Remove pinning from StringBuilder

[stephentoub]

Switch from pointers to refs to avoid pinning the inputs.

As part of this, I also consolidated the fast-path that was there specifically for string inputs to also apply to span inputs, char arrays, pointers, etc.

Method	Toolchain	Value	Mean	Ratio	Code Size
String	\main\corerun.exe	a	2.958 ns	1.00	719 B
String	\pr\corerun.exe	a	2.127 ns	0.72	684 B
Span	\main\corerun.exe	a	7.652 ns	1.00	1,170 B
Span	\pr\corerun.exe	a	2.516 ns	0.33	693 B
CharArray	\main\corerun.exe	a	6.631 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	a	2.133 ns	0.32	684 B
AppendJoin	\main\corerun.exe	a	33.384 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	a	22.326 ns	0.67	811 B
String	\main\corerun.exe	ab	3.432 ns	1.00	719 B
String	\pr\corerun.exe	ab	2.391 ns	0.70	684 B
Span	\main\corerun.exe	ab	7.274 ns	1.00	1,170 B
Span	\pr\corerun.exe	ab	2.932 ns	0.40	693 B
CharArray	\main\corerun.exe	ab	6.384 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	ab	2.374 ns	0.37	684 B
AppendJoin	\main\corerun.exe	ab	36.239 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	ab	22.674 ns	0.63	811 B
String	\main\corerun.exe	abc	4.760 ns	1.00	719 B
String	\pr\corerun.exe	abc	4.348 ns	0.91	684 B
Span	\main\corerun.exe	abc	7.354 ns	1.00	1,170 B
Span	\pr\corerun.exe	abc	4.811 ns	0.66	693 B
CharArray	\main\corerun.exe	abc	6.372 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abc	4.330 ns	0.68	684 B
AppendJoin	\main\corerun.exe	abc	38.682 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abc	31.658 ns	0.82	811 B
String	\main\corerun.exe	abcd	4.699 ns	1.00	719 B
String	\pr\corerun.exe	abcd	4.599 ns	0.98	684 B
Span	\main\corerun.exe	abcd	7.296 ns	1.00	1,170 B
Span	\pr\corerun.exe	abcd	4.950 ns	0.68	693 B
CharArray	\main\corerun.exe	abcd	6.390 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abcd	4.469 ns	0.70	684 B
AppendJoin	\main\corerun.exe	abcd	39.048 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abcd	30.638 ns	0.78	811 B
String	\main\corerun.exe	abcdefgh	4.698 ns	1.00	719 B
String	\pr\corerun.exe	abcdefgh	4.504 ns	0.96	684 B
Span	\main\corerun.exe	abcdefgh	7.366 ns	1.00	1,170 B
Span	\pr\corerun.exe	abcdefgh	5.057 ns	0.69	693 B
CharArray	\main\corerun.exe	abcdefgh	6.353 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abcdefgh	4.546 ns	0.72	684 B
AppendJoin	\main\corerun.exe	abcdefgh	39.165 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abcdefgh	30.765 ns	0.79	811 B

usingSystem;usingSystem.Linq;usingSystem.Runtime.CompilerServices;usingSystem.Text;usingSystem.Text.RegularExpressions;usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;[DisassemblyDiagnoser]publicclassProgram{publicstaticvoidMain(string[]args)=>BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);privateconstintIterations=1000;privateStringBuilder_sb=newStringBuilder(100_000);privatechar[]_chars;privatestring[]_strings;[Params("a","ab","abc","abcd","abcdefgh")]publicstringValue{get;set;}[GlobalSetup]publicvoidSetup(){_chars=Value.ToCharArray();_strings=Enumerable.Repeat(Value,4).ToArray();}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidString(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append(Value);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidSpan(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append((ReadOnlySpan<char>)Value);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidCharArray(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append(_chars);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidAppendJoin(){_sb.Clear();for(inti=0;i<Iterations;i++){_sb.AppendJoin(", ",_strings);}}}

[ghost]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Switch from pointers to refs to avoid pinning the inputs.

As part of this, I also consolidated the fast-path that was there specifically for string inputs to also apply to span inputs, char arrays, pointers, etc.

