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Diffstat (limited to 'contrib/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp')
| -rw-r--r-- | contrib/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp | 609 |
1 files changed, 609 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp b/contrib/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp new file mode 100644 index 0000000..0c01ee5 --- /dev/null +++ b/contrib/llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp @@ -0,0 +1,609 @@ +//===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the CallGraphSCCPass class, which is used for passes +// which are implemented as bottom-up traversals on the call graph. Because +// there may be cycles in the call graph, passes of this type operate on the +// call-graph in SCC order: that is, they process function bottom-up, except for +// recursive functions, which they process all at once. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "cgscc-passmgr" +#include "llvm/CallGraphSCCPass.h" +#include "llvm/IntrinsicInst.h" +#include "llvm/Function.h" +#include "llvm/PassManagers.h" +#include "llvm/Analysis/CallGraph.h" +#include "llvm/ADT/SCCIterator.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/Timer.h" +#include "llvm/Support/raw_ostream.h" +using namespace llvm; + +static cl::opt<unsigned> +MaxIterations("max-cg-scc-iterations", cl::ReallyHidden, cl::init(4)); + +STATISTIC(MaxSCCIterations, "Maximum CGSCCPassMgr iterations on one SCC"); + +//===----------------------------------------------------------------------===// +// CGPassManager +// +/// CGPassManager manages FPPassManagers and CallGraphSCCPasses. + +namespace { + +class CGPassManager : public ModulePass, public PMDataManager { +public: + static char ID; + explicit CGPassManager(int Depth) + : ModulePass(&ID), PMDataManager(Depth) { } + + /// run - Execute all of the passes scheduled for execution. Keep track of + /// whether any of the passes modifies the module, and if so, return true. + bool runOnModule(Module &M); + + bool doInitialization(CallGraph &CG); + bool doFinalization(CallGraph &CG); + + /// Pass Manager itself does not invalidate any analysis info. + void getAnalysisUsage(AnalysisUsage &Info) const { + // CGPassManager walks SCC and it needs CallGraph. + Info.addRequired<CallGraph>(); + Info.setPreservesAll(); + } + + virtual const char *getPassName() const { + return "CallGraph Pass Manager"; + } + + virtual PMDataManager *getAsPMDataManager() { return this; } + virtual Pass *getAsPass() { return this; } + + // Print passes managed by this manager + void dumpPassStructure(unsigned Offset) { + errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n"; + for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) { + Pass *P = getContainedPass(Index); + P->dumpPassStructure(Offset + 1); + dumpLastUses(P, Offset+1); + } + } + + Pass *getContainedPass(unsigned N) { + assert(N < PassVector.size() && "Pass number out of range!"); + return static_cast<Pass *>(PassVector[N]); + } + + virtual PassManagerType getPassManagerType() const { + return PMT_CallGraphPassManager; + } + +private: + bool RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG, + bool &DevirtualizedCall); + + bool RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC, + CallGraph &CG, bool &CallGraphUpToDate, + bool &DevirtualizedCall); + bool RefreshCallGraph(CallGraphSCC &CurSCC, CallGraph &CG, + bool IsCheckingMode); +}; + +} // end anonymous namespace. + +char CGPassManager::ID = 0; + + +bool CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC, + CallGraph &CG, bool &CallGraphUpToDate, + bool &DevirtualizedCall) { + bool Changed = false; + PMDataManager *PM = P->getAsPMDataManager(); + + if (PM == 0) { + CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P; + if (!CallGraphUpToDate) { + DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false); + CallGraphUpToDate = true; + } + + { + TimeRegion PassTimer(getPassTimer(CGSP)); + Changed = CGSP->runOnSCC(CurSCC); + } + + // After the CGSCCPass is done, when assertions are enabled, use + // RefreshCallGraph to verify that the callgraph was correctly updated. +#ifndef NDEBUG + if (Changed) + RefreshCallGraph(CurSCC, CG, true); +#endif + + return Changed; + } + + + assert(PM->getPassManagerType() == PMT_FunctionPassManager && + "Invalid CGPassManager member"); + FPPassManager *FPP = (FPPassManager*)P; + + // Run pass P on all functions in the current SCC. + for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end(); + I != E; ++I) { + if (Function *F = (*I)->getFunction()) { + dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName()); + TimeRegion PassTimer(getPassTimer(FPP)); + Changed |= FPP->runOnFunction(*F); + } + } + + // The function pass(es) modified the IR, they may have clobbered the + // callgraph. + if (Changed && CallGraphUpToDate) { + DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: " + << P->getPassName() << '\n'); + CallGraphUpToDate = false; + } + return Changed; +} + + +/// RefreshCallGraph - Scan the functions in the specified CFG and resync the +/// callgraph with the call sites found in it. This is used after +/// FunctionPasses have potentially munged the callgraph, and can be used after +/// CallGraphSCC passes to verify that they correctly updated the callgraph. +/// +/// This function returns true if it devirtualized an existing function call, +/// meaning it turned an indirect call into a direct call. This happens when +/// a function pass like GVN optimizes away stuff feeding the indirect call. +/// This never happens in checking mode. +/// +bool CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC, + CallGraph &CG, bool CheckingMode) { + DenseMap<Value*, CallGraphNode*> CallSites; + + DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size() + << " nodes:\n"; + for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end(); + I != E; ++I) + (*I)->dump(); + ); + + bool MadeChange = false; + bool DevirtualizedCall = false; + + // Scan all functions in the SCC. + unsigned FunctionNo = 0; + for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end(); + SCCIdx != E; ++SCCIdx, ++FunctionNo) { + CallGraphNode *CGN = *SCCIdx; + Function *F = CGN->getFunction(); + if (F == 0 || F->isDeclaration()) continue; + + // Walk the function body looking for call sites. Sync up the call sites in + // CGN with those actually in the function. + + // Keep track of the number of direct and indirect calls that were + // invalidated and removed. + unsigned NumDirectRemoved = 0, NumIndirectRemoved = 0; + + // Get the set of call sites currently in the function. + for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) { + // If this call site is null, then the function pass deleted the call + // entirely and the WeakVH nulled it out. + if (I->first == 0 || + // If we've already seen this call site, then the FunctionPass RAUW'd + // one call with another, which resulted in two "uses" in the edge + // list of the same call. + CallSites.count(I->first) || + + // If the call edge is not from a call or invoke, then the function + // pass RAUW'd a call with another value. This can happen when + // constant folding happens of well known functions etc. + CallSite::get(I->first).getInstruction() == 0) { + assert(!CheckingMode && + "CallGraphSCCPass did not update the CallGraph correctly!"); + + // If this was an indirect call site, count it. + if (I->second->getFunction() == 0) + ++NumIndirectRemoved; + else + ++NumDirectRemoved; + + // Just remove the edge from the set of callees, keep track of whether + // I points to the last element of the vector. + bool WasLast = I + 1 == E; + CGN->removeCallEdge(I); + + // If I pointed to the last element of the vector, we have to bail out: + // iterator checking rejects comparisons of the resultant pointer with + // end. + if (WasLast) + break; + E = CGN->end(); + continue; + } + + assert(!CallSites.count(I->first) && + "Call site occurs in node multiple times"); + CallSites.insert(std::make_pair(I->first, I->second)); + ++I; + } + + // Loop over all of the instructions in the function, getting the callsites. + // Keep track of the number of direct/indirect calls added. + unsigned NumDirectAdded = 0, NumIndirectAdded = 0; + + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + CallSite CS = CallSite::get(I); + if (!CS.getInstruction() || isa<DbgInfoIntrinsic>(I)) continue; + + // If this call site already existed in the callgraph, just verify it + // matches up to expectations and remove it from CallSites. + DenseMap<Value*, CallGraphNode*>::iterator ExistingIt = + CallSites.find(CS.getInstruction()); + if (ExistingIt != CallSites.end()) { + CallGraphNode *ExistingNode = ExistingIt->second; + + // Remove from CallSites since we have now seen it. + CallSites.erase(ExistingIt); + + // Verify that the callee is right. + if (ExistingNode->getFunction() == CS.getCalledFunction()) + continue; + + // If we are in checking mode, we are not allowed to actually mutate + // the callgraph. If this is a case where we can infer that the + // callgraph is less precise than it could be (e.g. an indirect call + // site could be turned direct), don't reject it in checking mode, and + // don't tweak it to be more precise. + if (CheckingMode && CS.getCalledFunction() && + ExistingNode->getFunction() == 0) + continue; + + assert(!CheckingMode && + "CallGraphSCCPass did not update the CallGraph correctly!"); + + // If not, we either went from a direct call to indirect, indirect to + // direct, or direct to different direct. + CallGraphNode *CalleeNode; + if (Function *Callee = CS.getCalledFunction()) { + CalleeNode = CG.getOrInsertFunction(Callee); + // Keep track of whether we turned an indirect call into a direct + // one. + if (ExistingNode->getFunction() == 0) { + DevirtualizedCall = true; + DEBUG(dbgs() << " CGSCCPASSMGR: Devirtualized call to '" + << Callee->getName() << "'\n"); + } + } else { + CalleeNode = CG.getCallsExternalNode(); + } + + // Update the edge target in CGN. + CGN->replaceCallEdge(CS, CS, CalleeNode); + MadeChange = true; + continue; + } + + assert(!CheckingMode && + "CallGraphSCCPass did not update the CallGraph correctly!"); + + // If the call site didn't exist in the CGN yet, add it. + CallGraphNode *CalleeNode; + if (Function *Callee = CS.getCalledFunction()) { + CalleeNode = CG.getOrInsertFunction(Callee); + ++NumDirectAdded; + } else { + CalleeNode = CG.getCallsExternalNode(); + ++NumIndirectAdded; + } + + CGN->addCalledFunction(CS, CalleeNode); + MadeChange = true; + } + + // We scanned the old callgraph node, removing invalidated call sites and + // then added back newly found call sites. One thing that can happen is + // that an old indirect call site was deleted and replaced with a new direct + // call. In this case, we have devirtualized a call, and CGSCCPM would like + // to iteratively optimize the new code. Unfortunately, we don't really + // have a great way to detect when this happens. As an approximation, we + // just look at whether the number of indirect calls is reduced and the + // number of direct calls is increased. There are tons of ways to fool this + // (e.g. DCE'ing an indirect call and duplicating an unrelated block with a + // direct call) but this is close enough. + if (NumIndirectRemoved > NumIndirectAdded && + NumDirectRemoved < NumDirectAdded) + DevirtualizedCall = true; + + // After scanning this function, if we still have entries in callsites, then + // they are dangling pointers. WeakVH should save us for this, so abort if + // this happens. + assert(CallSites.empty() && "Dangling pointers found in call sites map"); + + // Periodically do an explicit clear to remove tombstones when processing + // large scc's. + if ((FunctionNo & 15) == 15) + CallSites.clear(); + } + + DEBUG(if (MadeChange) { + dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n"; + for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end(); + I != E; ++I) + (*I)->dump(); + if (DevirtualizedCall) + dbgs() << "CGSCCPASSMGR: Refresh devirtualized a call!