lib/Analysis/DataStructure/BottomUpClosure.cpp - llvm - Git at Google

 //===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
 //
 //                     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 file implements the BUDataStructures class, which represents the
 // Bottom-Up Interprocedural closure of the data structure graph over the
 // program.  This is useful for applications like pool allocation, but **not**
 // applications like alias analysis.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Analysis/DataStructure.h"
 #include "llvm/Module.h"
 #include "Support/Statistic.h"
 #include "Support/Debug.h"
 #include "DSCallSiteIterator.h"

 namespace {
   Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
   Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
   Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");

   RegisterAnalysis<BUDataStructures>
   X("budatastructure", "Bottom-up Data Structure Analysis");
 }

 using namespace DS;

 // run - Calculate the bottom up data structure graphs for each function in the
 // program.
 //
 bool BUDataStructures::run(Module &M) {
   LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
   GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph());
   GlobalsGraph->setPrintAuxCalls();

   Function *MainFunc = M.getMainFunction();
   if (MainFunc)
     calculateReachableGraphs(MainFunc);

   // Calculate the graphs for any functions that are unreachable from main...
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     if (!I->isExternal() && !DSInfo.count(I)) {
 #ifndef NDEBUG
       if (MainFunc)
         std::cerr << "*** Function unreachable from main: "
                   << I->getName() << "\n";
 #endif
       calculateReachableGraphs(I);    // Calculate all graphs...
     }

   NumCallEdges += ActualCallees.size();

   // At the end of the bottom-up pass, the globals graph becomes complete.
   // FIXME: This is not the right way to do this, but it is sorta better than
   // nothing!  In particular, externally visible globals and unresolvable call
   // nodes at the end of the BU phase should make things that they point to
   // incomplete in the globals graph.
   //
   GlobalsGraph->maskIncompleteMarkers();
   return false;
 }

 void BUDataStructures::calculateReachableGraphs(Function *F) {
   std::vector<Function*> Stack;
   hash_map<Function*, unsigned> ValMap;
   unsigned NextID = 1;
   calculateGraphs(F, Stack, NextID, ValMap);
 }

 DSGraph &BUDataStructures::getOrCreateGraph(Function *F) {
   // Has the graph already been created?
   DSGraph *&Graph = DSInfo[F];
   if (Graph) return *Graph;

   // Copy the local version into DSInfo...
   Graph = new DSGraph(getAnalysis<LocalDataStructures>().getDSGraph(*F));

   Graph->setGlobalsGraph(GlobalsGraph);
   Graph->setPrintAuxCalls();

   // Start with a copy of the original call sites...
   Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
   return *Graph;
 }

 unsigned BUDataStructures::calculateGraphs(Function *F,
                                            std::vector<Function*> &Stack,
                                            unsigned &NextID,
                                      hash_map<Function*, unsigned> &ValMap) {
   assert(ValMap.find(F) == ValMap.end() && "Shouldn't revisit functions!");
   unsigned Min = NextID++, MyID = Min;
   ValMap[F] = Min;
   Stack.push_back(F);

   if (F->isExternal()) {   // sprintf, fprintf, sscanf, etc...
     // No callees!
     Stack.pop_back();
     ValMap[F] = ~0;
     return Min;
   }

   DSGraph &Graph = getOrCreateGraph(F);

   // The edges out of the current node are the call site targets...
   for (DSCallSiteIterator I = DSCallSiteIterator::begin_aux(Graph),
          E = DSCallSiteIterator::end_aux(Graph); I != E; ++I) {
     Function *Callee = *I;
     unsigned M;
     // Have we visited the destination function yet?
     hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
     if (It == ValMap.end())  // No, visit it now.
       M = calculateGraphs(Callee, Stack, NextID, ValMap);
     else                    // Yes, get it's number.
       M = It->second;
     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.
   if (Stack.back() == F) {           // Special case the single "SCC" case here.
     DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
                     << F->getName() << "\n");
     Stack.pop_back();
     DSGraph &G = getDSGraph(*F);
     DEBUG(std::cerr << "  [BU] Calculating graph for: " << F->getName()<< "\n");
     calculateGraph(G);
     DEBUG(std::cerr << "  [BU] Done inlining: " << F->getName() << " ["
                     << G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
                     << "]\n");

     if (MaxSCC < 1) MaxSCC = 1;

     // Should we revisit the graph?
     if (DSCallSiteIterator::begin_aux(G) != DSCallSiteIterator::end_aux(G)) {
       ValMap.erase(F);
       return calculateGraphs(F, Stack, NextID, ValMap);
     } else {
       ValMap[F] = ~0U;
     }
     return MyID;

   } else {
     // SCCFunctions - Keep track of the functions in the current SCC
     //
     hash_set<Function*> SCCFunctions;

     Function *NF;
     std::vector<Function*>::iterator FirstInSCC = Stack.end();
     DSGraph *SCCGraph = 0;
     do {
       NF = *--FirstInSCC;
       ValMap[NF] = ~0U;
       SCCFunctions.insert(NF);

       // Figure out which graph is the largest one, in order to speed things up
       // a bit in situations where functions in the SCC have widely different
       // graph sizes.
       DSGraph &NFGraph = getDSGraph(*NF);
       if (!SCCGraph || SCCGraph->getGraphSize() < NFGraph.getGraphSize())
         SCCGraph = &NFGraph;
     } while (NF != F);

     std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
               << SCCFunctions.size() << "\n";

     // Compute the Max SCC Size...
     if (MaxSCC < SCCFunctions.size())
       MaxSCC = SCCFunctions.size();

     // First thing first, collapse all of the DSGraphs into a single graph for
     // the entire SCC.  We computed the largest graph, so clone all of the other
     // (smaller) graphs into it.  Discard all of the old graphs.
     //
     for (hash_set<Function*>::iterator I = SCCFunctions.begin(),
            E = SCCFunctions.end(); I != E; ++I) {
       DSGraph &G = getDSGraph(**I);
       if (&G != SCCGraph) {
         DSGraph::NodeMapTy NodeMap;
         SCCGraph->cloneInto(G, SCCGraph->getScalarMap(),
                             SCCGraph->getReturnNodes(), NodeMap, 0);
         // Update the DSInfo map and delete the old graph...
         DSInfo[*I] = SCCGraph;
         delete &G;
       }
     }

     // Clean up the graph before we start inlining a bunch again...
     SCCGraph->removeTriviallyDeadNodes();

     // Now that we have one big happy family, resolve all of the call sites in
     // the graph...
     calculateGraph(*SCCGraph);
     DEBUG(std::cerr << "  [BU] Done inlining SCC  [" << SCCGraph->getGraphSize()
                     << "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n");

     std::cerr << "DONE with SCC #: " << MyID << "\n";

     // We never have to revisit "SCC" processed functions...

     // Drop the stuff we don't need from the end of the stack
     Stack.erase(FirstInSCC, Stack.end());
     return MyID;
   }

   return MyID;  // == Min
 }


 // releaseMemory - If the pass pipeline is done with this pass, we can release
 // our memory... here...
 //
 void BUDataStructures::releaseMemory() {
   for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
          E = DSInfo.end(); I != E; ++I) {
     I->second->getReturnNodes().erase(I->first);
     if (I->second->getReturnNodes().empty())
       delete I->second;
   }

   // Empty map so next time memory is released, data structures are not
   // re-deleted.
   DSInfo.clear();
   delete GlobalsGraph;
   GlobalsGraph = 0;
 }

 void BUDataStructures::calculateGraph(DSGraph &Graph) {
   // Move our call site list into TempFCs so that inline call sites go into the
   // new call site list and doesn't invalidate our iterators!
   std::vector<DSCallSite> TempFCs;
   std::vector<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
   TempFCs.swap(AuxCallsList);

   DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

   // Loop over all of the resolvable call sites
   unsigned LastCallSiteIdx = ~0U;
   for (DSCallSiteIterator I = DSCallSiteIterator::begin(TempFCs),
          E = DSCallSiteIterator::end(TempFCs); I != E; ++I) {
     // If we skipped over any call sites, they must be unresolvable, copy them
     // to the real call site list.
     LastCallSiteIdx++;
     for (; LastCallSiteIdx < I.getCallSiteIdx(); ++LastCallSiteIdx)
       AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);
     LastCallSiteIdx = I.getCallSiteIdx();

