[llvm] AMDGPU: Libcall expand fast pow/powr/pown/rootn for float case (PR #180553)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-ubuntu` running on `as-builder-4` while building `llvm` at step 7 "test-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/187/builds/16928

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

```
Step 7 (test-check-all) failure: Test just built components: check-all completed (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/opt -S -mtriple=amdgcn-amd-amdhsa -passes=amdgpu-simplifylib,instcombine -amdgpu-prelink /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll | /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/FileCheck /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll
# executed command: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/opt -S -mtriple=amdgcn-amd-amdhsa -passes=amdgpu-simplifylib,instcombine -amdgpu-prelink /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll
# executed command: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/FileCheck /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll
# .---command stderr------------
# | /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll:87:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: [[TMP3:%.*]] = call nnan afn float @llvm.fabs.f32(float [[TMP2]])
# |               ^
# | <stdin>:88:64: note: scanning from here
# |  %2 = select nnan afn i1 %1, float 0x7FF8000000000000, float %x
# |                                                                ^
# | <stdin>:88:64: note: with "TMP2" equal to "%2"
# |  %2 = select nnan afn i1 %1, float 0x7FF8000000000000, float %x
# |                                                                ^
# | <stdin>:89:2: note: possible intended match here
# |  %3 = call nnan afn float @llvm.fabs.f32(float %x)
# |  ^
# | 
# | Input file: <stdin>
# | Check file: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-powr.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            .
# |            .
# |            .
# |           83:  ret float %26 
# |           84: } 
# |           85:  
# |           86: define float @test_powr_afn_f32_nnan(float %x, float %y) { 
# |           87:  %1 = fcmp nnan afn olt float %x, 0.000000e+00 
# |           88:  %2 = select nnan afn i1 %1, float 0x7FF8000000000000, float %x 
# | next:87'0                                                                    X error: no match found
# | next:87'1                                                                      with "TMP2" equal to "%2"
# |           89:  %3 = call nnan afn float @llvm.fabs.f32(float %x) 
# | next:87'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | next:87'2      ?                                                  possible intended match
# |           90:  %4 = call nnan afn float @llvm.log2.f32(float %3) 
# | next:87'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           91:  %5 = fmul nnan afn float %y, %4 
# | next:87'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           92:  %6 = call nnan afn float @llvm.exp2.f32(float %5) 
# | next:87'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/180553