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;
94 bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
95 CallGraph &CG, bool &CallGraphUpToDate) {
97 PMDataManager *PM = P->getAsPMDataManager();
100 CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
101 if (!CallGraphUpToDate) {
102 RefreshCallGraph(CurSCC, CG, false);
103 CallGraphUpToDate = true;
107 TimeRegion PassTimer(getPassTimer(CGSP));
108 Changed = CGSP->runOnSCC(CurSCC);
111 // After the CGSCCPass is done, when assertions are enabled, use
112 // RefreshCallGraph to verify that the callgraph was correctly updated.
115 RefreshCallGraph(CurSCC, CG, true);
122 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
123 "Invalid CGPassManager member");
124 FPPassManager *FPP = (FPPassManager*)P;
126 // Run pass P on all functions in the current SCC.
127 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
128 if (Function *F = CurSCC[i]->getFunction()) {
129 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
130 TimeRegion PassTimer(getPassTimer(FPP));
131 Changed |= FPP->runOnFunction(*F);
135 // The function pass(es) modified the IR, they may have clobbered the
137 if (Changed && CallGraphUpToDate) {
138 DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
139 << P->getPassName() << '\n');
140 CallGraphUpToDate = false;
146 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
147 /// callgraph with the call sites found in it. This is used after
148 /// FunctionPasses have potentially munged the callgraph, and can be used after
149 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
151 void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
152 CallGraph &CG, bool CheckingMode) {
153 DenseMap<Value*, CallGraphNode*> CallSites;
155 DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
157 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
161 bool MadeChange = false;
163 // Scan all functions in the SCC.
164 for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
165 CallGraphNode *CGN = CurSCC[sccidx];
166 Function *F = CGN->getFunction();
167 if (F == 0 || F->isDeclaration()) continue;
169 // Walk the function body looking for call sites. Sync up the call sites in
170 // CGN with those actually in the function.
172 // Get the set of call sites currently in the function.
173 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
174 // If this call site is null, then the function pass deleted the call
175 // entirely and the WeakVH nulled it out.
177 // If we've already seen this call site, then the FunctionPass RAUW'd
178 // one call with another, which resulted in two "uses" in the edge
179 // list of the same call.
180 CallSites.count(I->first) ||
182 // If the call edge is not from a call or invoke, then the function
183 // pass RAUW'd a call with another value. This can happen when
184 // constant folding happens of well known functions etc.
185 CallSite::get(I->first).getInstruction() == 0) {
186 assert(!CheckingMode &&
187 "CallGraphSCCPass did not update the CallGraph correctly!");
189 // Just remove the edge from the set of callees, keep track of whether
190 // I points to the last element of the vector.
191 bool WasLast = I + 1 == E;
192 CGN->removeCallEdge(I);
194 // If I pointed to the last element of the vector, we have to bail out:
195 // iterator checking rejects comparisons of the resultant pointer with
203 assert(!CallSites.count(I->first) &&
204 "Call site occurs in node multiple times");
205 CallSites.insert(std::make_pair(I->first, I->second));
209 // Loop over all of the instructions in the function, getting the callsites.
210 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
211 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
212 CallSite CS = CallSite::get(I);
213 if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
215 // If this call site already existed in the callgraph, just verify it
216 // matches up to expectations and remove it from CallSites.
217 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
218 CallSites.find(CS.getInstruction());
219 if (ExistingIt != CallSites.end()) {
220 CallGraphNode *ExistingNode = ExistingIt->second;
222 // Remove from CallSites since we have now seen it.
223 CallSites.erase(ExistingIt);
225 // Verify that the callee is right.
226 if (ExistingNode->getFunction() == CS.getCalledFunction())
229 // If we are in checking mode, we are not allowed to actually mutate
230 // the callgraph. If this is a case where we can infer that the
231 // callgraph is less precise than it could be (e.g. an indirect call
232 // site could be turned direct), don't reject it in checking mode, and
233 // don't tweak it to be more precise.
234 if (CheckingMode && CS.getCalledFunction() &&
235 ExistingNode->getFunction() == 0)
238 assert(!CheckingMode &&
239 "CallGraphSCCPass did not update the CallGraph correctly!");
241 // If not, we either went from a direct call to indirect, indirect to
242 // direct, or direct to different direct.
243 CallGraphNode *CalleeNode;
244 if (Function *Callee = CS.getCalledFunction())
245 CalleeNode = CG.getOrInsertFunction(Callee);
247 CalleeNode = CG.getCallsExternalNode();
249 // Update the edge target in CGN.