     // Resolve the current call...
     Function *Callee = *I;
     DSCallSite CS = I.getCallSite();

     if (Callee->isExternal()) {
       // Ignore this case, simple varargs functions we cannot stub out!
     } else if (ReturnNodes.find(Callee) != ReturnNodes.end()) {
       // Self recursion... simply link up the formal arguments with the
       // actual arguments...
       DEBUG(std::cerr << "    Self Inlining: " << Callee->getName() << "\n");

       // Handle self recursion by resolving the arguments and return value
       Graph.mergeInGraph(CS, *Callee, Graph, 0);

     } else {
       ActualCallees.insert(std::make_pair(CS.getCallSite().getInstruction(),
                                           Callee));

       // Get the data structure graph for the called function.
       //
       DSGraph &GI = getDSGraph(*Callee);  // Graph to inline

       DEBUG(std::cerr << "    Inlining graph for " << Callee->getName()
             << "[" << GI.getGraphSize() << "+"
             << GI.getAuxFunctionCalls().size() << "] into '"
             << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() << "+"
             << Graph.getAuxFunctionCalls().size() << "]\n");

       // Handle self recursion by resolving the arguments and return value
       Graph.mergeInGraph(CS, *Callee, GI,
                          DSGraph::KeepModRefBits |
                          DSGraph::StripAllocaBit | DSGraph::DontCloneCallNodes);
       ++NumBUInlines;

 #if 0
       Graph.writeGraphToFile(std::cerr, "bu_" + F.getName() + "_after_" +
                              Callee->getName());
 #endif
     }
   }

   // Make sure to catch any leftover unresolvable calls...
   for (++LastCallSiteIdx; LastCallSiteIdx < TempFCs.size(); ++LastCallSiteIdx)
     AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);

   TempFCs.clear();

   // Re-materialize nodes from the globals graph.
   // Do not ignore globals inlined from callees -- they are not up-to-date!
   Graph.getInlinedGlobals().clear();
   Graph.updateFromGlobalGraph();

   // Recompute the Incomplete markers
   Graph.maskIncompleteMarkers();
   Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);

   // Delete dead nodes.  Treat globals that are unreachable but that can
   // reach live nodes as live.
   Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

   //Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
 }
	//===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
	//
	// 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 file implements the BUDataStructures class, which represents the
	// Bottom-Up Interprocedural closure of the data structure graph over the
	// program. This is useful for applications like pool allocation, but not
	// applications like alias analysis.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Analysis/DataStructure.h"
	#include "llvm/Module.h"
	#include "Support/Statistic.h"
	#include "Support/Debug.h"
	#include "DSCallSiteIterator.h"

	namespace {
	Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
	Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
	Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");

	RegisterAnalysis<BUDataStructures>
	X("budatastructure", "Bottom-up Data Structure Analysis");
	}

	using namespace DS;

	// run - Calculate the bottom up data structure graphs for each function in the
	// program.
	//
	bool BUDataStructures::run(Module &M) {
	LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
	GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph());
	GlobalsGraph->setPrintAuxCalls();

	Function *MainFunc = M.getMainFunction();
	if (MainFunc)
	calculateReachableGraphs(MainFunc);

	// Calculate the graphs for any functions that are unreachable from main...
	for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
	if (!I->isExternal() && !DSInfo.count(I)) {
	#ifndef NDEBUG
	if (MainFunc)
	std::cerr << "*** Function unreachable from main: "
	<< I->getName() << "\n";
	#endif
	calculateReachableGraphs(I); // Calculate all graphs...
	}

	NumCallEdges += ActualCallees.size();

	// At the end of the bottom-up pass, the globals graph becomes complete.
	// FIXME: This is not the right way to do this, but it is sorta better than
	// nothing! In particular, externally visible globals and unresolvable call
	// nodes at the end of the BU phase should make things that they point to
	// incomplete in the globals graph.
	//
	GlobalsGraph->maskIncompleteMarkers();
	return false;
	}

	void BUDataStructures::calculateReachableGraphs(Function *F) {
	std::vector<Function*> Stack;
	hash_map<Function*, unsigned> ValMap;
	unsigned NextID = 1;
	calculateGraphs(F, Stack, NextID, ValMap);
	}

