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Add a New RISC-V Nop Instruction in LLVM

check full diff at

github.com/produktivkraft/llvm-project

notes

• add xyz.nop assembly instr

NOTE: this instruction takes no parameters

modify

llvm/lib/Target/RISCV/
llvm/lib/Target/RISCV/Disassembler/

• add llvm.riscv.xyz.nop llvm ir

• add clang builtin function __builtin_riscv_xyz_nop()

• In llvm Dialect, you can use llvm.inline_asm and llvm.call_intrinsic

eg:

  // inline_asm
  llvm.inline_asm "xyz.nop", "" : () -> ()
  // call_intrinsic
  llvm.call_intrinsic "llvm.riscv.xyz.nop" () : () -> () {}

refernce

• https://arxiv.org/abs/2310.18353 Supporting Custom Instructions with the LLVM Compiler for RISC-V Processor

• https://sites.google.com/view/isca-2024-tutorial-riscv-instr/home Tutorial: Expedited Development of Novel RISC-V Instructions Through an Emulation-Simulation Framework(Co-located with ISCA 2024)

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