llvm_22: pick patch for selectiondag freeze condition miscompile

see https://github.com/NixOS/nixpkgs/commit/f8a025c9646e61bc992f4f3d76dd4193d749f417.
this commit backports that same change to LLVM 22. the fix is not
available upstream since LLVM 22 is EOL, but we can pick the patch
from the Rust fork of LLVM, as that is currently on version 22.1.

pkgs/development/compilers/llvm/common/llvm/default.nix

@@ -234,6 +234,18 @@ stdenv.mkDerivation (
         # LLVM issue: https://github.com/llvm/llvm-project/issues/208611
         # LLVM PR: https://github.com/llvm/llvm-project/pull/208683
         (getVersionFile "llvm/sdag-freeze-condition-in-select-of-load-fold.patch")
+      ]
+      ++ lib.optionals (lib.versions.major release_version == "22") [
+        # Same issue and fix as above, for LLVM 22. While LLVM 22 was EOL at
+        # the time of the LLVM PR, and was thus not backported upstream, the
+        # backport was made to Rust's LLVM fork on LLVM 22.1. Accordingly, we
+        # fetch the patch from there.
+        (fetchpatch {
+          name = "llvm-22-sdag-freeze-condition-in-select-of-load-fold.patch";
+          url = "https://github.com/rust-lang/llvm-project/commit/abcef279cd33492fe8301c8873fc535fa4dbf0d5.patch";
+          stripLen = 1;
+          hash = "sha256-HHVMVL7ZWiZkbfnD37zYxFWnfvI3LNS0Z2oFHhOaZsU=";
+        })
       ];
 
     nativeBuildInputs = [