[llvm] AArch64: Add tests for atomicrmw fp operations (PR #103701)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ml-opt-dev-x86-64` running on `ml-opt-dev-x86-64-b2` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/137/builds/4277

<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/AArch64/atomicrmw-fmax.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/ml-opt-dev-x86-64-b1/build/bin/llc -mtriple=aarch64-linux-gnu -O1 -fast-isel=0 -global-isel=false /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll -o - | /b/ml-opt-dev-x86-64-b1/build/bin/FileCheck -check-prefix=NOLSE /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll
+ /b/ml-opt-dev-x86-64-b1/build/bin/FileCheck -check-prefix=NOLSE /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll
+ /b/ml-opt-dev-x86-64-b1/build/bin/llc -mtriple=aarch64-linux-gnu -O1 -fast-isel=0 -global-isel=false /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll -o -
/b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll:636:15: error: NOLSE-NEXT: is not on the line after the previous match
; NOLSE-NEXT: str q0, [sp, #48]
              ^
<stdin>:275:2: note: 'next' match was here
 str q0, [sp, #48]
 ^
<stdin>:271:10: note: previous match ended here
 bl fmaxl
         ^
<stdin>:272:1: note: non-matching line after previous match is here
 str q0, [sp, #64]
^

Input file: <stdin>
Check file: /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/CodeGen/AArch64/atomicrmw-fmax.ll

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

Input was:
<<<<<<
          .
          .
          .
        270:  ldr q1, [sp] // 16-byte Folded Reload 
        271:  bl fmaxl 
        272:  str q0, [sp, #64] 
        273:  ldr q0, [sp, #16] // 16-byte Folded Reload 
        274:  ldp x9, x8, [sp, #64] 
        275:  str q0, [sp, #48] 
next:636      !~~~~~~~~~~~~~~~~  error: match on wrong line
        276:  ldp x11, x10, [sp, #48] 
        277: .LBB6_3: // %atomicrmw.start 
        278:  // Parent Loop BB6_2 Depth=1 
        279:  // => This Inner Loop Header: Depth=2 
        280:  ldaxp x12, x13, [x19] 
          .
          .
          .
>>>>>>

--

...

```

</details>

https://github.com/llvm/llvm-project/pull/103701