Arm64/Sve: Enable Sve only if vector length is 128 #104174
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@dotnet/arm64-contrib |
jkotas
reviewed
Jun 28, 2024
Co-authored-by: Jan Kotas <[email protected]>
jkotas
reviewed
Jun 28, 2024
jkotas
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Jun 28, 2024
| if (((cpuFeatures & ARM64IntrinsicConstants_Sve) != 0) && CLRConfig::GetConfigValue(CLRConfig::EXTERNAL_EnableArm64Sve)) | ||
| { | ||
| uint32_t maxVectorTLength = (maxVectorTBitWidth / 8); | ||
| uint64_t sveLengthFromOS = GetSveLengthFromOS(); |
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This method to be adjusted to return 0 on Windows with this change as otherwise we could be in an unsupported state since it's currently hardcoded as:
;; uint64_t GetSveLengthFromOS(void);
LEAF_ENTRY GetSveLengthFromOS
;; TODO-SVE: Remove the hardcoded value 128 and uncomment once CI machines are updated to use MASM 14.4 or later
;; rdvl x0, 1
mov x0, #128
ret lr
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hhm, so this is the case where if windows is running on 256-bit machine, we shouldn't be returning 128-bits because that will falsely turn on SVE. Let me uncomment the right way to do it to see if helix machines got the assembler upgraded to understand rdvl.
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alright, so that seemed to be working now.
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In .NET 9, we will only support SVE if the system vector length of 128-bits. For supporting higher vector length, needs more work that will be done in future release.
References: