RFR: 8321542: C2: Missing ChaCha20 stub for x86_32 leads to crashes

[Christian Hagedorn]

On Tue, 12 Dec 2023 01:02:59 GMT, Jamil Nimeh <jnimeh at openjdk.org> wrote:

> This fix corrects an oversight in the ChaCha20 intrinsics delivered by JDK-8247645.  An ifdef guard is now part of the x86 ChaCha20 intrinsics code which disables them by default on 32-bit platforms, as this architecture was not part of the feature delivery.

Marked as reviewed by chagedorn (Reviewer).

src/hotspot/cpu/x86/vm_version_x86.cpp line 1152:

> 1150:   // No support currently for ChaCha20 intrinsics on 32-bit platforms
> 1151:   if (UseChaCha20Intrinsics) {
> 1152:       warning("Support for ChaCha20 intrinsics not available on this CPU.");

Maybe we can adapt the message to follow the convention of the other warning messages for intrinsics like AES
https://github.com/openjdk/jdk/blob/2611a49ea13ee7a07f22692c3a4b32856ec5898f/src/hotspot/cpu/x86/vm_version_x86.cpp#L1062-L1065
or CRC32C
https://github.com/openjdk/jdk/blob/2611a49ea13ee7a07f22692c3a4b32856ec5898f/src/hotspot/cpu/x86/vm_version_x86.cpp#L1116-L1118

Suggestion:

      warning("ChaCha20 intrinsics are not available on this CPU.");


Though I see that not all existing warning messages are consistent.

Anyway, the bailout looks good to me.

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PR Review: https://git.openjdk.org/jdk/pull/17072#pullrequestreview-1776952817
PR Review Comment: https://git.openjdk.org/jdk/pull/17072#discussion_r1423662348