Method	Toolchain	Value	Mean	Ratio	Code Size
String	\main\corerun.exe	a	2.958 ns	1.00	719 B
String	\pr\corerun.exe	a	2.127 ns	0.72	684 B
Span	\main\corerun.exe	a	7.652 ns	1.00	1,170 B
Span	\pr\corerun.exe	a	2.516 ns	0.33	693 B
CharArray	\main\corerun.exe	a	6.631 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	a	2.133 ns	0.32	684 B
AppendJoin	\main\corerun.exe	a	33.384 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	a	22.326 ns	0.67	811 B
String	\main\corerun.exe	ab	3.432 ns	1.00	719 B
String	\pr\corerun.exe	ab	2.391 ns	0.70	684 B
Span	\main\corerun.exe	ab	7.274 ns	1.00	1,170 B
Span	\pr\corerun.exe	ab	2.932 ns	0.40	693 B
CharArray	\main\corerun.exe	ab	6.384 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	ab	2.374 ns	0.37	684 B
AppendJoin	\main\corerun.exe	ab	36.239 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	ab	22.674 ns	0.63	811 B
String	\main\corerun.exe	abc	4.760 ns	1.00	719 B
String	\pr\corerun.exe	abc	4.348 ns	0.91	684 B
Span	\main\corerun.exe	abc	7.354 ns	1.00	1,170 B
Span	\pr\corerun.exe	abc	4.811 ns	0.66	693 B
CharArray	\main\corerun.exe	abc	6.372 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abc	4.330 ns	0.68	684 B
AppendJoin	\main\corerun.exe	abc	38.682 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abc	31.658 ns	0.82	811 B
String	\main\corerun.exe	abcd	4.699 ns	1.00	719 B
String	\pr\corerun.exe	abcd	4.599 ns	0.98	684 B
Span	\main\corerun.exe	abcd	7.296 ns	1.00	1,170 B
Span	\pr\corerun.exe	abcd	4.950 ns	0.68	693 B
CharArray	\main\corerun.exe	abcd	6.390 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abcd	4.469 ns	0.70	684 B
AppendJoin	\main\corerun.exe	abcd	39.048 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abcd	30.638 ns	0.78	811 B
String	\main\corerun.exe	abcdefgh	4.698 ns	1.00	719 B
String	\pr\corerun.exe	abcdefgh	4.504 ns	0.96	684 B
Span	\main\corerun.exe	abcdefgh	7.366 ns	1.00	1,170 B
Span	\pr\corerun.exe	abcdefgh	5.057 ns	0.69	693 B
CharArray	\main\corerun.exe	abcdefgh	6.353 ns	1.00	1,171 B
CharArray	\pr\corerun.exe	abcdefgh	4.546 ns	0.72	684 B
AppendJoin	\main\corerun.exe	abcdefgh	39.165 ns	1.00	821 B
AppendJoin	\pr\corerun.exe	abcdefgh	30.765 ns	0.79	811 B

usingSystem;usingSystem.Linq;usingSystem.Runtime.CompilerServices;usingSystem.Text;usingSystem.Text.RegularExpressions;usingBenchmarkDotNet.Attributes;usingBenchmarkDotNet.Running;[DisassemblyDiagnoser]publicclassProgram{publicstaticvoidMain(string[]args)=>BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);privateconstintIterations=1000;privateStringBuilder_sb=newStringBuilder(100_000);privatechar[]_chars;privatestring[]_strings;[Params("a","ab","abc","abcd","abcdefgh")]publicstringValue{get;set;}[GlobalSetup]publicvoidSetup(){_chars=Value.ToCharArray();_strings=Enumerable.Repeat(Value,4).ToArray();}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidString(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append(Value);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidSpan(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append((ReadOnlySpan<char>)Value);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidCharArray(){_sb.Clear();for(inti=0;i<Iterations;i++)_sb.Append(_chars);}[Benchmark(OperationsPerInvoke=Iterations)]publicvoidAppendJoin(){_sb.Clear();for(inti=0;i<Iterations;i++){_sb.AppendJoin(", ",_strings);}}}

Author:	stephentoub
Assignees:	stephentoub
Labels:	area-System.Runtime, tenet-performance
Milestone:	7.0.0

[EgorBo]

Improvements on Win-x64: dotnet/perf-autofiling-issues#3219

[stephentoub]

Improvements on Win-x64: dotnet/perf-autofiling-issues#3219

Nice, thanks.

[EgorBo]

Improvement for DateTimeOffset.ToString if it's related: dotnet/perf-autofiling-issues#3239

[stephentoub]

if it's related

Likely. That test uses ToString(null) which will end up formatting into a StringBuilder.