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1 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines various functions that are used to clone chunks of LLVM
11 // code for various purposes.  This varies from copying whole modules into new
12 // modules, to cloning functions with different arguments, to inlining
13 // functions, to copying basic blocks to support loop unrolling or superblock
14 // formation, etc.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H
19 #define LLVM_TRANSFORMS_UTILS_CLONING_H
20 
21 #include "llvm/ADT/ValueMap.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/Twine.h"
24 #include "llvm/Support/ValueHandle.h"
25 #include "llvm/Transforms/Utils/ValueMapper.h"
26 
27 namespace llvm {
28 
29 class Module;
30 class Function;
31 class Instruction;
32 class Pass;
33 class LPPassManager;
34 class BasicBlock;
35 class Value;
36 class CallInst;
37 class InvokeInst;
38 class ReturnInst;
39 class CallSite;
40 class Trace;
41 class CallGraph;
42 class TargetData;
43 class Loop;
44 class LoopInfo;
45 class AllocaInst;
46 
47 /// CloneModule - Return an exact copy of the specified module
48 ///
49 Module *CloneModule(const Module *M);
50 Module *CloneModule(const Module *M, ValueToValueMapTy &VMap);
51 
52 /// ClonedCodeInfo - This struct can be used to capture information about code
53 /// being cloned, while it is being cloned.
54 struct ClonedCodeInfo {
55   /// ContainsCalls - This is set to true if the cloned code contains a normal
56   /// call instruction.
57   bool ContainsCalls;
58 
59   /// ContainsUnwinds - This is set to true if the cloned code contains an
60   /// unwind instruction.
61   bool ContainsUnwinds;
62 
63   /// ContainsDynamicAllocas - This is set to true if the cloned code contains
64   /// a 'dynamic' alloca.  Dynamic allocas are allocas that are either not in
65   /// the entry block or they are in the entry block but are not a constant
66   /// size.
67   bool ContainsDynamicAllocas;
68 
ClonedCodeInfoClonedCodeInfo69   ClonedCodeInfo() {
70     ContainsCalls = false;
71     ContainsUnwinds = false;
72     ContainsDynamicAllocas = false;
73   }
74 };
75 
76 
77 /// CloneBasicBlock - Return a copy of the specified basic block, but without
78 /// embedding the block into a particular function.  The block returned is an
79 /// exact copy of the specified basic block, without any remapping having been
80 /// performed.  Because of this, this is only suitable for applications where
81 /// the basic block will be inserted into the same function that it was cloned
82 /// from (loop unrolling would use this, for example).
83 ///
84 /// Also, note that this function makes a direct copy of the basic block, and
85 /// can thus produce illegal LLVM code.  In particular, it will copy any PHI
86 /// nodes from the original block, even though there are no predecessors for the
87 /// newly cloned block (thus, phi nodes will have to be updated).  Also, this
88 /// block will branch to the old successors of the original block: these
89 /// successors will have to have any PHI nodes updated to account for the new
90 /// incoming edges.
91 ///
92 /// The correlation between instructions in the source and result basic blocks
93 /// is recorded in the VMap map.
94 ///
95 /// If you have a particular suffix you'd like to use to add to any cloned
96 /// names, specify it as the optional third parameter.
97 ///
98 /// If you would like the basic block to be auto-inserted into the end of a
99 /// function, you can specify it as the optional fourth parameter.
100 ///
101 /// If you would like to collect additional information about the cloned
102 /// function, you can specify a ClonedCodeInfo object with the optional fifth
103 /// parameter.
104 ///
105 BasicBlock *CloneBasicBlock(const BasicBlock *BB,
106                             ValueToValueMapTy &VMap,
107                             const Twine &NameSuffix = "", Function *F = 0,
108                             ClonedCodeInfo *CodeInfo = 0);
109 
110 /// CloneFunction - Return a copy of the specified function, but without
111 /// embedding the function into another module.  Also, any references specified
112 /// in the VMap are changed to refer to their mapped value instead of the
113 /// original one.  If any of the arguments to the function are in the VMap,
114 /// the arguments are deleted from the resultant function.  The VMap is
115 /// updated to include mappings from all of the instructions and basicblocks in
116 /// the function from their old to new values.  The final argument captures
117 /// information about the cloned code if non-null.
