Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- 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/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 CallGraph;

class DebugInfoFinder;

class DominatorTree;

class Function;

class Instruction;

class Loop;

class LoopInfo;

class Module;

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,

                            DebugInfoFinder *DIFinder = 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);

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);

/// This class captures the data input to the InlineFunction call, and records

/// the auxiliary results produced by it.

class InlineFunctionInfo {

public:

  explicit InlineFunctionInfo(

      CallGraph *cg = nullptr,

      function_ref<AssumptionCache &(Function &)> GetAssumptionCache = nullptr,

      ProfileSummaryInfo *PSI = nullptr,

      BlockFrequencyInfo *CallerBFI = nullptr,

      BlockFrequencyInfo *CalleeBFI = nullptr, bool UpdateProfile = true)

      : CG(cg), GetAssumptionCache(GetAssumptionCache), PSI(PSI),

        CallerBFI(CallerBFI), CalleeBFI(CalleeBFI),

        UpdateProfile(UpdateProfile) {}

  /// If non-null, InlineFunction will update the callgraph to reflect the

  /// changes it makes.

  CallGraph *CG;

  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);

/// 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(const SmallVectorImpl<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