RISC-V Support — Clang 23.1.0 documentation

# Clang 23.1.0 documentation

## RISC-V Support

## Intrinsic Detection Macros

Clang provides macros to detect which RISC-V intrinsics are supported by the toolchain. This is only available if intrinsics are ratified, in other word, experimental intrinsics do not have macro defined. Note: This is independent from assembler support.

### Intrinsic Detection

Macros of the form `__riscv_intrinsic_<extension>` indicate that the toolchain supports intrinsics for a given extension:

    #if defined(__riscv_intrinsic_zbb)
      // Toolchain supports Zbb scalar intrinsics like __riscv_orc_b_*
      // These can be used with target attributes even if -march doesn't include Zbb
      __attribute__((target("arch=+zbb")))
      unsigned long process_with_zbb(unsigned long x) {
        return __riscv_orc_b_64(x);
      }
    #endif

Composite extensions are also defined when all their sub-extensions are available, e.g.

  `__riscv_intrinsic_zkn` - zbkb + zbkc + zbkx + zkne + zknd + zknh