[llvm] [RISCV] Promote fixed-length bf16 arith vector ops with zvfbfmin (PR #112393)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lld-x86_64-win` running on `as-worker-93` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/146/builds/1387

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: Analysis/CostModel/RISCV/arith-fp.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
c:\a\lld-x86_64-win\build\bin\opt.exe -passes="print<cost-model>" 2>&1 -disable-output -mtriple=riscv64 -mattr=+v,+f,+d,+zfh,+zvfh,+zvfbfmin < C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll | c:\a\lld-x86_64-win\build\bin\filecheck.exe C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll --check-prefixes=CHECK,ZVFH
# executed command: 'c:\a\lld-x86_64-win\build\bin\opt.exe' '-passes=print<cost-model>' -disable-output -mtriple=riscv64 -mattr=+v,+f,+d,+zfh,+zvfh,+zvfbfmin
# executed command: 'c:\a\lld-x86_64-win\build\bin\filecheck.exe' 'C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll' --check-prefixes=CHECK,ZVFH
# .---command stderr------------
# | C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll:12:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %V1BF16 = fadd <1 x bfloat> undef, undef
# |               ^
# | <stdin>:4:90: note: scanning from here
# | Cost Model: Found an estimated cost of 2 for instruction: %F64 = fadd double undef, undef
# |                                                                                          ^
# | <stdin>:5:1: note: possible intended match here
# | Cost Model: Found an estimated cost of 5 for instruction: %V1BF16 = fadd <1 x bfloat> undef, undef
# | ^
# | C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll:140:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %V1BF16 = fsub <1 x bfloat> undef, undef
# |               ^
# | <stdin>:52:90: note: scanning from here
# | Cost Model: Found an estimated cost of 2 for instruction: %F64 = fsub double undef, undef
# |                                                                                          ^
# | <stdin>:53:1: note: possible intended match here
# | Cost Model: Found an estimated cost of 5 for instruction: %V1BF16 = fsub <1 x bfloat> undef, undef
# | ^
# | C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll:268:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %V1BF16 = fmul <1 x bfloat> undef, undef
# |               ^
# | <stdin>:100:90: note: scanning from here
# | Cost Model: Found an estimated cost of 2 for instruction: %F64 = fmul double undef, undef
# |                                                                                          ^
# | <stdin>:101:1: note: possible intended match here
# | Cost Model: Found an estimated cost of 5 for instruction: %V1BF16 = fmul <1 x bfloat> undef, undef
# | ^
# | C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll:396:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %V1BF16 = fdiv <1 x bfloat> undef, undef
# |               ^
# | <stdin>:148:90: note: scanning from here
# | Cost Model: Found an estimated cost of 2 for instruction: %F64 = fdiv double undef, undef
# |                                                                                          ^
# | <stdin>:149:1: note: possible intended match here
# | Cost Model: Found an estimated cost of 5 for instruction: %V1BF16 = fdiv <1 x bfloat> undef, undef
# | ^
# | C:\a\lld-x86_64-win\llvm-project\llvm\test\Analysis\CostModel\RISCV\arith-fp.ll:892:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: Cost Model: Found an estimated cost of 5 for instruction: %V1BF16 = call <1 x bfloat> @llvm.fma.v1bf16(<1 x bfloat> undef, <1 x bfloat> undef, <1 x bfloat> undef)
# |               ^
# | <stdin>:340:133: note: scanning from here
...

```

</details>

https://github.com/llvm/llvm-project/pull/112393