mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-02 14:26:02 +01:00
Dana Jansens
b705be9527
The current representation has two nested presence indicatators (the optional bool, the null pointer). Currently the pointer is never null, but the style guide suggests that T* should be used for parameters that may or may not be present, so we do not need the optional here. > When passing an object's address as an argument, use a reference > unless one of the following cases applies: > > - If the parameter is optional, use a pointer and document that it > may be null. Once the parameter is just a pointer, the ScopedTiming field does not need an optional either, and can just store the pointer. It would be more preferable to have an optional representation of a sometimes-null pointer like optional<T&> to describe a sometimes-null pointer, as this would allow clearer runtime diagnostics when used incorrectly (a check failure in unwrapping) and would be better self-documenting through syntax instead of a comment. But we do not currently have such a primitive.
80 lines
2.5 KiB
C++
80 lines
2.5 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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#ifndef CARBON_TOOLCHAIN_BASE_TIMINGS_H_
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#define CARBON_TOOLCHAIN_BASE_TIMINGS_H_
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#include <chrono>
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringRef.h"
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#include "toolchain/base/yaml.h"
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namespace Carbon {
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// Helps track timings for a compile.
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class Timings {
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public:
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// Records a timing for a scope, if the timings object is present.
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class ScopedTiming {
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public:
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// The `timings` may be null, in which case the `ScopedTiming` is a no-op.
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explicit ScopedTiming(Timings* timings, llvm::StringRef label)
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: timings_(timings),
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label_(label),
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start_(timings ? std::chrono::steady_clock::now()
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: std::chrono::steady_clock::time_point::min()) {}
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~ScopedTiming() {
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if (timings_) {
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timings_->Add(label_, std::chrono::steady_clock::now() - start_);
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}
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}
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private:
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Timings* timings_;
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llvm::StringRef label_;
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std::chrono::steady_clock::time_point start_;
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};
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// Adds tracking for nanoseconds, paired with the given label.
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auto Add(llvm::StringRef label, std::chrono::nanoseconds nanoseconds)
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-> void {
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timings_.push_back(
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{.label = std::string(label), .nanoseconds = nanoseconds});
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}
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auto OutputYaml(llvm::StringRef filename) const -> Yaml::OutputMapping {
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// Explicitly copy the filename.
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return Yaml::OutputMapping([&, filename](Yaml::OutputMapping::Map map) {
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map.Add("filename", filename);
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map.Add("nanoseconds",
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Yaml::OutputMapping([&](Yaml::OutputMapping::Map label_map) {
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std::chrono::nanoseconds total_nanoseconds(0);
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for (const auto& entry : timings_) {
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total_nanoseconds += entry.nanoseconds;
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label_map.Add(entry.label, static_cast<int64_t>(
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entry.nanoseconds.count()));
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}
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label_map.Add("Total",
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static_cast<int64_t>(total_nanoseconds.count()));
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}));
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});
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}
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private:
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// Timing for a specific label.
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struct Entry {
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std::string label;
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std::chrono::nanoseconds nanoseconds;
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};
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// The accumulated data on timings.
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llvm::SmallVector<Entry> timings_;
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};
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_BASE_TIMINGS_H_
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