[llvm] [LV] Ignore some costs when loop gets fully unrolled (PR #106699)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `mlir-nvidia` running on `mlir-nvidia` while building `llvm` at step 6 "build-check-mlir-build-only".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/138/builds/7515

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

```
Step 6 (build-check-mlir-build-only) failure: build (failure)
...
23.343 [439/10/4581] Building CXX object tools/llc/CMakeFiles/llc.dir/llc.cpp.o
23.348 [439/9/4582] Building CXX object tools/mlir/examples/toy/Ch7/CMakeFiles/toyc-ch7.dir/mlir/LowerToLLVM.cpp.o
23.356 [439/8/4583] Building CXX object tools/llc/CMakeFiles/llc.dir/NewPMDriver.cpp.o
23.357 [439/7/4584] Building CXX object tools/lli/CMakeFiles/lli.dir/lli.cpp.o
23.373 [439/6/4585] Linking CXX shared library lib/libLLVMX86Disassembler.so.20.0git
23.380 [438/6/4586] Creating library symlink lib/libLLVMX86Disassembler.so
23.382 [438/5/4587] Building CXX object tools/mlir/examples/toy/Ch7/CMakeFiles/toyc-ch7.dir/toyc.cpp.o
23.440 [438/4/4588] Linking CXX shared library lib/libLLVMX86Desc.so.20.0git
23.447 [437/4/4589] Creating library symlink lib/libLLVMX86Desc.so
23.934 [437/3/4590] Building CXX object lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o
FAILED: lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/LoopVectorize.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/clang++ -DGTEST_HAS_RTTI=0 -DLLVM_EXPORTS -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/vol/worker/mlir-nvidia/mlir-nvidia/llvm.obj/lib/Transforms/Vectorize -I/vol/worker/mlir-nvidia/mlir-nvidia/llvm.src/llvm/lib/Transforms/Vectorize -I/vol/worker/mlir-nvidia/mlir-nvidia/llvm.obj/include -I/vol/worker/mlir-nvidia/mlir-nvidia/llvm.src/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -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 -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -fPIC  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -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 /vol/worker/mlir-nvidia/mlir-nvidia/llvm.src/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
/vol/worker/mlir-nvidia/mlir-nvidia/llvm.src/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:2699:49: error: reference to local binding 'IV' declared in enclosing function 'addFullyUnrolledInstructionsToIgnore'
               [&](const User *U) { return U == IV || U == Cmp; }))
                                                ^
/vol/worker/mlir-nvidia/mlir-nvidia/llvm.src/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:2694:21: note: 'IV' declared here
  for (const auto &[IV, IndDesc] : IL) {
                    ^
1 error generated.
24.067 [437/2/4591] Building CXX object lib/MC/MCParser/CMakeFiles/LLVMMCParser.dir/AsmParser.cpp.o
30.282 [437/1/4592] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/106699