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carbon-lang/executable_semantics/interpreter/heap.cpp
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "executable_semantics/interpreter/heap.h"
#include "executable_semantics/common/error_builders.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Error.h"
namespace Carbon {
auto Heap::AllocateValue(Nonnull<const Value*> v) -> AllocationId {
// Putting the following two side effects together in this function
// ensures that we don't do anything else in between, which is really bad!
// Consider whether to include a copy of the input v in this function
// or to leave it up to the caller.
AllocationId a(values_.size());
values_.push_back(v);
alive_.push_back(true);
return a;
}
auto Heap::Read(const Address& a, SourceLocation source_loc) const
-> ErrorOr<Nonnull<const Value*>> {
RETURN_IF_ERROR(this->CheckAlive(a.allocation_, source_loc));
return values_[a.allocation_.index_]->GetField(arena_, a.field_path_,
source_loc);
}
auto Heap::Write(const Address& a, Nonnull<const Value*> v,
SourceLocation source_loc) -> ErrorOr<Success> {
RETURN_IF_ERROR(this->CheckAlive(a.allocation_, source_loc));
ASSIGN_OR_RETURN(values_[a.allocation_.index_],
values_[a.allocation_.index_]->SetField(
arena_, a.field_path_, v, source_loc));
return Success();
}
auto Heap::CheckAlive(AllocationId allocation, SourceLocation source_loc) const
-> ErrorOr<Success> {
if (!alive_[allocation.index_]) {
return RuntimeError(source_loc)
<< "undefined behavior: access to dead value "
<< *values_[allocation.index_];
}
return Success();
}
void Heap::Deallocate(AllocationId allocation) {
if (alive_[allocation.index_]) {
alive_[allocation.index_] = false;
} else {
FATAL() << "deallocating an already dead value: "
<< *values_[allocation.index_];
}
}
void Heap::Print(llvm::raw_ostream& out) const {
llvm::ListSeparator sep;
for (size_t i = 0; i < values_.size(); ++i) {
out << sep;
if (!alive_[i]) {
out << "!!";
}
out << *values_[i];
}
}
} // namespace Carbon