[llvm] [RISCV][GISel] Support select G_INSERT_SUBVECTOR (PR #171092)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 166862 tests passed
* 2910 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM
<details>
<summary>LLVM.CodeGen/RISCV/GlobalISel/rvv/insert-subvector.ll</summary>

```
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 2
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc -mtriple riscv32 -global-isel -mattr=+m,+d,+zvfh,+v,+zvfbfmin -verify-machineinstrs < /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/rvv/insert-subvector.ll | /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/rvv/insert-subvector.ll
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/llc -mtriple riscv32 -global-isel -mattr=+m,+d,+zvfh,+v,+zvfbfmin -verify-machineinstrs
# .---command stderr------------
# | LLVM ERROR: cannot select: %9:vrb(<vscale x 2 x s32>) = G_VSLIDEUP_VL %3:vrb, %5:vrb, %10:gprb(s32), %7:vrb(<vscale x 16 x s1>), %11:gprb(s32), 1 (in function: insert_nxv16i32_nxv1i32_1)
# `-----------------------------
# error: command failed with exit status: 1
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/rvv/insert-subvector.ll
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/rvv/insert-subvector.ll
# `-----------------------------
# error: command failed with exit status: 2

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/171092