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, CallGraphSCC &CurSCC,
85 CallGraph &CG, bool &CallGraphUpToDate);
86 void RefreshCallGraph(CallGraphSCC &CurSCC, CallGraph &CG,
90 } // end anonymous namespace.
92 char CGPassManager::ID = 0;
95 bool CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &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 (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
130 if (Function *F = (*I)->getFunction()) {
131 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
132 TimeRegion PassTimer(getPassTimer(FPP));
133 Changed |= FPP->runOnFunction(*F);
137 // The function pass(es) modified the IR, they may have clobbered the
139 if (Changed && CallGraphUpToDate) {
140 DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
141 << P->getPassName() << '\n');
142 CallGraphUpToDate = false;
148 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
149 /// callgraph with the call sites found in it. This is used after
150 /// FunctionPasses have potentially munged the callgraph, and can be used after
151 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
153 void CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC,
154 CallGraph &CG, bool CheckingMode) {
155 DenseMap<Value*, CallGraphNode*> CallSites;
157 DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
159 for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
164 bool MadeChange = false;
166 // Scan all functions in the SCC.
167 unsigned FunctionNo = 0;
168 for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end();
169 SCCIdx != E; ++SCCIdx, ++FunctionNo) {
170 CallGraphNode *CGN = *SCCIdx;
171 Function *F = CGN->getFunction();
172 if (F == 0 || F->isDeclaration()) continue;
174 // Walk the function body looking for call sites. Sync up the call sites in
175 // CGN with those actually in the function.
177 // Get the set of call sites currently in the function.
178 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
179 // If this call site is null, then the function pass deleted the call
180 // entirely and the WeakVH nulled it out.
182 // If we've already seen this call site, then the FunctionPass RAUW'd
183 // one call with another, which resulted in two "uses" in the edge
184 // list of the same call.
185 CallSites.count(I->first) ||
187 // If the call edge is not from a call or invoke, then the function
188 // pass RAUW'd a call with another value. This can happen when
189 // constant folding happens of well known functions etc.
190 CallSite::get(I->first).getInstruction() == 0) {
191 assert(!CheckingMode &&
192 "CallGraphSCCPass did not update the CallGraph correctly!");
194 // Just remove the edge from the set of callees, keep track of whether
195 // I points to the last element of the vector.
196 bool WasLast = I + 1 == E;
197 CGN->removeCallEdge(I);
199 // If I pointed to the last element of the vector, we have to bail out:
200 // iterator checking rejects comparisons of the resultant pointer with
208 assert(!CallSites.count(I->first) &&
209 "Call site occurs in node multiple times");
210 CallSites.insert(std::make_pair(I->first, I->second));
214 // Loop over all of the instructions in the function, getting the callsites.
215 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
216 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
217 CallSite CS = CallSite::get(I);
218 if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
220 // If this call site already existed in the callgraph, just verify it
221 // matches up to expectations and remove it from CallSites.
222 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
223 CallSites.find(CS.getInstruction());
224 if (ExistingIt != CallSites.end()) {
225 CallGraphNode *ExistingNode = ExistingIt->second;
227 // Remove from CallSites since we have now seen it.
228 CallSites.erase(ExistingIt);
230 // Verify that the callee is right.
231 if (ExistingNode->getFunction() == CS.getCalledFunction())
234 // If we are in checking mode, we are not allowed to actually mutate
235 // the callgraph. If this is a case where we can infer that the
236 // callgraph is less precise than it could be (e.g. an indirect call
237 // site could be turned direct), don't reject it in checking mode, and
238 // don't tweak it to be more precise.
239 if (CheckingMode && CS.getCalledFunction() &&
240 ExistingNode->getFunction() == 0)
243 assert(!CheckingMode &&
244 "CallGraphSCCPass did not update the CallGraph correctly!");
246 // If not, we either went from a direct call to indirect, indirect to
247 // direct, or direct to different direct.
248 CallGraphNode *CalleeNode;
249 if (Function *Callee = CS.getCalledFunction())
250 CalleeNode = CG.getOrInsertFunction(Callee);
252 CalleeNode = CG.getCallsExternalNode();
254 // Update the edge target in CGN.
255 for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
256 assert(I != CGN->end() && "Didn't find call entry");
257 if (I->first == CS.getInstruction()) {
258 I->second = CalleeNode;
266 assert(!CheckingMode &&
267 "CallGraphSCCPass did not update the CallGraph correctly!");
269 // If the call site didn't exist in the CGN yet, add it. We assume that
270 // newly introduced call sites won't be indirect. This could be fixed
272 CallGraphNode *CalleeNode;
273 if (Function *Callee = CS.getCalledFunction())
274 CalleeNode = CG.getOrInsertFunction(Callee);
276 CalleeNode = CG.getCallsExternalNode();
278 CGN->addCalledFunction(CS, CalleeNode);
282 // After scanning this function, if we still have entries in callsites, then
283 // they are dangling pointers. WeakVH should save us for this, so abort if
285 assert(CallSites.empty() && "Dangling pointers found in call sites map");
287 // Periodically do an explicit clear to remove tombstones when processing
289 if ((FunctionNo & 15) == 15)
293 DEBUG(if (MadeChange) {
294 dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
295 for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
299 dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
304 /// run - Execute all of the passes scheduled for execution. Keep track of
305 /// whether any of the passes modifies the module, and if so, return true.
