[llvm] [SelectionDAG] Introduce ISD::PTRADD (PR #140017)

[Alexander Richardson via llvm-commits]

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@@ -468,6 +468,11 @@ class TargetMachine {
     return false;
   }
 
+  /// True if target has some particular form of dealing with pointer arithmetic
+  /// semantics. False if pointer arithmetic should not be preserved for passes
+  /// such as instruction selection, and can fallback to regular arithmetic.
+  virtual bool shouldPreservePtrArith(const Function &F) const { return false; }
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arichardson wrote:

Passing the base pointer type would be great so it doesn't need to remain a downstream patch. Not sure if this is something AMDGPU would also need?

https://github.com/llvm/llvm-project/pull/140017