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@cshung cshung commented Mar 13, 2025

Backport of # to release/9.0-staging

/cc @cshung

Customer Impact

@Typhon226 reported on #112897 that, on some machines, buggy behavior in __builtin_cpu_supports for Unix platforms could lie to us that it supports AVX512 when it doesn't. This could lead to runtime crashes.

Regression

  • Yes
  • No

The regression was introduced in PR #98712, commit 68cf2dd when I enabled VxSort for unix platforms, but this is not the root cause.

Testing

Local testing is done on various machines, but none of them hit the __builtin_cpu_supports buggy behavior, so it worked both before and after the changes.
#113032 (comment)

Customer testing is done on the machines that hit the issue, and the fixed version works as expected, for both #112897 (comment) (9.0 binaries) and #112897 (comment) (10.0 binaries)

Risk

The risk is low, the same function is used by the JIT to determine if the CPU supports AVX512.

@Copilot Copilot AI review requested due to automatic review settings March 13, 2025 19:23
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Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

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@mangod9
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mangod9 commented Mar 14, 2025

the build is still failing to find an include file.

@cshung cshung force-pushed the backport/pr-113032-to-release/9.0-staging branch from 0399a20 to ef9bf29 Compare March 14, 2025 21:07
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lgtm. we will take for consideration in 9.0.x

@jeffschwMSFT jeffschwMSFT added the Servicing-consider Issue for next servicing release review label Mar 14, 2025
@jeffschwMSFT jeffschwMSFT added this to the 9.0.x milestone Mar 14, 2025
@leecow leecow added Servicing-approved Approved for servicing release and removed Servicing-consider Issue for next servicing release review labels Mar 18, 2025
@leecow leecow modified the milestones: 9.0.x, 9.0.5 Mar 18, 2025
@cshung cshung merged commit 9226298 into dotnet:release/9.0-staging Mar 18, 2025
96 of 97 checks passed
@cshung cshung deleted the backport/pr-113032-to-release/9.0-staging branch March 18, 2025 18:55
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4 participants