1 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
16 //===----------------------------------------------------------------------===//
18 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H
19 #define LLVM_TRANSFORMS_UTILS_CLONING_H
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"
37 class BlockFrequencyInfo;
40 class DebugInfoFinder;
48 class ProfileSummaryInfo;
51 /// 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);
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);
64 /// ClonedCodeInfo - This struct can be used to capture information about code
65 /// being cloned, while it is being cloned.
66 struct ClonedCodeInfo {
67 /// ContainsCalls - This is set to true if the cloned code contains a normal
69 bool ContainsCalls = false;
71 /// ContainsDynamicAllocas - This is set to true if the cloned code contains
72 /// a 'dynamic' alloca. Dynamic allocas are allocas that are either not in
73 /// the entry block or they are in the entry block but are not a constant
75 bool ContainsDynamicAllocas = false;
77 /// All cloned call sites that have operand bundles attached are appended to
78 /// this vector. This vector may contain nulls or undefs if some of the
79 /// originally inserted callsites were DCE'ed after they were cloned.
80 std::vector<WeakTrackingVH> OperandBundleCallSites;
82 ClonedCodeInfo() = default;
85 /// CloneBasicBlock - Return a copy of the specified basic block, but without
86 /// embedding the block into a particular function. The block returned is an
87 /// exact copy of the specified basic block, without any remapping having been
88 /// performed. Because of this, this is only suitable for applications where
89 /// the basic block will be inserted into the same function that it was cloned
90 /// from (loop unrolling would use this, for example).
92 /// Also, note that this function makes a direct copy of the basic block, and
93 /// can thus produce illegal LLVM code. In particular, it will copy any PHI
94 /// nodes from the original block, even though there are no predecessors for the
95 /// newly cloned block (thus, phi nodes will have to be updated). Also, this
96 /// block will branch to the old successors of the original block: these
97 /// successors will have to have any PHI nodes updated to account for the new
100 /// The correlation between instructions in the source and result basic blocks
101 /// is recorded in the VMap map.
103 /// If you have a particular suffix you'd like to use to add to any cloned
104 /// names, specify it as the optional third parameter.
106 /// If you would like the basic block to be auto-inserted into the end of a
107 /// function, you can specify it as the optional fourth parameter.
109 /// If you would like to collect additional information about the cloned
110 /// function, you can specify a ClonedCodeInfo object with the optional fifth
113 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
114 const Twine &NameSuffix = "", Function *F = nullptr,
115 ClonedCodeInfo *CodeInfo = nullptr,
116 DebugInfoFinder *DIFinder = nullptr);
118 /// CloneFunction - Return a copy of the specified function and add it to that
119 /// function's module. Also, any references specified in the VMap are changed
120 /// to refer to their mapped value instead of the original one. If any of the
121 /// arguments to the function are in the VMap, the arguments are deleted from
122 /// the resultant function. The VMap is updated to include mappings from all of
123 /// the instructions and basicblocks in the function from their old to new
124 /// values. The final argument captures information about the cloned code if
127 /// VMap contains no non-identity GlobalValue mappings and debug info metadata
128 /// will not be cloned.
130 Function *CloneFunction(Function *F, ValueToValueMapTy &VMap,
131 ClonedCodeInfo *CodeInfo = nullptr);
133 /// Clone OldFunc into NewFunc, transforming the old arguments into references
134 /// to VMap values. Note that if NewFunc already has basic blocks, the ones
135 /// cloned into it will be added to the end of the function. This function
136 /// fills in a list of return instructions, and can optionally remap types
137 /// and/or append the specified suffix to all values cloned.
139 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
142 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
143 ValueToValueMapTy &VMap, bool ModuleLevelChanges,
144 SmallVectorImpl<ReturnInst*> &Returns,
145 const char *NameSuffix = "",
146 ClonedCodeInfo *CodeInfo = nullptr,
147 ValueMapTypeRemapper *TypeMapper = nullptr,
148 ValueMaterializer *Materializer = nullptr);
150 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
151 const Instruction *StartingInst,
152 ValueToValueMapTy &VMap, bool ModuleLevelChanges,
153 SmallVectorImpl<ReturnInst *> &Returns,
154 const char *NameSuffix = "",
155 ClonedCodeInfo *CodeInfo = nullptr);
157 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
158 /// except that it does some simple constant prop and DCE on the fly. The
159 /// effect of this is to copy significantly less code in cases where (for
160 /// example) a function call with constant arguments is inlined, and those
161 /// constant arguments cause a significant amount of code in the callee to be
162 /// dead. Since this doesn't produce an exactly copy of the input, it can't be
163 /// used for things like CloneFunction or CloneModule.
