[llvm] [LLVM][MC][DecoderEmitter] Add support to specialize decoder per bitwidth (PR #154865)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/17763

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
71.931 [465/21/5709] Linking CXX shared module lib/CheckerOptionHandlingAnalyzerPlugin.so
73.321 [465/20/5710] Building AMDGPUGenPreLegalizeGICombiner.inc...
74.561 [465/19/5711] Building AMDGPUGenMCPseudoLowering.inc...
74.731 [465/18/5712] Building AMDGPUGenRegBankGICombiner.inc...
74.851 [465/17/5713] Linking CXX shared module lib/CheckerDependencyHandlingAnalyzerPlugin.so
75.131 [465/16/5714] Building AMDGPUGenSubtargetInfo.inc...
76.181 [465/15/5715] Building AMDGPUGenPostLegalizeGICombiner.inc...
78.443 [465/14/5716] Building CXX object lib/Target/ARM/Disassembler/CMakeFiles/LLVMARMDisassembler.dir/ARMDisassembler.cpp.o
78.781 [464/14/5717] Linking CXX static library lib/libLLVMARMDisassembler.a
79.522 [464/13/5718] Building CXX object lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o
FAILED: lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o 
ccache /usr/lib64/ccache/c++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/lib/Target/RISCV/Disassembler -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV/Disassembler -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/lib/Target/RISCV -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/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-noexcept-type -Wdelete-non-virtual-dtor -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17 -fvisibility=hidden  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o -MF lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o.d -o lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:705:13: error: explicit template specialization cannot have a storage class
 template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint16_t> = 16;
             ^~~~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:706:13: error: explicit template specialization cannot have a storage class
 template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
             ^~~~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:708:13: error: explicit template specialization cannot have a storage class
 template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 48;
             ^~~~~~
79.621 [464/12/5719] Building AMDGPUGenDisassemblerTables.inc...
83.012 [464/11/5720] Building AMDGPUGenMCCodeEmitter.inc...
88.091 [464/10/5721] Building AMDGPUGenCallingConv.inc...
92.591 [464/9/5722] Building AMDGPUGenAsmWriter.inc...
106.111 [464/8/5723] Building AMDGPUGenGlobalISel.inc...
107.251 [464/7/5724] Building AMDGPUGenAsmMatcher.inc...
108.691 [464/6/5725] Building AMDGPUGenInstrInfo.inc...
116.491 [464/5/5726] Building AMDGPUGenDAGISel.inc...
120.091 [464/4/5727] Linking CXX executable bin/clang-import-test
121.062 [464/3/5728] Building CXX object lib/Target/AArch64/Disassembler/CMakeFiles/LLVMAArch64Disassembler.dir/AArch64Disassembler.cpp.o
127.961 [464/2/5729] Building AMDGPUGenRegisterInfo.inc...
128.500 [464/1/5730] Building AMDGPUGenRegisterBank.inc...
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/154865