Fixes unit test to generate valid code

[iomaganaris]

• Changed g RANGE variable name to g_var to avoid issue with confusing g local variable for current with the instance variable g

C++ code generated

static inline double nrn_current(int id, int pnodecount, Exp2Syn_Instance* inst, double* data, const Datum* indexes, ThreadDatum* thread, NrnThread* nt, double v) {
        double current = 0.0;
        inst->ina[id] = inst->gna[id] * (v - inst->ena[id]);
        inst->g_var[id] = inst->B[id] - inst->A[id];
        inst->i[id] = inst->g_var[id] * (v - inst->e[id]);
        current += inst->i[id];
        current += inst->ina[id];
        return current;
    }


    /** update current */
    void nrn_cur_Exp2Syn(NrnThread* nt, Memb_list* ml, int type) {
        int nodecount = ml->nodecount;
        int pnodecount = ml->_nodecount_padded;
        const int* __restrict__ node_index = ml->nodeindices;
        double* __restrict__ data = ml->data;
        const double* __restrict__ voltage = nt->_actual_v;
        double* __restrict__  vec_rhs = nt->_actual_rhs;
        double* __restrict__  vec_d = nt->_actual_d;
        double* shadow_rhs = nt->_shadow_rhs;
        double* shadow_d = nt->_shadow_d;
        Datum* __restrict__ indexes = ml->pdata;
        ThreadDatum* __restrict__ thread = ml->_thread;
        Exp2Syn_Instance* __restrict__ inst = (Exp2Syn_Instance*) ml->instance;

        int start = 0;
        int end = nodecount;
        #pragma ivdep
        for (int id = start; id < end; id++) {
            int node_id = node_index[id];
            double v = voltage[node_id];
            #if NRN_PRCELLSTATE
            inst->v_unused[id] = v;
            #endif
            inst->ena[id] = inst->ion_ena[indexes[2*pnodecount + id]];
            double g = nrn_current(id, pnodecount, inst, data, indexes, thread, nt, v+0.001);
            double dina = inst->ina[id];
            double rhs = nrn_current(id, pnodecount, inst, data, indexes, thread, nt, v);
            g = (g-rhs)/0.001;
            inst->ion_dinadv[indexes[4*pnodecount + id]] += (dina-inst->ina[id])/0.001*1.e2/inst->node_area[indexes[0*pnodecount + id]];
            inst->ion_ina[indexes[3*pnodecount + id]] += inst->ina[id]*(1.e2/inst->node_area[indexes[0*pnodecount + id]]);
            double mfactor = 1.e2/inst->node_area[indexes[0*pnodecount + id]];
            g = g*mfactor;
            rhs = rhs*mfactor;
            #if NRN_PRCELLSTATE
            inst->g_unused[id] = g;
            #endif
            shadow_rhs[id] = rhs;
            shadow_d[id] = g;
        }
        for (int id = start; id < end; id++) {
            int node_id = node_index[id];
            vec_rhs[node_id] -= shadow_rhs[id];
            vec_d[node_id] += shadow_d[id];
        }
    }

LLVM IR code generated before (llvm branch):

