1 //===- ValueList.cpp - Internal BitcodeReader implementation --------------===//
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 #include "ValueList.h"
10 #include "llvm/ADT/SmallVector.h"
11 #include "llvm/IR/Argument.h"
12 #include "llvm/IR/Constant.h"
13 #include "llvm/IR/Constants.h"
14 #include "llvm/IR/GlobalValue.h"
15 #include "llvm/IR/Instruction.h"
16 #include "llvm/IR/Type.h"
17 #include "llvm/IR/User.h"
18 #include "llvm/IR/Value.h"
19 #include "llvm/Support/Casting.h"
20 #include "llvm/Support/Error.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include <cstddef>
23 
24 using namespace llvm;
25 
26 Error BitcodeReaderValueList::assignValue(unsigned Idx, Value *V,
27                                           unsigned TypeID) {
28   if (Idx == size()) {
29     push_back(V, TypeID);
30     return Error::success();
31   }
32 
33   if (Idx >= size())
34     resize(Idx + 1);
35 
36   auto &Old = ValuePtrs[Idx];
37   if (!Old.first) {
38     Old.first = V;
39     Old.second = TypeID;
40     return Error::success();
41   }
42 
43   assert(!isa<Constant>(&*Old.first) && "Shouldn't update constant");
44   // If there was a forward reference to this value, replace it.
45   Value *PrevVal = Old.first;
46   if (PrevVal->getType() != V->getType())
47     return createStringError(
48         std::errc::illegal_byte_sequence,
49         "Assigned value does not match type of forward declaration");
50   Old.first->replaceAllUsesWith(V);
51   PrevVal->deleteValue();
52   return Error::success();
53 }
54 
55 Value *BitcodeReaderValueList::getValueFwdRef(unsigned Idx, Type *Ty,
56                                               unsigned TyID,
57                                               BasicBlock *ConstExprInsertBB) {
58   // Bail out for a clearly invalid value.
59   if (Idx >= RefsUpperBound)
60     return nullptr;
61 
62   if (Idx >= size())
63     resize(Idx + 1);
64 
65   if (Value *V = ValuePtrs[Idx].first) {
66     // If the types don't match, it's invalid.
67     if (Ty && Ty != V->getType())
68       return nullptr;
69 
70     Expected<Value *> MaybeV = MaterializeValueFn(Idx, ConstExprInsertBB);
71     if (!MaybeV) {
72       // TODO: We might want to propagate the precise error message here.
73       consumeError(MaybeV.takeError());
74       return nullptr;
75     }
76     return MaybeV.get();
77   }
78 
79   // No type specified, must be invalid reference.
80   if (!Ty)
81     return nullptr;
82 
83   // Create and return a placeholder, which will later be RAUW'd.
84   Value *V = new Argument(Ty);
85   ValuePtrs[Idx] = {V, TyID};
86   return V;
87 }
88