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Merged
merged 6 commits into from
Feb 20, 2024
Merged

Expand String.EndsWith/MemoryExtensions.EndsWith in JIT #98593

merged 6 commits into from
Feb 20, 2024

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EgorBo
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@EgorBo EgorBo commented Feb 17, 2024 •
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It turns out it's not difficult to extend the existing *.StartsWith expansion to cover *.EndsWith as well. Example:

const string corelib = "System.Private.CoreLib.dll";

bool Test() => str.EndsWith(corelib, StringComparison.OrdinalIgnoreCase);

// Same for Span<char>/ReadOnlySpan<char> APIs

Old codegen:

; Assembly listing for method Program:Test
       mov      rdx, 0x20D80109480 ; 'System.Private.CoreLib.dll'
       mov      r8d, 5
       cmp      dword ptr [rcx], ecx
       tail.jmp [System.String:EndsWith(System.String,int):ubyte:this]

New codegen:

; Assembly listing for method Program:Test
       cmp      dword ptr [rcx+0x08], 26
       jl       SHORT G_M64019_IG04
       mov      eax, dword ptr [rcx+0x08]
       lea      rax, bword ptr [rcx+2*rax-0x34]
       vmovups  ymm0, ymmword ptr [rax+0x0C]
       vpor     ymm0, ymm0, ymmword ptr [reloc @RWD00]
       vpxor    ymm0, ymm0, ymmword ptr [reloc @RWD32]
       vmovups  ymm1, ymmword ptr [rax+0x20]
       vpor     ymm1, ymm1, ymmword ptr [reloc @RWD64]
       vpxor    ymm1, ymm1, ymmword ptr [reloc @RWD96]
       vpor     ymm0, ymm1, ymm0
       vptest   ymm0, ymm0
       sete     al
       movzx    rax, al
       jmp      SHORT G_M64019_IG05
G_M64019_IG04:
       xor      eax, eax
G_M64019_IG05:
       movzx    rax, al
       vzeroupper 
       ret      
RWD00  	dq	0020002000200020h, 0020000000200020h, ...
RWD32  	dq	0074007300790073h, 0070002E006D0065h, ...
RWD64  	dq	0020002000200020h, 0020002000200000h, ...
RWD96  	dq	0065007400610076h, 0072006F0063002Eh, ...

@ghost ghost assigned EgorBo Feb 17, 2024
@ghost ghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Feb 17, 2024
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ghost commented Feb 17, 2024

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Issue Details

It turns out it's not difficult to extend the existing *.StartsWith expansion to cover *.EndsWith as well. Affected APIs:

const string corelib = "System.Private.CoreLib.dll";

bool Test() => str.EndsWith(corelib, StringComparison.OrdinalIgnoreCase);

// Same for Span<char>/ReadOnlySpan<char> APIs

Old codegen:

; Assembly listing for method Program:Test
       mov      rdx, 0x20D80109480 ; 'System.Private.CoreLib.dll'
       mov      r8d, 5
       cmp      dword ptr [rcx], ecx
       tail.jmp [System.String:EndsWith(System.String,int):ubyte:this]

New codegen:

; Assembly listing for method Program:Test
       cmp      dword ptr [rcx+0x08], 26
       jl       SHORT G_M64019_IG04
       mov      eax, dword ptr [rcx+0x08]
       lea      rax, bword ptr [rcx+2*rax-0x34]
       vmovups  ymm0, ymmword ptr [rax+0x0C]
       vpor     ymm0, ymm0, ymmword ptr [reloc @RWD00]
       vpxor    ymm0, ymm0, ymmword ptr [reloc @RWD32]
       vmovups  ymm1, ymmword ptr [rax+0x20]
       vpor     ymm1, ymm1, ymmword ptr [reloc @RWD64]
       vpxor    ymm1, ymm1, ymmword ptr [reloc @RWD96]
       vpor     ymm0, ymm1, ymm0
       vptest   ymm0, ymm0
       sete     al
       movzx    rax, al
       jmp      SHORT G_M64019_IG05
G_M64019_IG04:
       xor      eax, eax
G_M64019_IG05:
       movzx    rax, al
       vzeroupper 
       ret      
RWD00  	dq	0020002000200020h, 0020000000200020h, ...
RWD32  	dq	0074007300790073h, 0070002E006D0065h, ...
RWD64  	dq	0020002000200020h, 0020002000200000h, ...
RWD96  	dq	0065007400610076h, 0072006F0063002Eh, ...
Author: EgorBo
Assignees: EgorBo
Labels:

area-CodeGen-coreclr
Milestone: -

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EgorBo commented Feb 17, 2024

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@EgorBo EgorBo marked this pull request as ready for review February 17, 2024 15:34
This was referenced Feb 17, 2024
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EgorBo commented Feb 19, 2024

@AndyAyersMS @jakobbotsch @dotnet/jit-contrib PTAL. Simple change to extend StartsWith expansion with EndsWith. Basically, EndsWith is SequenceEquals where we shift the offset to dataPtr + (stringLength * 2 - constValueLength * 2)

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EgorBo commented Feb 19, 2024

Actually, some of the unrolling can probably be removed entirely since we already have a generic SequenceEquals unrolling in a late phase. But it's still needed for a bit complicated OrdinalIgnoreCase

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LGTM otherwise

EgorBo and others added 2 commits February 20, 2024 15:41
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EgorBo commented Feb 20, 2024

CI Failure is #98406

@EgorBo EgorBo merged commit 46870a0 into dotnet:main Feb 20, 2024
@EgorBo EgorBo deleted the endswith branch February 20, 2024 18:37
@DrewScoggins DrewScoggins mentioned this pull request Feb 27, 2024
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@jakobbotsch jakobbotsch jakobbotsch approved these changes

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