Complete rewrite of the code that merges DS graphs for equivalence classes
of functions called at a common call site. The rewrite inlines the
resulting graphs bottom-up on the SCCs of the CBU call graph. It also
simplifies the merging of equivalence classes by exploiting the fact that
functions in non-trivial SCCs are already merged.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13645 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DataStructure/EquivClassGraphs.cpp b/lib/Analysis/DataStructure/EquivClassGraphs.cpp
new file mode 100644
index 0000000..450abcd
--- /dev/null
+++ b/lib/Analysis/DataStructure/EquivClassGraphs.cpp
@@ -0,0 +1,428 @@
+//===- EquivClassGraphs.cpp - Merge equiv-class graphs & inline bottom-up -===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is the same as the complete bottom-up graphs, but
+// with functions partitioned into equivalence classes and a single merged
+// DS graph for all functions in an equivalence class. After this merging,
+// graphs are inlined bottom-up on the SCCs of the final (CBU) call graph.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "ECGraphs"
+#include "EquivClassGraphs.h"
+#include "llvm/Analysis/DataStructure.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/DSGraph.h"
+#include "llvm/Support/CallSite.h"
+#include "Support/Debug.h"
+#include "Support/SCCIterator.h"
+#include "Support/Statistic.h"
+#include "Support/EquivalenceClasses.h"
+#include "Support/STLExtras.h"
+using namespace llvm;
+
+namespace llvm {
+ namespace PA {
+ Statistic<> NumFoldGraphInlines("Inline equiv-class graphs bottom up",
+ "Number of graphs inlined");
+
+ } // End PA namespace
+} // End llvm namespace
+
+
+namespace {
+ RegisterAnalysis<llvm::PA::EquivClassGraphs> X("equivdatastructure",
+ "Equivalence-class Bottom-up Data Structure Analysis");
+ Statistic<> NumEquivBUInlines("equivdatastructures", "Number of graphs inlined");
+}
+
+
+// getDSGraphForCallSite - Return the common data structure graph for
+// callees at the specified call site.
+//
+Function *llvm::PA::EquivClassGraphs::getSomeCalleeForCallSite(const CallSite &CS) const {
+ Function *thisFunc = CS.getCaller();
+ assert(thisFunc && "getDSGraphForCallSite(): Not a valid call site?");
+ DSNode *calleeNode = CBU->getDSGraph(*thisFunc).
+ getNodeForValue(CS.getCalledValue()).getNode();
+ std::map<DSNode*, Function *>::const_iterator I =
+ OneCalledFunction.find(calleeNode);
+ return (I == OneCalledFunction.end())? NULL : I->second;
+}
+
+// computeFoldedGraphs - Calculate the bottom up data structure
+// graphs for each function in the program.
+//
+void llvm::PA::EquivClassGraphs::computeFoldedGraphs(Module &M) {
+ CBU = &getAnalysis<CompleteBUDataStructures>();
+
+ // Find equivalence classes of functions called from common call sites.
+ // Fold the CBU graphs for all functions in an equivalence class.
+ buildIndirectFunctionSets(M);
+
+ // Stack of functions used for Tarjan's SCC-finding algorithm.
+ std::vector<Function*> Stack;
+ hash_map<Function*, unsigned> ValMap;
+ unsigned NextID = 1;
+
+ if (Function *Main = M.getMainFunction()) {
+ if (!Main->isExternal())
+ processSCC(getOrCreateGraph(*Main), *Main, Stack, NextID, ValMap);
+ } else {
+ std::cerr << "Fold Graphs: No 'main' function found!\n";
+ }
+
+ for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
+ if (!I->isExternal() && !FoldedGraphsMap.count(I))
+ processSCC(getOrCreateGraph(*I), *I, Stack, NextID, ValMap);
+
+ getGlobalsGraph().removeTriviallyDeadNodes();
+}
+
+
+// buildIndirectFunctionSets - Iterate over the module looking for indirect
+// calls to functions. If a call site can invoke any functions [F1, F2... FN],
+// unify the N functions together in the FuncECs set.
