[llvm] [DA] do not handle array accesses of different offsets (PR #123436)

[via llvm-commits]

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)' a15fedc399d5d1aa07c14531e5cd8d3efc583600 bff0b1b6c1fda3427d87acb0f8f9595acf8fecd9 llvm/test/Analysis/DependenceAnalysis/DifferentAccessSize.ll llvm/test/Analysis/DependenceAnalysis/DifferentOffsets.ll llvm/lib/Analysis/DependenceAnalysis.cpp llvm/test/Analysis/DependenceAnalysis/AA.ll llvm/test/Analysis/DependenceAnalysis/Banerjee.ll llvm/test/Analysis/DependenceAnalysis/BasePtrBug.ll llvm/test/Analysis/DependenceAnalysis/Constraints.ll llvm/test/Analysis/DependenceAnalysis/Coupled.ll llvm/test/Analysis/DependenceAnalysis/DADelin.ll llvm/test/Analysis/DependenceAnalysis/Dump.ll llvm/test/Analysis/DependenceAnalysis/ExactRDIV.ll llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll llvm/test/Analysis/DependenceAnalysis/GCD.ll llvm/test/Analysis/DependenceAnalysis/Invariant.ll llvm/test/Analysis/DependenceAnalysis/MIVCheckConst.ll llvm/test/Analysis/DependenceAnalysis/MIVMaxLevelThreshold.ll llvm/test/Analysis/DependenceAnalysis/MismatchingNestLevels.ll llvm/test/Analysis/DependenceAnalysis/NonAffineExpr.ll llvm/test/Analysis/DependenceAnalysis/NonCanonicalizedSubscript.ll llvm/test/Analysis/DependenceAnalysis/PR21585.ll llvm/test/Analysis/DependenceAnalysis/Preliminary.ll llvm/test/Analysis/DependenceAnalysis/PreliminaryNoValidityCheckFixedSize.ll llvm/test/Analysis/DependenceAnalysis/Propagating.ll llvm/test/Analysis/DependenceAnalysis/Separability.ll llvm/test/Analysis/DependenceAnalysis/SimpleSIVNoValidityCheck.ll llvm/test/Analysis/DependenceAnalysis/SimpleSIVNoValidityCheckFixedSize.ll llvm/test/Analysis/DependenceAnalysis/StrongSIV.ll llvm/test/Analysis/DependenceAnalysis/SymbolicRDIV.ll llvm/test/Analysis/DependenceAnalysis/SymbolicSIV.ll llvm/test/Analysis/DependenceAnalysis/UsefulGEP.ll llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll llvm/test/Analysis/DependenceAnalysis/WeakZeroDstSIV.ll llvm/test/Analysis/DependenceAnalysis/WeakZeroSrcSIV.ll llvm/test/Analysis/DependenceAnalysis/ZIV.ll llvm/test/Analysis/DependenceAnalysis/lcssa.ll llvm/test/Analysis/DependenceAnalysis/new-pm-invalidation.ll
``````````

</details>


The following files introduce new uses of undef:
 - llvm/test/Analysis/DependenceAnalysis/MIVCheckConst.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/123436