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 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines various functions that are used to clone chunks of LLVM
 // code for various purposes.  This varies from copying whole modules into new
 // modules, to cloning functions with different arguments, to inlining
 // functions, to copying basic blocks to support loop unrolling or superblock
 // formation, etc.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H
 #define LLVM_TRANSFORMS_UTILS_CLONING_H
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/InlineCost.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
 #include <functional>
 #include <memory>
 #include <vector>
 
 namespace llvm {
 
 class AAResults;
 class AllocaInst;
 class BasicBlock;
 class BlockFrequencyInfo;
 class DebugInfoFinder;
 class DominatorTree;
 class Function;
 class Instruction;
 class Loop;
 class LoopInfo;
 class Module;
 class PGOContextualProfile;
 class ProfileSummaryInfo;
 class ReturnInst;
 class DomTreeUpdater;
 
 /// Return an exact copy of the specified module
 std::unique_ptr<Module> CloneModule(const Module &M);
 std::unique_ptr<Module> CloneModule(const Module &M, ValueToValueMapTy &VMap);
 
 /// Return a copy of the specified module. The ShouldCloneDefinition function
 /// controls whether a specific GlobalValue's definition is cloned. If the
 /// function returns false, the module copy will contain an external reference
 /// in place of the global definition.
 std::unique_ptr<Module>
 CloneModule(const Module &M, ValueToValueMapTy &VMap,
             function_ref<bool(const GlobalValue *)> ShouldCloneDefinition);
 
 /// This struct can be used to capture information about code
 /// being cloned, while it is being cloned.
 struct ClonedCodeInfo {
   /// This is set to true if the cloned code contains a normal call instruction.
   bool ContainsCalls = false;
 
   /// This is set to true if there is memprof related metadata (memprof or
   /// callsite metadata) in the cloned code.
   bool ContainsMemProfMetadata = false;
 
   /// This is set to true if the cloned code contains a 'dynamic' alloca.
   /// Dynamic allocas are allocas that are either not in the entry block or they
   /// are in the entry block but are not a constant size.
   bool ContainsDynamicAllocas = false;
 
   /// All cloned call sites that have operand bundles attached are appended to
   /// this vector.  This vector may contain nulls or undefs if some of the
   /// originally inserted callsites were DCE'ed after they were cloned.
   std::vector<WeakTrackingVH> OperandBundleCallSites;
 
   /// Like VMap, but maps only unsimplified instructions. Values in the map
   /// may be dangling, it is only intended to be used via isSimplified(), to
   /// check whether the main VMap mapping involves simplification or not.
   DenseMap<const Value *, const Value *> OrigVMap;
 
   ClonedCodeInfo() = default;
 
   bool isSimplified(const Value *From, const Value *To) const {
     return OrigVMap.lookup(From) != To;
   }
 };
 
 /// Return a copy of the specified basic block, but without
 /// embedding the block into a particular function.  The block returned is an
 /// exact copy of the specified basic block, without any remapping having been
 /// performed.  Because of this, this is only suitable for applications where
 /// the basic block will be inserted into the same function that it was cloned
 /// from (loop unrolling would use this, for example).
 ///
 /// Also, note that this function makes a direct copy of the basic block, and
 /// can thus produce illegal LLVM code.  In particular, it will copy any PHI
 /// nodes from the original block, even though there are no predecessors for the
 /// newly cloned block (thus, phi nodes will have to be updated).  Also, this
 /// block will branch to the old successors of the original block: these
 /// successors will have to have any PHI nodes updated to account for the new
 /// incoming edges.
 ///
 /// The correlation between instructions in the source and result basic blocks
 /// is recorded in the VMap map.
 ///
 /// If you have a particular suffix you'd like to use to add to any cloned
 /// names, specify it as the optional third parameter.
 ///
 /// If you would like the basic block to be auto-inserted into the end of a
 /// function, you can specify it as the optional fourth parameter.
 ///
 /// If you would like to collect additional information about the cloned
 /// function, you can specify a ClonedCodeInfo object with the optional fifth
 /// parameter.
 BasicBlock *CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
                             const Twine &NameSuffix = "", Function *F = nullptr,
                             ClonedCodeInfo *CodeInfo = nullptr);
 
 /// Return a copy of the specified function and add it to that
 /// function's module.  Also, any references specified in the VMap are changed
 /// to refer to their mapped value instead of the original one.  If any of the
 /// arguments to the function are in the VMap, the arguments are deleted from
 /// the resultant function.  The VMap is updated to include mappings from all of
 /// the instructions and basicblocks in the function from their old to new
 /// values.  The final argument captures information about the cloned code if
 /// non-null.
 ///
 /// \pre VMap contains no non-identity GlobalValue mappings.
 ///
 Function *CloneFunction(Function *F, ValueToValueMapTy &VMap,
                         ClonedCodeInfo *CodeInfo = nullptr);
 
 enum class CloneFunctionChangeType {
   LocalChangesOnly,
   GlobalChanges,
   DifferentModule,
   ClonedModule,
 };
 
