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      1 //===---- llvm/MDBuilder.cpp - Builder for LLVM metadata ------------------===//
      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 #include "llvm/IR/MDBuilder.h"
     16 #include "llvm/IR/Constants.h"
     17 #include "llvm/IR/Metadata.h"
     18 using namespace llvm;
     19 
     20 MDString *MDBuilder::createString(StringRef Str) {
     21   return MDString::get(Context, Str);
     22 }
     23 
     24 ConstantAsMetadata *MDBuilder::createConstant(Constant *C) {
     25   return ConstantAsMetadata::get(C);
     26 }
     27 
     28 MDNode *MDBuilder::createFPMath(float Accuracy) {
     29   if (Accuracy == 0.0)
     30     return nullptr;
     31   assert(Accuracy > 0.0 && "Invalid fpmath accuracy!");
     32   auto *Op =
     33       createConstant(ConstantFP::get(Type::getFloatTy(Context), Accuracy));
     34   return MDNode::get(Context, Op);
     35 }
     36 
     37 MDNode *MDBuilder::createBranchWeights(uint32_t TrueWeight,
     38                                        uint32_t FalseWeight) {
     39   return createBranchWeights({TrueWeight, FalseWeight});
     40 }
     41 
     42 MDNode *MDBuilder::createBranchWeights(ArrayRef<uint32_t> Weights) {
     43   assert(Weights.size() >= 2 && "Need at least two branch weights!");
     44 
     45   SmallVector<Metadata *, 4> Vals(Weights.size() + 1);
     46   Vals[0] = createString("branch_weights");
     47 
     48   Type *Int32Ty = Type::getInt32Ty(Context);
     49   for (unsigned i = 0, e = Weights.size(); i != e; ++i)
     50     Vals[i + 1] = createConstant(ConstantInt::get(Int32Ty, Weights[i]));
     51 
     52   return MDNode::get(Context, Vals);
     53 }
     54 
     55 MDNode *MDBuilder::createUnpredictable() {
     56   return MDNode::get(Context, None);
     57 }
     58 
     59 MDNode *MDBuilder::createFunctionEntryCount(uint64_t Count) {
     60   Type *Int64Ty = Type::getInt64Ty(Context);
     61   return MDNode::get(Context,
     62                      {createString("function_entry_count"),
     63                       createConstant(ConstantInt::get(Int64Ty, Count))});
     64 }
     65 
     66 MDNode *MDBuilder::createRange(const APInt &Lo, const APInt &Hi) {
     67   assert(Lo.getBitWidth() == Hi.getBitWidth() && "Mismatched bitwidths!");
     68 
     69   Type *Ty = IntegerType::get(Context, Lo.getBitWidth());
     70   return createRange(ConstantInt::get(Ty, Lo), ConstantInt::get(Ty, Hi));
     71 }
     72 
     73 MDNode *MDBuilder::createRange(Constant *Lo, Constant *Hi) {
     74   // If the range is everything then it is useless.
     75   if (Hi == Lo)
     76     return nullptr;
     77 
     78   // Return the range [Lo, Hi).
     79   return MDNode::get(Context, {createConstant(Lo), createConstant(Hi)});
     80 }
     81 
     82 MDNode *MDBuilder::createAnonymousAARoot(StringRef Name, MDNode *Extra) {
     83   // To ensure uniqueness the root node is self-referential.
     84   auto Dummy = MDNode::getTemporary(Context, None);
     85 
     86   SmallVector<Metadata *, 3> Args(1, Dummy.get());
     87   if (Extra)
     88     Args.push_back(Extra);
     89   if (!Name.empty())
     90     Args.push_back(createString(Name));
     91   MDNode *Root = MDNode::get(Context, Args);
     92 
     93   // At this point we have
     94   //   !0 = metadata !{}            <- dummy
     95   //   !1 = metadata !{metadata !0} <- root
     96   // Replace the dummy operand with the root node itself and delete the dummy.
