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

Tue Sep 2 04:37:53 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-gcc-ubuntu-no-asserts` running on `doug-worker-6` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/202/builds/3140

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
175.534 [3778/8/3534] Building CXX object lib/Target/VE/MCTargetDesc/CMakeFiles/LLVMVEDesc.dir/VEMCCodeEmitter.cpp.o
175.570 [3777/8/3535] Building CXX object lib/Target/VE/MCTargetDesc/CMakeFiles/LLVMVEDesc.dir/VEMCTargetDesc.cpp.o
175.595 [3776/8/3536] Building WebAssemblyGenFastISel.inc...
175.603 [3775/8/3537] Building CXX object lib/Target/VE/MCTargetDesc/CMakeFiles/LLVMVEDesc.dir/VETargetStreamer.cpp.o
175.672 [3774/8/3538] Building WebAssemblyGenDAGISel.inc...
175.959 [3773/8/3539] Building WebAssemblyGenInstrInfo.inc...
176.451 [3772/8/3540] Building WebAssemblyGenMCCodeEmitter.inc...
176.551 [3771/8/3541] Building WebAssemblyGenDisassemblerTables.inc...
176.644 [3770/8/3542] Building WebAssemblyGenRegisterInfo.inc...
176.786 [3769/8/3543] Building CXX object lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o
FAILED: lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o 
/opt/ccache/bin/g++ -DGTEST_HAS_RTTI=0 -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/gcc-no-asserts/build/lib/Target/AMDGPU/Disassembler -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU -I/home/buildbot/buildbot-root/gcc-no-asserts/build/lib/Target/AMDGPU -I/home/buildbot/buildbot-root/gcc-no-asserts/build/include -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/include -I/home/buildbot/buildbot-root/gcc-no-asserts/build/lib/Target/AMDGPU/Disassembler/.. -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/.. -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 -std=c++17 -MD -MT lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o -MF lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o.d -o lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o -c /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp:451: error: explicit template specialization cannot have a storage class
  451 | template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
      | 
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp:452: error: explicit template specialization cannot have a storage class
  452 | template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 64;
      | 
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp:454: error: explicit template specialization cannot have a storage class
  454 | static constexpr uint32_t llvm::MCD::InsnBitWidth<std::bitset<96>> = 96;
      | 
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp:456: error: explicit template specialization cannot have a storage class
  456 | static constexpr uint32_t llvm::MCD::InsnBitWidth<std::bitset<128>> = 128;
      | 
177.008 [3769/7/3544] Building WebAssemblyGenSubtargetInfo.inc...
177.817 [3769/6/3545] Building CXX object lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o
FAILED: lib/Target/RISCV/Disassembler/CMakeFiles/LLVMRISCVDisassembler.dir/RISCVDisassembler.cpp.o 
/opt/ccache/bin/g++ -DGTEST_HAS_RTTI=0 -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/gcc-no-asserts/build/lib/Target/RISCV/Disassembler -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV/Disassembler -I/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV -I/home/buildbot/buildbot-root/gcc-no-asserts/build/lib/Target/RISCV -I/home/buildbot/buildbot-root/gcc-no-asserts/build/include -I/home/buildbot/buildbot-root/gcc-no-asserts/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 -std=c++17 -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/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:705:13: error: explicit template specialization cannot have a storage class
  705 | template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint16_t> = 16;
      |             ^~~~~~
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:706:13: error: explicit template specialization cannot have a storage class
  706 | template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
      |             ^~~~~~
/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp:708:13: error: explicit template specialization cannot have a storage class
  708 | template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 48;
      |             ^~~~~~
179.338 [3769/5/3546] Building X86GenCallingConv.inc...
179.513 [3769/4/3547] Building X86GenAsmWriter1.inc...
180.289 [3769/3/3548] Building X86GenAsmWriter.inc...
181.574 [3769/2/3549] Building CXX object lib/Target/SystemZ/Disassembler/CMakeFiles/LLVMSystemZDisassembler.dir/SystemZDisassembler.cpp.o
182.158 [3769/1/3550] Building CXX object lib/Target/VE/Disassembler/CMakeFiles/LLVMVEDisassembler.dir/VEDisassembler.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

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