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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/SmallVector.h"
22 #include "llvm/ADT/Twine.h"
23 #include "llvm/IR/ValueHandle.h"
24 #include "llvm/IR/ValueMap.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 DataLayout;
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   /// ContainsDynamicAllocas - This is set to true if the cloned code contains
60   /// a 'dynamic' alloca.  Dynamic allocas are allocas that are either not in
61   /// the entry block or they are in the entry block but are not a constant
62   /// size.
63   bool ContainsDynamicAllocas;
64 
ClonedCodeInfoClonedCodeInfo65   ClonedCodeInfo() : ContainsCalls(false), ContainsDynamicAllocas(false) {}
66 };
67 
68 /// CloneBasicBlock - Return a copy of the specified basic block, but without
69 /// embedding the block into a particular function.  The block returned is an
70 /// exact copy of the specified basic block, without any remapping having been
71 /// performed.  Because of this, this is only suitable for applications where
72 /// the basic block will be inserted into the same function that it was cloned
73 /// from (loop unrolling would use this, for example).
74 ///
75 /// Also, note that this function makes a direct copy of the basic block, and
76 /// can thus produce illegal LLVM code.  In particular, it will copy any PHI
77 /// nodes from the original block, even though there are no predecessors for the
78 /// newly cloned block (thus, phi nodes will have to be updated).  Also, this
79 /// block will branch to the old successors of the original block: these
80 /// successors will have to have any PHI nodes updated to account for the new
81 /// incoming edges.
82 ///
83 /// The correlation between instructions in the source and result basic blocks
84 /// is recorded in the VMap map.
85 ///
86 /// If you have a particular suffix you'd like to use to add to any cloned
87 /// names, specify it as the optional third parameter.
88 ///
89 /// If you would like the basic block to be auto-inserted into the end of a
90 /// function, you can specify it as the optional fourth parameter.
91 ///
92 /// If you would like to collect additional information about the cloned
93 /// function, you can specify a ClonedCodeInfo object with the optional fifth
94 /// parameter.
95 ///
96 BasicBlock *CloneBasicBlock(const BasicBlock *BB,
97                             ValueToValueMapTy &VMap,
98                             const Twine &NameSuffix = "", Function *F = nullptr,
99                             ClonedCodeInfo *CodeInfo = nullptr);
100 
101 /// CloneFunction - Return a copy of the specified function, but without
102 /// embedding the function into another module.  Also, any references specified
103 /// in the VMap are changed to refer to their mapped value instead of the
104 /// original one.  If any of the arguments to the function are in the VMap,
105 /// the arguments are deleted from the resultant function.  The VMap is
106 /// updated to include mappings from all of the instructions and basicblocks in
107 /// the function from their old to new values.  The final argument captures
108 /// information about the cloned code if non-null.
109 ///
110 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
111 /// mappings, and debug info metadata will not be cloned.
112 ///
113 Function *CloneFunction(const Function *F,
114                         ValueToValueMapTy &VMap,
115                         bool ModuleLevelChanges,
116                         ClonedCodeInfo *CodeInfo = nullptr);
117 
118 /// Clone OldFunc into NewFunc, transforming the old arguments into references
119 /// to VMap values.  Note that if NewFunc already has basic blocks, the ones
120 /// cloned into it will be added to the end of the function.  This function
121 /// fills in a list of return instructions, and can optionally remap types
122 /// and/or append the specified suffix to all values cloned.
123 ///
124 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
125 /// mappings.
126 ///
127 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
128                        ValueToValueMapTy &VMap,
129                        bool ModuleLevelChanges,
130                        SmallVectorImpl<ReturnInst*> &Returns,
131                        const char *NameSuffix = "",
132                        ClonedCodeInfo *CodeInfo = nullptr,
133                        ValueMapTypeRemapper *TypeMapper = nullptr,
134                        ValueMaterializer *Materializer = nullptr);
135 
136 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
137 /// except that it does some simple constant prop and DCE on the fly.  The
138 /// effect of this is to copy significantly less code in cases where (for
139 /// example) a function call with constant arguments is inlined, and those
140 /// constant arguments cause a significant amount of code in the callee to be
141 /// dead.  Since this doesn't produce an exactly copy of the input, it can't be
142 /// used for things like CloneFunction or CloneModule.
143 ///
144 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
145 /// mappings.
146 ///
147 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
148                                ValueToValueMapTy &VMap,
149                                bool ModuleLevelChanges,
150                                SmallVectorImpl<ReturnInst*> &Returns,
151                                const char *NameSuffix = "",
152                                ClonedCodeInfo *CodeInfo = nullptr,
153                                const DataLayout *DL = nullptr,
154                                Instruction *TheCall = nullptr);
155 
156 /// InlineFunctionInfo - This class captures the data input to the
157 /// InlineFunction call, and records the auxiliary results produced by it.
158 class InlineFunctionInfo {
159 public:
160   explicit InlineFunctionInfo(CallGraph *cg = nullptr, const DataLayout *DL = nullptr)
CG(cg)161     : CG(cg), DL(DL) {}
162 
163   /// CG - If non-null, InlineFunction will update the callgraph to reflect the
164   /// changes it makes.
165   CallGraph *CG;
166   const DataLayout *DL;
167 
168   /// StaticAllocas - InlineFunction fills this in with all static allocas that
169   /// get copied into the caller.
170   SmallVector<AllocaInst*, 4> StaticAllocas;
171 
172   /// InlinedCalls - InlineFunction fills this in with callsites that were
173   /// inlined from the callee.  This is only filled in if CG is non-null.
174   SmallVector<WeakVH, 8> InlinedCalls;
175 
reset()176   void reset() {
177     StaticAllocas.clear();
178     InlinedCalls.clear();
179   }
180 };
181 
182 /// InlineFunction - This function inlines the called function into the basic
183 /// block of the caller.  This returns false if it is not possible to inline
184 /// this call.  The program is still in a well defined state if this occurs
185 /// though.
186 ///
187 /// Note that this only does one level of inlining.  For example, if the
188 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
189 /// exists in the instruction stream.  Similarly this will inline a recursive
190 /// function by one level.
191 ///
192 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI, bool InsertLifetime = true);
193 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, bool InsertLifetime = true);
194 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI, bool InsertLifetime = true);
195 
196 } // End llvm namespace
197 
198 #endif
199