[llvm] [llvm] Use llvm::less_first and llvm::less_second (NFC) (PR #136272)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` 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/16/builds/17613

<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/AMDGPU/sched-group-barrier-pre-RA.mir' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn -mcpu=gfx908 -misched-cluster=false -run-pass=machine-scheduler -verify-misched -o - /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir # RUN: at line 2
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn -mcpu=gfx908 -misched-cluster=false -run-pass=machine-scheduler -verify-misched -o - /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir
/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn -mcpu=gfx908 -misched-cluster=false -run-pass=machine-scheduler -amdgpu-igrouplp-exact-solver -verify-misched -o - /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefix=EXACT /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir # RUN: at line 3
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefix=EXACT /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn -mcpu=gfx908 -misched-cluster=false -run-pass=machine-scheduler -amdgpu-igrouplp-exact-solver -verify-misched -o - /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir
/b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir:201:16: error: EXACT-NEXT: is not on the line after the previous match
 ; EXACT-NEXT: [[DEF2:%[0-9]+]]:areg_128 = IMPLICIT_DEF
               ^
<stdin>:394:2: note: 'next' match was here
 %2:areg_128 = IMPLICIT_DEF
 ^
<stdin>:390:58: note: previous match ended here
 %4:vgpr_32 = nsw V_MUL_LO_U32_e64 %3, %3, implicit $exec
                                                         ^
<stdin>:391:1: note: non-matching line after previous match is here
 GLOBAL_STORE_DWORD_SADDR %1, %4, %0, 0, 0, implicit $exec :: (store (s32) into %ir.out, !noalias !0, addrspace 1)
^
/b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir:293:16: error: EXACT-NEXT: is not on the line after the previous match
 ; EXACT-NEXT: [[V_MUL_LO_U32_e64_1:%[0-9]+]]:vgpr_32 = nsw V_MUL_LO_U32_e64 [[GLOBAL_LOAD_DWORD_SADDR]], [[DEF1]], implicit $exec
               ^
<stdin>:527:2: note: 'next' match was here
 %5:vgpr_32 = nsw V_MUL_LO_U32_e64 %3, %1, implicit $exec
 ^
<stdin>:523:91: note: previous match ended here
 %8:areg_128 = V_MFMA_F32_4X4X1F32_e64 %1, %3, %7, 0, 0, 0, implicit $mode, implicit $exec
                                                                                          ^
<stdin>:524:1: note: non-matching line after previous match is here
 S_NOP 0
^

Input file: <stdin>
Check file: /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/sched-group-barrier-pre-RA.mir

-dump-input=help explains the following input dump.

Input was:
<<<<<<
          .
          .
          .
        389:  %3:vgpr_32 = GLOBAL_LOAD_DWORD_SADDR %0, %1, 0, 0, implicit $exec :: (load (s32) from %ir.in, !alias.scope !0, addrspace 1) 
        390:  %4:vgpr_32 = nsw V_MUL_LO_U32_e64 %3, %3, implicit $exec 
        391:  GLOBAL_STORE_DWORD_SADDR %1, %4, %0, 0, 0, implicit $exec :: (store (s32) into %ir.out, !noalias !0, addrspace 1) 
        392:  S_NOP 0 
...

```

</details>

https://github.com/llvm/llvm-project/pull/136272