OpenBLAS/kernel/riscv64/nrm2_vector.c

/***************************************************************************
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#include "common.h"

#ifdef RISCV64_ZVL256B
#       define LMUL m1
#       if defined(DOUBLE)
#               define ELEN 64
#               define MLEN 64
#       else
#               define ELEN 32
#               define MLEN 32
#       endif
#else
#       define LMUL m4
#       if defined(DOUBLE)
#               define ELEN 64
#               define MLEN 16
#       else
#               define ELEN 32
#               define MLEN 8
#       endif
#endif

#define _
#define JOIN2_X(x, y) x ## y
#define JOIN2(x, y) JOIN2_X(x, y)
#define JOIN(v, w, x, y, z) JOIN2( JOIN2( JOIN2( JOIN2( v, w ), x), y), z)

#define VSETVL          JOIN(__riscv_vsetvl,    _e,     ELEN,   LMUL,   _)
#define FLOAT_V_T       JOIN(vfloat,            ELEN,   LMUL,   _t,     _)
#define FLOAT_V_T_M1    JOIN(vfloat,            ELEN,   m1,     _t,     _)
#define VLEV_FLOAT      JOIN(__riscv_vle,       ELEN,   _v_f,   ELEN,   LMUL)
#define VLSEV_FLOAT     JOIN(__riscv_vlse,      ELEN,   _v_f,   ELEN,   LMUL)
#define VFMVVF_FLOAT    JOIN(__riscv_vfmv,      _v_f_f, ELEN,   LMUL,   _)
#define VFMVSF_FLOAT    JOIN(__riscv_vfmv,      _s_f_f, ELEN,   LMUL,   _)
#define VFMVVF_FLOAT_M1 JOIN(__riscv_vfmv,      _v_f_f, ELEN,   m1,     _)
#define MASK_T          JOIN(vbool,             MLEN,   _t,     _,      _)
#define VFABS           JOIN(__riscv_vfabs,     _v_f,   ELEN,   LMUL,   _)
#define VMFNE           JOIN(__riscv_vmfne_vf_f,ELEN,   LMUL,   _b,     MLEN)
#define VMFGT           JOIN(__riscv_vmfgt_vv_f,ELEN,   LMUL,   _b,     MLEN)
#define VMFEQ           JOIN(__riscv_vmfeq_vf_f,ELEN,   LMUL,   _b,     MLEN)
#define VCPOP           JOIN(__riscv_vcpop,     _m_b,   MLEN,   _,      _)
#define VFREDMAX        JOIN(__riscv_vfredmax_vs_f,ELEN,LMUL,   JOIN2(_f, ELEN), m1)
#define VFREDMIN        JOIN(__riscv_vfredmin_vs_f,ELEN,LMUL,   JOIN2(_f, ELEN), m1)
#define VFIRST          JOIN(__riscv_vfirst,    _m_b,   MLEN,   _,      _)
#define VRGATHER        JOIN(__riscv_vrgather,  _vx_f,  ELEN,   LMUL,   _)
#define VFDIV           JOIN(__riscv_vfdiv,     _vv_f,  ELEN,   LMUL,   _)
#define VFDIV_M         JOIN(__riscv_vfdiv,     _vv_f,  ELEN,   LMUL,   _mu)
#define VFMUL           JOIN(__riscv_vfmul,     _vv_f,  ELEN,   LMUL,   _)
#define VFMUL_M         JOIN(__riscv_vfmul,     _vv_f,  ELEN,   LMUL,   _mu)
#define VFMACC          JOIN(__riscv_vfmacc,    _vv_f,  ELEN,   LMUL,   _)
#define VFMACC_M        JOIN(__riscv_vfmacc,    _vv_f,  ELEN,   LMUL,   _mu)
#define VMSBF           JOIN(__riscv_vmsbf,     _m_b,   MLEN,   _,      _)
#define VMSOF           JOIN(__riscv_vmsof,     _m_b,   MLEN,   _,      _)
#define VMAND           JOIN(__riscv_vmand,     _mm_b,  MLEN,   _,      _)
#define VMANDN          JOIN(__riscv_vmandn,    _mm_b,  MLEN,   _,      _)
#define VFREDSUM        JOIN(__riscv_vfredusum_vs_f,ELEN,LMUL,  JOIN2(_f, ELEN), m1)
#define VMERGE          JOIN(__riscv_vmerge,    _vvm_f, ELEN,   LMUL,   _)

#define VSEV_FLOAT      JOIN(__riscv_vse,       ELEN,   _v_f,   ELEN,   LMUL)

