1 //===- IPModRef.h - 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 //===----------------------------------------------------------------------===//
12 // class IPModRef is an interprocedural analysis pass that computes
13 // flow-insensitive IP Mod and Ref information for every function
14 // (the GMOD and GREF problems) and for every call site (MOD and REF).
16 // In practice, this needs to do NO real interprocedural work because
17 // all that is needed is done by the data structure analysis.
18 // This uses the top-down DS graph for a function and the bottom-up DS graph
19 // for each callee (including the Mod/Ref flags in the bottom-up graph)
20 // to compute the set of nodes that are Mod and Ref for the function and
21 // for each of its call sites.
24 // class FunctionModRefInfo:
26 // The results of IPModRef are encapsulated in the class FunctionModRefInfo.
27 // The results are stored as bit vectors: bit i represents node i
28 // in the TD DSGraph for the current function. (This node numbering is
29 // implemented by class FunctionModRefInfo.) Each FunctionModRefInfo
31 // -- 2 bit vectors for the function (GMOD and GREF), and
32 // -- 2 bit vectors for each call site (MOD and REF).
35 // IPModRef vs. Alias Analysis for Clients:
37 // The IPModRef pass does not provide simpler query interfaces for specific
38 // LLVM values, instructions, or pointers because those results should be
39 // obtained through alias analysis (e.g., class DSAliasAnalysis).
40 // class IPModRef is primarily meant for other analysis passes that need to
41 // use Mod/Ref information efficiently for more complicated purposes;
42 // the bit-vector representations make propagation very efficient.
44 //===----------------------------------------------------------------------===//
46 #ifndef LLVM_ANALYSIS_IPMODREF_H
47 #define LLVM_ANALYSIS_IPMODREF_H
49 #include "llvm/Pass.h"
50 #include "Support/BitSetVector.h"
51 #include "Support/hash_map"
62 class ModRefInfo; // Result of IP Mod/Ref for one entity
63 class FunctionModRefInfo; // ModRefInfo for a func and all calls in it
64 class IPModRef; // Pass that computes IP Mod/Ref info
66 //---------------------------------------------------------------------------
70 // Representation of Mod/Ref information for a single function or callsite.
71 // This is represented as a pair of bit vectors, one each for Mod and Ref.
72 // Each bit vector is indexed by the node id of the DS graph node index.
73 //---------------------------------------------------------------------------
76 BitSetVector modNodeSet; // set of modified nodes
77 BitSetVector refNodeSet; // set of referenced nodes
81 // Methods to construct ModRefInfo objects.
83 ModRefInfo(unsigned int numNodes)
84 : modNodeSet(numNodes),
85 refNodeSet(numNodes) { }
87 unsigned getSize() const {
88 assert(modNodeSet.size() == refNodeSet.size() &&
89 "Mod & Ref different size?");
90 return modNodeSet.size();
93 void setNodeIsMod (unsigned nodeId) { modNodeSet[nodeId] = true; }
94 void setNodeIsRef (unsigned nodeId) { refNodeSet[nodeId] = true; }
97 // Methods to query the mod/ref info
99 bool nodeIsMod (unsigned nodeId) const { return modNodeSet.test(nodeId); }
100 bool nodeIsRef (unsigned nodeId) const { return refNodeSet.test(nodeId); }
101 bool nodeIsKill(unsigned nodeId) const { return false; }
103 const BitSetVector& getModSet() const { return modNodeSet; }
104 BitSetVector& getModSet() { return modNodeSet; }
106 const BitSetVector& getRefSet() const { return refNodeSet; }
107 BitSetVector& getRefSet() { return refNodeSet; }
109 // Debugging support methods
110 void print(std::ostream &O, const std::string& prefix=std::string("")) const;
115 //----------------------------------------------------------------------------
116 // class FunctionModRefInfo
118 // Representation of the results of IP Mod/Ref analysis for a function
119 // and for each of the call sites within the function.
120 // Each of these are represented as bit vectors of size = the number of
121 // nodes in the top-dwon DS graph of the function. Nodes are identified by
122 // their nodeId, in the range [0 .. funcTDGraph.size()-1].
123 //----------------------------------------------------------------------------
125 class FunctionModRefInfo {
126 const Function& F; // The function
127 IPModRef& IPModRefObj; // The IPModRef Object owning this
128 DSGraph* funcTDGraph; // Top-down DS graph for function
129 ModRefInfo funcModRefInfo; // ModRefInfo for the function body
130 std::map<const Instruction*, ModRefInfo*>
131 callSiteModRefInfo; // ModRefInfo for each callsite
132 std::map<const DSNode*, unsigned> NodeIds;
134 friend class IPModRef;
136 void computeModRef (const Function &func);
137 void computeModRef (CallSite call);
138 DSGraph *ResolveCallSiteModRefInfo(CallSite CS,
139 hash_map<const DSNode*, DSNodeHandle> &NodeMap);
142 /* ctor */ FunctionModRefInfo (const Function& func,
143 IPModRef& IPModRefObj,
145 /* dtor */ ~FunctionModRefInfo ();
147 // Identify the function and its relevant DS graph
149 const Function& getFunction() const { return F; }
150 const DSGraph& getFuncGraph() const { return *funcTDGraph; }
152 // Retrieve Mod/Ref results for a single call site and for the function body
154 const ModRefInfo* getModRefInfo (const Function& func) const {
155 return &funcModRefInfo;
157 const ModRefInfo* getModRefInfo (const CallInst& callInst) const {
158 std::map<const Instruction*, ModRefInfo*>::const_iterator I =
159 callSiteModRefInfo.find((Instruction*)&callInst);
160 return (I == callSiteModRefInfo.end()) ? NULL : I->second;
162 const ModRefInfo* getModRefInfo (const InvokeInst& II) const {
163 std::map<const Instruction*, ModRefInfo*>::const_iterator I =
164 callSiteModRefInfo.find((Instruction*)&II);
165 return (I == callSiteModRefInfo.end()) ? NULL : I->second;
168 // Get the nodeIds used to index all Mod/Ref information for current function
170 unsigned getNodeId (const DSNode* node) const {
171 std::map<const DSNode*, unsigned>::const_iterator iter = NodeIds.find(node);
172 assert(iter != NodeIds.end() && iter->second < funcModRefInfo.getSize());
176 unsigned getNodeId (const Value* value) const;
178 // Debugging support methods
179 void print(std::ostream &O) const;
184 //----------------------------------------------------------------------------
188 // An interprocedural pass that computes IP Mod/Ref info for functions and
189 // for individual call sites.
191 // Given the DSGraph of a function, this class can be queried for
192 // a ModRefInfo object describing all the nodes in the DSGraph that are
193 // (a) modified, and (b) referenced during an execution of the function
194 // from an arbitrary callsite, or during an execution of a single call-site
195 // within the function.
196 //----------------------------------------------------------------------------
198 class IPModRef : public Pass {
199 std::map<const Function*, FunctionModRefInfo*> funcToModRefInfoMap;
202 FunctionModRefInfo& getFuncInfo(const Function& func,
203 bool computeIfMissing = false);
205 IPModRef() : M(NULL) { }
208 // Driver function to run IP Mod/Ref on a Module.
209 // This initializes the module reference, and then computes IPModRef
210 // results immediately if demand-driven analysis was *not* specified.
212 virtual bool run(Module &M);
214 // Retrieve the Mod/Ref information for a single function
216 const FunctionModRefInfo& getFunctionModRefInfo(const Function& func) {
217 return getFuncInfo(func);
220 /// getBUDSGraph - This method returns the BU data structure graph for F
221 /// through the use of the BUDataStructures object.
223 const DSGraph &getBUDSGraph(const Function &F);
225 // Debugging support methods
227 void print(std::ostream &O) const;
230 // Release memory held by this pass when the pass pipeline is done
232 virtual void releaseMemory();
234 // getAnalysisUsage - This pass requires top-down data structure graphs.
235 // It modifies nothing.
237 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
240 //===----------------------------------------------------------------------===//