[llvm] [RISCV][TTI] Use processShuffleMask for shuffle legalization estimate (PR #136191)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-gcc-ubuntu` running on `sie-linux-worker3` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/174/builds/16598

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
8.179 [90/12/138] Linking CXX executable unittests/tools/llvm-cfi-verify/CFIVerifyTests
8.183 [90/11/139] Linking CXX executable unittests/Transforms/Utils/UtilsTests
8.226 [90/10/140] Linking CXX executable tools/clang/unittests/Serialization/SerializationTests
8.335 [90/9/141] Linking CXX executable tools/clang/unittests/Sema/SemaTests
8.577 [90/8/142] Linking CXX executable unittests/Analysis/AnalysisTests
8.600 [90/7/143] Linking CXX executable unittests/IR/IRTests
8.702 [90/6/144] Linking CXX executable unittests/Transforms/Scalar/ScalarTests
8.716 [90/5/145] Linking CXX executable unittests/Passes/Plugins/PluginsTests
9.151 [90/4/146] Linking CXX executable bin/clang-tidy
12.863 [90/3/147] Building CXX object lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o
FAILED: lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o 
/opt/ccache/bin/g++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/lib/Target/RISCV -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/include -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -fvisibility=hidden  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o -MF lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o.d -o lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o -c /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp: In member function ‘llvm::InstructionCost llvm::RISCVTTIImpl::getShuffleCost(llvm::TargetTransformInfo::ShuffleKind, llvm::VectorType*, llvm::ArrayRef<int>, llvm::TargetTransformInfo::TargetCostKind, int, llvm::VectorType*, llvm::ArrayRef<const llvm::Value*>, const llvm::Instruction*) const’:
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp:710: error: binding reference of type ‘llvm::RISCVTTIImpl&’ to ‘const llvm::RISCVTTIImpl’ discards qualifiers
  710 |           costShuffleViaSplitting(*this, LT.second, FVTp, Mask, CostKind);
      | 
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp:392: note:   initializing argument 1 of ‘llvm::InstructionCost costShuffleViaSplitting(llvm::RISCVTTIImpl&, llvm::MVT, llvm::VectorType*, llvm::ArrayRef<int>, llvm::TargetTransformInfo::TargetCostKind)’
  392 | static InstructionCost costShuffleViaSplitting(RISCVTTIImpl &TTI, MVT LegalVT,
      | 
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp: At global scope:
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp:392: warning: ‘llvm::InstructionCost costShuffleViaSplitting(llvm::RISCVTTIImpl&, llvm::MVT, llvm::VectorType*, llvm::ArrayRef<int>, llvm::TargetTransformInfo::TargetCostKind)’ defined but not used [-Wunused-function]
15.265 [90/2/148] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
16.324 [90/1/149] Building CXX object lib/LTO/CMakeFiles/LLVMLTO.dir/LTO.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/136191