 /// Clone OldFunc into NewFunc, transforming the old arguments into references
 /// to VMap values.  Note that if NewFunc already has basic blocks, the ones
 /// cloned into it will be added to the end of the function.  This function
 /// fills in a list of return instructions, and can optionally remap types
 /// and/or append the specified suffix to all values cloned.
 ///
 /// If \p Changes is \a CloneFunctionChangeType::LocalChangesOnly, VMap is
 /// required to contain no non-identity GlobalValue mappings. Otherwise,
 /// referenced metadata will be cloned.
 ///
 /// If \p Changes is less than \a CloneFunctionChangeType::DifferentModule
 /// indicating cloning into the same module (even if it's LocalChangesOnly), if
 /// debug info metadata transitively references a \a DISubprogram, it will be
 /// cloned, effectively upgrading \p Changes to GlobalChanges while suppressing
 /// cloning of types and compile units.
 ///
 /// If \p Changes is \a CloneFunctionChangeType::DifferentModule, the new
 /// module's \c !llvm.dbg.cu will get updated with any newly created compile
 /// units. (\a CloneFunctionChangeType::ClonedModule leaves that work for the
 /// caller.)
 ///
 /// FIXME: Consider simplifying this function by splitting out \a
 /// CloneFunctionMetadataInto() and expecting / updating callers to call it
 /// first when / how it's needed.
 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
                        ValueToValueMapTy &VMap, CloneFunctionChangeType Changes,
                        SmallVectorImpl<ReturnInst *> &Returns,
                        const char *NameSuffix = "",
                        ClonedCodeInfo *CodeInfo = nullptr,
                        ValueMapTypeRemapper *TypeMapper = nullptr,
                        ValueMaterializer *Materializer = nullptr);
 
 /// Clone OldFunc's attributes into NewFunc, transforming values based on the
 /// mappings in VMap.
 void CloneFunctionAttributesInto(Function *NewFunc, const Function *OldFunc,
                                  ValueToValueMapTy &VMap,
                                  bool ModuleLevelChanges,
                                  ValueMapTypeRemapper *TypeMapper = nullptr,
                                  ValueMaterializer *Materializer = nullptr);
 
 /// Clone OldFunc's metadata into NewFunc.
 ///
 /// The caller is expected to populate \p VMap beforehand and set an appropriate
 /// \p RemapFlag. Subprograms/CUs/types that were already mapped to themselves
 /// won't be duplicated.
 ///
 /// NOTE: This function doesn't clone !llvm.dbg.cu when cloning into a different
 /// module. Use CloneFunctionInto for that behavior.
 void CloneFunctionMetadataInto(Function &NewFunc, const Function &OldFunc,
                                ValueToValueMapTy &VMap, RemapFlags RemapFlag,
                                ValueMapTypeRemapper *TypeMapper = nullptr,
                                ValueMaterializer *Materializer = nullptr,
                                const MetadataSetTy *IdentityMD = nullptr);
 
 /// Clone OldFunc's body into NewFunc.
 void CloneFunctionBodyInto(Function &NewFunc, const Function &OldFunc,
                            ValueToValueMapTy &VMap, RemapFlags RemapFlag,
                            SmallVectorImpl<ReturnInst *> &Returns,
                            const char *NameSuffix = "",
                            ClonedCodeInfo *CodeInfo = nullptr,
                            ValueMapTypeRemapper *TypeMapper = nullptr,
                            ValueMaterializer *Materializer = nullptr,
                            const MetadataSetTy *IdentityMD = nullptr);
 
 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 exactly like CloneFunctionInto,
 /// except that it does some simple constant prop and DCE on the fly.  The
 /// effect of this is to copy significantly less code in cases where (for
 /// example) a function call with constant arguments is inlined, and those
 /// constant arguments cause a significant amount of code in the callee to be
 /// dead.  Since this doesn't produce an exactly copy of the input, it can't be
 /// used for things like CloneFunction or CloneModule.
 ///
 /// If ModuleLevelChanges is false, VMap contains no non-identity GlobalValue
 /// mappings.
 ///
 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
                                ValueToValueMapTy &VMap, bool ModuleLevelChanges,
                                SmallVectorImpl<ReturnInst*> &Returns,
                                const char *NameSuffix = "",
                                ClonedCodeInfo *CodeInfo = nullptr);
 
