1 //===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
10 // which are implemented as bottom-up traversals on the call graph.  Because
11 // there may be cycles in the call graph, passes of this type operate on the
12 // call-graph in SCC order: that is, they process function bottom-up, except for
89     errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";  in dumpPassStructure()
196 /// callgraph with the call sites found in it.  This is used after
200 /// This function returns true if it devirtualized an existing function call,
201 /// meaning it turned an indirect call into a direct call.  This happens when
202 /// a function pass like GVN optimizes away stuff feeding the indirect call.
224     // Walk the function body looking for call sites.  Sync up the call sites in  in RefreshCallGraph()
249     // Get the set of call sites currently in the function.  in RefreshCallGraph()
251       // Delete "reference" call records that do not have call instruction. We  in RefreshCallGraph()
263       // If this call site is null, then the function pass deleted the call  in RefreshCallGraph()
265       auto *Call = dyn_cast_or_null<CallBase>(*I->first);  in RefreshCallGraph()  local
266       if (!Call ||  in RefreshCallGraph()
267           // If we've already seen this call site, then the FunctionPass RAUW'd  in RefreshCallGraph()
268           // one call with another, which resulted in two "uses" in the edge  in RefreshCallGraph()
269           // list of the same call.  in RefreshCallGraph()
270           Calls.count(Call)) {  in RefreshCallGraph()
274         // If this was an indirect call site, count it.  in RefreshCallGraph()
285       assert(!Calls.count(Call) && "Call site occurs in node multiple times");  in RefreshCallGraph()
287       if (Call) {  in RefreshCallGraph()
288         Function *Callee = Call->getCalledFunction();  in RefreshCallGraph()
291           Calls.insert(std::make_pair(Call, I->second));  in RefreshCallGraph()
302         auto *Call = dyn_cast<CallBase>(&I);  in RefreshCallGraph()  local
303         if (!Call)  in RefreshCallGraph()
305         Function *Callee = Call->getCalledFunction();  in RefreshCallGraph()
313           forEachCallbackFunction(*Call, [&](Function *CB) {  in RefreshCallGraph()
318         // If this call site already existed in the callgraph, just verify it  in RefreshCallGraph()
321             Calls.find(Call);  in RefreshCallGraph()
329           if (ExistingNode->getFunction() == Call->getCalledFunction())  in RefreshCallGraph()
334           // callgraph is less precise than it could be (e.g. an indirect call  in RefreshCallGraph()
337           if (CheckingMode && Call->getCalledFunction() &&  in RefreshCallGraph()
344           // If not, we either went from a direct call to indirect, indirect to  in RefreshCallGraph()
347           if (Function *Callee = Call->getCalledFunction()) {  in RefreshCallGraph()
349             // Keep track of whether we turned an indirect call into a direct  in RefreshCallGraph()
353               LLVM_DEBUG(dbgs() << "  CGSCCPASSMGR: Devirtualized call to '"  in RefreshCallGraph()
361           CGN->replaceCallEdge(*Call, *Call, CalleeNode);  in RefreshCallGraph()
369         // If the call site didn't exist in the CGN yet, add it.  in RefreshCallGraph()
371         if (Function *Callee = Call->getCalledFunction()) {  in RefreshCallGraph()
379         CGN->addCalledFunction(Call, CalleeNode);  in RefreshCallGraph()
383     // We scanned the old callgraph node, removing invalidated call sites and  in RefreshCallGraph()
384     // then added back newly found call sites.  One thing that can happen is  in RefreshCallGraph()
385     // that an old indirect call site was deleted and replaced with a new direct  in RefreshCallGraph()
386     // call.  In this case, we have devirtualized a call, and CGSCCPM would like  in RefreshCallGraph()
391     // (e.g. DCE'ing an indirect call and duplicating an unrelated block with a  in RefreshCallGraph()
392     // direct call) but this is close enough.  in RefreshCallGraph()
401     assert(Calls.empty() && "Dangling pointers found in call sites map");  in RefreshCallGraph()
414       dbgs() << "CGSCCPASSMGR: Refresh devirtualized a call!\n";  in RefreshCallGraph()
416     dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";  in RefreshCallGraph()
434   // call graph by introducing new calls or deleting other ones.  This flag  in RunAllPassesOnSCC()
516     // case where a function pass devirtualizes a call to a function.  For  in runOnModule()
518     // to eliminate the addressing that feeds into a call.  With that improved  in runOnModule()
519     // information, we would like the call to be an inline candidate, infer  in runOnModule()
523     // This only happens in the case of a devirtualized call, so we only burn  in runOnModule()
617   assert(!PMS.empty() && "Unable to handle Call Graph Pass");  in assignPassManager()
623     // Create new Call Graph SCC Pass Manager if it does not exist.  in assignPassManager()
624     assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");  in assignPassManager()
627     // [1] Create new Call Graph Pass Manager  in assignPassManager()
646 /// For this class, we declare that we require and preserve the call graph.
648 /// always explicitly call the implementation here.
660   /// PrintCallGraphPass - Print a Module corresponding to a call graph.