VOID nrn_cur_exp2syn(INSTANCE_STRUCT *mech){
    INTEGER id
    INTEGER node_id, ena_id, node_area_id, ion_dinadv_id, ion_ina_id
    DOUBLE v, g, rhs, v_org, current, dina, mfactor
    for(id = 0; id<mech->node_count; id = id+1) {
        node_id = mech->node_index[id]
        ena_id = mech->ion_ena_index[id]
        node_area_id = mech->node_area_index[id]
        ion_dinadv_id = mech->ion_dinadv_index[id]
        ion_ina_id = mech->ion_ina_index[id]
        v = mech->voltage[node_id]
        mech->ena[id] = mech->ion_ena[ena_id]
        v_org = v
        v = v+0.001
        {
            current = 0
            mech->ina[id] = mech->gna[id]*(v-mech->ena[id])
            mech->g[id] = mech->B[id]-mech->A[id]
            mech->i[id] = mech->g[id]*(v-mech->e[id])
            current = current+mech->i[id]
            current = current+mech->ina[id]
            mech->g[id] = current
        }
        dina = mech->ina[id]
        v = v_org
        {
            current = 0
            mech->ina[id] = mech->gna[id]*(v-mech->ena[id])
            mech->g[id] = mech->B[id]-mech->A[id]
            mech->i[id] = mech->g[id]*(v-mech->e[id])
            current = current+mech->i[id]
            current = current+mech->ina[id]
            rhs = current
        }
        mech->g[id] = (mech->g[id]-rhs)/0.001
        mech->ion_dinadv[ion_dinadv_id] = mech->ion_dinadv[ion_dinadv_id]+(dina-mech->ina[id])/0.001*1.e2/mech->node_area[node_area_id]
        mech->ion_ina[ion_ina_id] += mech->ina[id]*(1.e2/mech->node_area[node_area_id])
        mfactor = 1.e2/mech->node_area[node_area_id]
        mech->g[id] = mech->g[id]*mfactor
        rhs = rhs*mfactor
        mech->vec_rhs[node_id] = mech->vec_rhs[node_id]-rhs
        mech->vec_d[node_id] = mech->vec_d[node_id]+mech->g[id]
    }
}

Code generated after this fix:

VOID nrn_cur_exp2syn(INSTANCE_STRUCT *mech){
    INTEGER id
    INTEGER node_id, ena_id, node_area_id, ion_dinadv_id, ion_ina_id
    DOUBLE v, g, rhs, v_org, current, dina, mfactor
    for(id = 0; id<mech->node_count; id = id+1) {
        node_id = mech->node_index[id]
        ena_id = mech->ion_ena_index[id]
        node_area_id = mech->node_area_index[id]
        ion_dinadv_id = mech->ion_dinadv_index[id]
        ion_ina_id = mech->ion_ina_index[id]
        v = mech->voltage[node_id]
        mech->ena[id] = mech->ion_ena[ena_id]
        v_org = v
        v = v+0.001
        {
            current = 0
            mech->ina[id] = mech->gna[id]*(v-mech->ena[id])
            mech->g_var[id] = mech->B[id]-mech->A[id]
            mech->i[id] = mech->g_var[id]*(v-mech->e[id])
            current = current+mech->i[id]
            current = current+mech->ina[id]
            g = current
        }
        dina = mech->ina[id]
        v = v_org
        {
            current = 0
            mech->ina[id] = mech->gna[id]*(v-mech->ena[id])
            mech->g_var[id] = mech->B[id]-mech->A[id]
            mech->i[id] = mech->g_var[id]*(v-mech->e[id])
            current = current+mech->i[id]
            current = current+mech->ina[id]
            rhs = current
        }
        g = (g-rhs)/0.001
        mech->ion_dinadv[ion_dinadv_id] = mech->ion_dinadv[ion_dinadv_id]+(dina-mech->ina[id])/0.001*1.e2/mech->node_area[node_area_id]
        mech->ion_ina[ion_ina_id] += mech->ina[id]*(1.e2/mech->node_area[node_area_id])
        mfactor = 1.e2/mech->node_area[node_area_id]
        g = g*mfactor
        rhs = rhs*mfactor
        mech->vec_rhs[node_id] = mech->vec_rhs[node_id]-rhs
        mech->vec_d[node_id] = mech->vec_d[node_id]+g
    }
}

In the C++ and fixed LLVM IR code g local variable is used to assign current to while before inst->g[id] was used in LLVM IR that generated wrong code.

Related to #869

[bbpbuildbot]

Logfiles from GitLab pipeline #64821 (:white_check_mark:) have been uploaded here!

Status and direct links:

• ✅ spack_setup
• ✅ build:intel
• ✅ build_cuda:gcc
• ✅ test:intel
• ✅ test_benchmark:gcc

[pramodk]

LGTM

[bbpbuildbot]

Logfiles from GitLab pipeline #65850 (:white_check_mark:) have been uploaded here!

Status and direct links:

• ✅ spack_setup
• ✅ build:intel
• ✅ build_cuda:gcc
• ✅ test:intel
• ✅ test_benchmark:gcc