1 //===- IPModRef.h - Compute IP Mod/Ref information --------------*- C++ -*-===//
5 // class IPModRef is an interprocedural analysis pass that computes
6 // flow-insensitive IP Mod and Ref information for every function
7 // (the GMOD and GREF problems) and for every call site (MOD and REF).
9 // In practice, this needs to do NO real interprocedural work because
10 // all that is needed is done by the data structure analysis.
11 // This uses the top-down DS graph for a function and the bottom-up DS graph
12 // for each callee (including the Mod/Ref flags in the bottom-up graph)
13 // to compute the set of nodes that are Mod and Ref for the function and
14 // for each of its call sites.
17 // class FunctionModRefInfo:
19 // The results of IPModRef are encapsulated in the class FunctionModRefInfo.
20 // The results are stored as bit vectors: bit i represents node i
21 // in the TD DSGraph for the current function. (This node numbering is
22 // implemented by class FunctionModRefInfo.) Each FunctionModRefInfo
24 // -- 2 bit vectors for the function (GMOD and GREF), and
25 // -- 2 bit vectors for each call site (MOD and REF).
28 // IPModRef vs. Alias Analysis for Clients:
30 // The IPModRef pass does not provide simpler query interfaces for specific
31 // LLVM values, instructions, or pointers because those results should be
32 // obtained through alias analysis (e.g., class DSAliasAnalysis).
33 // class IPModRef is primarily meant for other analysis passes that need to
34 // use Mod/Ref information efficiently for more complicated purposes;
35 // the bit-vector representations make propagation very efficient.
37 //===----------------------------------------------------------------------===//
39 #ifndef LLVM_ANALYSIS_IPMODREF_H
40 #define LLVM_ANALYSIS_IPMODREF_H
42 #include "llvm/Pass.h"
43 #include "Support/BitSetVector.h"
51 class ModRefInfo; // Result of IP Mod/Ref for one entity
52 class FunctionModRefInfo; // ModRefInfo for a func and all calls in it
53 class IPModRef; // Pass that computes IP Mod/Ref info
55 //---------------------------------------------------------------------------
59 // Representation of Mod/Ref information for a single function or callsite.
60 // This is represented as a pair of bit vectors, one each for Mod and Ref.
61 // Each bit vector is indexed by the node id of the DS graph node index.
62 //---------------------------------------------------------------------------
65 BitSetVector modNodeSet; // set of modified nodes
66 BitSetVector refNodeSet; // set of referenced nodes
70 // Methods to construct ModRefInfo objects.
72 ModRefInfo(unsigned int numNodes)
73 : modNodeSet(numNodes),
74 refNodeSet(numNodes) { }
76 unsigned getSize() const {
77 assert(modNodeSet.size() == refNodeSet.size() &&
78 "Mod & Ref different size?");
79 return modNodeSet.size();
82 void setNodeIsMod (unsigned nodeId) { modNodeSet[nodeId] = true; }
83 void setNodeIsRef (unsigned nodeId) { refNodeSet[nodeId] = true; }
86 // Methods to query the mod/ref info
88 bool nodeIsMod (unsigned nodeId) const { return modNodeSet.test(nodeId); }
89 bool nodeIsRef (unsigned nodeId) const { return refNodeSet.test(nodeId); }
90 bool nodeIsKill(unsigned nodeId) const { return false; }
92 const BitSetVector& getModSet() const { return modNodeSet; }
93 BitSetVector& getModSet() { return modNodeSet; }
95 const BitSetVector& getRefSet() const { return refNodeSet; }
96 BitSetVector& getRefSet() { return refNodeSet; }
98 // Debugging support methods
99 void print(std::ostream &O) const;
104 //----------------------------------------------------------------------------
105 // class FunctionModRefInfo
107 // Representation of the results of IP Mod/Ref analysis for a function
108 // and for each of the call sites within the function.
109 // Each of these are represented as bit vectors of size = the number of
110 // nodes in the top-dwon DS graph of the function. Nodes are identified by
111 // their nodeId, in the range [0 .. funcTDGraph.size()-1].
112 //----------------------------------------------------------------------------
114 class FunctionModRefInfo {
115 const Function& F; // The function
116 IPModRef& IPModRefObj; // The IPModRef Object owning this
117 const DSGraph& funcTDGraph; // Top-down DS graph for function
118 const DSGraph& funcLocalGraph; // Local DS graph for function
119 ModRefInfo funcModRefInfo; // ModRefInfo for the function body
120 std::map<const CallInst*, ModRefInfo*>
121 callSiteModRefInfo; // ModRefInfo for each callsite
122 std::map<const DSNode*, unsigned> NodeIds;
124 friend class IPModRef;
126 void computeModRef (const Function &func);
127 void computeModRef (const CallInst& callInst);
128 DSGraph *ResolveCallSiteModRefInfo(CallInst &CI,
129 std::map<const DSNode*, DSNodeHandle> &NodeMap);
132 /* ctor */ FunctionModRefInfo (const Function& func,
133 IPModRef& IPModRefObj,
136 /* dtor */ ~FunctionModRefInfo ();
138 // Identify the function and its relevant DS graph
140 const Function& getFunction() const { return F; }
141 const DSGraph& getFuncGraph() const { return funcTDGraph; }
143 // Retrieve Mod/Ref results for a single call site and for the function body
145 const ModRefInfo* getModRefInfo (const Function& func) const {
146 return &funcModRefInfo;
148 const ModRefInfo* getModRefInfo (const CallInst& callInst) const {
149 std::map<const CallInst*, ModRefInfo*>::const_iterator I =
150 callSiteModRefInfo.find(&callInst);
151 return (I == callSiteModRefInfo.end())? NULL : I->second;
154 // Get the nodeIds used to index all Mod/Ref information for current function
156 unsigned getNodeId (const DSNode* node) const {
157 std::map<const DSNode*, unsigned>::const_iterator iter = NodeIds.find(node);
158 assert(iter == NodeIds.end() || iter->second < funcModRefInfo.getSize());
159 return (iter == NodeIds.end())? funcModRefInfo.getSize() : iter->second;
162 unsigned getNodeId (const Value* value) const;
164 // Debugging support methods
165 void print(std::ostream &O) const;
170 //----------------------------------------------------------------------------
174 // An interprocedural pass that computes IP Mod/Ref info for functions and
175 // for individual call sites.
177 // Given the DSGraph of a function, this class can be queried for
178 // a ModRefInfo object describing all the nodes in the DSGraph that are
179 // (a) modified, and (b) referenced during an execution of the function
180 // from an arbitrary callsite, or during an execution of a single call-site
181 // within the function.
182 //----------------------------------------------------------------------------
184 class IPModRef : public Pass {
185 std::map<const Function*, FunctionModRefInfo*> funcToModRefInfoMap;
188 FunctionModRefInfo& getFuncInfo(const Function& func,
189 bool computeIfMissing = false);
191 IPModRef() : M(NULL) { }
194 // Driver function to run IP Mod/Ref on a Module.
195 // This initializes the module reference, and then computes IPModRef
196 // results immediately if demand-driven analysis was *not* specified.
198 virtual bool run(Module &M);
200 // Retrieve the Mod/Ref information for a single function
202 const FunctionModRefInfo& getFunctionModRefInfo(const Function& func) {
203 return getFuncInfo(func);
206 /// getBUDSGraph - This method returns the BU data structure graph for F
207 /// through the use of the BUDataStructures object.
209 const DSGraph &getBUDSGraph(const Function &F);
211 // Debugging support methods
213 void print(std::ostream &O) const;
216 // Release memory held by this pass when the pass pipeline is done
218 virtual void releaseMemory();
220 // getAnalysisUsage - This pass requires top-down data structure graphs.
221 // It modifies nothing.
223 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
226 //===----------------------------------------------------------------------===//