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 virtual PMDataManager *getAsPMDataManager() { return this; }
61 virtual Pass *getAsPass() { return this; }
63 // Print passes managed by this manager
64 void dumpPassStructure(unsigned Offset) {
65 errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
66 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
67 Pass *P = getContainedPass(Index);
68 P->dumpPassStructure(Offset + 1);
69 dumpLastUses(P, Offset+1);
73 Pass *getContainedPass(unsigned N) {
74 assert(N < PassVector.size() && "Pass number out of range!");
75 return static_cast<Pass *>(PassVector[N]);
78 virtual PassManagerType getPassManagerType() const {
79 return PMT_CallGraphPassManager;
83 bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
84 CallGraph &CG, bool &CallGraphUpToDate);
85 void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
89 } // end anonymous namespace.
91 char CGPassManager::ID = 0;
93 bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
94 CallGraph &CG, bool &CallGraphUpToDate) {
96 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass*>(P)) {
97 if (!CallGraphUpToDate) {
98 RefreshCallGraph(CurSCC, CG, false);
99 CallGraphUpToDate = true;
102 Timer *T = StartPassTimer(CGSP);
103 Changed = CGSP->runOnSCC(CurSCC);
104 StopPassTimer(CGSP, T);
106 // After the CGSCCPass is done, when assertions are enabled, use
107 // RefreshCallGraph to verify that the callgraph was correctly updated.
110 RefreshCallGraph(CurSCC, CG, true);
116 FPPassManager *FPP = dynamic_cast<FPPassManager *>(P);
117 assert(FPP && "Invalid CGPassManager member");
119 // Run pass P on all functions in the current SCC.
120 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
121 if (Function *F = CurSCC[i]->getFunction()) {
122 dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
123 Timer *T = StartPassTimer(FPP);
124 Changed |= FPP->runOnFunction(*F);
125 StopPassTimer(FPP, T);
129 // The function pass(es) modified the IR, they may have clobbered the
131 if (Changed && CallGraphUpToDate) {
132 DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
133 << P->getPassName() << '\n');
134 CallGraphUpToDate = false;
140 /// RefreshCallGraph - Scan the functions in the specified CFG and resync the
141 /// callgraph with the call sites found in it. This is used after
142 /// FunctionPasses have potentially munged the callgraph, and can be used after
143 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
145 void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
146 CallGraph &CG, bool CheckingMode) {
147 DenseMap<Value*, CallGraphNode*> CallSites;
149 DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
151 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
155 bool MadeChange = false;
157 // Scan all functions in the SCC.
158 for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
159 CallGraphNode *CGN = CurSCC[sccidx];
160 Function *F = CGN->getFunction();
161 if (F == 0 || F->isDeclaration()) continue;
163 // Walk the function body looking for call sites. Sync up the call sites in
164 // CGN with those actually in the function.
166 // Get the set of call sites currently in the function.
167 for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
168 // If this call site is null, then the function pass deleted the call
169 // entirely and the WeakVH nulled it out.
171 // If we've already seen this call site, then the FunctionPass RAUW'd
172 // one call with another, which resulted in two "uses" in the edge
173 // list of the same call.
174 CallSites.count(I->first) ||
176 // If the call edge is not from a call or invoke, then the function
177 // pass RAUW'd a call with another value. This can happen when
178 // constant folding happens of well known functions etc.
179 CallSite::get(I->first).getInstruction() == 0) {
180 assert(!CheckingMode &&
181 "CallGraphSCCPass did not update the CallGraph correctly!");
183 // Just remove the edge from the set of callees, keep track of whether
184 // I points to the last element of the vector.
185 bool WasLast = I + 1 == E;
186 CGN->removeCallEdge(I);
188 // If I pointed to the last element of the vector, we have to bail out:
189 // iterator checking rejects comparisons of the resultant pointer with
197 assert(!CallSites.count(I->first) &&
198 "Call site occurs in node multiple times");
199 CallSites.insert(std::make_pair(I->first, I->second));
203 // Loop over all of the instructions in the function, getting the callsites.
204 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
205 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
206 CallSite CS = CallSite::get(I);
207 if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue;
209 // If this call site already existed in the callgraph, just verify it
210 // matches up to expectations and remove it from CallSites.
211 DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
212 CallSites.find(CS.getInstruction());
213 if (ExistingIt != CallSites.end()) {
214 CallGraphNode *ExistingNode = ExistingIt->second;
216 // Remove from CallSites since we have now seen it.
217 CallSites.erase(ExistingIt);
219 // Verify that the callee is right.
220 if (ExistingNode->getFunction() == CS.getCalledFunction())
223 // If we are in checking mode, we are not allowed to actually mutate
224 // the callgraph. If this is a case where we can infer that the
225 // callgraph is less precise than it could be (e.g. an indirect call
226 // site could be turned direct), don't reject it in checking mode, and
227 // don't tweak it to be more precise.
228 if (CheckingMode && CS.getCalledFunction() &&
229 ExistingNode->getFunction() == 0)
232 assert(!CheckingMode &&
233 "CallGraphSCCPass did not update the CallGraph correctly!");
235 // If not, we either went from a direct call to indirect, indirect to
236 // direct, or direct to different direct.
237 CallGraphNode *CalleeNode;
238 if (Function *Callee = CS.getCalledFunction())
239 CalleeNode = CG.getOrInsertFunction(Callee);
241 CalleeNode = CG.getCallsExternalNode();
243 // Update the edge target in CGN.
