This test - `compiler/vectorization/TestFloat16VectorOperations.java` fails on both AArch64 and x86_64 machines on the master branch of mainline JDK when run with these stress flags - `-XX:+UnlockDiagnosticVMOptions -XX:-TieredCompilation -XX:+StressArrayCopyMacroNode -XX:+StressLCM -XX:+StressGCM -XX:+StressIGVN -XX:+StressCCP -XX:+StressMacroExpansion -XX:+StressMethodHandleLinkerInlining -XX:+StressCompiledExceptionHandlers -XX:VerifyConstraintCasts=1 -XX:+StressLoopPeeling`.

Some of the IR rules fail -

One or more @IR rules failed:

Failed IR Rules (11) of Methods (11)
------------------------------------
1) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorAddConstInputFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#ADD_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(AddVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

2) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorAddFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#ADD_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(AddVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

3) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorDivFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#DIV_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(DivVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

4) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorFmaFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#FMA_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(FmaVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

5) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorFmaFloat16MixedConstants()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#FMA_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(FmaVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

6) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorFmaFloat16ScalarMixedConstants()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#FMA_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(FmaVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

7) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorMaxFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#MAX_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(MaxVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

8) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorMinFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#MIN_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(MinVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

9) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorMulFloat16()" - [Failed IR rules: 1]:
   * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#MUL_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
     > Phase "PrintIdeal":
       - counts: Graph contains wrong number of nodes:
         * Constraint 1: "(\d+(\s){2}(MulVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
           - Failed comparison: [found] 0 > 0 [given]
           - No nodes matched!

10) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorSqrtFloat16()" - [Failed IR rules: 1]:
    * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#SQRT_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
      > Phase "PrintIdeal":
        - counts: Graph contains wrong number of nodes:
          * Constraint 1: "(\d+(\s){2}(SqrtVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
            - Failed comparison: [found] 0 > 0 [given]
            - No nodes matched!

11) Method "public void compiler.vectorization.TestFloat16VectorOperations.vectorSubFloat16()" - [Failed IR rules: 1]:
    * @IR rule 2: "@compiler.lib.ir_framework.IR(phase={DEFAULT}, applyIfPlatformAnd={}, applyIfCPUFeatureOr={}, counts={"_#V#SUB_VHF#_", " >0 "}, failOn={}, applyIfPlatform={}, applyIfPlatformOr={}, applyIfOr={}, applyIfCPUFeatureAnd={"fphp", "true", "asimdhp", "true"}, applyIf={}, applyIfCPUFeature={}, applyIfAnd={}, applyIfNot={})"
      > Phase "PrintIdeal":
        - counts: Graph contains wrong number of nodes:
          * Constraint 1: "(\d+(\s){2}(SubVHF.*)+(\s){2}===.*vector[A-Za-z]<S,8>)"
            - Failed comparison: [found] 0 > 0 [given]
            - No nodes matched!



Running this test multiple times with these stress flags leads to a different mix of failures (of IR rules) every time.