RFR: 8358592: Assert in Assembler::ptest due to missing SSE42 support

guanqiang han duke at openjdk.org
Mon Jul 7 02:57:13 UTC 2025


Setting "-XX:UseSSE=1" in command line prevents the code from entering the block shown below, which causes UseSSE42Intrinsics to not be correctly set. Because supports_sse3() return false.
![图片1](https://github.com/user-attachments/assets/d3cdb1fe-f0e0-41dc-98c9-4427eaffdb0e)
in addition , setting "-XX:+UseSSE42Intrinsics" in command line set UseVectorizedMismatchIntrinsic to True shown below.
![图片2](https://github.com/user-attachments/assets/bbe623a3-453a-483d-b34c-1cdb394f2d4e)
The above code causes the ptest instruction to be invoked.
The assertion "assert(VM_Version::supports_sse4_1() || VM_Version::supports_avx(), "")" in ptest was triggered and caused the crash because of the following reason:
Setting "-XX:UseSSE=1" in command line  cause "CPU_SSE4_1" was cleared and cause "VM_Version::supports_sse4_1()" return false ,related code as below:
![图片3](https://github.com/user-attachments/assets/e9a8a690-dd4d-4216-b09f-be8439a9a73b)
Setting "-XX:UseSSE=1" in command line  cause "UseAVX=0" and cause "VM_Version::supports_avx()" return false ,related code as below:
![image](https://github.com/user-attachments/assets/6d9e770b-0a7a-43cd-a4bc-d15247f6478e)
all of these above cause this issue.
i fix this issue by correcting UseSSE42Intrinsics to false when "UseSSE" in command line was set to 1, so that UseVectorizedMismatchIntrinsic will be set false and ptest was not triggered.

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Commit messages:
 - 8358592: Assert in Assembler::ptest due to missing SSE42 support

Changes: https://git.openjdk.org/jdk/pull/26151/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26151&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358592
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26151.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26151/head:pull/26151

PR: https://git.openjdk.org/jdk/pull/26151


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