	DSGraph &BUDataStructures::getOrCreateGraph(Function *F) {
	// Has the graph already been created?
	DSGraph *&Graph = DSInfo[F];
	if (Graph) return *Graph;

	// Copy the local version into DSInfo...
	Graph = new DSGraph(getAnalysis<LocalDataStructures>().getDSGraph(*F));

	Graph->setGlobalsGraph(GlobalsGraph);
	Graph->setPrintAuxCalls();

	// Start with a copy of the original call sites...
	Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
	return *Graph;
	}

	unsigned BUDataStructures::calculateGraphs(Function *F,
	std::vector<Function*> &Stack,
	unsigned &NextID,
	hash_map<Function*, unsigned> &ValMap) {
	assert(ValMap.find(F) == ValMap.end() && "Shouldn't revisit functions!");
	unsigned Min = NextID++, MyID = Min;
	ValMap[F] = Min;
	Stack.push_back(F);

	if (F->isExternal()) { // sprintf, fprintf, sscanf, etc...
	// No callees!
	Stack.pop_back();
	ValMap[F] = ~0;
	return Min;
	}

	DSGraph &Graph = getOrCreateGraph(F);

	// The edges out of the current node are the call site targets...
	for (DSCallSiteIterator I = DSCallSiteIterator::begin_aux(Graph),
	E = DSCallSiteIterator::end_aux(Graph); I != E; ++I) {
	Function Callee = I;
	unsigned M;
	// Have we visited the destination function yet?
	hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
	if (It == ValMap.end()) // No, visit it now.
	M = calculateGraphs(Callee, Stack, NextID, ValMap);
	else // Yes, get it's number.
	M = It->second;
	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.
	if (Stack.back() == F) { // Special case the single "SCC" case here.
	DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
	<< F->getName() << "\n");
	Stack.pop_back();
	DSGraph &G = getDSGraph(*F);
	DEBUG(std::cerr << " [BU] Calculating graph for: " << F->getName()<< "\n");
	calculateGraph(G);
	DEBUG(std::cerr << " [BU] Done inlining: " << F->getName() << " ["
	<< G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
	<< "]\n");

	if (MaxSCC < 1) MaxSCC = 1;

	// Should we revisit the graph?
	if (DSCallSiteIterator::begin_aux(G) != DSCallSiteIterator::end_aux(G)) {
	ValMap.erase(F);
	return calculateGraphs(F, Stack, NextID, ValMap);
	} else {
	ValMap[F] = ~0U;
	}
	return MyID;

	} else {
	// SCCFunctions - Keep track of the functions in the current SCC
	//
	hash_set<Function*> SCCFunctions;

	Function *NF;
	std::vector<Function*>::iterator FirstInSCC = Stack.end();
	DSGraph *SCCGraph = 0;
	do {
	NF = *--FirstInSCC;
	ValMap[NF] = ~0U;
	SCCFunctions.insert(NF);

	// Figure out which graph is the largest one, in order to speed things up
	// a bit in situations where functions in the SCC have widely different
	// graph sizes.
	DSGraph &NFGraph = getDSGraph(*NF);
	if (!SCCGraph \|\| SCCGraph->getGraphSize() < NFGraph.getGraphSize())
	SCCGraph = &NFGraph;
	} while (NF != F);

	std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
	<< SCCFunctions.size() << "\n";

	// Compute the Max SCC Size...
	if (MaxSCC < SCCFunctions.size())
	MaxSCC = SCCFunctions.size();

	// First thing first, collapse all of the DSGraphs into a single graph for
	// the entire SCC. We computed the largest graph, so clone all of the other
	// (smaller) graphs into it. Discard all of the old graphs.
	//
	for (hash_set<Function*>::iterator I = SCCFunctions.begin(),
	E = SCCFunctions.end(); I != E; ++I) {
	DSGraph &G = getDSGraph(**I);
	if (&G != SCCGraph) {
	DSGraph::NodeMapTy NodeMap;
	SCCGraph->cloneInto(G, SCCGraph->getScalarMap(),
	SCCGraph->getReturnNodes(), NodeMap, 0);
	// Update the DSInfo map and delete the old graph...
	DSInfo[*I] = SCCGraph;
	delete &G;
	}
	}

	// Clean up the graph before we start inlining a bunch again...
	SCCGraph->removeTriviallyDeadNodes();

	// Now that we have one big happy family, resolve all of the call sites in
	// the graph...
	calculateGraph(*SCCGraph);
	DEBUG(std::cerr << " [BU] Done inlining SCC [" << SCCGraph->getGraphSize()
	<< "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n");

	std::cerr << "DONE with SCC #: " << MyID << "\n";

	// We never have to revisit "SCC" processed functions...