250 for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
251 assert(I != CGN->end() && "Didn't find call entry");
252 if (I->first == CS.getInstruction()) {
253 I->second = CalleeNode;
261 assert(!CheckingMode &&
262 "CallGraphSCCPass did not update the CallGraph correctly!");
264 // If the call site didn't exist in the CGN yet, add it. We assume that
265 // newly introduced call sites won't be indirect. This could be fixed
267 CallGraphNode *CalleeNode;
268 if (Function *Callee = CS.getCalledFunction())
269 CalleeNode = CG.getOrInsertFunction(Callee);
271 CalleeNode = CG.getCallsExternalNode();
273 CGN->addCalledFunction(CS, CalleeNode);
277 // After scanning this function, if we still have entries in callsites, then
278 // they are dangling pointers. WeakVH should save us for this, so abort if
280 assert(CallSites.empty() && "Dangling pointers found in call sites map");
282 // Periodically do an explicit clear to remove tombstones when processing
284 if ((sccidx & 15) == 0)
288 DEBUG(if (MadeChange) {
289 dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
290 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
293 dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
298 /// run - Execute all of the passes scheduled for execution. Keep track of
299 /// whether any of the passes modifies the module, and if so, return true.
300 bool CGPassManager::runOnModule(Module &M) {
301 CallGraph &CG = getAnalysis<CallGraph>();
302 bool Changed = doInitialization(CG);
304 std::vector<CallGraphNode*> CurSCC;
306 // Walk the callgraph in bottom-up SCC order.
307 for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
309 // Copy the current SCC and increment past it so that the pass can hack
310 // on the SCC if it wants to without invalidating our iterator.
315 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
316 // up-to-date or not. The CGSSC pass manager runs two types of passes:
317 // CallGraphSCC Passes and other random function passes. Because other
318 // random function passes are not CallGraph aware, they may clobber the
319 // call graph by introducing new calls or deleting other ones. This flag
320 // is set to false when we run a function pass so that we know to clean up
321 // the callgraph when we need to run a CGSCCPass again.
322 bool CallGraphUpToDate = true;
324 // Run all passes on current SCC.
325 for (unsigned PassNo = 0, e = getNumContainedPasses();
326 PassNo != e; ++PassNo) {
327 Pass *P = getContainedPass(PassNo);
329 // If we're in -debug-pass=Executions mode, construct the SCC node list,
330 // otherwise avoid constructing this string as it is expensive.
331 if (isPassDebuggingExecutionsOrMore()) {
332 std::string Functions;
334 raw_string_ostream OS(Functions);
335 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
337 CurSCC[i]->print(OS);
341 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
345 initializeAnalysisImpl(P);
347 // Actually run this pass on the current SCC.
348 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
351 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
354 verifyPreservedAnalysis(P);
355 removeNotPreservedAnalysis(P);
356 recordAvailableAnalysis(P);
357 removeDeadPasses(P, "", ON_CG_MSG);
360 // If the callgraph was left out of date (because the last pass run was a
361 // functionpass), refresh it before we move on to the next SCC.
362 if (!CallGraphUpToDate)
363 RefreshCallGraph(CurSCC, CG, false);
365 Changed |= doFinalization(CG);
370 bool CGPassManager::doInitialization(CallGraph &CG) {
371 bool Changed = false;
372 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
373 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
374 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
375 "Invalid CGPassManager member");
376 Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule());
378 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG);
385 bool CGPassManager::doFinalization(CallGraph &CG) {
386 bool Changed = false;
387 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
388 if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
389 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
390 "Invalid CGPassManager member");
391 Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule());
393 Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG);
399 /// Assign pass manager to manage this pass.
400 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
401 PassManagerType PreferredType) {
402 // Find CGPassManager
403 while (!PMS.empty() &&
404 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
407 assert(!PMS.empty() && "Unable to handle Call Graph Pass");
410 if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
411 CGP = (CGPassManager*)PMS.top();
413 // Create new Call Graph SCC Pass Manager if it does not exist.
414 assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
415 PMDataManager *PMD = PMS.top();
417 // [1] Create new Call Graph Pass Manager
418 CGP = new CGPassManager(PMD->getDepth() + 1);
420 // [2] Set up new manager's top level manager
421 PMTopLevelManager *TPM = PMD->getTopLevelManager();
422 TPM->addIndirectPassManager(CGP);
424 // [3] Assign manager to manage this new manager. This may create
425 // and push new managers into PMS
427 TPM->schedulePass(P);
429 // [4] Push new manager into PMS
436 /// getAnalysisUsage - For this class, we declare that we require and preserve
437 /// the call graph. If the derived class implements this method, it should
438 /// always explicitly call the implementation here.
439 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
440 AU.addRequired<CallGraph>();
441 AU.addPreserved<CallGraph>();