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67 lines
2.5 KiB
C++
67 lines
2.5 KiB
C++
//===--- Timer.h - Shared timers for compilation phases ---------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_BASIC_TIMER_H
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#define SWIFT_BASIC_TIMER_H
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#include "swift/Basic/LLVM.h"
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#include "llvm/ADT/Optional.h"
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#include "llvm/Support/Timer.h"
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namespace swift {
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/// A convenience class for declaring a timer that's part of the Swift
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/// compilation timers group.
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///
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/// Please don't use this class directly for anything other than the flat,
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/// top-level compilation-phase timing numbers; unadorned SharedTimers are
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/// enabled, summed and reported via -debug-time-compilation, using LLVM's
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/// built-in logic for timer groups, and that logic doesn't work right if
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/// there's any nesting or reentry in timers at all (crashes on reentry,
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/// simply mis-reports nesting). Additional SharedTimers also confuse users
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/// who are expecting to see only top-level phase timings when they pass
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/// -debug-time-compilation.
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///
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/// Instead, please use FrontendStatsTracer objects and the -stats-output-dir
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/// subsystem in include/swift/Basic/Statistic.h. In addition to not
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/// interfering with users passing -debug-time-compilation, the
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/// FrontendStatsTracer objects automatically instantiate nesting-safe and
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/// reentry-safe SharedTimers themselves, as well as supporting event and
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/// source-entity tracing and profiling.
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class SharedTimer {
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enum class State {
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Initial,
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Skipped,
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Enabled
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};
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static State CompilationTimersEnabled;
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Optional<llvm::NamedRegionTimer> Timer;
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public:
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explicit SharedTimer(StringRef name) {
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if (CompilationTimersEnabled == State::Enabled)
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Timer.emplace(name, name, "swift", "Swift compilation");
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else
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CompilationTimersEnabled = State::Skipped;
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}
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/// Must be called before any SharedTimers have been created.
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static void enableCompilationTimers() {
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assert(CompilationTimersEnabled != State::Skipped &&
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"a timer has already been created");
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CompilationTimersEnabled = State::Enabled;
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}
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};
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} // end namespace swift
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#endif // SWIFT_BASIC_TIMER_H
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