+//
+void llvm::PA::EquivClassGraphs::buildIndirectFunctionSets(Module &M) {
+ const ActualCalleesTy& AC = CBU->getActualCallees();
+
+ // Loop over all of the indirect calls in the program. If a call site can
+ // call multiple different functions, we need to unify all of the callees into
+ // the same equivalence class.
+ Instruction *LastInst = 0;
+ Function *FirstFunc = 0;
+ for (ActualCalleesTy::const_iterator I=AC.begin(), E=AC.end(); I != E; ++I) {
+ if (I->second->isExternal())
+ continue; // Ignore functions we cannot modify
+
+ CallSite CS = CallSite::get(I->first);
+
+ if (CS.getCalledFunction()) { // Direct call:
+ FuncECs.addElement(I->second); // -- Make sure function has equiv class
+ FirstFunc = I->second; // -- First callee at this site
+ } else { // Else indirect call
+ // DEBUG(std::cerr << "CALLEE: " << I->second->getName()
+ // << " from : " << I->first);
+ if (I->first != LastInst) {
+ // This is the first callee from this call site.
+ LastInst = I->first;
+ FirstFunc = I->second;
+ // Instead of storing the lastInst For Indirection call Sites we store
+ // the DSNode for the function ptr arguemnt
+ Function *thisFunc = LastInst->getParent()->getParent();
+ DSNode *calleeNode = CBU->getDSGraph(*thisFunc).getNodeForValue(CS.getCalledValue()).getNode();
+ OneCalledFunction[calleeNode] = FirstFunc;
+ FuncECs.addElement(I->second);
+ } else {
+ // This is not the first possible callee from a particular call site.
+ // Union the callee in with the other functions.
+ FuncECs.unionSetsWith(FirstFunc, I->second);
+#ifndef NDEBUG
+ Function *thisFunc = LastInst->getParent()->getParent();
+ DSNode *calleeNode = CBU->getDSGraph(*thisFunc).getNodeForValue(CS.getCalledValue()).getNode();
+ assert(OneCalledFunction.count(calleeNode) > 0 && "Missed a call?");
+#endif
+ }
+ }
+
+ // Now include all functions that share a graph with any function in the
+ // equivalence class. More precisely, if F is in the class, and G(F) is
+ // its graph, then we include all other functions that are also in G(F).
+ // Currently, that is just the functions in the same call-graph-SCC as F.
+ //
+ DSGraph& funcDSGraph = CBU->getDSGraph(*I->second);
+ const DSGraph::ReturnNodesTy &RetNodes = funcDSGraph.getReturnNodes();
+ for (DSGraph::ReturnNodesTy::const_iterator RI=RetNodes.begin(),
+ RE=RetNodes.end(); RI != RE; ++RI)
+ FuncECs.unionSetsWith(FirstFunc, RI->first);
+ }
+
+ // Now that all of the equivalences have been built, merge the graphs for
+ // each equivalence class.
+ //
+ std::set<Function*> &leaderSet = FuncECs.getLeaderSet();
+ DEBUG(std::cerr << "\nIndirect Function Equivalence Sets:\n");
+ for (std::set<Function*>::iterator LI = leaderSet.begin(),
+ LE = leaderSet.end(); LI != LE; ++LI) {
+
+ Function* LF = *LI;
+ const std::set<Function*>& EqClass = FuncECs.getEqClass(LF);
+
+#ifndef NDEBUG
+ if (EqClass.size() > 1) {
+ DEBUG(std::cerr <<" Equivalence set for leader " <<LF->getName()<<" = ");
+ for (std::set<Function*>::const_iterator EqI = EqClass.begin(),
+ EqEnd = EqClass.end(); EqI != EqEnd; ++EqI)
+ DEBUG(std::cerr << " " << (*EqI)->getName() << ",");
+ DEBUG(std::cerr << "\n");
+ }
+#endif
+
+ if (EqClass.size() > 1) {
+ // This equiv class has multiple functions: merge their graphs.