118 ///
119 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
120 /// mappings.
121 ///
122 Function *CloneFunction(const Function *F,
123                         ValueToValueMapTy &VMap,
124                         bool ModuleLevelChanges,
125                         ClonedCodeInfo *CodeInfo = 0);
126 
127 /// CloneFunction - Version of the function that doesn't need the VMap.
128 ///
129 inline Function *CloneFunction(const Function *F, ClonedCodeInfo *CodeInfo = 0){
130   ValueToValueMapTy VMap;
131   return CloneFunction(F, VMap, CodeInfo);
132 }
133 
134 /// Clone OldFunc into NewFunc, transforming the old arguments into references
135 /// to VMap values.  Note that if NewFunc already has basic blocks, the ones
136 /// cloned into it will be added to the end of the function.  This function
137 /// fills in a list of return instructions, and can optionally append the
138 /// specified suffix to all values cloned.
139 ///
140 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
141 /// mappings.
142 ///
143 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
144                        ValueToValueMapTy &VMap,
145                        bool ModuleLevelChanges,
146                        SmallVectorImpl<ReturnInst*> &Returns,
147                        const char *NameSuffix = "",
148                        ClonedCodeInfo *CodeInfo = 0);
149 
150 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
151 /// except that it does some simple constant prop and DCE on the fly.  The
152 /// effect of this is to copy significantly less code in cases where (for
153 /// example) a function call with constant arguments is inlined, and those
154 /// constant arguments cause a significant amount of code in the callee to be
155 /// dead.  Since this doesn't produce an exactly copy of the input, it can't be
156 /// used for things like CloneFunction or CloneModule.
157 ///
158 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
159 /// mappings.
160 ///
161 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
162                                ValueToValueMapTy &VMap,
163                                bool ModuleLevelChanges,
164                                SmallVectorImpl<ReturnInst*> &Returns,
165                                const char *NameSuffix = "",
166                                ClonedCodeInfo *CodeInfo = 0,
167                                const TargetData *TD = 0,
168                                Instruction *TheCall = 0);
169 
170 
171 /// InlineFunctionInfo - This class captures the data input to the
172 /// InlineFunction call, and records the auxiliary results produced by it.
173 class InlineFunctionInfo {
174 public:
175   explicit InlineFunctionInfo(CallGraph *cg = 0, const TargetData *td = 0)
CG(cg)176     : CG(cg), TD(td) {}
177 
178   /// CG - If non-null, InlineFunction will update the callgraph to reflect the
179   /// changes it makes.
180   CallGraph *CG;
181   const TargetData *TD;
182 
183   /// StaticAllocas - InlineFunction fills this in with all static allocas that
184   /// get copied into the caller.
185   SmallVector<AllocaInst*, 4> StaticAllocas;
186 
187   /// InlinedCalls - InlineFunction fills this in with callsites that were
188   /// inlined from the callee.  This is only filled in if CG is non-null.
189   SmallVector<WeakVH, 8> InlinedCalls;
190 
reset()191   void reset() {
192     StaticAllocas.clear();
193     InlinedCalls.clear();
194   }
195 };
196 
197 /// InlineFunction - This function inlines the called function into the basic
198 /// block of the caller.  This returns false if it is not possible to inline
199 /// this call.  The program is still in a well defined state if this occurs
200 /// though.
201 ///
202 /// Note that this only does one level of inlining.  For example, if the
203 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
204 /// exists in the instruction stream.  Similarly this will inline a recursive
205 /// function by one level.
206 ///
207 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI);
208 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI);
209 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI);
210 
211 } // End llvm namespace
212 
213 #endif
214