[MSAN] fork avx512vl-intrinsics and x86-vpermi2 tests

[fmayer]

No description provided.

[github-actions]

⚠️ undef deprecator found issues in your code. ⚠️

You can test this locally with the following command:

git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' 'HEAD~1' HEAD llvm/test/Instrumentation/MemorySanitizer/X86/avx512vl-intrinsics.ll llvm/test/Instrumentation/MemorySanitizer/X86/x86-vpermi2.ll

The following files introduce new uses of undef:

• llvm/test/Instrumentation/MemorySanitizer/X86/avx512vl-intrinsics.ll

Undef is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields undef. You should use poison values for placeholders instead.

In tests, avoid using undef and having tests that trigger undefined behavior. If you need an operand with some unimportant value, you can add a new argument to the function and use that instead.

For example, this is considered a bad practice:

define void @fn() {
  ...
  br i1 undef, ...
}

Please use the following instead:

define void @fn(i1 %cond) {
  ...
  br i1 %cond, ...
}

Please refer to the Undefined Behavior Manual for more information.

[fmayer]

accidentally created second #143643