LLVM  10.0.0svn
Cloning.h
Go to the documentation of this file.
1 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines various functions that are used to clone chunks of LLVM
10 // code for various purposes. This varies from copying whole modules into new
11 // modules, to cloning functions with different arguments, to inlining
12 // functions, to copying basic blocks to support loop unrolling or superblock
13 // formation, etc.
14 //
15 //===----------------------------------------------------------------------===//
16
17 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H
18 #define LLVM_TRANSFORMS_UTILS_CLONING_H
19
25 #include "llvm/IR/CallSite.h"
26 #include "llvm/IR/ValueHandle.h"
28 #include <functional>
29 #include <memory>
30 #include <vector>
31
32 namespace llvm {
33
34 class AllocaInst;
35 class BasicBlock;
36 class BlockFrequencyInfo;
37 class CallInst;
38 class CallGraph;
39 class DebugInfoFinder;
40 class DominatorTree;
41 class Function;
42 class Instruction;
43 class InvokeInst;
44 class Loop;
45 class LoopInfo;
46 class Module;
47 class ProfileSummaryInfo;
48 class ReturnInst;
49 class DomTreeUpdater;
50
51 /// Return an exact copy of the specified module
52 std::unique_ptr<Module> CloneModule(const Module &M);
53 std::unique_ptr<Module> CloneModule(const Module &M, ValueToValueMapTy &VMap);
54
55 /// Return a copy of the specified module. The ShouldCloneDefinition function
56 /// controls whether a specific GlobalValue's definition is cloned. If the
57 /// function returns false, the module copy will contain an external reference
58 /// in place of the global definition.
59 std::unique_ptr<Module>
60 CloneModule(const Module &M, ValueToValueMapTy &VMap,
61  function_ref<bool(const GlobalValue *)> ShouldCloneDefinition);
62
63 /// This struct can be used to capture information about code
64 /// being cloned, while it is being cloned.
66  /// This is set to true if the cloned code contains a normal call instruction.
67  bool ContainsCalls = false;
68
69  /// This is set to true if the cloned code contains a 'dynamic' alloca.
70  /// Dynamic allocas are allocas that are either not in the entry block or they
71  /// are in the entry block but are not a constant size.
72  bool ContainsDynamicAllocas = false;
73
74  /// All cloned call sites that have operand bundles attached are appended to
75  /// this vector. This vector may contain nulls or undefs if some of the
76  /// originally inserted callsites were DCE'ed after they were cloned.
77  std::vector<WeakTrackingVH> OperandBundleCallSites;
78
79  ClonedCodeInfo() = default;
80 };
81
82 /// Return a copy of the specified basic block, but without
83 /// embedding the block into a particular function. The block returned is an
84 /// exact copy of the specified basic block, without any remapping having been
85 /// performed. Because of this, this is only suitable for applications where
86 /// the basic block will be inserted into the same function that it was cloned
87 /// from (loop unrolling would use this, for example).
88 ///
89 /// Also, note that this function makes a direct copy of the basic block, and
90 /// can thus produce illegal LLVM code. In particular, it will copy any PHI
91 /// nodes from the original block, even though there are no predecessors for the
92 /// newly cloned block (thus, phi nodes will have to be updated). Also, this
93 /// block will branch to the old successors of the original block: these
94 /// successors will have to have any PHI nodes updated to account for the new
95 /// incoming edges.
96 ///
97 /// The correlation between instructions in the source and result basic blocks
98 /// is recorded in the VMap map.
99 ///
100 /// If you have a particular suffix you'd like to use to add to any cloned
101 /// names, specify it as the optional third parameter.
102 ///
103 /// If you would like the basic block to be auto-inserted into the end of a
104 /// function, you can specify it as the optional fourth parameter.
105 ///
106 /// If you would like to collect additional information about the cloned
107 /// function, you can specify a ClonedCodeInfo object with the optional fifth
108 /// parameter.
110  const Twine &NameSuffix = "", Function *F = nullptr,
111  ClonedCodeInfo *CodeInfo = nullptr,
112  DebugInfoFinder *DIFinder = nullptr);
113
114 /// Return a copy of the specified function and add it to that
115 /// function's module. Also, any references specified in the VMap are changed
116 /// to refer to their mapped value instead of the original one. If any of the
117 /// arguments to the function are in the VMap, the arguments are deleted from
118 /// the resultant function. The VMap is updated to include mappings from all of
119 /// the instructions and basicblocks in the function from their old to new
120 /// values. The final argument captures information about the cloned code if
121 /// non-null.
122 ///
123 /// VMap contains no non-identity GlobalValue mappings and debug info metadata
124 /// will not be cloned.
125 ///
127  ClonedCodeInfo *CodeInfo = nullptr);
128
129 /// Clone OldFunc into NewFunc, transforming the old arguments into references
130 /// to VMap values. Note that if NewFunc already has basic blocks, the ones
131 /// cloned into it will be added to the end of the function. This function
132 /// fills in a list of return instructions, and can optionally remap types
133 /// and/or append the specified suffix to all values cloned.
