1 //===- IPModRef.cpp - Compute IP Mod/Ref information ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // See high-level comments in include/llvm/Analysis/IPModRef.h
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/IPModRef.h"
15 #include "llvm/Analysis/DataStructure.h"
16 #include "llvm/Analysis/DSGraph.h"
17 #include "llvm/Module.h"
18 #include "llvm/Function.h"
19 #include "llvm/iMemory.h"
20 #include "llvm/iOther.h"
21 #include "Support/Statistic.h"
22 #include "Support/STLExtras.h"
23 #include "Support/StringExtras.h"
26 //----------------------------------------------------------------------------
27 // Private constants and data
28 //----------------------------------------------------------------------------
30 static RegisterAnalysis<IPModRef>
31 Z("ipmodref", "Interprocedural mod/ref analysis");
34 //----------------------------------------------------------------------------
36 //----------------------------------------------------------------------------
38 void ModRefInfo::print(std::ostream &O,
39 const std::string& sprefix) const
41 O << sprefix << "Modified nodes = " << modNodeSet;
42 O << sprefix << "Referenced nodes = " << refNodeSet;
45 void ModRefInfo::dump() const
50 //----------------------------------------------------------------------------
51 // class FunctionModRefInfo
52 //----------------------------------------------------------------------------
55 // This constructor computes a node numbering for the TD graph.
57 FunctionModRefInfo::FunctionModRefInfo(const Function& func,
60 : F(func), IPModRefObj(ipmro),
61 funcTDGraph(tdgClone),
62 funcModRefInfo(tdgClone->getGraphSize())
64 for (unsigned i=0, N = funcTDGraph->getGraphSize(); i < N; ++i)
65 NodeIds[funcTDGraph->getNodes()[i]] = i;
69 FunctionModRefInfo::~FunctionModRefInfo()
71 for(std::map<const Instruction*, ModRefInfo*>::iterator
72 I=callSiteModRefInfo.begin(), E=callSiteModRefInfo.end(); I != E; ++I)
75 // Empty map just to make problems easier to track down
76 callSiteModRefInfo.clear();
81 unsigned FunctionModRefInfo::getNodeId(const Value* value) const {
82 return getNodeId(funcTDGraph->getNodeForValue(const_cast<Value*>(value))
88 // Compute Mod/Ref bit vectors for the entire function.
89 // These are simply copies of the Read/Write flags from the nodes of
90 // the top-down DS graph.
92 void FunctionModRefInfo::computeModRef(const Function &func)
94 // Mark all nodes in the graph that are marked MOD as being mod
95 // and all those marked REF as being ref.
96 for (unsigned i = 0, N = funcTDGraph->getGraphSize(); i < N; ++i)
98 if (funcTDGraph->getNodes()[i]->isModified())
99 funcModRefInfo.setNodeIsMod(i);
100 if (funcTDGraph->getNodes()[i]->isRead())
101 funcModRefInfo.setNodeIsRef(i);
104 // Compute the Mod/Ref info for all call sites within the function.
105 // The call sites are recorded in the TD graph.
106 const std::vector<DSCallSite>& callSites = funcTDGraph->getFunctionCalls();
107 for (unsigned i = 0, N = callSites.size(); i < N; ++i)
108 computeModRef(callSites[i].getCallSite());
112 // ResolveCallSiteModRefInfo - This method performs the following actions:
114 // 1. It clones the top-down graph for the current function
115 // 2. It clears all of the mod/ref bits in the cloned graph
116 // 3. It then merges the bottom-up graph(s) for the specified call-site into
117 // the clone (bringing new mod/ref bits).
118 // 4. It returns the clone, and a mapping of nodes from the original TDGraph to
119 // the cloned graph with Mod/Ref info for the callsite.
121 // NOTE: Because this clones a dsgraph and returns it, the caller is responsible
122 // for deleting the returned graph!
123 // NOTE: This method may return a null pointer if it is unable to determine the
124 // requested information (because the call site calls an external
125 // function or we cannot determine the complete set of functions invoked).
127 DSGraph* FunctionModRefInfo::ResolveCallSiteModRefInfo(CallSite CS,
128 hash_map<const DSNode*, DSNodeHandle> &NodeMap)
130 // Step #0: Quick check if we are going to fail anyway: avoid
131 // all the graph cloning and map copying in steps #1 and #2.
133 if (const Function *F = CS.getCalledFunction()) {
135 return 0; // We cannot compute Mod/Ref info for this callsite...
137 // Eventually, should check here if any callee is external.
138 // For now we are not handling this case anyway.
139 std::cerr << "IP Mod/Ref indirect call not implemented yet: "
140 << "Being conservative\n";
141 return 0; // We cannot compute Mod/Ref info for this callsite...
144 // Step #1: Clone the top-down graph...
145 DSGraph *Result = new DSGraph(*funcTDGraph, NodeMap);
147 // Step #2: Clear Mod/Ref information...
