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carbon-lang/toolchain/base/value_store_impl.h
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Chandler Carruth d010d52f37 Switch the ValueStore-related templates to use explicit instantiation (#7116)
As part of this, move functions that seem reasonable to make out-of-line
to a separate `_impl.h` header file that is only included where the
explicit instantiation _definition_ is provided.

By using explicit instantiation we can make these templates behave more
like non-template classes in terms of supporting out-of-line definitions
that don't need to be compiled by every translation unit. The set of
eventual instantiations here is fundamentally known, and there tend to
be headers that define a canonical "leaf" type where it makes sense to
trigger the explicit instantiation.

Where we already had a `.cpp` file to put the explicit instantiation
definition, use it. But in some places we didn't have such a `.cpp` file
so this PR adds those.

This also requires that we have precise constraints on APIs that _can't_
be instantiated for specific argument types, as now we don't do this
lazily.

Combined, this appears to reduce the sum of object file sizes in the
`check` directory by almost 40% (122mb -> 74mb) in my measurement.

My actual goal was to improve compile times, but so far I don't have a
great methodology for measuring these... But the object file size
reduction seems to confirm this is a net win and likely represents a
non-trivial improvement in compile time.

Assisted-by: Antigravity with Gemini
2026-05-14 08:29:17 +00:00

109 lines
4.0 KiB
C++

// 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
#ifndef CARBON_TOOLCHAIN_BASE_VALUE_STORE_IMPL_H_
#define CARBON_TOOLCHAIN_BASE_VALUE_STORE_IMPL_H_
#include "toolchain/base/value_store.h"
namespace Carbon {
template <typename IdT, typename ValueT, typename TagIdT>
ValueStore<IdT, ValueT, TagIdT>::ValueStore()
requires(IdTagIsUntagged<IdTagType>)
= default;
template <typename IdT, typename ValueT, typename TagIdT>
ValueStore<IdT, ValueT, TagIdT>::ValueStore(IdTagType tag)
requires(!IdTagIsUntagged<IdTagType>)
: tag_(tag) {}
template <typename IdT, typename ValueT, typename TagIdT>
ValueStore<IdT, ValueT, TagIdT>::ValueStore(
typename ValueStore<IdT, ValueT, TagIdT>::IdTagType::TagIdType id,
int32_t initial_reserved_ids)
requires(!IdTagIsUntagged<IdTagType>)
: tag_(id, initial_reserved_ids) {}
template <typename IdT, typename ValueT, typename TagIdT>
ValueStore<IdT, ValueT, TagIdT>::~ValueStore() = default;
template <typename IdT, typename ValueT, typename TagIdT>
ValueStore<IdT, ValueT, TagIdT>::ValueStore(ValueStore&&) noexcept = default;
template <typename IdT, typename ValueT, typename TagIdT>
auto ValueStore<IdT, ValueT, TagIdT>::operator=(ValueStore&&) noexcept
-> ValueStore& = default;
template <typename IdT, typename ValueT, typename TagIdT>
auto ValueStore<IdT, ValueT, TagIdT>::Resize(int32_t size,
ConstRefType default_value) -> void
requires(std::is_copy_constructible_v<ValueT>)
{
if (size <= size_) {
return;
}
auto [begin_chunk_index, begin_pos] = RawIndexToChunkIndices(size_);
// Use an inclusive range so that if `size` would be the next chunk, we
// don't try doing something with it.
auto [end_chunk_index, end_pos] = RawIndexToChunkIndices(size - 1);
chunks_.resize(end_chunk_index + 1);
// If the begin and end chunks are the same, we only fill from begin to end.
if (begin_chunk_index == end_chunk_index) {
chunks_[begin_chunk_index].UninitializedFill(end_pos - begin_pos + 1,
default_value);
} else {
// Otherwise, we do partial fills on the begin and end chunk, and full
// fills on intermediate chunks.
chunks_[begin_chunk_index].UninitializedFill(Chunk::Capacity() - begin_pos,
default_value);
for (auto i = begin_chunk_index + 1; i < end_chunk_index; ++i) {
chunks_[i].UninitializedFill(Chunk::Capacity(), default_value);
}
chunks_[end_chunk_index].UninitializedFill(end_pos + 1, default_value);
}
// Update size.
size_ = size;
}
template <typename IdT, typename ValueT, typename TagIdT>
auto ValueStore<IdT, ValueT, TagIdT>::Chunk::UninitializedFill(
int32_t fill_count,
typename ValueStore<IdT, ValueT, TagIdT>::ConstRefType default_value)
-> void
requires(std::is_copy_constructible_v<ValueT>)
{
CARBON_DCHECK(num_ + fill_count <= Capacity());
std::uninitialized_fill_n(buf_ + num_, fill_count, default_value);
num_ += fill_count;
}
template <typename IdT, typename ValueT, typename TagIdT>
auto ValueStore<IdT, ValueT, TagIdT>::OutputYaml() const
-> Yaml::OutputMapping {
return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
for (auto [id, value] : enumerate()) {
if constexpr (requires(llvm::raw_ostream& out) { out << value; }) {
map.Add(PrintToString(id), Yaml::OutputScalar(value));
} else {
map.Add(PrintToString(id), Yaml::OutputScalar("<unprintable>"));
}
}
});
}
template <typename IdT, typename ValueT, typename TagIdT>
auto ValueStore<IdT, ValueT, TagIdT>::CollectMemUsage(
MemUsage& mem_usage, llvm::StringRef label) const -> void {
mem_usage.Add(label.str(), size_ * sizeof(ValueType),
Chunk::CapacityBytes * chunks_.size());
}
} // namespace Carbon
#endif // CARBON_TOOLCHAIN_BASE_VALUE_STORE_IMPL_H_