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_MDBUILDER_H
16#define LLVM_MDBUILDER_H
17
18#include "llvm/Constants.h"
19#include "llvm/DerivedTypes.h"
20#include "llvm/LLVMContext.h"
21#include "llvm/Metadata.h"
22#include "llvm/ADT/APInt.h"
23
24namespace llvm {
25
26  class MDBuilder {
27    LLVMContext &Context;
28
29  public:
30    MDBuilder(LLVMContext &context) : Context(context) {}
31
32    /// \brief Return the given string as metadata.
33    MDString *createString(StringRef Str) {
34      return MDString::get(Context, Str);
35    }
36
37    //===------------------------------------------------------------------===//
38    // FPMath metadata.
39    //===------------------------------------------------------------------===//
40
41    /// \brief Return metadata with the given settings.  The special value 0.0
42    /// for the Accuracy parameter indicates the default (maximal precision)
43    /// setting.
44    MDNode *createFPMath(float Accuracy) {
45      if (Accuracy == 0.0)
46        return 0;
47      assert(Accuracy > 0.0 && "Invalid fpmath accuracy!");
48      Value *Op = ConstantFP::get(Type::getFloatTy(Context), Accuracy);
49      return MDNode::get(Context, Op);
50    }
51
52    //===------------------------------------------------------------------===//
53    // Prof metadata.
54    //===------------------------------------------------------------------===//
55
56    /// \brief Return metadata containing two branch weights.
57    MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight) {
58      uint32_t Weights[] = { TrueWeight, FalseWeight };
59      return createBranchWeights(Weights);
60    }
61
62    /// \brief Return metadata containing a number of branch weights.
63    MDNode *createBranchWeights(ArrayRef<uint32_t> Weights) {
64      assert(Weights.size() >= 2 && "Need at least two branch weights!");
65
66      SmallVector<Value *, 4> Vals(Weights.size()+1);
67      Vals[0] = createString("branch_weights");
68
69      Type *Int32Ty = Type::getInt32Ty(Context);
70      for (unsigned i = 0, e = Weights.size(); i != e; ++i)
71        Vals[i+1] = ConstantInt::get(Int32Ty, Weights[i]);
72
73      return MDNode::get(Context, Vals);
74    }
75
76    //===------------------------------------------------------------------===//
77    // Range metadata.
78    //===------------------------------------------------------------------===//
79
80    /// \brief Return metadata describing the range [Lo, Hi).
81    MDNode *createRange(const APInt &Lo, const APInt &Hi) {
82      assert(Lo.getBitWidth() == Hi.getBitWidth() && "Mismatched bitwidths!");
83      // If the range is everything then it is useless.
84      if (Hi == Lo)
85        return 0;
86
87      // Return the range [Lo, Hi).
88      Type *Ty = IntegerType::get(Context, Lo.getBitWidth());
89      Value *Range[2] = { ConstantInt::get(Ty, Lo), ConstantInt::get(Ty, Hi) };
90      return MDNode::get(Context, Range);
91    }
92
93
94    //===------------------------------------------------------------------===//
95    // TBAA metadata.
96    //===------------------------------------------------------------------===//
97
98    /// \brief Return metadata appropriate for a TBAA root node.  Each returned
99    /// node is distinct from all other metadata and will never be identified
100    /// (uniqued) with anything else.
101    MDNode *createAnonymousTBAARoot() {
102      // To ensure uniqueness the root node is self-referential.
103      MDNode *Dummy = MDNode::getTemporary(Context, ArrayRef<Value*>());
104      MDNode *Root = MDNode::get(Context, Dummy);
105      // At this point we have
106      //   !0 = metadata !{}            <- dummy
107      //   !1 = metadata !{metadata !0} <- root
108      // Replace the dummy operand with the root node itself and delete the dummy.
109      Root->replaceOperandWith(0, Root);
110      MDNode::deleteTemporary(Dummy);
111      // We now have
112      //   !1 = metadata !{metadata !1} <- self-referential root
113      return Root;
114    }
115
116    /// \brief Return metadata appropriate for a TBAA root node with the given
117    /// name.  This may be identified (uniqued) with other roots with the same
118    /// name.
119    MDNode *createTBAARoot(StringRef Name) {
120      return MDNode::get(Context, createString(Name));
121    }
122
123    /// \brief Return metadata for a non-root TBAA node with the given name,
124    /// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
125    MDNode *createTBAANode(StringRef Name, MDNode *Parent,
126                           bool isConstant = false) {
127      if (isConstant) {
128        Constant *Flags = ConstantInt::get(Type::getInt64Ty(Context), 1);
129        Value *Ops[3] = { createString(Name), Parent, Flags };
130        return MDNode::get(Context, Ops);
131      } else {
132        Value *Ops[2] = { createString(Name), Parent };
133        return MDNode::get(Context, Ops);
134      }
135    }
136
137    struct TBAAStructField {
138      uint64_t Offset;
139      uint64_t Size;
140      MDNode *TBAA;
141      TBAAStructField(uint64_t Offset, uint64_t Size, MDNode *TBAA) :
142        Offset(Offset), Size(Size), TBAA(TBAA) {}
143    };
144
145    /// \brief Return metadata for a tbaa.struct node with the given
146    /// struct field descriptions.
147    MDNode *createTBAAStructNode(ArrayRef<TBAAStructField> Fields) {
148      SmallVector<Value *, 4> Vals(Fields.size() * 3);
149      Type *Int64 = IntegerType::get(Context, 64);
150      for (unsigned i = 0, e = Fields.size(); i != e; ++i) {
151        Vals[i * 3 + 0] = ConstantInt::get(Int64, Fields[i].Offset);
152        Vals[i * 3 + 1] = ConstantInt::get(Int64, Fields[i].Size);
153        Vals[i * 3 + 2] = Fields[i].TBAA;
154      }
155      return MDNode::get(Context, Vals);
156    }
157
158  };
159
160} // end namespace llvm
161
162#endif
163