148 Result->maskNodeTypes(~(DSNode::Modified | DSNode::Read));
150 // Step #3: clone the bottom up graphs for the callees into the caller graph
151 if (Function *F = CS.getCalledFunction())
153 assert(!F->isExternal());
155 // Build up a DSCallSite for our invocation point here...
157 // If the call returns a value, make sure to merge the nodes...
159 if (DS::isPointerType(CS.getInstruction()->getType()))
160 RetVal = Result->getNodeForValue(CS.getInstruction());
162 // Populate the arguments list...
163 std::vector<DSNodeHandle> Args;
164 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
166 if (DS::isPointerType((*I)->getType()))
167 Args.push_back(Result->getNodeForValue(*I));
169 // Build the call site...
170 DSCallSite NCS(CS, RetVal, F, Args);
172 // Perform the merging now of the graph for the callee, which will
173 // come with mod/ref bits set...
174 Result->mergeInGraph(NCS, *F, IPModRefObj.getBUDSGraph(*F),
175 DSGraph::StripAllocaBit
176 | DSGraph::DontCloneCallNodes
177 | DSGraph::DontCloneAuxCallNodes);
180 assert(0 && "See error message");
182 // Remove dead nodes aggressively to match the caller's original graph.
183 Result->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
185 // Step #4: Return the clone + the mapping (by ref)
189 // Compute Mod/Ref bit vectors for a single call site.
190 // These are copies of the Read/Write flags from the nodes of
191 // the graph produced by clearing all flags in the caller's TD graph
192 // and then inlining the callee's BU graph into the caller's TD graph.
195 FunctionModRefInfo::computeModRef(CallSite CS)
197 // Allocate the mod/ref info for the call site. Bits automatically cleared.
198 ModRefInfo* callModRefInfo = new ModRefInfo(funcTDGraph->getGraphSize());
199 callSiteModRefInfo[CS.getInstruction()] = callModRefInfo;
201 // Get a copy of the graph for the callee with the callee inlined
202 hash_map<const DSNode*, DSNodeHandle> NodeMap;
203 DSGraph* csgp = ResolveCallSiteModRefInfo(CS, NodeMap);
205 { // Callee's side effects are unknown: mark all nodes Mod and Ref.
206 // Eventually this should only mark nodes visible to the callee, i.e.,
207 // exclude stack variables not reachable from any outgoing argument
209 callModRefInfo->getModSet().set();
210 callModRefInfo->getRefSet().set();
214 // For all nodes in the graph, extract the mod/ref information
215 const std::vector<DSNode*>& csgNodes = csgp->getNodes();
216 const std::vector<DSNode*>& origNodes = funcTDGraph->getNodes();
217 assert(csgNodes.size() == origNodes.size());
218 for (unsigned i=0, N = origNodes.size(); i < N; ++i)
220 DSNode* csgNode = NodeMap[origNodes[i]].getNode();
221 assert(csgNode && "Inlined and original graphs do not correspond!");
222 if (csgNode->isModified())
223 callModRefInfo->setNodeIsMod(getNodeId(origNodes[i]));
224 if (csgNode->isRead())
225 callModRefInfo->setNodeIsRef(getNodeId(origNodes[i]));
228 // Drop nodemap before we delete the graph...
234 class DSGraphPrintHelper {
235 const DSGraph& tdGraph;
236 std::vector<std::vector<const Value*> > knownValues; // identifiable objects
239 /*ctor*/ DSGraphPrintHelper(const FunctionModRefInfo& fmrInfo)
240 : tdGraph(fmrInfo.getFuncGraph())
242 knownValues.resize(tdGraph.getGraphSize());
244 // For every identifiable value, save Value pointer in knownValues[i]
245 for (hash_map<Value*, DSNodeHandle>::const_iterator
246 I = tdGraph.getScalarMap().begin(),
247 E = tdGraph.getScalarMap().end(); I != E; ++I)
248 if (isa<GlobalValue>(I->first) ||
249 isa<Argument>(I->first) ||
250 isa<LoadInst>(I->first) ||
251 isa<AllocaInst>(I->first) ||
252 isa<MallocInst>(I->first))
254 unsigned nodeId = fmrInfo.getNodeId(I->second.getNode());
255 knownValues[nodeId].push_back(I->first);
259 void printValuesInBitVec(std::ostream &O, const BitSetVector& bv) const
261 assert(bv.size() == knownValues.size());
264 { // No bits are set: just say so and return
270 { // All bits are set: just say so and return
271 O << "\tALL GRAPH NODES.\n";
275 for (unsigned i=0, N=bv.size(); i < N; ++i)
278 O << "\tNode# " << i << " : ";
279 if (! knownValues[i].empty())
280 for (unsigned j=0, NV=knownValues[i].size(); j < NV; j++)
282 const Value* V = knownValues[i][j];
284 if (isa<GlobalValue>(V)) O << "(Global) ";
285 else if (isa<Argument>(V)) O << "(Target of FormalParm) ";
286 else if (isa<LoadInst>(V)) O << "(Target of LoadInst ) ";
287 else if (isa<AllocaInst>(V)) O << "(Target of AllocaInst) ";
288 else if (isa<MallocInst>(V)) O << "(Target of MallocInst) ";
290 if (V->hasName()) O << V->getName();
291 else if (isa<Instruction>(V)) O << *V;
292 else O << "(Value*) 0x" << (void*) V;
294 O << std::string((j < NV-1)? "; " : "\n");
297 tdGraph.getNodes()[i]->print(O, /*graph*/ NULL);
303 // Print the results of the pass.
