Improving Arm64 Performance in .NET 9.0

[kunalspathak]

Overview

As we did in the past for .NET 5, .NET 7 and .NET 8, we would like to continue improving Arm64 in .NET 9 as well. Here are the top-level themes we plan to address. Some of the issues are from the past releases that we did not get time to work upon. while others are about adding instructions of newer arm versions or exposing the Arm functionality to the .NET API level.

New instructions

• Arm64: Add SVE/SVE2 support in .NET 9 #93095
• [API Proposal]: Arm64 [Load/Store]Vector64 and [Load/Store]Vector128 for 2,3 and 4 variants #84510
• Explore new instructions added in Armv8.3 ~ Armv9 and see if we can use them in JIT
• Start using Post increment addressing mode in JIT wherever applicable.

Performance improvements

• Review the multi-op instruction usage for Arm64 #68028
• Consider using SIMD registers for "hot" local variables instead of placing them on stack when out of free GP registers #10444
• Arm64: Use VectorTableLookup/VectorTableLookupExtension APIs in libraries #84328
• Consume LoadVector/StoreVector in .NET libraries
• Improve Vector128.ExtractMostSignificantBits for arm64 #76047
• ARM64: Suboptimal codegen for addressing modes #93263

Stretch goals

• Consume SVE2 APIs in .NET libraries
• Investigate instability in TE for Arm64 #77916
• Experiment how much TP impact we will see if enabled pointer authentication for coreclr. Depending on that, decide if it should be enabled for JIT.

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Issue Details

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Overview

As we did in the past for .NET 5, .NET 7 and .NET 8, we would like to continue improving Arm64 in .NET 9 as well. Here are the top-level themes we plan to address. Some of the issues are from the past releases that we did not get time to work upon. while others are about adding instructions of newer arm versions or exposing the Arm functionality to the .NET API level.

New instructions

• Arm64: Add SVE/SVE2 support in .NET 9 #93095
• [API Proposal]: Arm64 [Load/Store]Vector64 and [Load/Store]Vector128 for 2,3 and 4 variants #84510
• Explore new instructions added in Armv8.3 ~ Armv9 and see if we can use them in JIT
• Start using Post increment addressing mode in JIT wherever applicable.

Performance improvements

• Review the multi-op instruction usage for Arm64 #68028
• Consider using SIMD registers for "hot" local variables instead of placing them on stack when out of free GP registers #10444
• Arm64: Use VectorTableLookup/VectorTableLookupExtension APIs in libraries #84328
• Consume LoadVector/StoreVector in .NET libraries
• Improve Vector128.ExtractMostSignificantBits for arm64 #76047

Stretch goals

• Consume SVE2 APIs in .NET libraries
• Investigate instability in TE for Arm64 #77916
• Experiment how much TP impact we will see if enabled pointer authentication for coreclr. Depending on that, decide if it should be enabled for JIT.

Author:	kunalspathak
Assignees:	-
Labels:	area-CodeGen-coreclr, User Story
Milestone:	-

[neon-sunset]

@kunalspathak Please also link #93263 to this. There might be some other untracked issues for ARM64, I think? Perhaps makes sense to go through the label and link them unless I misunderstood the way this issue is written and it's supposed to link only major action items? Thanks!

[kunalspathak]

Please also link #93263 to this

Done.

[JulieLeeMSFT]

Closing this user story and replan for .NET 10. Most of work during .NET 9 was to enable SVE APIs, tracked in #93095.