 /// Collect debug information such as types, compile units, and other
 /// subprograms that are reachable from \p F and can be considered global for
 /// the purposes of cloning (and hence not needing to be cloned).
 ///
 /// What debug information should be processed depends on \p Changes: when
 /// cloning into the same module we process \p F's subprogram and instructions;
 /// when into a cloned module, neither of those.
 ///
 /// Returns DISubprogram of the cloned function when cloning into the same
 /// module or nullptr otherwise.
 DISubprogram *CollectDebugInfoForCloning(const Function &F,
                                          CloneFunctionChangeType Changes,
                                          DebugInfoFinder &DIFinder);
 
 /// Based on \p Changes and \p DIFinder return debug info that needs to be
 /// identity mapped during Metadata cloning.
 ///
 /// NOTE: Such \a MetadataSetTy can be used by \a CloneFunction* to directly
 /// specify metadata that should be identity mapped (and hence not cloned). The
 /// metadata will be identity mapped in \a ValueToValueMapTy on first use. There
 /// are several reasons for doing it this way rather than eagerly identity
 /// mapping metadata nodes in a \a ValueMap:
 /// 1. Mapping metadata is not cheap, particularly because of tracking.
 /// 2. When cloning a Function we identity map lots of global module-level
 ///    metadata to avoid cloning it, while only a fraction of it is actually
 ///    used by the function. Mapping on first use is a lot faster for modules
 ///    with meaningful amount of debug info.
 /// 3. Eagerly identity mapping metadata makes it harder to cache module-level
 ///    data (e.g. a set of metadata nodes in a \a DICompileUnit).
 MetadataSetTy FindDebugInfoToIdentityMap(CloneFunctionChangeType Changes,
                                          DebugInfoFinder &DIFinder,
                                          DISubprogram *SPClonedWithinModule);
 
 /// This class captures the data input to the InlineFunction call, and records
 /// the auxiliary results produced by it.
 class InlineFunctionInfo {
 public:
   explicit InlineFunctionInfo(
       function_ref<AssumptionCache &(Function &)> GetAssumptionCache = nullptr,
       ProfileSummaryInfo *PSI = nullptr,
       BlockFrequencyInfo *CallerBFI = nullptr,
       BlockFrequencyInfo *CalleeBFI = nullptr, bool UpdateProfile = true)
       : GetAssumptionCache(GetAssumptionCache), PSI(PSI), CallerBFI(CallerBFI),
         CalleeBFI(CalleeBFI), UpdateProfile(UpdateProfile) {}
 
   /// If non-null, InlineFunction will update the callgraph to reflect the
   /// changes it makes.
   function_ref<AssumptionCache &(Function &)> GetAssumptionCache;
   ProfileSummaryInfo *PSI;
   BlockFrequencyInfo *CallerBFI, *CalleeBFI;
 
   /// InlineFunction fills this in with all static allocas that get copied into
   /// the caller.
   SmallVector<AllocaInst *, 4> StaticAllocas;
 
   /// InlineFunction fills this in with callsites that were inlined from the
   /// callee. This is only filled in if CG is non-null.
   SmallVector<WeakTrackingVH, 8> InlinedCalls;
 
   /// All of the new call sites inlined into the caller.
   ///
   /// 'InlineFunction' fills this in by scanning the inlined instructions, and
   /// only if CG is null. If CG is non-null, instead the value handle
   /// `InlinedCalls` above is used.
   SmallVector<CallBase *, 8> InlinedCallSites;
 
   /// Update profile for callee as well as cloned version. We need to do this
   /// for regular inlining, but not for inlining from sample profile loader.
   bool UpdateProfile;
 
   void reset() {
     StaticAllocas.clear();
     InlinedCalls.clear();
     InlinedCallSites.clear();
   }
 };
 
 /// This function inlines the called function into the basic
 /// block of the caller.  This returns false if it is not possible to inline
 /// this call.  The program is still in a well defined state if this occurs
 /// though.
 ///
 /// Note that this only does one level of inlining.  For example, if the
 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
 /// exists in the instruction stream.  Similarly this will inline a recursive
 /// function by one level.
 ///
 /// Note that while this routine is allowed to cleanup and optimize the
 /// *inlined* code to minimize the actual inserted code, it must not delete
 /// code in the caller as users of this routine may have pointers to
 /// instructions in the caller that need to remain stable.
 ///
 /// If ForwardVarArgsTo is passed, inlining a function with varargs is allowed
 /// and all varargs at the callsite will be passed to any calls to
 /// ForwardVarArgsTo. The caller of InlineFunction has to make sure any varargs
 /// are only used by ForwardVarArgsTo.
 ///
 /// The callee's function attributes are merged into the callers' if
 /// MergeAttributes is set to true.
 InlineResult InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
                             bool MergeAttributes = false,
                             AAResults *CalleeAAR = nullptr,
                             bool InsertLifetime = true,
                             Function *ForwardVarArgsTo = nullptr);
 
