[llvm] InstCombine: Add baseline test for fcmp-0-select combine (PR #172380)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve2-vla` running on `linaro-g4-01` while building `llvm` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/198/builds/11859

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

```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM :: Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/stage1/bin/opt -S -p=instcombine < /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/llvm/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll | /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/llvm/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/stage1/bin/opt -S -p=instcombine
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/llvm/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# .---command stderr------------
# | /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/llvm/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll:376:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: [[MUL_FABS_X:%.*]] = fmul float [[FABS_X]], 0x4170000000000000
# |               ^
# | <stdin>:179:52: note: scanning from here
# |  %fabs.x = call nnan float @llvm.fabs.f32(float %x)
# |                                                    ^
# | <stdin>:179:52: note: with "FABS_X" equal to "%fabs.x"
# |  %fabs.x = call nnan float @llvm.fabs.f32(float %x)
# |                                                    ^
# | <stdin>:180:21: note: possible intended match here
# |  %mul.fabs.x = fmul nnan float %fabs.x, 0x4170000000000000
# |                     ^
# | 
# | Input file: <stdin>
# | Check file: /home/tcwg-buildbot/worker/clang-aarch64-sve2-vla/llvm/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |           174:  %select = select i1 %x.is.zero, float %mul.fabs.x, float %fabs.x 
# |           175:  ret float %select 
# |           176: } 
# |           177:  
# |           178: define float @cmp_one_nnan_fabs(float %x) { 
# |           179:  %fabs.x = call nnan float @llvm.fabs.f32(float %x) 
# | next:376'0                                                        X error: no match found
# | next:376'1                                                          with "FABS_X" equal to "%fabs.x"
# |           180:  %mul.fabs.x = fmul nnan float %fabs.x, 0x4170000000000000 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | next:376'2                         ?                                       possible intended match
# |           181:  %x.is.not.zero = fcmp one float %x, 0.000000e+00 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           182:  %select = select i1 %x.is.not.zero, float %fabs.x, float %mul.fabs.x 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           183:  ret float %select 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/172380