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

Tue Sep 2 23:52:01 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-with-lto-ubuntu` running on `as-worker-91` while building `llvm` at step 6 "build-stage1-compiler".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/49/builds/2141

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

```
Step 6 (build-stage1-compiler) failure: build (failure)
...
361.279 [3828/72/2773] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIProgramInfo.cpp.o
361.463 [3827/72/2774] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIPostRABundler.cpp.o
361.582 [3826/72/2775] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIOptimizeExecMaskingPreRA.cpp.o
362.002 [3825/72/2776] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIFoldOperands.cpp.o
362.060 [3824/72/2777] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIFixSGPRCopies.cpp.o
362.170 [3823/72/2778] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIPreEmitPeephole.cpp.o
362.275 [3822/72/2779] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/AMDGPURegisterBankInfo.cpp.o
362.337 [3821/72/2780] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/R600ISelDAGToDAG.cpp.o
362.497 [3820/72/2781] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SILowerWWMCopies.cpp.o
362.787 [3819/72/2782] Building CXX object lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o
FAILED: lib/Target/AMDGPU/Disassembler/CMakeFiles/LLVMAMDGPUDisassembler.dir/AMDGPUDisassembler.cpp.o 
/usr/bin/c++ -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/as-worker-91/clang-with-lto-ubuntu/build/stage1/lib/Target/AMDGPU/Disassembler -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/llvm-project/llvm/lib/Target/AMDGPU/Disassembler -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/llvm-project/llvm/lib/Target/AMDGPU -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/build/stage1/lib/Target/AMDGPU -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/build/stage1/include -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/llvm-project/llvm/include -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/build/stage1/lib/Target/AMDGPU/Disassembler/.. -I/home/buildbot/as-worker-91/clang-with-lto-ubuntu/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 -Wctad-maybe-unsupported -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/as-worker-91/clang-with-lto-ubuntu/llvm-project/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
/home/buildbot/as-worker-91/clang-with-lto-ubuntu/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/as-worker-91/clang-with-lto-ubuntu/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/as-worker-91/clang-with-lto-ubuntu/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/as-worker-91/clang-with-lto-ubuntu/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;
      | 
363.022 [3819/71/2783] Building CXX object lib/Target/PowerPC/MCTargetDesc/CMakeFiles/LLVMPowerPCDesc.dir/PPCMCCodeEmitter.cpp.o
363.099 [3819/70/2784] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIPeepholeSDWA.cpp.o
363.166 [3819/69/2785] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIMemoryLegalizer.cpp.o
363.367 [3819/68/2786] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIFrameLowering.cpp.o
363.759 [3819/67/2787] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SILateBranchLowering.cpp.o
363.858 [3819/66/2788] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIShrinkInstructions.cpp.o
363.951 [3819/65/2789] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/GISel/PPCCallLowering.cpp.o
364.158 [3819/64/2790] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SILowerSGPRSpills.cpp.o
364.868 [3819/63/2791] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SILowerControlFlow.cpp.o
365.379 [3819/62/2792] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCISelLowering.cpp.o
365.686 [3819/61/2793] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIMachineFunctionInfo.cpp.o
365.713 [3819/60/2794] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIPreAllocateWWMRegs.cpp.o
365.829 [3819/59/2795] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/R600ISelLowering.cpp.o
366.009 [3819/58/2796] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIMachineScheduler.cpp.o
366.075 [3819/57/2797] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIInsertWaitcnts.cpp.o
366.261 [3819/56/2798] Building CXX object lib/Target/AMDGPU/MCTargetDesc/CMakeFiles/LLVMAMDGPUDesc.dir/AMDGPUInstPrinter.cpp.o
366.975 [3819/55/2799] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIOptimizeVGPRLiveRange.cpp.o
367.528 [3819/54/2800] Building CXX object lib/Target/PowerPC/CMakeFiles/LLVMPowerPCCodeGen.dir/PPCGenScalarMASSEntries.cpp.o
367.759 [3819/53/2801] Building CXX object lib/Target/AMDGPU/MCTargetDesc/CMakeFiles/LLVMAMDGPUDesc.dir/AMDGPUMCExpr.cpp.o
367.948 [3819/52/2802] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/SIWholeQuadMode.cpp.o
368.076 [3819/51/2803] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/AMDGPUTargetTransformInfo.cpp.o
368.217 [3819/50/2804] Building CXX object lib/Target/PowerPC/AsmParser/CMakeFiles/LLVMPowerPCAsmParser.dir/PPCAsmParser.cpp.o
368.940 [3819/49/2805] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/R600TargetTransformInfo.cpp.o
369.053 [3819/48/2806] Building CXX object lib/Target/RISCV/CMakeFiles/LLVMRISCVCodeGen.dir/RISCVRedundantCopyElimination.cpp.o
369.798 [3819/47/2807] Building CXX object lib/Target/AMDGPU/CMakeFiles/LLVMAMDGPUCodeGen.dir/AMDGPUInstructionSelector.cpp.o

```

</details>

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