Clean up Stopwatch a bit by stephentoub · Pull Request #111834 · dotnet/runtime

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

stephentoub · 2025-01-26T01:59:45Z

Remove unnecessary Reset call from ctor
Remove unnecessary branch for _elapsed < 0 (Stop is now more inlineable)
Remove some defunct comments
Clean up style of Stop to match that of Start

Closes#66734
Related to #111829

Method	Toolchain	Mean	Ratio	Code Size	Allocated	Alloc Ratio
Time	\main\corerun.exe	38.51 ns	1.00	363 B	40 B	1.00
Time	\pr\corerun.exe	30.35 ns	0.79	156 B	-	0.00

usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;usingSystem.Diagnostics;usingSystem.Runtime.CompilerServices;BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);[DisassemblyDiagnoser][MemoryDiagnoser(false)]publicpartialclassTests{[Benchmark]publicTimeSpanTime(){Stopwatchsw=Stopwatch.StartNew();Nop();sw.Stop();returnsw.Elapsed;}[MethodImpl(MethodImplOptions.NoInlining)]publicstaticvoidNop(){}}

- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

paulbartrum · 2025-01-26T09:58:11Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

stephentoub · 2025-01-26T12:43:13Z

Are the Debug.Assert(IsHighResolution); asserts still needed? These will always be true as far as I can tell.

They're not needed.

MihaZupan

Nice

stephentoub · 2025-01-26T18:08:12Z

/ba-g unrelated infra

tannergooding

LGTM.

* main: (22 commits) Clean up Stopwatch a bit (dotnet#111834) JIT: Fix embedded broadcast simd size (dotnet#111638) Revert potential UB due to aliasing + more WB removals (dotnet#111733) re-enable acceleration of Vector512<long>.op_Multiply (dotnet#111832) Handle OSSL 3.4 change to SAN:othername formatting JIT: Fix stack allocated arrays for NativeAOT (dotnet#111827) JIT: enhance RBO inference for similar compares to constants (dotnet#111766) JIT: Don't run optSetBlockWeights when we have PGO data (dotnet#111764) [Android] Make sure RuntimeFlavor=CoreCLR when clr subset is specified (dotnet#111821) Change empty subject test certificate to include a critical SAN. Fix reversed code offsets in GcInfo (dotnet#111792) Swap some libraries areas between leads (dotnet#111816) Add left-handed spherical and cylindrical billboards (dotnet#109605) JIT: revise `optRelopImpliesRelop` to always set `reverseSense` (dotnet#111803) Fix Zip64ExtraField handling (dotnet#111802) Add build support for Android+CoreCLR (dotnet#110471) arm64: Add bic(s) compact encoding (dotnet#111452) JIT: Ensure `BBF_PROF_WEIGHT` flag is set when we have PGO data (dotnet#111780) Add support for AVX10.2, Add AVX10.2 API surface and template tests (dotnet#111209) JIT: Preliminary for enabling inlining late devirted calls (dotnet#111782) ...

TonyValenti · 2025-01-27T14:11:22Z

Regarding negative values, I THINK I have observed this in the past and attributed it to either a daylight savings time adjustment or windows time synchronization. Maybe those are no longer issues but I wanted to share.

stephentoub · 2025-01-27T14:14:35Z

It's worth reiterating that this special-casing was only in Stop. It didn't apply if you did:

sw.Start();
...;TimeSpanelapsed=sw.Elapsed;

only if you did:

sw.Start();
...;sw.Stop();TimeSpanelapsed=sw.Elapsed;

That's true on .NET Framework as well.

Given that, even if there are still some machines in circulation where this could manifest, I'm comfortable removing this one place it was being special-cased.

Clean up Stopwatch a bit
2fbfd15
- Remove unnecessary Reset call from ctor - Remove unnecessary branch for _elapsed < 0 - Remove some defunct comments - Clean up style of Stop to match that of Start

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stephentoub added area-System.Diagnostics and removed needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners labels Jan 26, 2025

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stephentoub requested a review from MihaZupan January 26, 2025 02:00

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restarted. Azure DevOps can't recover from restarts. dotnet/dnceng#3879
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More stylistic cleanup
df34222
- Use expression-bodied properties - Remove unnecessary Debug.Asserts - Remove private method whose impl could just have been that of an existing public property - Change a private GetXx method to an Xx property. - Remove some type names that could be inferred

MihaZupan approved these changes Jan 26, 2025
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stephentoub merged commit f41b65f into dotnet:mainJan 26, 2025

stephentoub deleted the stopwatchstop branch January 26, 2025 18:09

tannergooding reviewed Jan 26, 2025
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Comment threadsrc/libraries/System.Private.CoreLib/src/System/Diagnostics/Stopwatch.cs

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ymalich mentioned this pull request Jan 27, 2025
Micro-optimization suggestion: Allocate less memory for Stopwatch object on the heap #111829
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