+ // First, clone the CBU graph for the leader and make it the
+ // common graph for the equivalence graph.
+ DSGraph* mergedG = cloneGraph(*LF);
+
+ // Record the argument nodes for use in merging later below
+ EquivClassGraphArgsInfo& GraphInfo = getECGraphInfo(mergedG);
+ for (Function::aiterator AI1 = LF->abegin(); AI1 != LF->aend(); ++AI1)
+ GraphInfo.argNodes.push_back(mergedG->getNodeForValue(AI1));
+
+ // Merge in the graphs of all other functions in this equiv. class.
+ // Note that two or more functions may have the same graph, and it
+ // only needs to be merged in once. Use a set to find repetitions.
+ std::set<DSGraph*> GraphsMerged;
+ for (std::set<Function*>::const_iterator EqI = EqClass.begin(),
+ EqEnd = EqClass.end(); EqI != EqEnd; ++EqI) {
+ Function* F = *EqI;
+ DSGraph*& FG = FoldedGraphsMap[F];
+ if (F == LF || FG == mergedG)
+ continue;
+
+ // Record the "folded" graph for the function.
+ FG = mergedG;
+
+ // Clone this member of the equivalence class into mergedG
+ DSGraph* CBUGraph = &CBU->getDSGraph(*F);
+ if (GraphsMerged.count(CBUGraph) > 0)
+ continue;
+
+ GraphsMerged.insert(CBUGraph);
+ DSGraph::NodeMapTy NodeMap;
+ mergedG->cloneInto(*CBUGraph, mergedG->getScalarMap(),
+ mergedG->getReturnNodes(), NodeMap, 0);
+
+ // Merge the return nodes of all functions together.
+ mergedG->getReturnNodes()[LF].mergeWith(mergedG->getReturnNodes()[F]);
+
+ // Merge the function arguments with all argument nodes found so far.
+ // If there are extra function args, add them to the vector of argNodes
+ Function::aiterator AI2 = F->abegin(), AI2end = F->aend();
+ for (unsigned arg=0, numArgs=GraphInfo.argNodes.size();
+ arg < numArgs && AI2 != AI2end; ++AI2, ++arg)
+ GraphInfo.argNodes[arg].mergeWith(mergedG->getNodeForValue(AI2));
+ for ( ; AI2 != AI2end; ++AI2)
+ GraphInfo.argNodes.push_back(mergedG->getNodeForValue(AI2));
+ }
+ }
+ }
+ DEBUG(std::cerr << "\n");
+}
+
+
+DSGraph &llvm::PA::EquivClassGraphs::getOrCreateGraph(Function &F) {
+ // Has the graph already been created?
+ DSGraph *&Graph = FoldedGraphsMap[&F];
+ if (Graph) return *Graph;
+
+ // Use the CBU graph directly without copying it.
+ // This automatically updates the FoldedGraphsMap via the reference.
+ Graph = &CBU->getDSGraph(F);
+
+ return *Graph;
+}
+
+DSGraph* llvm::PA::EquivClassGraphs::cloneGraph(Function &F) {
+ DSGraph *&Graph = FoldedGraphsMap[&F];
+ DSGraph &CBUGraph = CBU->getDSGraph(F);
+ assert(Graph == NULL || Graph == &CBUGraph && "Cloning a graph twice?");
+
+ // Copy the CBU graph...
+ Graph = new DSGraph(CBUGraph); // updates the map via reference
+ Graph->setGlobalsGraph(&getGlobalsGraph());
+ Graph->setPrintAuxCalls();
+
+ // Make sure to update the FoldedGraphsMap map for all functions in the graph!
