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/Analysis/AliasAnalysis.h" |
24 | #include "llvm/Analysis/AssumptionCache.h" |
25 | #include "llvm/Analysis/InlineCost.h" |
26 | #include "llvm/IR/CallSite.h" |
27 | #include "llvm/IR/ValueHandle.h" |
28 | #include "llvm/Transforms/Utils/ValueMapper.h" |
29 | #include <functional> |
30 | #include <memory> |
31 | #include <vector> |
32 | |
33 | namespace llvm { |
34 | |
35 | class AllocaInst; |
36 | class BasicBlock; |
37 | class BlockFrequencyInfo; |
38 | class CallInst; |
39 | class CallGraph; |
40 | class DebugInfoFinder; |
41 | class DominatorTree; |
42 | class Function; |
43 | class Instruction; |
44 | class InvokeInst; |
45 | class Loop; |
46 | class LoopInfo; |
47 | class Module; |
48 | class ProfileSummaryInfo; |
49 | class ReturnInst; |
50 | class DomTreeUpdater; |
51 | |
52 | /// Return an exact copy of the specified module |
53 | std::unique_ptr<Module> CloneModule(const Module &M); |
54 | std::unique_ptr<Module> CloneModule(const Module &M, ValueToValueMapTy &VMap); |
55 | |
56 | /// Return a copy of the specified module. The ShouldCloneDefinition function |
57 | /// controls whether a specific GlobalValue's definition is cloned. If the |
58 | /// function returns false, the module copy will contain an external reference |
59 | /// in place of the global definition. |
60 | std::unique_ptr<Module> |
61 | CloneModule(const Module &M, ValueToValueMapTy &VMap, |
62 | function_ref<bool(const GlobalValue *)> ShouldCloneDefinition); |
63 | |
64 | /// This struct can be used to capture information about code |
65 | /// being cloned, while it is being cloned. |
66 | struct ClonedCodeInfo { |
67 | /// This is set to true if the cloned code contains a normal call instruction. |
68 | bool ContainsCalls = false; |
69 | |
70 | /// This is set to true if the cloned code contains a 'dynamic' alloca. |
71 | /// Dynamic allocas are allocas that are either not in the entry block or they |
72 | /// are in the entry block but are not a constant size. |
73 | bool ContainsDynamicAllocas = false; |
74 | |
75 | /// All cloned call sites that have operand bundles attached are appended to |
76 | /// this vector. This vector may contain nulls or undefs if some of the |
77 | /// originally inserted callsites were DCE'ed after they were cloned. |
78 | std::vector<WeakTrackingVH> OperandBundleCallSites; |
79 | |
80 | ClonedCodeInfo() = default; |
81 | }; |
82 | |
83 | /// Return a copy of the specified basic block, but without |
84 | /// embedding the block into a particular function. The block returned is an |
85 | /// exact copy of the specified basic block, without any remapping having been |
86 | /// performed. Because of this, this is only suitable for applications where |
87 | /// the basic block will be inserted into the same function that it was cloned |
88 | /// from (loop unrolling would use this, for example). |
89 | /// |
90 | /// Also, note that this function makes a direct copy of the basic block, and |
91 | /// can thus produce illegal LLVM code. In particular, it will copy any PHI |
92 | /// nodes from the original block, even though there are no predecessors for the |
93 | /// newly cloned block (thus, phi nodes will have to be updated). Also, this |
94 | /// block will branch to the old successors of the original block: these |
95 | /// successors will have to have any PHI nodes updated to account for the new |
96 | /// incoming edges. |
97 | /// |
98 | /// The correlation between instructions in the source and result basic blocks |
99 | /// is recorded in the VMap map. |
100 | /// |
101 | /// If you have a particular suffix you'd like to use to add to any cloned |
102 | /// names, specify it as the optional third parameter. |
103 | /// |
104 | /// If you would like the basic block to be auto-inserted into the end of a |
105 | /// function, you can specify it as the optional fourth parameter. |
106 | /// |
107 | /// If you would like to collect additional information about the cloned |
108 | /// function, you can specify a ClonedCodeInfo object with the optional fifth |