 /// Same as above, but it will update the contextual profile. If the contextual
 /// profile is invalid (i.e. not loaded because it is not present), it defaults
 /// to the behavior of the non-contextual profile updating variant above. This
 /// makes it easy to drop-in replace uses of the non-contextual overload.
 InlineResult InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
                             PGOContextualProfile &CtxProf,
                             bool MergeAttributes = false,
                             AAResults *CalleeAAR = nullptr,
                             bool InsertLifetime = true,
                             Function *ForwardVarArgsTo = nullptr);
 
 /// Clones a loop \p OrigLoop.  Returns the loop and the blocks in \p
 /// Blocks.
 ///
 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
 /// \p LoopDomBB.  Insert the new blocks before block specified in \p Before.
 /// Note: Only innermost loops are supported.
 Loop *cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
                              Loop *OrigLoop, ValueToValueMapTy &VMap,
                              const Twine &NameSuffix, LoopInfo *LI,
                              DominatorTree *DT,
                              SmallVectorImpl<BasicBlock *> &Blocks);
 
 /// Remaps instructions in \p Blocks using the mapping in \p VMap.
 void remapInstructionsInBlocks(ArrayRef<BasicBlock *> Blocks,
                                ValueToValueMapTy &VMap);
 
 /// Split edge between BB and PredBB and duplicate all non-Phi instructions
 /// from BB between its beginning and the StopAt instruction into the split
 /// block. Phi nodes are not duplicated, but their uses are handled correctly:
 /// we replace them with the uses of corresponding Phi inputs. ValueMapping
 /// is used to map the original instructions from BB to their newly-created
 /// copies. Returns the split block.
 BasicBlock *DuplicateInstructionsInSplitBetween(BasicBlock *BB,
                                                 BasicBlock *PredBB,
                                                 Instruction *StopAt,
                                                 ValueToValueMapTy &ValueMapping,
                                                 DomTreeUpdater &DTU);
 
 /// Updates profile information by adjusting the entry count by adding
 /// EntryDelta then scaling callsite information by the new count divided by the
 /// old count. VMap is used during inlinng to also update the new clone
 void updateProfileCallee(
     Function *Callee, int64_t EntryDelta,
     const ValueMap<const Value *, WeakTrackingVH> *VMap = nullptr);
 
 /// Find the 'llvm.experimental.noalias.scope.decl' intrinsics in the specified
 /// basic blocks and extract their scope. These are candidates for duplication
 /// when cloning.
 void identifyNoAliasScopesToClone(
     ArrayRef<BasicBlock *> BBs, SmallVectorImpl<MDNode *> &NoAliasDeclScopes);
 
 /// Find the 'llvm.experimental.noalias.scope.decl' intrinsics in the specified
 /// instruction range and extract their scope. These are candidates for
 /// duplication when cloning.
 void identifyNoAliasScopesToClone(
     BasicBlock::iterator Start, BasicBlock::iterator End,
     SmallVectorImpl<MDNode *> &NoAliasDeclScopes);
 
 /// Duplicate the specified list of noalias decl scopes.
 /// The 'Ext' string is added as an extension to the name.
 /// Afterwards, the ClonedScopes contains the mapping of the original scope
 /// MDNode onto the cloned scope.
 /// Be aware that the cloned scopes are still part of the original scope domain.
 void cloneNoAliasScopes(
     ArrayRef<MDNode *> NoAliasDeclScopes,
     DenseMap<MDNode *, MDNode *> &ClonedScopes,
     StringRef Ext, LLVMContext &Context);
 
 /// Adapt the metadata for the specified instruction according to the
 /// provided mapping. This is normally used after cloning an instruction, when
 /// some noalias scopes needed to be cloned.
 void adaptNoAliasScopes(
     llvm::Instruction *I, const DenseMap<MDNode *, MDNode *> &ClonedScopes,
     LLVMContext &Context);
 
 /// Clone the specified noalias decl scopes. Then adapt all instructions in the
 /// NewBlocks basicblocks to the cloned versions.
 /// 'Ext' will be added to the duplicate scope names.
 void cloneAndAdaptNoAliasScopes(ArrayRef<MDNode *> NoAliasDeclScopes,
                                 ArrayRef<BasicBlock *> NewBlocks,
                                 LLVMContext &Context, StringRef Ext);
 
 /// Clone the specified noalias decl scopes. Then adapt all instructions in the
 /// [IStart, IEnd] (IEnd included !) range to the cloned versions. 'Ext' will be
 /// added to the duplicate scope names.
 void cloneAndAdaptNoAliasScopes(ArrayRef<MDNode *> NoAliasDeclScopes,
                                 Instruction *IStart, Instruction *IEnd,
                                 LLVMContext &Context, StringRef Ext);
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_UTILS_CLONING_H

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