llvm/lib/Bitcode/Reader/ValueList.cpp

   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 }