Use usize::repeat_u8 instead of implementing repeat_byte in memchr.rs

[WaffleLapkin]

It's simpler that way and the tricks don't actually make a difference: https://godbolt.org/z/zrvYY1dGx

[rustbot]

r? @m-ou-se

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[m-ou-se]

@bors r+ rollup=never

[bors]

📌 Commit 234e950 has been approved by m-ou-se

It is now in the queue for this repository.

[bors]

⌛ Testing commit 234e950 with merge 896f7bf...

[rust-log-analyzer]

The job x86_64-mingw failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

failures:

---- [rustdoc] tests\rustdoc\intra-doc\builtin-macros.rs stdout ----

error: rustdoc failed!
status: exit code: 0xc00000fd
command: PATH="C:\a\rust\rust\build\x86_64-pc-windows-gnu\stage2\bin;C:\a\rust\rust\build\x86_64-pc-windows-gnu\stage0-bootstrap-tools\x86_64-pc-windows-gnu\release\deps;C:\a\rust\rust\build\x86_64-pc-windows-gnu\stage0\bin;C:\a\rust\rust\ninja;C:\a\rust\rust\mingw64\bin;C:\hostedtoolcache\windows\Python\3.12.0\x64\Scripts;C:\hostedtoolcache\windows\Python\3.12.0\x64;C:\msys64\usr\bin;C:\a\rust\rust\sccache;C:\PROGRA~1\MongoDB\bin;C:\aliyun-cli;C:\vcpkg;C:\cf-cli;C:\Program Files (x86)\NSIS;C:\tools\zstd;C:\Program Files\Mercurial;C:\hostedtoolcache\windows\stack\2.13.1\x64;C:\cabal\bin;C:\ghcup\bin;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 5.7\bin;C:\Program Files\R\R-4.3.2\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.20.11\x64\bin;C:\hostedtoolcache\windows\Python\3.7.9\x64\Scripts;C:\hostedtoolcache\windows\Python\3.7.9\x64;C:\hostedtoolcache\windows\Ruby\2.5.9\x64\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\8.0.392-8\x64\bin;C:\Program Files\ImageMagick-7.1.1-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\Program Files\Eclipse Foundation\jdk-8.0.302.8-hotspot\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\ProgramData\Chocolatey\bin;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files (x86)\Microsoft SQL Server\110\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\120\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\130\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\140\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\150\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\160\DTS\Binn;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\TortoiseSVN\bin;C:\Program Files\CMake\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.7\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files\nodejs;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\SeleniumWebDrivers\ChromeDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\bin;C:\Program Files (x86)\Microsoft BizTalk Server;C:\Program Files\LLVM\bin;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps" "C:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\bin\\rustdoc.exe" "-L" "C:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\stage2\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-L" "C:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\test\\rustdoc\\intra-doc\\builtin-macros\\auxiliary" "-o" "C:\\a\\rust\\rust\\build\\x86_64-pc-windows-gnu\\test\\rustdoc\\intra-doc\\builtin-macros" "--deny" "warnings" "C:\\a\\rust\\rust\\tests\\rustdoc\\intra-doc\\builtin-macros.rs" "-A" "internal_features"
--- stderr -------------------------------

thread 'main' has overflowed its stack
------------------------------------------

[bors]

💔 Test failed - checks-actions

[WaffleLapkin]

error: rustdoc failed!
...
thread 'main' has overflowed its stack

Looks spurious.
@bors retry

[bors]

⌛ Testing commit 234e950 with merge abe34e9...

[bors]

☀️ Test successful - checks-actions
Approved by: m-ou-se
Pushing abe34e9 to master...

[rust-timer]

Finished benchmarking commit (abe34e9): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.1%	[5.1%, 5.1%]	1
Improvements ✅ (primary)	-3.7%	[-3.7%, -3.7%]	1
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	-3.7%	[-3.7%, -3.7%]	1

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 672.005s -> 673.033s (0.15%)
Artifact size: 313.36 MiB -> 313.38 MiB (0.01%)