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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/DenseSet.h"
     19 #include "llvm/ADT/StringRef.h"
     20 #include "llvm/IR/GlobalValue.h"
     21 #include "llvm/Support/DataTypes.h"
     22 #include <utility>
     23 
     24 namespace llvm {
     25 
     26 class APInt;
     27 template <typename T> class ArrayRef;
     28 class LLVMContext;
     29 class Constant;
     30 class ConstantAsMetadata;
     31 class MDNode;
     32 class MDString;
     33 
     34 class MDBuilder {
     35   LLVMContext &Context;
     36 
     37 public:
     38   MDBuilder(LLVMContext &context) : Context(context) {}
     39 
     40   /// \brief Return the given string as metadata.
     41   MDString *createString(StringRef Str);
     42 
     43   /// \brief Return the given constant as metadata.
     44   ConstantAsMetadata *createConstant(Constant *C);
     45 
     46   //===------------------------------------------------------------------===//
     47   // FPMath metadata.
     48   //===------------------------------------------------------------------===//
     49 
     50   /// \brief Return metadata with the given settings.  The special value 0.0
     51   /// for the Accuracy parameter indicates the default (maximal precision)
     52   /// setting.
     53   MDNode *createFPMath(float Accuracy);
     54 
     55   //===------------------------------------------------------------------===//
     56   // Prof metadata.
     57   //===------------------------------------------------------------------===//
     58 
     59   /// \brief Return metadata containing two branch weights.
     60   MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight);
     61 
     62   /// \brief Return metadata containing a number of branch weights.
     63   MDNode *createBranchWeights(ArrayRef<uint32_t> Weights);
     64 
     65   /// Return metadata specifying that a branch or switch is unpredictable.
     66   MDNode *createUnpredictable();
     67 
     68   /// Return metadata containing the entry \p Count for a function, and the
     69   /// GUIDs stored in \p Imports that need to be imported for sample PGO, to
     70   /// enable the same inlines as the profiled optimized binary
     71   MDNode *createFunctionEntryCount(uint64_t Count,
     72                                    const DenseSet<GlobalValue::GUID> *Imports);
     73 
     74   /// Return metadata containing the section prefix for a function.
     75   MDNode *createFunctionSectionPrefix(StringRef Prefix);
     76 
     77   //===------------------------------------------------------------------===//
     78   // Range metadata.
     79   //===------------------------------------------------------------------===//
     80 
     81   /// \brief Return metadata describing the range [Lo, Hi).
     82   MDNode *createRange(const APInt &Lo, const APInt &Hi);
     83 
     84   /// \brief Return metadata describing the range [Lo, Hi).
     85   MDNode *createRange(Constant *Lo, Constant *Hi);
     86 
     87   //===------------------------------------------------------------------===//
     88   // AA metadata.
     89   //===------------------------------------------------------------------===//
     90 
     91 protected:
     92   /// \brief Return metadata appropriate for a AA root node (scope or TBAA).
     93   /// Each returned node is distinct from all other metadata and will never
     94   /// be identified (uniqued) with anything else.
     95   MDNode *createAnonymousAARoot(StringRef Name = StringRef(),
     96                                 MDNode *Extra = nullptr);
     97 
     98 public:
     99   /// \brief Return metadata appropriate for a TBAA root node. Each returned
    100   /// node is distinct from all other metadata and will never be identified
    101   /// (uniqued) with anything else.
    102   MDNode *createAnonymousTBAARoot() {
    103     return createAnonymousAARoot();
    104   }
    105 
    106   /// \brief Return metadata appropriate for an alias scope domain node.
    107   /// Each returned node is distinct from all other metadata and will never
    108   /// be identified (uniqued) with anything else.
    109   MDNode *createAnonymousAliasScopeDomain(StringRef Name = StringRef()) {
    110     return createAnonymousAARoot(Name);
    111   }
    112 
    113   /// \brief Return metadata appropriate for an alias scope root node.
    114   /// Each returned node is distinct from all other metadata and will never
    115   /// be identified (uniqued) with anything else.
    116   MDNode *createAnonymousAliasScope(MDNode *Domain,
    117                                     StringRef Name = StringRef()) {
    118     return createAnonymousAARoot(Name, Domain);
    119   }
    120 
    121   /// \brief Return metadata appropriate for a TBAA root node with the given
    122   /// name.  This may be identified (uniqued) with other roots with the same
    123   /// name.
    124   MDNode *createTBAARoot(StringRef Name);
    125 
    126   /// \brief Return metadata appropriate for an alias scope domain node with
    127   /// the given name. This may be identified (uniqued) with other roots with
    128   /// the same name.
    129   MDNode *createAliasScopeDomain(StringRef Name);
    130 
    131   /// \brief Return metadata appropriate for an alias scope node with
    132   /// the given name. This may be identified (uniqued) with other scopes with
    133   /// the same name and domain.
    134   MDNode *createAliasScope(StringRef Name, MDNode *Domain);
    135 
    136   /// \brief Return metadata for a non-root TBAA node with the given name,
    137   /// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
    138   MDNode *createTBAANode(StringRef Name, MDNode *Parent,
    139                          bool isConstant = false);
    140 
    141   struct TBAAStructField {
    142     uint64_t Offset;
    143     uint64_t Size;
    144     MDNode *TBAA;
    145     TBAAStructField(uint64_t Offset, uint64_t Size, MDNode *TBAA) :
    146       Offset(Offset), Size(Size), TBAA(TBAA) {}
    147   };
    148 
    149   /// \brief Return metadata for a tbaa.struct node with the given
    150   /// struct field descriptions.
    151   MDNode *createTBAAStructNode(ArrayRef<TBAAStructField> Fields);
    152 
    153   /// \brief Return metadata for a TBAA struct node in the type DAG
    154   /// with the given name, a list of pairs (offset, field type in the type DAG).
    155   MDNode *
    156   createTBAAStructTypeNode(StringRef Name,
    157                            ArrayRef<std::pair<MDNode *, uint64_t>> Fields);
    158 
    159   /// \brief Return metadata for a TBAA scalar type node with the
    160   /// given name, an offset and a parent in the TBAA type DAG.
    161   MDNode *createTBAAScalarTypeNode(StringRef Name, MDNode *Parent,
    162                                    uint64_t Offset = 0);
    163 
    164   /// \brief Return metadata for a TBAA tag node with the given
    165   /// base type, access type and offset relative to the base type.
    166   MDNode *createTBAAStructTagNode(MDNode *BaseType, MDNode *AccessType,
    167                                   uint64_t Offset, bool IsConstant = false);
    168 };
    169 
    170 } // end namespace llvm
    171 
    172 #endif
    173