On Thu, 26 Feb 2026 06:59:34 GMT, xinyangwu <[email protected]> wrote:
>>> Not a review! I've seen the `hotspot-compiler` label and I've just run some >>> testing. I've got a failure on the test >>> `compiler/codegen/aes/TestAESMain.java` using flags `-XX:UseAVX=3 >>> -XX:+UnlockDiagnosticVMOptions -XX:+UseKNLSetting` on a machine with an >>> Intel Xeon Platinum 8358 Processor. >> >> Thank you for your testing @marc-chevalier. Interesting, as I wasn't able >> to reproduce this issue using the same options on a AMD EPYC 9J14 96-core >> processor. > >> Not a review! I've seen the `hotspot-compiler` label and I've just run some >> testing. I've got a failure on the test >> `compiler/codegen/aes/TestAESMain.java` using flags `-XX:UseAVX=3 >> -XX:+UnlockDiagnosticVMOptions -XX:+UseKNLSetting` on a machine with an >> Intel Xeon Platinum 8358 Processor. > > Thanks a lot for testing and reporting @marc-chevalier. > > I noticed that `-XX:+UseKNLSetting` clears several Intel AVX-512 features > (AVX512_VAES, AVX512BW, AVX512VL, etc.) in `vm_version_x86.cpp`, which > changes the AES intrinsic path. Unfortunately, I don’t currently have access > to an Intel AVX-512 machine to reproduce this directly. > > I tried to simulate a similar setup on an AMD EPYC 9755 (AVX-512 capable) > machine by changing `is_intel()` to `is_amd()`, but I wasn’t able to > reproduce the failure. > > There may be some differences between Intel and AMD AVX-512 behavior, or my > simulation might not be fully equivalent to `UseKNLSetting` on Intel. > > I’ll keep investigating this and try to reproduce it on an Intel system if > possible. Thanks again for the detailed report! > As @reverse-kong noticed, I think `UseKNLSetting` is used only for > > https://github.com/openjdk/jdk/blob/fd48f68a2cc69a0cccbc2503f29aad2de19ec098/src/hotspot/cpu/x86/vm_version_x86.hpp#L838 > > > Does the AMD EPYC 9J14 is recognized as a Knights one here? I think AMD EPYC 9J14 can be recognized as Knights here, but only Intel CPUs actually clear those AVX-512 features. So my guess is that this failure only shows up on Intel AVX-512 machines when `-XX:+UseKNLSetting` is enabled. https://github.com/openjdk/jdk/blob/fd48f68a2cc69a0cccbc2503f29aad2de19ec098/src/hotspot/cpu/x86/vm_version_x86.cpp#L1064-L1087 > @reverse-kong Could using [Intel > SDE](https://www.intel.com/content/www/us/en/developer/articles/tool/software-development-emulator.html) > help with that? I’ll try using Intel SDE to reproduce this @marc-chevalier. Thanks for the suggestion! ------------- PR Comment: https://git.openjdk.org/jdk/pull/29385#issuecomment-3964992589