244 for (CallGraphNode::iterator I = CGN->begin(); ; ++I) {
245 assert(I != CGN->end() && "Didn't find call entry");
246 if (I->first == CS.getInstruction()) {
247 I->second = CalleeNode;
255 assert(!CheckingMode &&
256 "CallGraphSCCPass did not update the CallGraph correctly!");
258 // If the call site didn't exist in the CGN yet, add it. We assume that
259 // newly introduced call sites won't be indirect. This could be fixed
261 CallGraphNode *CalleeNode;
262 if (Function *Callee = CS.getCalledFunction())
263 CalleeNode = CG.getOrInsertFunction(Callee);
265 CalleeNode = CG.getCallsExternalNode();
267 CGN->addCalledFunction(CS, CalleeNode);
271 // After scanning this function, if we still have entries in callsites, then
272 // they are dangling pointers. WeakVH should save us for this, so abort if
274 assert(CallSites.empty() && "Dangling pointers found in call sites map");
276 // Periodically do an explicit clear to remove tombstones when processing
278 if ((sccidx & 15) == 0)
282 DEBUG(if (MadeChange) {
283 dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
284 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
287 dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
292 /// run - Execute all of the passes scheduled for execution. Keep track of
293 /// whether any of the passes modifies the module, and if so, return true.
294 bool CGPassManager::runOnModule(Module &M) {
295 CallGraph &CG = getAnalysis<CallGraph>();
296 bool Changed = doInitialization(CG);
298 std::vector<CallGraphNode*> CurSCC;
300 // Walk the callgraph in bottom-up SCC order.
301 for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
303 // Copy the current SCC and increment past it so that the pass can hack
304 // on the SCC if it wants to without invalidating our iterator.
309 // CallGraphUpToDate - Keep track of whether the callgraph is known to be
310 // up-to-date or not. The CGSSC pass manager runs two types of passes:
311 // CallGraphSCC Passes and other random function passes. Because other
312 // random function passes are not CallGraph aware, they may clobber the
313 // call graph by introducing new calls or deleting other ones. This flag
314 // is set to false when we run a function pass so that we know to clean up
315 // the callgraph when we need to run a CGSCCPass again.
316 bool CallGraphUpToDate = true;
318 // Run all passes on current SCC.
319 for (unsigned PassNo = 0, e = getNumContainedPasses();
320 PassNo != e; ++PassNo) {
321 Pass *P = getContainedPass(PassNo);
323 // If we're in -debug-pass=Executions mode, construct the SCC node list,
324 // otherwise avoid constructing this string as it is expensive.
325 if (isPassDebuggingExecutionsOrMore()) {
326 std::string Functions;
328 raw_string_ostream OS(Functions);
329 for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
331 CurSCC[i]->print(OS);
335 dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
339 initializeAnalysisImpl(P);
341 // Actually run this pass on the current SCC.
342 Changed |= RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate);
345 dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
348 verifyPreservedAnalysis(P);
349 removeNotPreservedAnalysis(P);
350 recordAvailableAnalysis(P);
351 removeDeadPasses(P, "", ON_CG_MSG);
354 // If the callgraph was left out of date (because the last pass run was a
355 // functionpass), refresh it before we move on to the next SCC.
356 if (!CallGraphUpToDate)
357 RefreshCallGraph(CurSCC, CG, false);
359 Changed |= doFinalization(CG);
364 bool CGPassManager::doInitialization(CallGraph &CG) {
365 bool Changed = false;
366 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
367 Pass *P = getContainedPass(Index);
368 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
369 Changed |= CGSP->doInitialization(CG);
371 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
372 assert (FP && "Invalid CGPassManager member");
373 Changed |= FP->doInitialization(CG.getModule());
380 bool CGPassManager::doFinalization(CallGraph &CG) {
381 bool Changed = false;
382 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
383 Pass *P = getContainedPass(Index);
384 if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) {
385 Changed |= CGSP->doFinalization(CG);
387 FPPassManager *FP = dynamic_cast<FPPassManager *>(P);
388 assert (FP && "Invalid CGPassManager member");
389 Changed |= FP->doFinalization(CG.getModule());
395 /// Assign pass manager to manage this pass.
396 void CallGraphSCCPass::assignPassManager(PMStack &PMS,
397 PassManagerType PreferredType) {
398 // Find CGPassManager
399 while (!PMS.empty() &&
400 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
403 assert (!PMS.empty() && "Unable to handle Call Graph Pass");
404 CGPassManager *CGP = dynamic_cast<CGPassManager *>(PMS.top());
406 // Create new Call Graph SCC Pass Manager if it does not exist.
409 assert (!PMS.empty() && "Unable to create Call Graph Pass Manager");
410 PMDataManager *PMD = PMS.top();
412 // [1] Create new Call Graph Pass Manager
413 CGP = new CGPassManager(PMD->getDepth() + 1);
415 // [2] Set up new manager's top level manager
416 PMTopLevelManager *TPM = PMD->getTopLevelManager();
417 TPM->addIndirectPassManager(CGP);
419 // [3] Assign manager to manage this new manager. This may create
420 // and push new managers into PMS
421 Pass *P = dynamic_cast<Pass *>(CGP);
422 TPM->schedulePass(P);
424 // [4] Push new manager into PMS
431 /// getAnalysisUsage - For this class, we declare that we require and preserve
432 /// the call graph. If the derived class implements this method, it should
433 /// always explicitly call the implementation here.
434 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
435 AU.addRequired<CallGraph>();
436 AU.addPreserved<CallGraph>();