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 
26 namespace llvm {
27 
28 class Module;
29 class Function;
30 class Instruction;
31 class Pass;
32 class LPPassManager;
33 class BasicBlock;
34 class Value;
35 class CallInst;
36 class InvokeInst;
37 class ReturnInst;
38 class CallSite;
39 class Trace;
40 class CallGraph;
41 class TargetData;
42 class Loop;
43 class LoopInfo;
44 class AllocaInst;
45 
46 /// CloneModule - Return an exact copy of the specified module
47 ///
48 Module *CloneModule(const Module *M);
49 Module *CloneModule(const Module *M, ValueMap<const Value*, Value*> &VMap);
50 
51 /// ClonedCodeInfo - This struct can be used to capture information about code
52 /// being cloned, while it is being cloned.
53 struct ClonedCodeInfo {
54   /// ContainsCalls - This is set to true if the cloned code contains a normal
55   /// call instruction.
56   bool ContainsCalls;
57 
58   /// ContainsUnwinds - This is set to true if the cloned code contains an
59   /// unwind instruction.
60   bool ContainsUnwinds;
61 
62   /// ContainsDynamicAllocas - This is set to true if the cloned code contains
63   /// a 'dynamic' alloca.  Dynamic allocas are allocas that are either not in
64   /// the entry block or they are in the entry block but are not a constant
65   /// size.
66   bool ContainsDynamicAllocas;
67 
ClonedCodeInfoClonedCodeInfo68   ClonedCodeInfo() {
69     ContainsCalls = false;
70     ContainsUnwinds = false;
71     ContainsDynamicAllocas = false;
72   }
73 };
74 
75 
76 /// CloneBasicBlock - Return a copy of the specified basic block, but without
77 /// embedding the block into a particular function.  The block returned is an
78 /// exact copy of the specified basic block, without any remapping having been
79 /// performed.  Because of this, this is only suitable for applications where
80 /// the basic block will be inserted into the same function that it was cloned
81 /// from (loop unrolling would use this, for example).
82 ///
83 /// Also, note that this function makes a direct copy of the basic block, and
84 /// can thus produce illegal LLVM code.  In particular, it will copy any PHI
85 /// nodes from the original block, even though there are no predecessors for the
86 /// newly cloned block (thus, phi nodes will have to be updated).  Also, this
87 /// block will branch to the old successors of the original block: these
88 /// successors will have to have any PHI nodes updated to account for the new
89 /// incoming edges.
90 ///
91 /// The correlation between instructions in the source and result basic blocks
92 /// is recorded in the VMap map.
93 ///
94 /// If you have a particular suffix you'd like to use to add to any cloned
95 /// names, specify it as the optional third parameter.
96 ///
97 /// If you would like the basic block to be auto-inserted into the end of a
98 /// function, you can specify it as the optional fourth parameter.
99 ///
100 /// If you would like to collect additional information about the cloned
101 /// function, you can specify a ClonedCodeInfo object with the optional fifth
102 /// parameter.
103 ///
104 BasicBlock *CloneBasicBlock(const BasicBlock *BB,
105                             ValueMap<const Value*, Value*> &VMap,
106                             const Twine &NameSuffix = "", Function *F = 0,
107                             ClonedCodeInfo *CodeInfo = 0);
108 
109 
110 /// CloneLoop - Clone Loop. Clone dominator info for loop insiders. Populate
111 /// VMap using old blocks to new blocks mapping.
112 Loop *CloneLoop(Loop *L, LPPassManager *LPM, LoopInfo *LI,
113                 ValueMap<const Value *, Value *> &VMap, Pass *P);
114 
115 /// CloneFunction - Return a copy of the specified function, but without
116 /// embedding the function into another module.  Also, any references specified
117 /// in the VMap are changed to refer to their mapped value instead of the
118 /// original one.  If any of the arguments to the function are in the VMap,
119 /// the arguments are deleted from the resultant function.  The VMap is
120 /// updated to include mappings from all of the instructions and basicblocks in
121 /// the function from their old to new values.  The final argument captures
122 /// information about the cloned code if non-null.