+ for (DSGraph::ReturnNodesTy::iterator I = Graph->getReturnNodes().begin();
+ I != Graph->getReturnNodes().end(); ++I)
+ if (I->first != &F) {
+ DSGraph*& FG = FoldedGraphsMap[I->first];
+ assert(FG == NULL || FG == &CBU->getDSGraph(*I->first) &&
+ "Merging function in SCC twice?");
+ FG = Graph;
+ }
+
+ return Graph;
+}
+
+
+unsigned llvm::PA::EquivClassGraphs::processSCC(DSGraph &FG, Function& F,
+ std::vector<Function*> &Stack,
+ unsigned &NextID,
+ hash_map<Function*, unsigned> &ValMap) {
+ DEBUG(std::cerr << " ProcessSCC for function " << F.getName() << "\n");
+
+ assert(!ValMap.count(&F) && "Shouldn't revisit functions!");
+ unsigned Min = NextID++, MyID = Min;
+ ValMap[&F] = Min;
+ Stack.push_back(&F);
+
+ // The edges out of the current node are the call site targets...
+ for (unsigned i = 0, e = FG.getFunctionCalls().size(); i != e; ++i) {
+ Instruction *Call = FG.getFunctionCalls()[i].getCallSite().getInstruction();
+
+ // Loop over all of the actually called functions...
+ ActualCalleesTy::const_iterator I, E;
+ for (tie(I, E) = getActualCallees().equal_range(Call); I != E; ++I)
+ if (!I->second->isExternal()) {
+ DSGraph &CalleeG = getOrCreateGraph(*I->second);
+
+ // Have we visited the destination function yet?
+ hash_map<Function*, unsigned>::iterator It = ValMap.find(I->second);
+ unsigned M = (It == ValMap.end()) // No, visit it now.
+ ? processSCC(CalleeG, *I->second, Stack, NextID, ValMap)
+ : It->second; // Yes, get it's number.
+
+ if (M < Min) Min = M;
+ }
+ }
+
+ assert(ValMap[&F] == MyID && "SCC construction assumption wrong!");
+ if (Min != MyID)
+ return Min; // This is part of a larger SCC!
+
+ // If this is a new SCC, process it now.
+ bool IsMultiNodeSCC = false;
+ while (Stack.back() != &F) {
+ DSGraph *NG = &getOrCreateGraph(* Stack.back());
+ ValMap[Stack.back()] = ~0U;
+
+ // Since all SCCs must be the same as those found in CBU, we do not need to
+ // do any merging. Make sure all functions in the SCC share the same graph.
+ assert(NG == &FG &&
+ "FoldGraphs: Functions in the same SCC have different graphs?");
+
+ Stack.pop_back();
+ IsMultiNodeSCC = true;
+ }
+
+ // Clean up the graph before we start inlining a bunch again...
+ if (IsMultiNodeSCC)
+ FG.removeTriviallyDeadNodes();
+
+ Stack.pop_back();
+ processGraph(FG, F);
+ ValMap[&F] = ~0U;
+ return MyID;
+}
+
+
+/// processGraph - Process the CBU graphs for the program in bottom-up order on
+/// the SCC of the __ACTUAL__ call graph. This builds final folded CBU graphs.
+void llvm::PA::EquivClassGraphs::processGraph(DSGraph &G, Function& F) {
+ DEBUG(std::cerr << " ProcessGraph for function " << F.getName() << "\n");
+
+ hash_set<Instruction*> calls;
+
+ DSGraph* CallerGraph = sameAsCBUGraph(F)? NULL : &getOrCreateGraph(F);
+
+ // If the function has not yet been cloned, let's check if any callees
+ // need to be inlined before cloning it.
+ //
+ for (unsigned i=0, e=G.getFunctionCalls().size(); i!=e && !CallerGraph; ++i) {
+ const DSCallSite &CS = G.getFunctionCalls()[i];
+ Instruction *TheCall = CS.getCallSite().getInstruction();
+
+ // Loop over all potential callees to find the first non-external callee.
+ // Some inlining is needed if there is such a callee and it has changed.
+ ActualCalleesTy::const_iterator I, E;
+ for (tie(I, E) = getActualCallees().equal_range(TheCall); I != E; ++I)
+ if (!I->second->isExternal() && !sameAsCBUGraph(*I->second)) {
+ // Ok, the caller does need to be cloned... go ahead and do it now.
