mirror of
https://github.com/carbon-language/carbon-lang.git
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Geoff Romer
0df9e8666c
This lets us statically distinguish between code that works with arbitrary `Address`es and code that can only work with pointers to separately-allocated storage, and so we no longer need to worry about the latter code crashing at run-time (as `Heap::Deallocate` did) or silently doing the wrong thing (as `Heap::PrintAddress` did) if it's given the wrong kind of `Address`.
70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "executable_semantics/interpreter/heap.h"
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#include "executable_semantics/common/error.h"
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#include "llvm/ADT/StringExtras.h"
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namespace Carbon {
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auto Heap::AllocateValue(Nonnull<const Value*> v) -> AllocationId {
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// Putting the following two side effects together in this function
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// ensures that we don't do anything else in between, which is really bad!
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// Consider whether to include a copy of the input v in this function
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// or to leave it up to the caller.
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AllocationId a(values_.size());
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values_.push_back(v);
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alive_.push_back(true);
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return a;
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}
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auto Heap::Read(const Address& a, SourceLocation source_loc)
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-> Nonnull<const Value*> {
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this->CheckAlive(a.allocation_, source_loc);
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return values_[a.allocation_.index_]->GetField(arena_, a.field_path_,
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source_loc);
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}
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void Heap::Write(const Address& a, Nonnull<const Value*> v,
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SourceLocation source_loc) {
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this->CheckAlive(a.allocation_, source_loc);
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values_[a.allocation_.index_] = values_[a.allocation_.index_]->SetField(
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arena_, a.field_path_, v, source_loc);
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}
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void Heap::CheckAlive(AllocationId allocation, SourceLocation source_loc) {
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if (!alive_[allocation.index_]) {
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FATAL_RUNTIME_ERROR(source_loc)
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<< "undefined behavior: access to dead value "
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<< *values_[allocation.index_];
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}
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}
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void Heap::Deallocate(AllocationId allocation) {
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if (alive_[allocation.index_]) {
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alive_[allocation.index_] = false;
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} else {
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FATAL_RUNTIME_ERROR_NO_LINE() << "deallocating an already dead value";
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}
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}
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void Heap::Print(llvm::raw_ostream& out) const {
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llvm::ListSeparator sep;
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for (size_t i = 0; i < values_.size(); ++i) {
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out << sep;
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PrintAllocation(AllocationId(i), out);
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}
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}
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void Heap::PrintAllocation(AllocationId allocation,
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llvm::raw_ostream& out) const {
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if (!alive_[allocation.index_]) {
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out << "!!";
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}
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out << *values_[allocation.index_];
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}
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} // namespace Carbon
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