	// Drop the stuff we don't need from the end of the stack
	Stack.erase(FirstInSCC, Stack.end());
	return MyID;
	}

	return MyID; // == Min
	}


	// releaseMemory - If the pass pipeline is done with this pass, we can release
	// our memory... here...
	//
	void BUDataStructures::releaseMemory() {
	for (hash_map<Function, DSGraph>::iterator I = DSInfo.begin(),
	E = DSInfo.end(); I != E; ++I) {
	I->second->getReturnNodes().erase(I->first);
	if (I->second->getReturnNodes().empty())
	delete I->second;
	}

	// Empty map so next time memory is released, data structures are not
	// re-deleted.
	DSInfo.clear();
	delete GlobalsGraph;
	GlobalsGraph = 0;
	}

	void BUDataStructures::calculateGraph(DSGraph &Graph) {
	// Move our call site list into TempFCs so that inline call sites go into the
	// new call site list and doesn't invalidate our iterators!
	std::vector<DSCallSite> TempFCs;
	std::vector<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
	TempFCs.swap(AuxCallsList);

	DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

	// Loop over all of the resolvable call sites
	unsigned LastCallSiteIdx = ~0U;
	for (DSCallSiteIterator I = DSCallSiteIterator::begin(TempFCs),
	E = DSCallSiteIterator::end(TempFCs); I != E; ++I) {
	// If we skipped over any call sites, they must be unresolvable, copy them
	// to the real call site list.
	LastCallSiteIdx++;
	for (; LastCallSiteIdx < I.getCallSiteIdx(); ++LastCallSiteIdx)
	AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);
	LastCallSiteIdx = I.getCallSiteIdx();

	// Resolve the current call...
	Function Callee = I;
	DSCallSite CS = I.getCallSite();

	if (Callee->isExternal()) {
	// Ignore this case, simple varargs functions we cannot stub out!
	} else if (ReturnNodes.find(Callee) != ReturnNodes.end()) {
	// Self recursion... simply link up the formal arguments with the
	// actual arguments...
	DEBUG(std::cerr << " Self Inlining: " << Callee->getName() << "\n");

	// Handle self recursion by resolving the arguments and return value
	Graph.mergeInGraph(CS, *Callee, Graph, 0);

	} else {
	ActualCallees.insert(std::make_pair(CS.getCallSite().getInstruction(),
	Callee));

	// Get the data structure graph for the called function.
	//
	DSGraph &GI = getDSGraph(*Callee); // Graph to inline

	DEBUG(std::cerr << " Inlining graph for " << Callee->getName()
	<< "[" << GI.getGraphSize() << "+"
	<< GI.getAuxFunctionCalls().size() << "] into '"
	<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() << "+"
	<< Graph.getAuxFunctionCalls().size() << "]\n");

	// Handle self recursion by resolving the arguments and return value
	Graph.mergeInGraph(CS, *Callee, GI,
	DSGraph::KeepModRefBits \|
	DSGraph::StripAllocaBit \| DSGraph::DontCloneCallNodes);
	++NumBUInlines;

	#if 0
	Graph.writeGraphToFile(std::cerr, "bu_" + F.getName() + "_after_" +
	Callee->getName());
	#endif
	}
	}

	// Make sure to catch any leftover unresolvable calls...
	for (++LastCallSiteIdx; LastCallSiteIdx < TempFCs.size(); ++LastCallSiteIdx)
	AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);

	TempFCs.clear();

	// Re-materialize nodes from the globals graph.
	// Do not ignore globals inlined from callees -- they are not up-to-date!
	Graph.getInlinedGlobals().clear();
	Graph.updateFromGlobalGraph();

	// Recompute the Incomplete markers
	Graph.maskIncompleteMarkers();
	Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);

	// Delete dead nodes. Treat globals that are unreachable but that can
	// reach live nodes as live.
	Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

	//Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
	}