1 //===-- Bitcode/Reader/ValueList.h - Number values --------------*- 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 class gives values and types Unique ID's.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_BITCODE_READER_VALUELIST_H
15 #define LLVM_LIB_BITCODE_READER_VALUELIST_H
16 
17 #include "llvm/IR/ValueHandle.h"
18 #include <cassert>
19 #include <utility>
20 #include <vector>
21 
22 namespace llvm {
23 
24 class Constant;
25 class LLVMContext;
26 class Type;
27 class Value;
28 
29 class BitcodeReaderValueList {
30   std::vector<WeakTrackingVH> ValuePtrs;
31 
32   /// As we resolve forward-referenced constants, we add information about them
33   /// to this vector.  This allows us to resolve them in bulk instead of
34   /// resolving each reference at a time.  See the code in
35   /// ResolveConstantForwardRefs for more information about this.
36   ///
37   /// The key of this vector is the placeholder constant, the value is the slot
38   /// number that holds the resolved value.
39   using ResolveConstantsTy = std::vector<std::pair<Constant *, unsigned>>;
40   ResolveConstantsTy ResolveConstants;
41   LLVMContext &Context;
42 
43 public:
BitcodeReaderValueList(LLVMContext & C)44   BitcodeReaderValueList(LLVMContext &C) : Context(C) {}
45 
~BitcodeReaderValueList()46   ~BitcodeReaderValueList() {
47     assert(ResolveConstants.empty() && "Constants not resolved?");
48   }
49 
50   // vector compatibility methods
size()51   unsigned size() const { return ValuePtrs.size(); }
resize(unsigned N)52   void resize(unsigned N) { ValuePtrs.resize(N); }
push_back(Value * V)53   void push_back(Value *V) { ValuePtrs.emplace_back(V); }
54 
clear()55   void clear() {
56     assert(ResolveConstants.empty() && "Constants not resolved?");
57     ValuePtrs.clear();
58   }
59 
60   Value *operator[](unsigned i) const {
61     assert(i < ValuePtrs.size());
62     return ValuePtrs[i];
63   }
64 
back()65   Value *back() const { return ValuePtrs.back(); }
pop_back()66   void pop_back() { ValuePtrs.pop_back(); }
empty()67   bool empty() const { return ValuePtrs.empty(); }
68 
shrinkTo(unsigned N)69   void shrinkTo(unsigned N) {
70     assert(N <= size() && "Invalid shrinkTo request!");
71     ValuePtrs.resize(N);
72   }
73 
74   Constant *getConstantFwdRef(unsigned Idx, Type *Ty);
75   Value *getValueFwdRef(unsigned Idx, Type *Ty);
76 
77   void assignValue(Value *V, unsigned Idx);
78 
79   /// Once all constants are read, this method bulk resolves any forward
80   /// references.
81   void resolveConstantForwardRefs();
82 };
83 
84 } // end namespace llvm
85 
86 #endif // LLVM_LIB_BITCODE_READER_VALUELIST_H
87