304 // Currently this just prints bit-vectors and is not very readable.
306 void FunctionModRefInfo::print(std::ostream &O) const
308 DSGraphPrintHelper DPH(*this);
310 O << "========== Mod/ref information for function "
311 << F.getName() << "========== \n\n";
313 // First: Print Globals and Locals modified anywhere in the function.
315 O << " -----Mod/Ref in the body of function " << F.getName()<< ":\n";
317 O << " --Objects modified in the function body:\n";
318 DPH.printValuesInBitVec(O, funcModRefInfo.getModSet());
320 O << " --Objects referenced in the function body:\n";
321 DPH.printValuesInBitVec(O, funcModRefInfo.getRefSet());
323 O << " --Mod and Ref vectors for the nodes listed above:\n";
324 funcModRefInfo.print(O, "\t");
328 // Second: Print Globals and Locals modified at each call site in function
330 for (std::map<const Instruction *, ModRefInfo*>::const_iterator
331 CI = callSiteModRefInfo.begin(), CE = callSiteModRefInfo.end();
334 O << " ----Mod/Ref information for call site\n" << CI->first;
336 O << " --Objects modified at call site:\n";
337 DPH.printValuesInBitVec(O, CI->second->getModSet());
339 O << " --Objects referenced at call site:\n";
340 DPH.printValuesInBitVec(O, CI->second->getRefSet());
342 O << " --Mod and Ref vectors for the nodes listed above:\n";
343 CI->second->print(O, "\t");
351 void FunctionModRefInfo::dump() const
357 //----------------------------------------------------------------------------
358 // class IPModRef: An interprocedural pass that computes IP Mod/Ref info.
359 //----------------------------------------------------------------------------
361 // Free the FunctionModRefInfo objects cached in funcToModRefInfoMap.
363 void IPModRef::releaseMemory()
365 for(std::map<const Function*, FunctionModRefInfo*>::iterator
366 I=funcToModRefInfoMap.begin(), E=funcToModRefInfoMap.end(); I != E; ++I)
369 // Clear map so memory is not re-released if we are called again
370 funcToModRefInfoMap.clear();
373 // Run the "interprocedural" pass on each function. This needs to do
374 // NO real interprocedural work because all that has been done the
375 // data structure analysis.
377 bool IPModRef::run(Module &theModule)
381 for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI)
382 if (! FI->isExternal())
383 getFuncInfo(*FI, /*computeIfMissing*/ true);
388 FunctionModRefInfo& IPModRef::getFuncInfo(const Function& func,
389 bool computeIfMissing)
391 FunctionModRefInfo*& funcInfo = funcToModRefInfoMap[&func];
392 assert (funcInfo != NULL || computeIfMissing);
393 if (funcInfo == NULL)
394 { // Create a new FunctionModRefInfo object.
395 // Clone the top-down graph and remove any dead nodes first, because
396 // otherwise original and merged graphs will not match.
397 // The memory for this graph clone will be freed by FunctionModRefInfo.
398 DSGraph* funcTDGraph =
399 new DSGraph(getAnalysis<TDDataStructures>().getDSGraph(func));
400 funcTDGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
402 funcInfo = new FunctionModRefInfo(func, *this, funcTDGraph); //auto-insert
403 funcInfo->computeModRef(func); // computes the mod/ref info
408 /// getBUDSGraph - This method returns the BU data structure graph for F through
409 /// the use of the BUDataStructures object.
411 const DSGraph &IPModRef::getBUDSGraph(const Function &F) {
412 return getAnalysis<BUDataStructures>().getDSGraph(F);
416 // getAnalysisUsage - This pass requires top-down data structure graphs.
417 // It modifies nothing.
419 void IPModRef::getAnalysisUsage(AnalysisUsage &AU) const {
420 AU.setPreservesAll();
421 AU.addRequired<LocalDataStructures>();
422 AU.addRequired<BUDataStructures>();
423 AU.addRequired<TDDataStructures>();
427 void IPModRef::print(std::ostream &O) const
429 O << "\nRESULTS OF INTERPROCEDURAL MOD/REF ANALYSIS:\n\n";
431 for (std::map<const Function*, FunctionModRefInfo*>::const_iterator
432 mapI = funcToModRefInfoMap.begin(), mapE = funcToModRefInfoMap.end();
433 mapI != mapE; ++mapI)
434 mapI->second->print(O);
440 void IPModRef::dump() const