[llvm] [LV][NFC] Add more debug when setting the widening decision (PR #227617)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `release-noassertions-warnings` running on `google-integrate-b1` while building `llvm` at step 6 "build-default".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/228/builds/13364

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

```
Step 6 (build-default) failure: cmake (failure)
...
33.479 [4808/34/4053] Building SPIRVOpsTypes.h.inc...
33.485 [4807/34/4054] Building TosaOpsDialect.h.inc...
33.486 [4806/34/4055] Building TosaInterfaces.h.inc...
33.486 [4805/34/4056] Building LLVMDialectBytecode.cpp.inc...
33.497 [4804/34/4057] Building SPIRVOpsTypes.cpp.inc...
33.502 [4803/34/4058] Building TosaOpsTypes.cpp.inc...
33.505 [4802/34/4059] Building SPIRVOpsDialect.h.inc...
33.506 [4801/34/4060] Building TosaAttributes.cpp.inc...
33.507 [4800/34/4061] Building TosaOpsTypes.h.inc...
33.515 [4799/34/4062] Building CXX object lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o
FAILED: lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o 
CCACHE_DEPEND=1 CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros /usr/bin/ccache /usr/bin/c++ -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/release-noassertions-warnings-build/build/lib/Transforms/Vectorize -I/b/release-noassertions-warnings-build/llvm-project/llvm/lib/Transforms/Vectorize -I/b/release-noassertions-warnings-build/build/include -I/b/release-noassertions-warnings-build/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wno-pass-failed -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Xclang -fno-pch-timestamp -O3 -DNDEBUG -std=c++17 -fno-exceptions -funwind-tables -fno-rtti -Winvalid-pch -Xclang -include-pch -Xclang /b/release-noassertions-warnings-build/build/lib/IR/CMakeFiles/LLVMCore.dir/cmake_pch.hxx.pch -Xclang -include -Xclang /b/release-noassertions-warnings-build/build/lib/IR/CMakeFiles/LLVMCore.dir/cmake_pch.hxx -MD -MT lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o -MF lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o.d -o lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o -c /b/release-noassertions-warnings-build/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
/b/release-noassertions-warnings-build/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:4699:12: error: unused variable 'UI' [-Werror,-Wunused-variable]
 4699 |       auto UI = cast<Instruction>(U);
      |            ^~
1 error generated.
33.529 [4799/33/4063] Building BasicPtxBuilderInterface.cpp.inc...
33.530 [4799/32/4064] Building TosaAttributes.h.inc...
33.530 [4799/31/4065] Building TosaOpsTypesBase.cpp.inc...
33.531 [4799/30/4066] Building TosaOps.cpp.inc...
33.534 [4799/29/4067] Building Passes.h.inc...
33.534 [4799/28/4068] Building TosaOps.h.inc...
33.534 [4799/27/4069] Building Passes.capi.cpp.inc...
33.535 [4799/26/4070] Building Passes.capi.h.inc...
33.535 [4799/25/4071] Building BasicPtxBuilderInterface.h.inc...
33.543 [4799/24/4072] Building TosaOpsTypesBase.h.inc...
33.546 [4799/23/4073] Linking CXX static library lib/libLLVMBitWriter.a
33.554 [4799/22/4074] Linking CXX static library lib/libLLVMFrontendAtomic.a
33.555 [4799/21/4075] Linking CXX static library lib/libLLVMIRPrinter.a
33.555 [4799/20/4076] Linking CXX static library lib/libLLVMTarget.a
33.570 [4799/19/4077] Linking CXX static library lib/libLLVMSandboxIR.a
33.596 [4799/18/4078] Building SPIRVOps.cpp.inc...
33.608 [4799/17/4079] Building SPIRVOps.h.inc...
33.759 [4799/16/4080] Linking CXX static library lib/libLLVMTransformUtils.a
33.853 [4799/15/4081] Building X86GenFastISel.inc...
34.272 [4799/14/4082] Building X86GenGlobalISel.inc...
35.387 [4799/13/4083] Building X86GenDAGISel.inc...
36.771 [4799/12/4084] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
37.863 [4799/11/4085] Building CXX object lib/LTO/CMakeFiles/LLVMLTO.dir/LTO.cpp.o
38.360 [4799/10/4086] Building X86GenSubtargetInfo.inc...
38.969 [4799/9/4087] Building X86GenInstrInfo.inc...
39.054 [4799/8/4088] Building AMDGPUGenCallingConv.inc...
41.656 [4799/7/4089] Building AMDGPUGenAsmWriter.inc...
43.246 [4799/6/4090] Building AMDGPUGenRegisterBank.inc...
45.213 [4799/5/4091] Building AMDGPUGenAsmMatcher.inc...
45.963 [4799/4/4092] Building AMDGPUGenInstrInfo.inc...
46.118 [4799/3/4093] Building AMDGPUGenRegisterInfo.inc...
46.660 [4799/2/4094] Building AMDGPUGenDAGISel.inc...
47.454 [4799/1/4095] Building AMDGPUGenGlobalISel.inc...

```

</details>

https://github.com/llvm/llvm-project/pull/227617