[llvm] [LV][NFC] Fix "vectorization is possible but not beneficial" message (PR #228024)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 143121 tests passed
* 3408 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM
<details>
<summary>LLVM.CodeGen/Hexagon/autohvx/float-cost.ll</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\opt.exe -passes=loop-vectorize -hexagon-autohvx -debug-only=loop-vectorize -S < C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Hexagon\autohvx\float-cost.ll 2>&1 | c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Hexagon\autohvx\float-cost.ll
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\opt.exe' -passes=loop-vectorize -hexagon-autohvx -debug-only=loop-vectorize -S
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Hexagon\autohvx\float-cost.ll'
# .---command stderr------------
# | C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Hexagon\autohvx\float-cost.ll:5:10: error: CHECK: expected string not found in input
# | ; CHECK: LV: Vectorization is possible but not beneficial
# |          ^
# | <stdin>:1:1: note: scanning from here
# | 
# | ^
# | <stdin>:16:17: note: possible intended match here
# | LV: Loop passed LoopVectorizationLegality checks (with a runtime bound check)!
# |                 ^
# | 
# | Input file: <stdin>
# | Check file: C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Hexagon\autohvx\float-cost.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1:  
# | check:5'0    {   search range start (exclusive)
# | check:5'1        error: no match found in search range
# |            2: LV: Checking a loop in 'f0' from <stdin> 
# |            3: LV: Loop hints: force=? width=0 interleave=0 
# |            4: LV: Found a loop: b3 
# |            5: LV: Found an induction variable. 
# |            6: LV: Found FP op with unsafe algebra. 
# |            .
# |            .
# |            .
# |           11: LV: Found FP op with unsafe algebra. 
# |           12: LV: Found FP op with unsafe algebra. 
# |           13: LV: Found FP op with unsafe algebra. 
# |           14: LV: Found FP op with unsafe algebra. 
# |           15: LV: Found FP op with unsafe algebra. 
# |           16: LV: Loop passed LoopVectorizationLegality checks (with a runtime bound check)! 
# | check:5'2                     ?                                                                possible intended match
# |           17: LV: Loop does not require scalar epilogue 
# |           18: LV: Found trip count: 0 
# |           19: LV: Found maximum trip count: 2147483647 
# |           20: LV: Loop does not require scalar epilogue 
# |           21: LV: The max safe fixed VF is: 268435456. 
# |            .
# |            .
# |            .
# |         1317:  
# |         1318: attributes #0 = { norecurse nounwind "target-cpu"="hexagonv65" "target-features"="+hvx-length128b,+hvxv65" } 
# |         1319:  
# |         1320: !0 = !{!1, !1, i64 0} 
# |         1321: !1 = !{!"omnipotent char", !2, i64 0} 
# |         1322: !2 = !{!"Simple C/C++ TBAA"} 
# | check:5'3                                  } search range end (exclusive)
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/228024