123 ///
124 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
125 /// mappings.
126 ///
127 Function *CloneFunction(const Function *F,
128                         ValueMap<const Value*, Value*> &VMap,
129                         bool ModuleLevelChanges,
130                         ClonedCodeInfo *CodeInfo = 0);
131 
132 /// CloneFunction - Version of the function that doesn't need the VMap.
133 ///
134 inline Function *CloneFunction(const Function *F, ClonedCodeInfo *CodeInfo = 0){
135   ValueMap<const Value*, Value*> VMap;
136   return CloneFunction(F, VMap, CodeInfo);
137 }
138 
139 /// Clone OldFunc into NewFunc, transforming the old arguments into references
140 /// to VMap values.  Note that if NewFunc already has basic blocks, the ones
141 /// cloned into it will be added to the end of the function.  This function
142 /// fills in a list of return instructions, and can optionally append the
143 /// specified suffix to all values cloned.
144 ///
145 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
146 /// mappings.
147 ///
148 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
149                        ValueMap<const Value*, Value*> &VMap,
150                        bool ModuleLevelChanges,
151                        SmallVectorImpl<ReturnInst*> &Returns,
152                        const char *NameSuffix = "",
153                        ClonedCodeInfo *CodeInfo = 0);
154 
155 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
156 /// except that it does some simple constant prop and DCE on the fly.  The
157 /// effect of this is to copy significantly less code in cases where (for
158 /// example) a function call with constant arguments is inlined, and those
159 /// constant arguments cause a significant amount of code in the callee to be
160 /// dead.  Since this doesn't produce an exactly copy of the input, it can't be
161 /// used for things like CloneFunction or CloneModule.
162 ///
163 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
164 /// mappings.
165 ///
166 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
167                                ValueMap<const Value*, Value*> &VMap,
168                                bool ModuleLevelChanges,
169                                SmallVectorImpl<ReturnInst*> &Returns,
170                                const char *NameSuffix = "",
171                                ClonedCodeInfo *CodeInfo = 0,
172                                const TargetData *TD = 0,
173                                Instruction *TheCall = 0);
174 
175 
176 /// InlineFunctionInfo - This class captures the data input to the
177 /// InlineFunction call, and records the auxiliary results produced by it.
178 class InlineFunctionInfo {
179 public:
180   explicit InlineFunctionInfo(CallGraph *cg = 0, const TargetData *td = 0)
CG(cg)181     : CG(cg), TD(td) {}
182 
183   /// CG - If non-null, InlineFunction will update the callgraph to reflect the
184   /// changes it makes.
185   CallGraph *CG;
186   const TargetData *TD;
187 
188   /// StaticAllocas - InlineFunction fills this in with all static allocas that
189   /// get copied into the caller.
190   SmallVector<AllocaInst*, 4> StaticAllocas;
191 
192   /// InlinedCalls - InlineFunction fills this in with callsites that were
193   /// inlined from the callee.  This is only filled in if CG is non-null.
194   SmallVector<WeakVH, 8> InlinedCalls;
195 
reset()196   void reset() {
197     StaticAllocas.clear();
198     InlinedCalls.clear();
199   }
200 };
201 
202 /// InlineFunction - This function inlines the called function into the basic
203 /// block of the caller.  This returns false if it is not possible to inline
204 /// this call.  The program is still in a well defined state if this occurs
205 /// though.
206 ///
207 /// Note that this only does one level of inlining.  For example, if the
208 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
209 /// exists in the instruction stream.  Similiarly this will inline a recursive
210 /// function by one level.
211 ///
212 bool InlineFunction(CallInst *C, InlineFunctionInfo &IFI);
213 bool InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI);
214 bool InlineFunction(CallSite CS, InlineFunctionInfo &IFI);
215 
216 } // End llvm namespace
217 
218 #endif
219