+ // clone the CBU graph for F now because we have not cloned it so far
+ CallerGraph = cloneGraph(F);
+ break;
+ }
+ }
+
+ if (!CallerGraph) { // No inlining is needed.
+ DEBUG(std::cerr << " --DONE ProcessGraph for function " << F.getName()
+ << " (NO INLINING NEEDED)\n");
+ return;
+ }
+
+ // Else we need to inline some callee graph. Visit all call sites.
+ // The edges out of the current node are the call site targets...
+ for (unsigned i=0, e = CallerGraph->getFunctionCalls().size(); i != e; ++i) {
+ const DSCallSite &CS = CallerGraph->getFunctionCalls()[i];
+ Instruction *TheCall = CS.getCallSite().getInstruction();
+
+ assert(calls.insert(TheCall).second &&
+ "Call instruction occurs multiple times in graph??");
+
+ // Inline the common callee graph into the current graph, if the callee
+ // graph has not changed. Note that all callees should have the same
+ // graph so we only need to do this once.
+ //
+ DSGraph* CalleeGraph = NULL;
+ ActualCalleesTy::const_iterator I, E;
+ tie(I, E) = getActualCallees().equal_range(TheCall);
+ unsigned TNum, Num;
+
+ // Loop over all potential callees to find the first non-external callee.
+ for (TNum = 0, Num = std::distance(I, E); I != E; ++I, ++TNum)
+ if (!I->second->isExternal())
+ break;
+
+ // Now check if the graph has changed and if so, clone and inline it.
+ if (I != E && !sameAsCBUGraph(*I->second)) {
+ Function *CalleeFunc = I->second;
+
+ // Merge the callee's graph into this graph, if not already the same.
+ // Callees in the same equivalence class (which subsumes those
+ // in the same SCCs) have the same graph. Note that all recursion
+ // including self-recursion have been folded in the equiv classes.
+ //
+ CalleeGraph = &getOrCreateGraph(*CalleeFunc);
+ if (CalleeGraph != CallerGraph) {
+ ++NumFoldGraphInlines;
+ CallerGraph->mergeInGraph(CS, *CalleeFunc, *CalleeGraph,
+ DSGraph::KeepModRefBits |
+ DSGraph::StripAllocaBit |
+ DSGraph::DontCloneCallNodes |
+ DSGraph::DontCloneAuxCallNodes);
+ DEBUG(std::cerr << " Inlining graph [" << i << "/" << e-1
+ << ":" << TNum << "/" << Num-1 << "] for "
+ << CalleeFunc->getName() << "["
+ << CalleeGraph->getGraphSize() << "+"
+ << CalleeGraph->getAuxFunctionCalls().size()
+ << "] into '" /*<< CallerGraph->getFunctionNames()*/ << "' ["
+ << CallerGraph->getGraphSize() << "+"
+ << CallerGraph->getAuxFunctionCalls().size()
+ << "]\n");
+ }
+ }
+
+#ifndef NDEBUG
+ // Now loop over the rest of the callees and make sure they have the
+ // same graph as the one inlined above.
+ if (CalleeGraph)
+ for (++I, ++TNum; I != E; ++I, ++TNum)
+ if (!I->second->isExternal())
+ assert(CalleeGraph == &getOrCreateGraph(*I->second) &&
+ "Callees at a call site have different graphs?");
+#endif
+ }
+
+ // Recompute the Incomplete markers
+ if (CallerGraph != NULL) {
+ assert(CallerGraph->getInlinedGlobals().empty());
+ CallerGraph->maskIncompleteMarkers();
+ CallerGraph->markIncompleteNodes(DSGraph::MarkFormalArgs);
+
+ // Delete dead nodes. Treat globals that are unreachable but that can
+ // reach live nodes as live.
+ CallerGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
+ }
+
+ DEBUG(std::cerr << " --DONE ProcessGraph for function " << F.getName() << "\n");
+}