134 ///
135 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
136 /// mappings.
137 ///
138 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
139  ValueToValueMapTy &VMap, bool ModuleLevelChanges,
141  const char *NameSuffix = "",
142  ClonedCodeInfo *CodeInfo = nullptr,
143  ValueMapTypeRemapper *TypeMapper = nullptr,
144  ValueMaterializer *Materializer = nullptr);
145
146 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
147  const Instruction *StartingInst,
148  ValueToValueMapTy &VMap, bool ModuleLevelChanges,
150  const char *NameSuffix = "",
151  ClonedCodeInfo *CodeInfo = nullptr);
152
153 /// This works exactly like CloneFunctionInto,
154 /// except that it does some simple constant prop and DCE on the fly. The
155 /// effect of this is to copy significantly less code in cases where (for
156 /// example) a function call with constant arguments is inlined, and those
157 /// constant arguments cause a significant amount of code in the callee to be
158 /// dead. Since this doesn't produce an exactly copy of the input, it can't be
159 /// used for things like CloneFunction or CloneModule.
160 ///
161 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
162 /// mappings.
163 ///
164 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
165  ValueToValueMapTy &VMap, bool ModuleLevelChanges,
167  const char *NameSuffix = "",
168  ClonedCodeInfo *CodeInfo = nullptr,
169  Instruction *TheCall = nullptr);
170
171 /// This class captures the data input to the InlineFunction call, and records
172 /// the auxiliary results produced by it.
174 public:
175  explicit InlineFunctionInfo(CallGraph *cg = nullptr,
177  *GetAssumptionCache = nullptr,
178  ProfileSummaryInfo *PSI = nullptr,
179  BlockFrequencyInfo *CallerBFI = nullptr,
180  BlockFrequencyInfo *CalleeBFI = nullptr)
181  : CG(cg), GetAssumptionCache(GetAssumptionCache), PSI(PSI),
182  CallerBFI(CallerBFI), CalleeBFI(CalleeBFI) {}
183
184  /// If non-null, InlineFunction will update the callgraph to reflect the
185  /// changes it makes.
187  std::function<AssumptionCache &(Function &)> *GetAssumptionCache;
190
191  /// InlineFunction fills this in with all static allocas that get copied into
192  /// the caller.
194
195  /// InlineFunction fills this in with callsites that were inlined from the
196  /// callee. This is only filled in if CG is non-null.
198
199  /// All of the new call sites inlined into the caller.
200  ///
201  /// 'InlineFunction' fills this in by scanning the inlined instructions, and
202  /// only if CG is null. If CG is non-null, instead the value handle
203  /// InlinedCalls above is used.
205
206  void reset() {
207  StaticAllocas.clear();
208  InlinedCalls.clear();
209  InlinedCallSites.clear();
210  }
211 };
212
213 /// This function inlines the called function into the basic
214 /// block of the caller. This returns false if it is not possible to inline
215 /// this call. The program is still in a well defined state if this occurs
216 /// though.
217 ///
218 /// Note that this only does one level of inlining. For example, if the
219 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
220 /// exists in the instruction stream. Similarly this will inline a recursive
221 /// function by one level.
222 ///
223 /// Note that while this routine is allowed to cleanup and optimize the
224 /// *inlined* code to minimize the actual inserted code, it must not delete
225 /// code in the caller as users of this routine may have pointers to
226 /// instructions in the caller that need to remain stable.
227 ///
228 /// If ForwardVarArgsTo is passed, inlining a function with varargs is allowed
229 /// and all varargs at the callsite will be passed to any calls to
230 /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs
231 /// are only used by ForwardVarArgsTo.
233  AAResults *CalleeAAR = nullptr,
236  AAResults *CalleeAAR = nullptr,
238  Function *ForwardVarArgsTo = nullptr);
239
240 /// Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
241 /// Blocks.
242 ///
243 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
244 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
245 /// Note: Only innermost loops are supported.
246 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
247  Loop *OrigLoop, ValueToValueMapTy &VMap,
248  const Twine &NameSuffix, LoopInfo *LI,
249  DominatorTree *DT,
251
252 /// Remaps instructions in \p Blocks using the mapping in \p VMap.
254  ValueToValueMapTy &VMap);
255
256 /// Split edge between BB and PredBB and duplicate all non-Phi instructions
257 /// from BB between its beginning and the StopAt instruction into the split
258 /// block. Phi nodes are not duplicated, but their uses are handled correctly:
259 /// we replace them with the uses of corresponding Phi inputs. ValueMapping
260 /// is used to map the original instructions from BB to their newly-created
261 /// copies. Returns the split block.
263  BasicBlock *PredBB,
264  Instruction *StopAt,
266  DomTreeUpdater &DTU);
267
269 /// entryDelta then scaling callsite information by the new count divided by the
270 /// old count. VMap is used during inlinng to also update the new clone
272  Function *Callee, int64_t entryDelta,
273  const ValueMap<const Value *, WeakTrackingVH> *VMap = nullptr);
274
275 } // end namespace llvm
276
277 #endif // LLVM_TRANSFORMS_UTILS_CLONING_H
BasicBlock * DuplicateInstructionsInSplitBetween(BasicBlock *BB, BasicBlock *PredBB, Instruction *StopAt, ValueToValueMapTy &ValueMapping, DomTreeUpdater &DTU)
Split edge between BB and PredBB and duplicate all non-Phi instructions from BB between its beginning...
