[llvm] [X86] combineINSERT_SUBVECTOR - pull out common variables. NFC. (PR #133705)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vla-2stage` running on `linaro-g3-01` while building `llvm` at step 12 "ninja check 2".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/41/builds/5855

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 12 (ninja check 2) failure: stage 2 checked (failure)
...
PASS: Clangd Unit Tests :: ./ClangdTests/80/81 (25172 of 97492)
PASS: Flang :: Driver/linker-flags.f90 (25173 of 97492)
PASS: Flang :: Driver/fveclib-codegen.f90 (25174 of 97492)
PASS: Flang :: Driver/macro-def-undef.F90 (25175 of 97492)
PASS: Flang :: Driver/predefined-macros-x86.f90 (25176 of 97492)
PASS: Flang :: Driver/print-effective-triple.f90 (25177 of 97492)
PASS: Flang :: Driver/color-diagnostics.f90 (25178 of 97492)
PASS: Flang :: Driver/parse-error.ll (25179 of 97492)
PASS: Flang :: Driver/predefined-macros-compiler-version.F90 (25180 of 97492)
UNRESOLVED: Flang :: Driver/slp-vectorize.ll (25181 of 97492)
******************** TEST 'Flang :: Driver/slp-vectorize.ll' FAILED ********************
Test has no 'RUN:' line
********************
PASS: Flang :: Driver/print-resource-dir.F90 (25182 of 97492)
PASS: Flang :: Driver/print-target-triple.f90 (25183 of 97492)
PASS: Flang :: Driver/scanning-error.f95 (25184 of 97492)
PASS: Flang :: Driver/pass-plugin-not-found.f90 (25185 of 97492)
PASS: Flang :: Driver/phases.f90 (25186 of 97492)
PASS: Flang :: Driver/include-header.f90 (25187 of 97492)
PASS: Flang :: Driver/pthread.f90 (25188 of 97492)
PASS: Flang :: Driver/override-triple.ll (25189 of 97492)
PASS: Flang :: Driver/print-pipeline-passes.f90 (25190 of 97492)
PASS: Flang :: Driver/mlir-pass-pipeline.f90 (25191 of 97492)
PASS: Flang :: Driver/parse-fir-error.ll (25192 of 97492)
PASS: Flang :: Driver/std2018-wrong.f90 (25193 of 97492)
PASS: Flang :: Driver/pp-fixed-form.f90 (25194 of 97492)
PASS: Flang :: Driver/fd-lines-as.f90 (25195 of 97492)
PASS: Flang :: Driver/supported-suffices/f08-suffix.f08 (25196 of 97492)
PASS: Flang :: Driver/supported-suffices/f03-suffix.f03 (25197 of 97492)
PASS: Flang :: Driver/missing-arg.f90 (25198 of 97492)
PASS: Flang :: Driver/bbc-openmp-version-macro.f90 (25199 of 97492)
PASS: Flang :: Driver/q-unused-arguments.f90 (25200 of 97492)
PASS: Flang :: Driver/target.f90 (25201 of 97492)
PASS: Flang :: Driver/mlink-builtin-bc.f90 (25202 of 97492)
PASS: Flang :: Driver/tco-code-gen-llvm.fir (25203 of 97492)
PASS: Flang :: Driver/config-file.f90 (25204 of 97492)
PASS: Flang :: Driver/target-gpu-features.f90 (25205 of 97492)
PASS: Flang :: Driver/fdefault.f90 (25206 of 97492)
PASS: Flang :: Driver/parse-ir-error.f95 (25207 of 97492)
PASS: Flang :: Driver/no-duplicate-main.f90 (25208 of 97492)
PASS: Flang :: Driver/unparse-with-modules.f90 (25209 of 97492)
PASS: Flang :: Driver/unsupported-vscale-max-min.f90 (25210 of 97492)
PASS: Flang :: Driver/lto-flags.f90 (25211 of 97492)
PASS: Clangd Unit Tests :: ./ClangdTests/8/81 (25212 of 97492)
PASS: Flang :: Driver/input-from-stdin/input-from-stdin.f90 (25213 of 97492)
PASS: Flang :: Driver/optimization-remark-backend.f90 (25214 of 97492)
PASS: Flang :: Driver/save-temps-use-module.f90 (25215 of 97492)
PASS: Flang :: Driver/multiple-input-files.f90 (25216 of 97492)
PASS: Flang :: Driver/w-arg-unsupported.f90 (25217 of 97492)

```

</details>

https://github.com/llvm/llvm-project/pull/133705