/* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */ static void lower_fddy(lower_wpos_ytransform_state *state, nir_alu_instr *fddy) { nir_builder *b = &state->b; nir_ssa_def *p, *pt, *trans; b->cursor = nir_before_instr(&fddy->instr); p = nir_ssa_for_alu_src(b, fddy, 0); trans = get_transform(state); pt = nir_fmul(b, p, nir_channel(b, trans, 0)); nir_instr_rewrite_src(&fddy->instr, &fddy->src[0].src, nir_src_for_ssa(pt)); for (unsigned i = 0; i < 4; i++) fddy->src[0].swizzle[i] = MIN2(i, pt->num_components - 1); }
static void convert_instr(nir_builder *bld, nir_alu_instr *alu) { nir_ssa_def *numer, *denom, *af, *bf, *a, *b, *q, *r; nir_op op = alu->op; bool is_signed; if ((op != nir_op_idiv) && (op != nir_op_udiv) && (op != nir_op_umod)) return; is_signed = (op == nir_op_idiv); bld->cursor = nir_before_instr(&alu->instr); numer = nir_ssa_for_alu_src(bld, alu, 0); denom = nir_ssa_for_alu_src(bld, alu, 1); if (is_signed) { af = nir_i2f(bld, numer); bf = nir_i2f(bld, denom); af = nir_fabs(bld, af); bf = nir_fabs(bld, bf); a = nir_iabs(bld, numer); b = nir_iabs(bld, denom); } else { af = nir_u2f(bld, numer); bf = nir_u2f(bld, denom); a = numer; b = denom; } /* get first result: */ bf = nir_frcp(bld, bf); bf = nir_isub(bld, bf, nir_imm_int(bld, 2)); /* yes, really */ q = nir_fmul(bld, af, bf); if (is_signed) { q = nir_f2i(bld, q); } else { q = nir_f2u(bld, q); } /* get error of first result: */ r = nir_imul(bld, q, b); r = nir_isub(bld, a, r); r = nir_u2f(bld, r); r = nir_fmul(bld, r, bf); r = nir_f2u(bld, r); /* add quotients: */ q = nir_iadd(bld, q, r); /* correction: if modulus >= divisor, add 1 */ r = nir_imul(bld, q, b); r = nir_isub(bld, a, r); r = nir_uge(bld, r, b); r = nir_b2i(bld, r); q = nir_iadd(bld, q, r); if (is_signed) { /* fix the sign: */ r = nir_ixor(bld, numer, denom); r = nir_ushr(bld, r, nir_imm_int(bld, 31)); r = nir_i2b(bld, r); b = nir_ineg(bld, q); q = nir_bcsel(bld, r, b, q); } if (op == nir_op_umod) { /* division result in q */ r = nir_imul(bld, q, b); q = nir_isub(bld, a, r); } assert(alu->dest.dest.is_ssa); nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(q)); }