[llvm] [RISCV] GISel custom lowering for G_ADD/G_SUB (PR #121587)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/15699

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/RISCV/GlobalISel/combine-neg-abs.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv32 -global-isel -verify-machineinstrs < /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll    | /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV32I
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv32 -global-isel -verify-machineinstrs
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV32I
RUN: at line 4: /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv32 -global-isel -mattr=+zbb -verify-machineinstrs < /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll    | /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV32ZBB
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv32 -global-isel -mattr=+zbb -verify-machineinstrs
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV32ZBB
RUN: at line 6: /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv64 -global-isel -verify-machineinstrs < /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll    | /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV64I
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll --check-prefixes=RV64I
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/llc -mtriple=riscv64 -global-isel -verify-machineinstrs
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll:30:15: error: RV64I-NEXT: expected string not found in input
; RV64I-NEXT: neg a1, a0
              ^
<stdin>:10:9: note: scanning from here
# %bb.0:
        ^
<stdin>:11:2: note: possible intended match here
 negw a1, a0
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll:72:15: error: RV64I-NEXT: expected string not found in input
; RV64I-NEXT: neg a1, a0
              ^
<stdin>:28:9: note: scanning from here
# %bb.0:
        ^
<stdin>:29:2: note: possible intended match here
 negw a1, a0
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll:254:15: error: RV64I-NEXT: expected string not found in input
; RV64I-NEXT: neg a1, a0
              ^
<stdin>:80:9: note: scanning from here
# %bb.0:
        ^
<stdin>:81:2: note: possible intended match here
 negw a1, a0
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/CodeGen/RISCV/GlobalISel/combine-neg-abs.ll:296:15: error: RV64I-NEXT: expected string not found in input
; RV64I-NEXT: neg a1, a0
              ^
<stdin>:98:9: note: scanning from here
# %bb.0:
        ^
<stdin>:99:2: note: possible intended match here
 negw a1, a0
 ^
...

```

</details>

https://github.com/llvm/llvm-project/pull/121587