109 | /// parameter. |
110 | BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, |
111 | const Twine &NameSuffix = "" , Function *F = nullptr, |
112 | ClonedCodeInfo *CodeInfo = nullptr, |
113 | DebugInfoFinder *DIFinder = nullptr); |
114 | |
115 | /// Return a copy of the specified function and add it to that |
116 | /// function's module. Also, any references specified in the VMap are changed |
117 | /// to refer to their mapped value instead of the original one. If any of the |
118 | /// arguments to the function are in the VMap, the arguments are deleted from |
119 | /// the resultant function. The VMap is updated to include mappings from all of |
120 | /// the instructions and basicblocks in the function from their old to new |
121 | /// values. The final argument captures information about the cloned code if |
122 | /// non-null. |
123 | /// |
124 | /// VMap contains no non-identity GlobalValue mappings and debug info metadata |
125 | /// will not be cloned. |
126 | /// |
127 | Function *CloneFunction(Function *F, ValueToValueMapTy &VMap, |
128 | ClonedCodeInfo *CodeInfo = nullptr); |
129 | |
130 | /// Clone OldFunc into NewFunc, transforming the old arguments into references |
131 | /// to VMap values. Note that if NewFunc already has basic blocks, the ones |
132 | /// cloned into it will be added to the end of the function. This function |
133 | /// fills in a list of return instructions, and can optionally remap types |
134 | /// and/or append the specified suffix to all values cloned. |
135 | /// |
136 | /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue |
137 | /// mappings. |
138 | /// |
139 | void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, |
140 | ValueToValueMapTy &VMap, bool ModuleLevelChanges, |
141 | SmallVectorImpl<ReturnInst*> &Returns, |
142 | const char *NameSuffix = "" , |
143 | ClonedCodeInfo *CodeInfo = nullptr, |
144 | ValueMapTypeRemapper *TypeMapper = nullptr, |
145 | ValueMaterializer *Materializer = nullptr); |
146 | |
147 | void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, |
148 | const Instruction *StartingInst, |
149 | ValueToValueMapTy &VMap, bool ModuleLevelChanges, |
150 | SmallVectorImpl<ReturnInst *> &Returns, |
151 | const char *NameSuffix = "" , |
152 | ClonedCodeInfo *CodeInfo = nullptr); |
153 | |
154 | /// This works exactly like CloneFunctionInto, |
155 | /// except that it does some simple constant prop and DCE on the fly. The |
156 | /// effect of this is to copy significantly less code in cases where (for |
157 | /// example) a function call with constant arguments is inlined, and those |
158 | /// constant arguments cause a significant amount of code in the callee to be |
159 | /// dead. Since this doesn't produce an exactly copy of the input, it can't be |
160 | /// used for things like CloneFunction or CloneModule. |
161 | /// |
162 | /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue |
163 | /// mappings. |
164 | /// |
165 | void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, |
166 | ValueToValueMapTy &VMap, bool ModuleLevelChanges, |
167 | SmallVectorImpl<ReturnInst*> &Returns, |
168 | const char *NameSuffix = "" , |
169 | ClonedCodeInfo *CodeInfo = nullptr, |
170 | Instruction *TheCall = nullptr); |
171 | |
172 | /// This class captures the data input to the InlineFunction call, and records |
173 | /// the auxiliary results produced by it. |
174 | class InlineFunctionInfo { |
175 | public: |
176 | explicit InlineFunctionInfo(CallGraph *cg = nullptr, |
177 | std::function<AssumptionCache &(Function &)> |
178 | *GetAssumptionCache = nullptr, |
179 | ProfileSummaryInfo *PSI = nullptr, |
180 | BlockFrequencyInfo *CallerBFI = nullptr, |
181 | BlockFrequencyInfo *CalleeBFI = nullptr) |
182 | : CG(cg), GetAssumptionCache(GetAssumptionCache), PSI(PSI), |
183 | CallerBFI(CallerBFI), CalleeBFI(CalleeBFI) {} |
184 | |
185 | /// If non-null, InlineFunction will update the callgraph to reflect the |
186 | /// changes it makes. |
187 | CallGraph *CG; |
188 | std::function<AssumptionCache &(Function &)> *GetAssumptionCache; |
189 | ProfileSummaryInfo *PSI; |
