[clang] [llvm] [Sanitizers] Support sanitizer instrumentation regions in KMSAN, KASAN, KCOV and KCSAN (PR #231374)

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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)' 'HEAD~1' HEAD clang/test/CodeGen/sanitizer-instrumentation-builtins.c clang/test/CodeGen/sanitizer-instrumentation-regions-diagnostics.c clang/test/CodeGen/sanitizer-instrumentation-regions-pipeline.c llvm/test/CodeGen/Generic/sanitizer-instrumentation-intrinsics.ll llvm/test/CodeGen/X86/sanitizer-instrumentation-intrinsics.ll llvm/test/Instrumentation/AddressSanitizer/sanitizer-instrumentation-regions.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-intrinsics.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-region-dataflow.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-region-mem-intrinsics.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-region-outside.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-region-userspace.ll llvm/test/Instrumentation/MemorySanitizer/kmsan-region-varargs.ll llvm/test/Instrumentation/SanitizerCoverage/sanitizer-instrumentation-regions.ll llvm/test/Instrumentation/ThreadSanitizer/sanitizer-instrumentation-regions.ll llvm/test/Instrumentation/sanitizer-instrumentation-regions-diagnostics.ll llvm/test/Transforms/PhaseOrdering/sanitizer-instrumentation-markers.ll llvm/unittests/Transforms/Utils/SanitizerRegionsTest.cpp clang/include/clang/CodeGenUtils/BackendDiagnosticHandler.h clang/lib/CodeGen/CGBuiltin.cpp clang/lib/CodeGenUtils/BackendDiagnosticHandler.cpp llvm/include/llvm/IR/DiagnosticInfo.h llvm/include/llvm/Transforms/Utils/Instrumentation.h llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp llvm/lib/CodeGen/SelectionDAG/FastISel.cpp llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp llvm/lib/IR/DiagnosticInfo.cpp llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp llvm/lib/Transforms/Utils/Instrumentation.cpp
``````````

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The following files introduce new uses of undef:
 - llvm/test/Instrumentation/MemorySanitizer/kmsan-region-outside.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/231374