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
33namespace llvm {
34
35class AllocaInst;
36class BasicBlock;
37class BlockFrequencyInfo;
38class CallInst;
39class CallGraph;
40class DebugInfoFinder;
41class DominatorTree;
42class Function;
43class Instruction;
44class InvokeInst;
45class Loop;
46class LoopInfo;
47class Module;
48class ProfileSummaryInfo;
49class ReturnInst;
50class DomTreeUpdater;
51
52/// Return an exact copy of the specified module
53std::unique_ptr<Module> CloneModule(const Module &M);
54std::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.
60std::unique_ptr<Module>
61CloneModule(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.
66struct 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.
110BasicBlock *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///
127Function *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///
139void 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
147void 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///
165void 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.
174class InlineFunctionInfo {
175public:
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.
233InlineResult InlineFunction(CallInst *C, InlineFunctionInfo &IFI,
234 AAResults *CalleeAAR = nullptr,
235 bool InsertLifetime = true);
236InlineResult InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
237 AAResults *CalleeAAR = nullptr,
238 bool InsertLifetime = true);
239InlineResult 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.
250Loop *cloneLoopWithPreheader(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.
257void 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.
266BasicBlock *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