OpenBLAS/driver/others/detect_riscv64.c

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#include <stdint.h>

#ifdef __riscv_v_intrinsic
#include <riscv_vector.h>
#endif

unsigned detect_riscv64_get_vlenb(void) {
#ifdef __riscv_v_intrinsic
	return __riscv_vlenb();
#else
	return 0;
#endif
}

/*
 * Based on the approach taken here:
 * https://code.videolan.org/videolan/dav1d/-/merge_requests/1629
 *
 * Only to be called after we've determined we have some sort of
 * RVV support.
 */

uint64_t detect_riscv64_rvv100(void)
{
	uint64_t rvv10_supported;

	/*
	 * After the vsetvli statement vtype will either be a value > 0 if the
	 * vsetvli succeeded or less than 0 if it failed.  If 0 < vtype
	 * we're good and the function will return 1, otherwise there's no
	 * RVV 1.0 and we return 0.
	 */

	asm volatile("vsetvli x0, x0, e8, m1, ta, ma\n\t"
		     "csrr %0, vtype\n\t"
		     "slt %0, x0, %0\n"
		     : "=r" (rvv10_supported)
		     :
		     :);

	return rvv10_supported;
}