\n"; + + } else { + dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n"; + } + ); + + return DevirtualizedCall; +} + +/// RunAllPassesOnSCC - Execute the body of the entire pass manager on the +/// specified SCC. This keeps track of whether a function pass devirtualizes +/// any calls and returns it in DevirtualizedCall. +bool CGPassManager::RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG, + bool &DevirtualizedCall) { + bool Changed = false; + + // CallGraphUpToDate - Keep track of whether the callgraph is known to be + // up-to-date or not. The CGSSC pass manager runs two types of passes: + // CallGraphSCC Passes and other random function passes. Because other + // random function passes are not CallGraph aware, they may clobber the + // call graph by introducing new calls or deleting other ones. This flag + // is set to false when we run a function pass so that we know to clean up + // the callgraph when we need to run a CGSCCPass again. + bool CallGraphUpToDate = true; + + // Run all passes on current SCC. + for (unsigned PassNo = 0, e = getNumContainedPasses(); + PassNo != e; ++PassNo) { + Pass *P = getContainedPass(PassNo); + + // If we're in -debug-pass=Executions mode, construct the SCC node list, + // otherwise avoid constructing this string as it is expensive. + if (isPassDebuggingExecutionsOrMore()) { + std::string Functions; + #ifndef NDEBUG + raw_string_ostream OS(Functions); + for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end(); + I != E; ++I) { + if (I != CurSCC.begin()) OS << ", "; + (*I)->print(OS); + } + OS.flush(); + #endif + dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions); + } + dumpRequiredSet(P); + + initializeAnalysisImpl(P); + + // Actually run this pass on the current SCC. + Changed |= RunPassOnSCC(P, CurSCC, CG, + CallGraphUpToDate, DevirtualizedCall); + + if (Changed) + dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, ""); + dumpPreservedSet(P); + + verifyPreservedAnalysis(P); + removeNotPreservedAnalysis(P); + recordAvailableAnalysis(P); + removeDeadPasses(P, "", ON_CG_MSG); + } + + // If the callgraph was left out of date (because the last pass run was a + // functionpass), refresh it before we move on to the next SCC. + if (!CallGraphUpToDate) + DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false); + return Changed; +} + +/// run - Execute all of the passes scheduled for execution. Keep track of +/// whether any of the passes modifies the module, and if so, return true. +bool CGPassManager::runOnModule(Module &M) { + CallGraph &CG = getAnalysis<CallGraph>(); + bool Changed = doInitialization(CG); + + // Walk the callgraph in bottom-up SCC order. + scc_iterator<CallGraph*> CGI = scc_begin(&CG); + + CallGraphSCC CurSCC(&CGI); + while (!CGI.isAtEnd()) { + // Copy the current SCC and increment past it so that the pass can hack + // on the SCC if it wants to without invalidating our iterator. + std::vector<CallGraphNode*> &NodeVec = *CGI; + CurSCC.initialize(&NodeVec[0], &NodeVec[0]+NodeVec.size()); + ++CGI; + + // At the top level, we run all the passes in this pass manager on the + // functions in this SCC. However, we support iterative compilation in the + // case where a function pass devirtualizes a call to a function. For + // example, it is very common for a function pass (often GVN or instcombine) + // to eliminate the addressing that feeds into a call. With that improved + // information, we would like the call to be an inline candidate, infer + // mod-ref information etc. + // + // Because of this, we allow iteration up to a specified iteration count. + // This only happens in the case of a devirtualized call, so we only burn + // compile time in the case that we're making progress. We also have a hard + // iteration count limit in case there is crazy code. + unsigned Iteration = 0; + bool DevirtualizedCall = false; + do { + DEBUG(if (Iteration) + dbgs() << " SCCPASSMGR: Re-visiting SCC, iteration #" + << Iteration << '\n'); + DevirtualizedCall = false; + Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall); + } while (Iteration++ < MaxIterations && DevirtualizedCall); + + if (DevirtualizedCall) + DEBUG(dbgs() << " CGSCCPASSMGR: Stopped iteration after " << Iteration + << " times, due to -max-cg-scc-iterations\n"); + + if (Iteration > MaxSCCIterations) + MaxSCCIterations = Iteration; + + } + Changed |= doFinalization(CG); + return Changed; +} + + +/// Initialize CG +bool CGPassManager::doInitialization(CallGraph &CG) { + bool Changed = false; + for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) { + if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) { + assert(PM->getPassManagerType() == PMT_FunctionPassManager && + "Invalid CGPassManager member"); + Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule()); + } else { + Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG); + } + } + return Changed; +} + +/// Finalize CG +bool CGPassManager::doFinalization(CallGraph &CG) { + bool Changed = false; + for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) { + if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) { + assert(PM->getPassManagerType() == PMT_FunctionPassManager && + "Invalid CGPassManager member"); + Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule()); + } else { + Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG); + } + } + return Changed; +} + +//===----------------------------------------------------------------------===// +// CallGraphSCC Implementation +//===----------------------------------------------------------------------===// + +/// ReplaceNode - This informs the SCC and the pass manager that the specified +/// Old node has been deleted, and New is to be used in its place. +void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) { + assert(Old != New && "Should not replace node with self"); + for (unsigned i = 0; ; ++i) { + assert(i != Nodes.size() && "Node not in SCC"); + if (Nodes[i] != Old) continue; + Nodes[i] = New; + break; + } + + // Update the active scc_iterator so that it doesn't contain dangling + // pointers to the old CallGraphNode. + scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context; + CGI->ReplaceNode(Old, New); +} + + +//===----------------------------------------------------------------------===// +// CallGraphSCCPass Implementation +//===----------------------------------------------------------------------===// + +/// Assign pass manager to manage this pass. +void CallGraphSCCPass::assignPassManager(PMStack &PMS, + PassManagerType PreferredType) { + // Find CGPassManager + while (!PMS.empty() && + PMS.top()->getPassManagerType() > PMT_CallGraphPassManager) + PMS.pop(); + + assert(!PMS.empty() && "Unable to handle Call Graph Pass"); + CGPassManager *CGP; + + if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager) + CGP = (CGPassManager*)PMS.top(); + else { + // Create new Call Graph SCC Pass Manager if it does not exist. + assert(!PMS.empty() && "Unable to create Call Graph Pass Manager"); + PMDataManager *PMD = PMS.top(); + + // [1] Create new Call Graph Pass Manager + CGP = new CGPassManager(PMD->getDepth() + 1); + + // [2] Set up new manager's top level manager + PMTopLevelManager *TPM = PMD->getTopLevelManager(); + TPM->addIndirectPassManager(CGP); + + // [3] Assign manager to manage this new manager. This may create + // and push new managers into PMS + Pass *P = CGP; + TPM->schedulePass(P); + + // [4] Push new manager into PMS + PMS.push(CGP); + } + + CGP->add(this); +} + +/// getAnalysisUsage - For this class, we declare that we require and preserve +/// the call graph. If the derived class implements this method, it should +/// always explicitly call the implementation here. +void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired<CallGraph>(); + AU.addPreserved<CallGraph>(); +} + + +//===----------------------------------------------------------------------===// +// PrintCallGraphPass Implementation +//===----------------------------------------------------------------------===// + +namespace { + /// PrintCallGraphPass - Print a Module corresponding to a call graph. + /// + class PrintCallGraphPass : public CallGraphSCCPass { + std::string Banner; + raw_ostream &Out; // raw_ostream to print on. + + public: + static char ID; + PrintCallGraphPass() : CallGraphSCCPass(&ID), Out(dbgs()) {} + PrintCallGraphPass(const std::string &B, raw_ostream &o) + : CallGraphSCCPass(&ID), Banner(B), Out(o) {} + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + } + + bool runOnSCC(CallGraphSCC &SCC) { + Out << Banner; + for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) + (*I)->getFunction()->print(Out); + return false; + } + }; + +} // end anonymous namespace. + +char PrintCallGraphPass::ID = 0; + +Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O, + const std::string &Banner) const { + return new PrintCallGraphPass(Banner, O); +} + |