This class represents lattice values for constants.
Definition: AllocatorList.h:23
CallGraph * CG
If non-null, InlineFunction will update the callgraph to reflect the changes it makes.
Definition: Cloning.h:186
Various leaf nodes.
Definition: ISDOpcodes.h:59
std::function< AssumptionCache &(Function &)> * GetAssumptionCache
Definition: Cloning.h:187
Analysis providing profile information.
Function * CloneFunction(Function *F, ValueToValueMapTy &VMap, ClonedCodeInfo *CodeInfo=nullptr)
Return a copy of the specified function and add it to that function&#39;s module.
A cache of @llvm.assume calls within a function.
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1100
F(f)
This class captures the data input to the InlineFunction call, and records the auxiliary results prod...
Definition: Cloning.h:173
void CloneFunctionInto(Function *NewFunc, const Function *OldFunc, ValueToValueMapTy &VMap, bool ModuleLevelChanges, SmallVectorImpl< ReturnInst *> &Returns, const char *NameSuffix="", ClonedCodeInfo *CodeInfo=nullptr, ValueMapTypeRemapper *TypeMapper=nullptr, ValueMaterializer *Materializer=nullptr)
Clone OldFunc into NewFunc, transforming the old arguments into references to VMap values...
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:80
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
Utility to find all debug info in a module.
Definition: DebugInfo.h:64
void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, ValueToValueMapTy &VMap, bool ModuleLevelChanges, SmallVectorImpl< ReturnInst *> &Returns, const char *NameSuffix="", ClonedCodeInfo *CodeInfo=nullptr, Instruction *TheCall=nullptr)
This works exactly like CloneFunctionInto, except that it does some simple constant prop and DCE on t...
std::vector< WeakTrackingVH > OperandBundleCallSites
All cloned call sites that have operand bundles attached are appended to this vector.
Definition: Cloning.h:77
InlineResult is basically true or false.
Definition: InlineCost.h:135
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
ClonedCodeInfo()=default
std::unique_ptr< Module > CloneModule(const Module &M)
Return an exact copy of the specified module.
Definition: CloneModule.cpp:34
BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to estimate IR basic block frequen...
This is a class that can be implemented by clients to materialize Values on demand.
Definition: ValueMapper.h:50
SmallVector< CallSite, 8 > InlinedCallSites
All of the new call sites inlined into the caller.
Definition: Cloning.h:204
ValueMap< const Value *, WeakTrackingVH > ValueToValueMapTy
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
ProfileSummaryInfo * PSI
Definition: Cloning.h:188
void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc, const Instruction *StartingInst, ValueToValueMapTy &VMap, bool ModuleLevelChanges, SmallVectorImpl< ReturnInst *> &Returns, const char *NameSuffix="", ClonedCodeInfo *CodeInfo=nullptr)
This works like CloneAndPruneFunctionInto, except that it does not clone the entire function...
InlineResult InlineFunction(CallBase *CB, InlineFunctionInfo &IFI, AAResults *CalleeAAR=nullptr, bool InsertLifetime=true)
This function inlines the called function into the basic block of the caller.
InlineFunctionInfo(CallGraph *cg=nullptr, std::function< AssumptionCache &(Function &)> *GetAssumptionCache=nullptr, ProfileSummaryInfo *PSI=nullptr, BlockFrequencyInfo *CallerBFI=nullptr, BlockFrequencyInfo *CalleeBFI=nullptr)
Definition: Cloning.h:175
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
BasicBlock * CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap, const Twine &NameSuffix="", Function *F=nullptr, ClonedCodeInfo *CodeInfo=nullptr, DebugInfoFinder *DIFinder=nullptr)
Return a copy of the specified basic block, but without embedding the block into a particular functio...
amdgpu Simplify well known AMD library false FunctionCallee Callee
This is a class that can be implemented by clients to remap types when cloning constants and instruct...
Definition: ValueMapper.h:37
bool ContainsCalls
This is set to true if the cloned code contains a normal call instruction.
Definition: Cloning.h:67
SmallVector< AllocaInst *, 4 > StaticAllocas
InlineFunction fills this in with all static allocas that get copied into the caller.
Definition: Cloning.h:193
The basic data container for the call graph of a Module of IR.
Definition: CallGraph.h:73
SmallVector< WeakTrackingVH, 8 > InlinedCalls
InlineFunction fills this in with callsites that were inlined from the callee.
Definition: Cloning.h:197
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:506
This struct can be used to capture information about code being cloned, while it is being cloned...
Definition: Cloning.h:65
void updateProfileCallee(Function *Callee, int64_t entryDelta, const ValueMap< const Value *, WeakTrackingVH > *VMap=nullptr)