165 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
168 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
169 ValueToValueMapTy &VMap, bool ModuleLevelChanges,
170 SmallVectorImpl<ReturnInst*> &Returns,
171 const char *NameSuffix = "",
172 ClonedCodeInfo *CodeInfo = nullptr,
173 Instruction *TheCall = nullptr);
175 /// InlineFunctionInfo - This class captures the data input to the
176 /// InlineFunction call, and records the auxiliary results produced by it.
177 class InlineFunctionInfo {
179 explicit InlineFunctionInfo(CallGraph *cg = nullptr,
180 std::function<AssumptionCache &(Function &)>
181 *GetAssumptionCache = nullptr,
182 ProfileSummaryInfo *PSI = nullptr,
183 BlockFrequencyInfo *CallerBFI = nullptr,
184 BlockFrequencyInfo *CalleeBFI = nullptr)
185 : CG(cg), GetAssumptionCache(GetAssumptionCache), PSI(PSI),
186 CallerBFI(CallerBFI), CalleeBFI(CalleeBFI) {}
188 /// CG - If non-null, InlineFunction will update the callgraph to reflect the
189 /// changes it makes.
191 std::function<AssumptionCache &(Function &)> *GetAssumptionCache;
192 ProfileSummaryInfo *PSI;
193 BlockFrequencyInfo *CallerBFI, *CalleeBFI;
195 /// StaticAllocas - InlineFunction fills this in with all static allocas that
196 /// get copied into the caller.
197 SmallVector<AllocaInst *, 4> StaticAllocas;
199 /// InlinedCalls - InlineFunction fills this in with callsites that were
200 /// inlined from the callee. This is only filled in if CG is non-null.
201 SmallVector<WeakTrackingVH, 8> InlinedCalls;
203 /// All of the new call sites inlined into the caller.
205 /// 'InlineFunction' fills this in by scanning the inlined instructions, and
206 /// only if CG is null. If CG is non-null, instead the value handle
207 /// `InlinedCalls` above is used.
208 SmallVector<CallSite, 8> InlinedCallSites;
211 StaticAllocas.clear();
212 InlinedCalls.clear();
213 InlinedCallSites.clear();
217 /// InlineFunction - This function inlines the called function into the basic
218 /// block of the caller. This returns false if it is not possible to inline
219 /// this call. The program is still in a well defined state if this occurs
222 /// Note that this only does one level of inlining. For example, if the
223 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
224 /// exists in the instruction stream. Similarly this will inline a recursive
225 /// function by one level.
227 /// Note that while this routine is allowed to cleanup and optimize the
228 /// *inlined* code to minimize the actual inserted code, it must not delete
229 /// code in the caller as users of this routine may have pointers to
230 /// instructions in the caller that need to remain stable.
232 /// If ForwardVarArgsTo is passed, inlining a function with varargs is allowed
233 /// and all varargs at the callsite will be passed to any calls to
234 /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs
235 /// are only used by ForwardVarArgsTo.
236 InlineResult InlineFunction(CallInst *C, InlineFunctionInfo &IFI,
237 AAResults *CalleeAAR = nullptr,
238 bool InsertLifetime = true);
239 InlineResult InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
240 AAResults *CalleeAAR = nullptr,
241 bool InsertLifetime = true);
242 InlineResult InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
243 AAResults *CalleeAAR = nullptr,
244 bool InsertLifetime = true,
245 Function *ForwardVarArgsTo = nullptr);
247 /// Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
250 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
251 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
252 /// Note: Only innermost loops are supported.
253 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
254 Loop *OrigLoop, ValueToValueMapTy &VMap,
255 const Twine &NameSuffix, LoopInfo *LI,
257 SmallVectorImpl<BasicBlock *> &Blocks);
259 /// Remaps instructions in \p Blocks using the mapping in \p VMap.
260 void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks,
261 ValueToValueMapTy &VMap);
263 /// Split edge between BB and PredBB and duplicate all non-Phi instructions
264 /// from BB between its beginning and the StopAt instruction into the split
265 /// block. Phi nodes are not duplicated, but their uses are handled correctly:
266 /// we replace them with the uses of corresponding Phi inputs. ValueMapping
267 /// is used to map the original instructions from BB to their newly-created
268 /// copies. Returns the split block.
270 DuplicateInstructionsInSplitBetween(BasicBlock *BB, BasicBlock *PredBB,
272 ValueToValueMapTy &ValueMapping,
273 DominatorTree *DT = nullptr);
274 } // end namespace llvm
276 #endif // LLVM_TRANSFORMS_UTILS_CLONING_H