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;
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);
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 /// 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;
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;
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;
80 ClonedCodeInfo() = default;
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).
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
98 /// The correlation between instructions in the source and result basic blocks
99 /// is recorded in the VMap map.
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.
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.
107 /// If you would like to collect additional information about the cloned
108 /// function, you can specify a ClonedCodeInfo object with the optional fifth
110 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
111 const Twine &NameSuffix = "", Function *F = nullptr,
112 ClonedCodeInfo *CodeInfo = nullptr,
113 DebugInfoFinder *DIFinder = nullptr);
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
124 /// VMap contains no non-identity GlobalValue mappings and debug info metadata
125 /// will not be cloned.
127 Function *CloneFunction(Function *F, ValueToValueMapTy &VMap,
128 ClonedCodeInfo *CodeInfo = nullptr);
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.
136 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
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);
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);
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.
162 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
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);
172 /// This class captures the data input to the InlineFunction call, and records
173 /// the auxiliary results produced by it.
174 class InlineFunctionInfo {
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) {}
185 /// If non-null, InlineFunction will update the callgraph to reflect the
186 /// changes it makes.
188 std::function<AssumptionCache &(Function &)> *GetAssumptionCache;
189 ProfileSummaryInfo *PSI;
190 BlockFrequencyInfo *CallerBFI, *CalleeBFI;
192 /// InlineFunction fills this in with all static allocas that get copied into
194 SmallVector<AllocaInst *, 4> StaticAllocas;
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;
200 /// All of the new call sites inlined into the caller.
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;
208 StaticAllocas.clear();
209 InlinedCalls.clear();
210 InlinedCallSites.clear();
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
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.
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.
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);
244 /// Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
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 *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
251 Loop *OrigLoop, ValueToValueMapTy &VMap,
252 const Twine &NameSuffix, LoopInfo *LI,
254 SmallVectorImpl<BasicBlock *> &Blocks);
256 /// Remaps instructions in \p Blocks using the mapping in \p VMap.
257 void remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock *> &Blocks,
258 ValueToValueMapTy &VMap);
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,
269 ValueToValueMapTy &ValueMapping,
270 DomTreeUpdater &DTU);
272 } // end namespace llvm
274 #endif // LLVM_TRANSFORMS_UTILS_CLONING_H