190 | BlockFrequencyInfo *CallerBFI, *CalleeBFI; |
191 | |
192 | /// InlineFunction fills this in with all static allocas that get copied into |
193 | /// the caller. |
194 | SmallVector<AllocaInst *, 4> StaticAllocas; |
195 | |
196 | /// InlineFunction fills this in with callsites that were inlined from the |
197 | /// callee. This is only filled in if CG is non-null. |
198 | SmallVector<WeakTrackingVH, 8> InlinedCalls; |
199 | |
200 | /// All of the new call sites inlined into the caller. |
201 | /// |
202 | /// 'InlineFunction' fills this in by scanning the inlined instructions, and |
203 | /// only if CG is null. If CG is non-null, instead the value handle |
204 | /// `InlinedCalls` above is used. |
205 | SmallVector<CallSite, 8> InlinedCallSites; |
206 | |
207 | void reset() { |
208 | StaticAllocas.clear(); |
209 | InlinedCalls.clear(); |
210 | InlinedCallSites.clear(); |
211 | } |
212 | }; |
213 | |
214 | /// This function inlines the called function into the basic |
215 | /// block of the caller. This returns false if it is not possible to inline |
216 | /// this call. The program is still in a well defined state if this occurs |
217 | /// though. |
218 | /// |
219 | /// Note that this only does one level of inlining. For example, if the |
220 | /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now |
221 | /// exists in the instruction stream. Similarly this will inline a recursive |
222 | /// function by one level. |
223 | /// |
224 | /// Note that while this routine is allowed to cleanup and optimize the |
225 | /// *inlined* code to minimize the actual inserted code, it must not delete |
226 | /// code in the caller as users of this routine may have pointers to |
227 | /// instructions in the caller that need to remain stable. |
228 | /// |
229 | /// If ForwardVarArgsTo is passed, inlining a function with varargs is allowed |
230 | /// and all varargs at the callsite will be passed to any calls to |
231 | /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs |
232 | /// are only used by ForwardVarArgsTo. |
233 | InlineResult InlineFunction(CallInst *C, InlineFunctionInfo &IFI, |
234 | AAResults *CalleeAAR = nullptr, |
235 | bool InsertLifetime = true); |
236 | InlineResult InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI, |
237 | AAResults *CalleeAAR = nullptr, |
238 | bool InsertLifetime = true); |
239 | InlineResult InlineFunction(CallSite CS, InlineFunctionInfo &IFI, |
240 | AAResults *CalleeAAR = nullptr, |
241 | bool InsertLifetime = true, |
242 | Function *ForwardVarArgsTo = nullptr); |
243 | |
244 | /// Clones a loop \p OrigLoop. Returns the loop and the blocks in \p |
245 | /// Blocks. |
246 | /// |
247 | /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block |
248 | /// \p LoopDomBB. Insert the new blocks before block specified in \p Before. |
249 | /// Note: Only innermost loops are supported. |
250 | Loop *(BasicBlock *Before, BasicBlock *LoopDomBB, |
251 | Loop *OrigLoop, ValueToValueMapTy &VMap, |
252 | const Twine &NameSuffix, LoopInfo *LI, |
253 | DominatorTree *DT, |
254 | SmallVectorImpl<BasicBlock *> &Blocks); |
255 | |
256 | /// Remaps instructions in \p Blocks using the mapping in \p VMap. |
257 | void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks, |
258 | ValueToValueMapTy &VMap); |
259 | |
260 | /// Split edge between BB and PredBB and duplicate all non-Phi instructions |
261 | /// from BB between its beginning and the StopAt instruction into the split |
262 | /// block. Phi nodes are not duplicated, but their uses are handled correctly: |
263 | /// we replace them with the uses of corresponding Phi inputs. ValueMapping |
264 | /// is used to map the original instructions from BB to their newly-created |
265 | /// copies. Returns the split block. |
266 | BasicBlock *DuplicateInstructionsInSplitBetween(BasicBlock *BB, |
267 | BasicBlock *PredBB, |
268 | Instruction *StopAt, |
269 | ValueToValueMapTy &ValueMapping, |
270 | DomTreeUpdater &DTU); |
271 | |
272 | } // end namespace llvm |
273 | |
274 | #endif // LLVM_TRANSFORMS_UTILS_CLONING_H |
275 | |