[llvm] [VPlan] Introduce m_Cmp; match more compares (PR #154771)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-5` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/26009

<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/single-early-exit-interleave-only.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt -p loop-vectorize -force-vector-width=1 -force-vector-interleave=2 -S /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll | /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll # RUN: at line 2
+ /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/opt -p loop-vectorize -force-vector-width=1 -force-vector-interleave=2 -S /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll
+ /Volumes/ExternalSSD/buildbot-root/aarch64-darwin/build/bin/FileCheck /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll
/Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll:22:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i8 [[TMP3]], 0
              ^
<stdin>:18:20: note: scanning from here
 %4 = and i8 %2, %g
                   ^
<stdin>:18:20: note: with "TMP3" equal to "%3"
 %4 = and i8 %2, %g
                   ^
<stdin>:43:2: note: possible intended match here
 %c = icmp eq i8 %a, 0
 ^
/Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll:91:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i32 [[TMP3]], 0
              ^
<stdin>:71:32: note: scanning from here
 %4 = load i32, ptr %2, align 4
                               ^
<stdin>:71:32: note: with "TMP3" equal to "%3"
 %4 = load i32, ptr %2, align 4
                               ^
<stdin>:96:2: note: possible intended match here
 %c = icmp eq i32 %l, 0
 ^

Input file: <stdin>
Check file: /Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll

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

Input was:
<<<<<<
            1: ; ModuleID = '/Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll' 
            2: source_filename = "/Users/buildbot/buildbot-root2/aarch64-darwin/llvm-project/llvm/test/Transforms/LoopVectorize/single-early-exit-interleave-only.ll" 
            3:  
            4: define i8 @iv_used_in_exit_with_math(i8 noundef %g) { 
label:8'0      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
label:8'1      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
same:9'0                                            ^~~~~~~~~~~~~~~~
same:9'1                                                       ^~     captured var "G"
            5: entry: 
next:10'0      ^~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/154771