[llvm] [TySan] A Type Sanitizer (LLVM) (PR #76259)

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github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {undef deprecator}-->


:warning: undef deprecator found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' 8ea9576d94ec6b15a2a3ba181af15d136283bde4 9af0ba5754154d7fcfd22d43e21ea394f4af6caf llvm/include/llvm/Transforms/Instrumentation/TypeSanitizer.h llvm/lib/Transforms/Instrumentation/TypeSanitizer.cpp llvm/test/Instrumentation/TypeSanitizer/access-with-offset.ll llvm/test/Instrumentation/TypeSanitizer/alloca-only.ll llvm/test/Instrumentation/TypeSanitizer/alloca.ll llvm/test/Instrumentation/TypeSanitizer/anon.ll llvm/test/Instrumentation/TypeSanitizer/basic-nosan.ll llvm/test/Instrumentation/TypeSanitizer/basic.ll llvm/test/Instrumentation/TypeSanitizer/byval.ll llvm/test/Instrumentation/TypeSanitizer/globals.ll llvm/test/Instrumentation/TypeSanitizer/invalid-metadata.ll llvm/test/Instrumentation/TypeSanitizer/memintrinsics.ll llvm/test/Instrumentation/TypeSanitizer/nosanitize.ll llvm/test/Instrumentation/TypeSanitizer/sanitize-no-tbaa.ll llvm/test/Instrumentation/TypeSanitizer/swifterror.ll llvm/include/llvm/Analysis/TypeBasedAliasAnalysis.h llvm/include/llvm/Bitcode/LLVMBitCodes.h llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp llvm/lib/Bitcode/Reader/BitcodeReader.cpp llvm/lib/Bitcode/Writer/BitcodeWriter.cpp llvm/lib/CodeGen/ShrinkWrap.cpp llvm/lib/Passes/PassBuilder.cpp llvm/lib/Transforms/Utils/CodeExtractor.cpp llvm/unittests/Analysis/AliasSetTrackerTest.cpp
``````````

</details>


The following files introduce new uses of undef:
 - llvm/test/Instrumentation/TypeSanitizer/invalid-metadata.ll

[Undef](https://llvm.org/docs/LangRef.html#undefined-values) 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:
```llvm
define void @fn() {
  ...
  br i1 undef, ...
}
```

Please use the following instead:
```llvm
define void @fn(i1 %cond) {
  ...
  br i1 %cond, ...
}
```

Please refer to the [Undefined Behavior Manual](https://llvm.org/docs/UndefinedBehavior.html) for more information.



https://github.com/llvm/llvm-project/pull/76259