[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 `ml-opt-rel-x86-64` running on `ml-opt-rel-x86-64-b1` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/185/builds/17089

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
49.396 [403/13/3444] Building CXX object tools/llvm-exegesis/lib/RISCV/CMakeFiles/LLVMExegesisRISCV.dir/Target.cpp.o
49.887 [403/12/3445] Linking CXX executable bin/llvm-cgdata
50.838 [403/11/3446] Building AMDGPUGenGlobalISel.inc...
51.490 [403/10/3447] Building AMDGPUGenAsmWriter.inc...
53.005 [403/9/3448] Building AMDGPUGenDAGISel.inc...
53.612 [403/8/3449] Building AMDGPUGenInstrInfo.inc...
53.664 [403/7/3450] Building AMDGPUGenAsmMatcher.inc...
56.428 [403/6/3451] Building AMDGPUGenRegisterBank.inc...
57.573 [403/5/3452] Building AMDGPUGenRegisterInfo.inc...
62.595 [402/5/3453] Building CXX object lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o
FAILED: lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVTargetTransformInfo.cpp.o 
ccache /usr/bin/c++ -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/b/ml-opt-rel-x86-64-b1/build/lib/Target/RISCV -I/b/ml-opt-rel-x86-64-b1/llvm-project/llvm/lib/Target/RISCV -I/var/lib/buildbot/.local/lib/python3.7/site-packages/tensorflow/include -I/b/ml-opt-rel-x86-64-b1/build/include -I/b/ml-opt-rel-x86-64-b1/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 /b/ml-opt-rel-x86-64-b1/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp
/b/ml-opt-rel-x86-64-b1/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’:
/b/ml-opt-rel-x86-64-b1/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);
      | 
/b/ml-opt-rel-x86-64-b1/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,
      | 
/b/ml-opt-rel-x86-64-b1/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp: At global scope:
/b/ml-opt-rel-x86-64-b1/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]
64.668 [402/4/3454] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
66.338 [402/3/3455] Building CXX object lib/LTO/CMakeFiles/LLVMLTO.dir/LTO.cpp.o
72.712 [402/2/3456] Building InstCombineTables.inc...
103.412 [402/1/3457] Building CXX object lib/Transforms/Vectorize/CMakeFiles/LLVMVectorize.dir/SLPVectorizer.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

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