[llvm] [Attributor] Don't replace `AddrSpaceCast` with `ConstantPointerNull` (PR #126779)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,39 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=attributor $s -o - | FileCheck %s
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arsenm wrote:

$s?

https://github.com/llvm/llvm-project/pull/126779