1 //===-- Bitcode/Reader/ValueList.h - Number values --------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This class gives values and types Unique ID's.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_BITCODE_READER_VALUELIST_H
14 #define LLVM_LIB_BITCODE_READER_VALUELIST_H
15 
16 #include "llvm/IR/ValueHandle.h"
17 #include <cassert>
18 #include <utility>
19 #include <vector>
20 
21 namespace llvm {
22 
23 class Constant;
24 class LLVMContext;
25 class Type;
26 class Value;
27 
28 class BitcodeReaderValueList {
29   std::vector<WeakTrackingVH> ValuePtrs;
30 
31   /// As we resolve forward-referenced constants, we add information about them
32   /// to this vector.  This allows us to resolve them in bulk instead of
33   /// resolving each reference at a time.  See the code in
34   /// ResolveConstantForwardRefs for more information about this.
35   ///
36   /// The key of this vector is the placeholder constant, the value is the slot
37   /// number that holds the resolved value.
38   using ResolveConstantsTy = std::vector<std::pair<Constant *, unsigned>>;
39   ResolveConstantsTy ResolveConstants;
40   LLVMContext &Context;
41 
42 public:
43   BitcodeReaderValueList(LLVMContext &C) : Context(C) {}
44 
45   ~BitcodeReaderValueList() {
46     assert(ResolveConstants.empty() && "Constants not resolved?");
47   }
48 
49   // vector compatibility methods
50   unsigned size() const { return ValuePtrs.size(); }
51   void resize(unsigned N) { ValuePtrs.resize(N); }
52   void push_back(Value *V) { ValuePtrs.emplace_back(V); }
53 
54   void clear() {
55     assert(ResolveConstants.empty() && "Constants not resolved?");
56     ValuePtrs.clear();
57   }
58 
59   Value *operator[](unsigned i) const {
60     assert(i < ValuePtrs.size());
61     return ValuePtrs[i];
62   }
63 
64   Value *back() const { return ValuePtrs.back(); }
65   void pop_back() { ValuePtrs.pop_back(); }
66   bool empty() const { return ValuePtrs.empty(); }
67 
68   void shrinkTo(unsigned N) {
69     assert(N <= size() && "Invalid shrinkTo request!");
70     ValuePtrs.resize(N);
71   }
72 
73   Constant *getConstantFwdRef(unsigned Idx, Type *Ty);
74   Value *getValueFwdRef(unsigned Idx, Type *Ty);
75 
76   void assignValue(Value *V, unsigned Idx);
77 
78   /// Once all constants are read, this method bulk resolves any forward
79   /// references.
80   void resolveConstantForwardRefs();
81 };
82 
83 } // end namespace llvm
84 
85 #endif // LLVM_LIB_BITCODE_READER_VALUELIST_H
86