#if defined(DOUBLE)
#define ABS fabs
#else
#define ABS fabsf
#endif

#define EXTRACT_FLOAT0_V(v) JOIN(__riscv_vfmv_f_s_f, ELEN, LMUL, _f, ELEN)(v)

//#define DUMP( label, v0, gvl )
#define DUMP( label, v0, gvl ) do{ FLOAT x[16]; VSEV_FLOAT( x, v0, gvl ); printf ("%s(%d): %s [ ", __FILE__, __LINE__, label); for( int xxx = 0; xxx < gvl; ++xxx ) { printf("%f, ", x[xxx]); } printf(" ]\n"); } while(0)

FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x)
{
	BLASLONG i=0;

	if(n <= 0)  return(0.0);
        if(n == 1) return (ABS(x[0]));

        unsigned int gvl = 0;

        MASK_T nonzero_mask;
        MASK_T scale_mask;

        gvl = VSETVL(n);
        FLOAT_V_T v0;
        FLOAT_V_T v_ssq = VFMVVF_FLOAT(0, gvl);
        FLOAT_V_T v_scale = VFMVVF_FLOAT(0, gvl);

        FLOAT scale = 0;
        FLOAT ssq = 0;
        unsigned int stride_x = inc_x * sizeof(FLOAT);
        int idx = 0;

        if( n >= gvl ) // don't pay overheads if we're not doing useful work
        {
                for(i=0; i<n/gvl; i++){
                        v0 = VLSEV_FLOAT( &x[idx], stride_x, gvl );
                        nonzero_mask = VMFNE( v0, 0, gvl );
                        v0 = VFABS( v0, gvl );
                        scale_mask = VMFGT( v0, v_scale, gvl );

                        // assume scale changes are relatively infrequent

                        // unclear if the vcpop+branch is actually a win
                        // since the operations being skipped are predicated anyway
                        // need profiling to confirm
                        if( VCPOP(scale_mask, gvl) ) 
                        {
                                v_scale = VFDIV_M( scale_mask, v_scale, v_scale, v0, gvl );
                                v_scale = VFMUL_M( scale_mask, v_scale, v_scale, v_scale, gvl );
                                v_ssq = VFMUL_M( scale_mask, v_ssq, v_ssq, v_scale, gvl );
                                v_scale = VMERGE( v_scale, v0, scale_mask, gvl );
                        }
                        v0 = VFDIV_M( nonzero_mask, v0, v0, v_scale, gvl );
                        v_ssq = VFMACC_M( nonzero_mask, v_ssq, v0, v0, gvl );
                        idx += inc_x * gvl;
                }

                // we have gvl elements which we accumulated independently, with independent scales
                // we need to combine these
                // naive sort so we process small values first to avoid losing information
                // could use vector sort extensions where available, but we're dealing with gvl elts at most

                FLOAT * out_ssq = alloca(gvl*sizeof(FLOAT));
                FLOAT * out_scale = alloca(gvl*sizeof(FLOAT));
                VSEV_FLOAT( out_ssq, v_ssq, gvl );
                VSEV_FLOAT( out_scale, v_scale, gvl );
                for( int a = 0; a < (gvl-1); ++a )
                {
                        int smallest = a;
                        for( size_t b = a+1; b < gvl; ++b )
                                if( out_scale[b] < out_scale[smallest] )
                                        smallest = b;
                        if( smallest != a )
                        {
                                FLOAT tmp1 = out_ssq[a];
                                FLOAT tmp2 = out_scale[a];
                                out_ssq[a] = out_ssq[smallest];
                                out_scale[a] = out_scale[smallest];
                                out_ssq[smallest] = tmp1;
                                out_scale[smallest] = tmp2;
                        }
                }

                int a = 0;
                while( a<gvl && out_scale[a] == 0 )
                        ++a;

                if( a < gvl ) 
                {
                        ssq = out_ssq[a];
                        scale = out_scale[a];
                        ++a;
                        for( ; a < gvl; ++a ) 
                        {
                                ssq = ssq * ( scale / out_scale[a] ) * ( scale / out_scale[a] ) + out_ssq[a];
                                scale = out_scale[a];
                        }
                }
        }

        //finish any tail using scalar ops
        i*=gvl*inc_x;
        n*=inc_x;
        while(i < n){
                if ( x[i] != 0.0 ){
                        FLOAT absxi = ABS( x[i] );
                        if ( scale < absxi ){
                                ssq = 1 + ssq * ( scale / absxi ) * ( scale / absxi );
                                scale = absxi ;
                        }
                        else{
                                ssq += ( absxi/scale ) * ( absxi/scale );
                        }

                }

                i += inc_x;
        }

	return(scale * sqrt(ssq));
}