCC.
349 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
352 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
355 verifyPreservedAnalysis(P);
356 removeNotPreservedAnalysis(P);
357 recordAvailableAnalysis(P);
358 removeDeadPasses(P, "", ON_CG_MSG);
361 // If the callgraph was left out of date (because the last pass run was a
362 // functionpass), refresh it before we move on to the next SCC.
363 if (!CallGraphUpToDate)
364 RefreshCallGraph(CurSCC, CG, false);
366 Changed |= doFinalization(CG);
371 bool CGPassManager::doInitialization(CallGraph &CG) {
372 bool Changed = false;
373 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
374 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
375 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
376 "Invalid CGPassManager member");
377 Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule());
379 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG);
386 bool CGPassManager::doFinalization(CallGraph &CG) {
387 bool Changed = false;
388 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
389 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
390 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
391 "Invalid CGPassManager member");
392 Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule());
394 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG);
400 //===----------------------------------------------------------------------===//
401 // CallGraphSCCPass Implementation
402 //===----------------------------------------------------------------------===//
404 /// Assign pass manager to manage this pass.
405 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
406 PassManagerType PreferredType) {
407 // Find CGPassManager
408 while (!PMS.empty() &&
409 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
412 assert(!PMS.empty() && "Unable to handle Call Graph Pass");
415 if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
416 CGP = (CGPassManager*)PMS.top();
418 // Create new Call Graph SCC Pass Manager if it does not exist.
419 assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
420 PMDataManager *PMD = PMS.top();
422 // [1] Create new Call Graph Pass Manager
423 CGP = new CGPassManager(PMD->getDepth() + 1);
425 // [2] Set up new manager's top level manager
426 PMTopLevelManager *TPM = PMD->getTopLevelManager();
427 TPM->addIndirectPassManager(CGP);
429 // [3] Assign manager to manage this new manager. This may create
430 // and push new managers into PMS
432 TPM->schedulePass(P);
434 // [4] Push new manager into PMS
441 /// getAnalysisUsage - For this class, we declare that we require and preserve
442 /// the call graph. If the derived class implements this method, it should
443 /// always explicitly call the implementation here.
444 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
445 AU.addRequired<CallGraph>();
446 AU.addPreserved<CallGraph>();
450 //===----------------------------------------------------------------------===//
451 // PrintCallGraphPass Implementation
452 //===----------------------------------------------------------------------===//
455 /// PrintCallGraphPass - Print a Module corresponding to a call graph.
457 class PrintCallGraphPass : public CallGraphSCCPass {
459 raw_ostream &Out; // raw_ostream to print on.
463 PrintCallGraphPass() : CallGraphSCCPass(&ID), Out(dbgs()) {}
464 PrintCallGraphPass(const std::string &B, raw_ostream &o)
465 : CallGraphSCCPass(&ID), Banner(B), Out(o) {}
467 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
468 AU.setPreservesAll();
471 bool runOnSCC(std::vector<CallGraphNode *> &SCC) {
473 for (unsigned i = 0, e = SCC.size(); i != e; ++i)
474 SCC[i]->getFunction()->print(Out);
479 } // end anonymous namespace.
481 char PrintCallGraphPass::ID = 0;
483 Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
484 const std::string &Banner) const {
485 return new PrintCallGraphPass(Banner, O);