306 bool CGPassManager::runOnModule(Module &M) {
307 CallGraph &CG = getAnalysis<CallGraph>();
308 bool Changed = doInitialization(CG);
310 // Walk the callgraph in bottom-up SCC order.
311 scc_iterator<CallGraph*> CGI = scc_begin(&CG);
313 CallGraphSCC CurSCC(&CGI);
314 while (!CGI.isAtEnd()) {
315 // Copy the current SCC and increment past it so that the pass can hack
316 // on the SCC if it wants to without invalidating our iterator.
317 std::vector<CallGraphNode*> &NodeVec = *CGI;
318 CurSCC.initialize(&NodeVec[0], &NodeVec[0]+NodeVec.size());
321 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
322 // up-to-date or not. The CGSSC pass manager runs two types of passes:
323 // CallGraphSCC Passes and other random function passes. Because other
324 // random function passes are not CallGraph aware, they may clobber the
325 // call graph by introducing new calls or deleting other ones. This flag
326 // is set to false when we run a function pass so that we know to clean up
327 // the callgraph when we need to run a CGSCCPass again.
328 bool CallGraphUpToDate = true;
330 // Run all passes on current SCC.
331 for (unsigned PassNo = 0, e = getNumContainedPasses();
332 PassNo != e; ++PassNo) {
333 Pass *P = getContainedPass(PassNo);
335 // If we're in -debug-pass=Executions mode, construct the SCC node list,
336 // otherwise avoid constructing this string as it is expensive.
337 if (isPassDebuggingExecutionsOrMore()) {
338 std::string Functions;
340 raw_string_ostream OS(Functions);
341 for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
343 if (I != CurSCC.begin()) OS << ", ";
348 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
352 initializeAnalysisImpl(P);
354 // Actually run this pass on the current SCC.
355 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
358 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
361 verifyPreservedAnalysis(P);
362 removeNotPreservedAnalysis(P);
363 recordAvailableAnalysis(P);
364 removeDeadPasses(P, "", ON_CG_MSG);
367 // If the callgraph was left out of date (because the last pass run was a
368 // functionpass), refresh it before we move on to the next SCC.
369 if (!CallGraphUpToDate)
370 RefreshCallGraph(CurSCC, CG, false);
372 Changed |= doFinalization(CG);
377 bool CGPassManager::doInitialization(CallGraph &CG) {
378 bool Changed = false;
379 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
380 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
381 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
382 "Invalid CGPassManager member");
383 Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule());
385 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG);
392 bool CGPassManager::doFinalization(CallGraph &CG) {
393 bool Changed = false;
394 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
395 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
396 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
397 "Invalid CGPassManager member");
398 Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule());
400 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG);
406 //===----------------------------------------------------------------------===//
407 // CallGraphSCC Implementation
408 //===----------------------------------------------------------------------===//
410 /// ReplaceNode - This informs the SCC and the pass manager that the specified
411 /// Old node has been deleted, and New is to be used in its place.
412 void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
413 assert(Old != New && "Should not replace node with self");
414 for (unsigned i = 0; ; ++i) {
415 assert(i != Nodes.size() && "Node not in SCC");
416 if (Nodes[i] != Old) continue;
423 //===----------------------------------------------------------------------===//
424 // CallGraphSCCPass Implementation
425 //===----------------------------------------------------------------------===//
427 /// Assign pass manager to manage this pass.
428 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
429 PassManagerType PreferredType) {
430 // Find CGPassManager
431 while (!PMS.empty() &&
432 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
435 assert(!PMS.empty() && "Unable to handle Call Graph Pass");
438 if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
439 CGP = (CGPassManager*)PMS.top();
441 // Create new Call Graph SCC Pass Manager if it does not exist.
442 assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
443 PMDataManager *PMD = PMS.top();
445 // [1] Create new Call Graph Pass Manager
446 CGP = new CGPassManager(PMD->getDepth() + 1);
448 // [2] Set up new manager's top level manager
449 PMTopLevelManager *TPM = PMD->getTopLevelManager();
450 TPM->addIndirectPassManager(CGP);
452 // [3] Assign manager to manage this new manager. This may create
453 // and push new managers into PMS
455 TPM->schedulePass(P);
457 // [4] Push new manager into PMS
464 /// getAnalysisUsage - For this class, we declare that we require and preserve
465 /// the call graph. If the derived class implements this method, it should
466 /// always explicitly call the implementation here.
467 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
468 AU.addRequired<CallGraph>();
469 AU.addPreserved<CallGraph>();
473 //===----------------------------------------------------------------------===//
474 // PrintCallGraphPass Implementation
475 //===----------------------------------------------------------------------===//
478 /// PrintCallGraphPass - Print a Module corresponding to a call graph.
480 class PrintCallGraphPass : public CallGraphSCCPass {
482 raw_ostream &Out; // raw_ostream to print on.
486 PrintCallGraphPass() : CallGraphSCCPass(&ID), Out(dbgs()) {}
487 PrintCallGraphPass(const std::string &B, raw_ostream &o)
488 : CallGraphSCCPass(&ID), Banner(B), Out(o) {}
490 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
491 AU.setPreservesAll();
494 bool runOnSCC(CallGraphSCC &SCC) {
496 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
497 (*I)->getFunction()->print(Out);
502 } // end anonymous namespace.
504 char PrintCallGraphPass::ID = 0;
506 Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
507 const std::string &Banner) const {
508 return new PrintCallGraphPass(Banner, O);