     97   Root->replaceOperandWith(0, Root);
     98 
     99   // We now have
    100   //   !1 = metadata !{metadata !1} <- self-referential root
    101   return Root;
    102 }
    103 
    104 MDNode *MDBuilder::createTBAARoot(StringRef Name) {
    105   return MDNode::get(Context, createString(Name));
    106 }
    107 
    108 /// \brief Return metadata for a non-root TBAA node with the given name,
    109 /// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
    110 MDNode *MDBuilder::createTBAANode(StringRef Name, MDNode *Parent,
    111                                   bool isConstant) {
    112   if (isConstant) {
    113     Constant *Flags = ConstantInt::get(Type::getInt64Ty(Context), 1);
    114     return MDNode::get(Context,
    115                        {createString(Name), Parent, createConstant(Flags)});
    116   }
    117   return MDNode::get(Context, {createString(Name), Parent});
    118 }
    119 
    120 MDNode *MDBuilder::createAliasScopeDomain(StringRef Name) {
    121   return MDNode::get(Context, createString(Name));
    122 }
    123 
    124 MDNode *MDBuilder::createAliasScope(StringRef Name, MDNode *Domain) {
    125   return MDNode::get(Context, {createString(Name), Domain});
    126 }
    127 
    128 /// \brief Return metadata for a tbaa.struct node with the given
    129 /// struct field descriptions.
    130 MDNode *MDBuilder::createTBAAStructNode(ArrayRef<TBAAStructField> Fields) {
    131   SmallVector<Metadata *, 4> Vals(Fields.size() * 3);
    132   Type *Int64 = Type::getInt64Ty(Context);
    133   for (unsigned i = 0, e = Fields.size(); i != e; ++i) {
    134     Vals[i * 3 + 0] = createConstant(ConstantInt::get(Int64, Fields[i].Offset));
    135     Vals[i * 3 + 1] = createConstant(ConstantInt::get(Int64, Fields[i].Size));
    136     Vals[i * 3 + 2] = Fields[i].TBAA;
    137   }
    138   return MDNode::get(Context, Vals);
    139 }
    140 
    141 /// \brief Return metadata for a TBAA struct node in the type DAG
    142 /// with the given name, a list of pairs (offset, field type in the type DAG).
    143 MDNode *MDBuilder::createTBAAStructTypeNode(
    144     StringRef Name, ArrayRef<std::pair<MDNode *, uint64_t>> Fields) {
    145   SmallVector<Metadata *, 4> Ops(Fields.size() * 2 + 1);
    146   Type *Int64 = Type::getInt64Ty(Context);
    147   Ops[0] = createString(Name);
    148   for (unsigned i = 0, e = Fields.size(); i != e; ++i) {
    149     Ops[i * 2 + 1] = Fields[i].first;
    150     Ops[i * 2 + 2] = createConstant(ConstantInt::get(Int64, Fields[i].second));
    151   }
    152   return MDNode::get(Context, Ops);
    153 }
    154 
    155 /// \brief Return metadata for a TBAA scalar type node with the
    156 /// given name, an offset and a parent in the TBAA type DAG.
    157 MDNode *MDBuilder::createTBAAScalarTypeNode(StringRef Name, MDNode *Parent,
    158                                             uint64_t Offset) {
    159   ConstantInt *Off = ConstantInt::get(Type::getInt64Ty(Context), Offset);
    160   return MDNode::get(Context,
    161                      {createString(Name), Parent, createConstant(Off)});
    162 }
    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 *MDBuilder::createTBAAStructTagNode(MDNode *BaseType, MDNode *AccessType,
    167                                            uint64_t Offset, bool IsConstant) {
    168   IntegerType *Int64 = Type::getInt64Ty(Context);
    169   ConstantInt *Off = ConstantInt::get(Int64, Offset);
    170   if (IsConstant) {
    171     return MDNode::get(Context, {BaseType, AccessType, createConstant(Off),
    172                                  createConstant(ConstantInt::get(Int64, 1))});
    173   }
    174   return MDNode::get(Context, {BaseType, AccessType, createConstant(Off)});
    175 }
    176