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src/i386-asm.c  view on Meta::CPAN

        op->reg = -1;
        op->is_memory = 0;
        op->is_rw = 0;
    }
    /* compute constraint priority and evaluate references to output
       constraints if input constraints */
    for(i=0;i<nb_operands;i++) {
        op = &operands[i];
        str = op->constraint;
        str = skip_constraint_modifiers(str);
        if (isnum(*str) || *str == '[') {
            /* this is a reference to another constraint */
            k = find_constraint(operands, nb_operands, str, NULL);
            if ((unsigned)k >= i || i < nb_outputs)
                tcc_error("invalid reference in constraint %d ('%s')",
                      i, str);
            op->ref_index = k;
            if (operands[k].input_index >= 0)
                tcc_error("cannot reference twice the same operand");
            operands[k].input_index = i;
            op->priority = 5;
        } else {
            op->priority = constraint_priority(str);
        }
    }

    /* sort operands according to their priority */
    for(i=0;i<nb_operands;i++)
        sorted_op[i] = i;
    for(i=0;i<nb_operands - 1;i++) {
        for(j=i+1;j<nb_operands;j++) {
            p1 = operands[sorted_op[i]].priority;
            p2 = operands[sorted_op[j]].priority;
            if (p2 < p1) {
                tmp = sorted_op[i];
                sorted_op[i] = sorted_op[j];
                sorted_op[j] = tmp;
            }
        }
    }

    for(i = 0;i < NB_ASM_REGS; i++) {
        if (clobber_regs[i])
            regs_allocated[i] = REG_IN_MASK | REG_OUT_MASK;
        else
            regs_allocated[i] = 0;
    }
    /* esp cannot be used */
    regs_allocated[4] = REG_IN_MASK | REG_OUT_MASK;
    /* ebp cannot be used yet */
    regs_allocated[5] = REG_IN_MASK | REG_OUT_MASK;

    /* allocate registers and generate corresponding asm moves */
    for(i=0;i<nb_operands;i++) {
        j = sorted_op[i];
        op = &operands[j];
        str = op->constraint;
        /* no need to allocate references */
        if (op->ref_index >= 0)
            continue;
        /* select if register is used for output, input or both */
        if (op->input_index >= 0) {
            reg_mask = REG_IN_MASK | REG_OUT_MASK;
        } else if (j < nb_outputs) {
            reg_mask = REG_OUT_MASK;
        } else {
            reg_mask = REG_IN_MASK;
        }
    try_next:
        c = *str++;
        switch(c) {
        case '=':
            goto try_next;
        case '+':
            op->is_rw = 1;
            /* FALL THRU */
        case '&':
            if (j >= nb_outputs)
                tcc_error("'%c' modifier can only be applied to outputs", c);
            reg_mask = REG_IN_MASK | REG_OUT_MASK;
            goto try_next;
        case 'A':
            /* allocate both eax and edx */
            if (is_reg_allocated(TREG_XAX) ||
                is_reg_allocated(TREG_XDX))
                goto try_next;
            op->is_llong = 1;
            op->reg = TREG_XAX;
            regs_allocated[TREG_XAX] |= reg_mask;
            regs_allocated[TREG_XDX] |= reg_mask;
            break;
        case 'a':
            reg = TREG_XAX;
            goto alloc_reg;
        case 'b':
            reg = 3;
            goto alloc_reg;
        case 'c':
            reg = TREG_XCX;
            goto alloc_reg;
        case 'd':
            reg = TREG_XDX;
            goto alloc_reg;
        case 'S':
            reg = 6;
            goto alloc_reg;
        case 'D':
            reg = 7;
        alloc_reg:
            if (is_reg_allocated(reg))
                goto try_next;
            goto reg_found;
        case 'q':
            /* eax, ebx, ecx or edx */
            for(reg = 0; reg < 4; reg++) {
                if (!is_reg_allocated(reg))
                    goto reg_found;
            }
            goto try_next;
        case 'r':
            /* any general register */