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      1 //===---- llvm/MDBuilder.h - Builder for LLVM metadata ----------*- 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 the MDBuilder class, which is used as a convenient way to
     11 // create LLVM metadata with a consistent and simplified interface.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_IR_MDBUILDER_H
     16 #define LLVM_IR_MDBUILDER_H
     17 
     18 #include "llvm/ADT/StringRef.h"
     19 #include "llvm/Support/DataTypes.h"
     20 #include <utility>
     21 
     22 namespace llvm {
     23 
     24 class APInt;
     25 template <typename T> class ArrayRef;
     26 class LLVMContext;
     27 class Constant;
     28 class ConstantAsMetadata;
     29 class MDNode;
     30 class MDString;
     31 
     32 class MDBuilder {
     33   LLVMContext &Context;
     34 
     35 public:
     36   MDBuilder(LLVMContext &context) : Context(context) {}
     37 
     38   /// \brief Return the given string as metadata.
     39   MDString *createString(StringRef Str);
     40 
     41   /// \brief Return the given constant as metadata.
     42   ConstantAsMetadata *createConstant(Constant *C);
     43 
     44   //===------------------------------------------------------------------===//
     45   // FPMath metadata.
     46   //===------------------------------------------------------------------===//
     47 
     48   /// \brief Return metadata with the given settings.  The special value 0.0
     49   /// for the Accuracy parameter indicates the default (maximal precision)
     50   /// setting.
     51   MDNode *createFPMath(float Accuracy);
     52 
     53   //===------------------------------------------------------------------===//
     54   // Prof metadata.
     55   //===------------------------------------------------------------------===//
     56 
     57   /// \brief Return metadata containing two branch weights.
     58   MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight);
     59 
     60   /// \brief Return metadata containing a number of branch weights.
     61   MDNode *createBranchWeights(ArrayRef<uint32_t> Weights);
     62 
     63   /// Return metadata specifying that a branch or switch is unpredictable.
     64   MDNode *createUnpredictable();
     65 
     66   /// Return metadata containing the entry count for a function.
     67   MDNode *createFunctionEntryCount(uint64_t Count);
     68 
     69   //===------------------------------------------------------------------===//
     70   // Range metadata.
     71   //===------------------------------------------------------------------===//
     72 
     73   /// \brief Return metadata describing the range [Lo, Hi).
     74   MDNode *createRange(const APInt &Lo, const APInt &Hi);
     75 
     76   /// \brief Return metadata describing the range [Lo, Hi).
     77   MDNode *createRange(Constant *Lo, Constant *Hi);
     78 
     79   //===------------------------------------------------------------------===//
     80   // AA metadata.
     81   //===------------------------------------------------------------------===//
     82 
     83 protected:
     84   /// \brief Return metadata appropriate for a AA root node (scope or TBAA).
     85   /// Each returned node is distinct from all other metadata and will never
     86   /// be identified (uniqued) with anything else.
     87   MDNode *createAnonymousAARoot(StringRef Name = StringRef(),
     88                                 MDNode *Extra = nullptr);
     89 
     90 public:
     91   /// \brief Return metadata appropriate for a TBAA root node. Each returned
     92   /// node is distinct from all other metadata and will never be identified
     93   /// (uniqued) with anything else.
     94   MDNode *createAnonymousTBAARoot() {
     95     return createAnonymousAARoot();
     96   }
     97 
     98   /// \brief Return metadata appropriate for an alias scope domain node.
     99   /// Each returned node is distinct from all other metadata and will never
    100   /// be identified (uniqued) with anything else.
    101   MDNode *createAnonymousAliasScopeDomain(StringRef Name = StringRef()) {
    102     return createAnonymousAARoot(Name);
    103   }
    104 
    105   /// \brief Return metadata appropriate for an alias scope root node.
    106   /// Each returned node is distinct from all other metadata and will never
    107   /// be identified (uniqued) with anything else.
    108   MDNode *createAnonymousAliasScope(MDNode *Domain,
    109                                     StringRef Name = StringRef()) {
    110     return createAnonymousAARoot(Name, Domain);
    111   }
    112 
    113   /// \brief Return metadata appropriate for a TBAA root node with the given
    114   /// name.  This may be identified (uniqued) with other roots with the same
    115   /// name.
    116   MDNode *createTBAARoot(StringRef Name);
    117 
    118   /// \brief Return metadata appropriate for an alias scope domain node with
    119   /// the given name. This may be identified (uniqued) with other roots with
    120   /// the same name.
    121   MDNode *createAliasScopeDomain(StringRef Name);
    122 
    123   /// \brief Return metadata appropriate for an alias scope node with
    124   /// the given name. This may be identified (uniqued) with other scopes with
    125   /// the same name and domain.
    126   MDNode *createAliasScope(StringRef Name, MDNode *Domain);
    127 
    128   /// \brief Return metadata for a non-root TBAA node with the given name,
    129   /// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
    130   MDNode *createTBAANode(StringRef Name, MDNode *Parent,
    131                          bool isConstant = false);
    132 
    133   struct TBAAStructField {
    134     uint64_t Offset;
    135     uint64_t Size;
    136     MDNode *TBAA;
    137     TBAAStructField(uint64_t Offset, uint64_t Size, MDNode *TBAA) :
    138       Offset(Offset), Size(Size), TBAA(TBAA) {}
    139   };
    140 
    141   /// \brief Return metadata for a tbaa.struct node with the given
    142   /// struct field descriptions.
    143   MDNode *createTBAAStructNode(ArrayRef<TBAAStructField> Fields);
    144 
    145   /// \brief Return metadata for a TBAA struct node in the type DAG
    146   /// with the given name, a list of pairs (offset, field type in the type DAG).
    147   MDNode *
    148   createTBAAStructTypeNode(StringRef Name,
    149                            ArrayRef<std::pair<MDNode *, uint64_t>> Fields);
    150 
    151   /// \brief Return metadata for a TBAA scalar type node with the
    152   /// given name, an offset and a parent in the TBAA type DAG.
    153   MDNode *createTBAAScalarTypeNode(StringRef Name, MDNode *Parent,
    154                                    uint64_t Offset = 0);
    155 
    156   /// \brief Return metadata for a TBAA tag node with the given
    157   /// base type, access type and offset relative to the base type.
    158   MDNode *createTBAAStructTagNode(MDNode *BaseType, MDNode *AccessType,
    159                                   uint64_t Offset, bool IsConstant = false);
    160 };
    161 
    162 } // end namespace llvm
    163 
    164 #endif
    165