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Expand String.EndsWith/MemoryExtensions.EndsWith in JIT #98593
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch Issue DetailsIt turns out it's not difficult to extend the existing
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, ...
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@AndyAyersMS @jakobbotsch @dotnet/jit-contrib PTAL. Simple change to extend |
Actually, some of the unrolling can probably be removed entirely since we already have a generic |
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LGTM otherwise
Co-authored-by: Jakob Botsch Nielsen <Jakob.botsch.nielsen@gmail.com>
CI Failure is #98406 |
It turns out it's not difficult to extend the existing
*.StartsWith
expansion to cover*.EndsWith
as well. Example:Old codegen:
New codegen: