[llvm] [VPlan] Format some print forms.NFC (PR #144644)

[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-b1` 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/20984

<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 :: Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/b/ml-opt-dev-x86-64-b1/build/bin/opt -passes=loop-vectorize,dce,instcombine -mtriple riscv64-linux-gnu    -mattr=+v -debug-only=loop-vectorize,vplan -scalable-vectorization=on    -riscv-v-vector-bits-min=128 -disable-output < /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll 2>&1 | /b/ml-opt-dev-x86-64-b1/build/bin/FileCheck /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll # RUN: at line 9
+ /b/ml-opt-dev-x86-64-b1/build/bin/FileCheck /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll
+ /b/ml-opt-dev-x86-64-b1/build/bin/opt -passes=loop-vectorize,dce,instcombine -mtriple riscv64-linux-gnu -mattr=+v -debug-only=loop-vectorize,vplan -scalable-vectorization=on -riscv-v-vector-bits-min=128 -disable-output
/b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll:277:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: LV: vectorizing VPBB:ir-bb<for.body.preheader> in BB:for.body.preheader
              ^
<stdin>:264:2: note: scanning from here
}
 ^
<stdin>:265:1: note: possible intended match here
LV: vectorizing VPBB: ir-bb<for.body.preheader> in BB: for.body.preheader
^
/b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll:686:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: LV: vectorizing VPBB:ir-bb<for.body.preheader> in BB:for.body.preheader
              ^
<stdin>:645:2: note: scanning from here
}
 ^
<stdin>:646:1: note: possible intended match here
LV: vectorizing VPBB: ir-bb<for.body.preheader> in BB: for.body.preheader
^

Input file: <stdin>
Check file: /b/ml-opt-dev-x86-64-b1/llvm-project/llvm/test/Transforms/LoopVectorize/RISCV/riscv-vector-reverse.ll

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

Input was:
<<<<<<
            .
            .
            .
          259:  IR %arrayidx3 = getelementptr inbounds i32, ptr %A, i64 %idxprom 
          260:  IR store i32 %add9, ptr %arrayidx3, align 4 
          261:  IR %cmp = icmp ugt i64 %indvars.iv, 1 
          262:  IR %indvars.iv.next = add nsw i64 %indvars.iv, -1 
          263: No successors 
          264: } 
next:277'0      X error: no match found
          265: LV: vectorizing VPBB: ir-bb<for.body.preheader> in BB: for.body.preheader 
next:277'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
next:277'1     ?                                                                          possible intended match
          266: LV: filled BB:  
next:277'0     ~~~~~~~~~~~~~~~~
          267: for.body.preheader: ; preds = %entry 
...

```

</details>

https://github.com/llvm/llvm-project/pull/144644