libdtrace/common/dt_regset.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2012 by Delphix. All rights reserved.
 */

#include <sys/types.h>
#include <sys/bitmap.h>
#include <assert.h>
#include <strings.h>
#include <stdlib.h>

#include <dt_regset.h>
#include <dt_impl.h>

dt_regset_t *
dt_regset_create(ulong_t nregs)
{
    ulong_t n = BT_BITOUL(nregs);
    dt_regset_t *drp = malloc(sizeof (dt_regset_t));

    if (drp == NULL)
        return (NULL);

    drp->dr_bitmap = malloc(sizeof (ulong_t) * n);
    drp->dr_size = nregs;

    if (drp->dr_bitmap == NULL) {
        dt_regset_destroy(drp);
        return (NULL);
    }

    bzero(drp->dr_bitmap, sizeof (ulong_t) * n);
    return (drp);
}

void
dt_regset_destroy(dt_regset_t *drp)
{
    free(drp->dr_bitmap);
    free(drp);
}

void
dt_regset_reset(dt_regset_t *drp)
{
    bzero(drp->dr_bitmap, sizeof (ulong_t) * BT_BITOUL(drp->dr_size));
}

void
dt_regset_assert_free(dt_regset_t *drp)
{
    int reg;
    boolean_t fail = B_FALSE;
    for (reg = 0; reg < drp->dr_size; reg++) {
        if (BT_TEST(drp->dr_bitmap, reg) != 0)  {
            dt_dprintf("%%r%d was left allocated\n", reg);
            fail = B_TRUE;
        }
    }

    /*
     * We set this during dtest runs to check for register leaks.
     */
    if (fail && getenv("DTRACE_DEBUG_REGSET") != NULL)
        abort();
}

int
dt_regset_alloc(dt_regset_t *drp)
{
    ulong_t nbits = drp->dr_size - 1;
    ulong_t maxw = nbits >> BT_ULSHIFT;
    ulong_t wx;

    for (wx = 0; wx <= maxw; wx++) {
        if (drp->dr_bitmap[wx] != ~0UL)
            break;
    }

    if (wx <= maxw) {
        ulong_t maxb = (wx == maxw) ? nbits & BT_ULMASK : BT_NBIPUL - 1;
        ulong_t word = drp->dr_bitmap[wx];
        ulong_t bit, bx;
        int reg;

        for (bit = 1, bx = 0; bx <= maxb; bx++, bit <<= 1) {
            if ((word & bit) == 0) {
                reg = (int)((wx << BT_ULSHIFT) | bx);
                BT_SET(drp->dr_bitmap, reg);
                return (reg);
            }
        }
    }

    xyerror(D_NOREG, "Insufficient registers to generate code");
    /*NOTREACHED*/
    return (-1);
}

void
dt_regset_free(dt_regset_t *drp, int reg)
{
    assert(reg >= 0 && reg < drp->dr_size);
    assert(BT_TEST(drp->dr_bitmap, reg) != 0);
    BT_CLEAR(drp->dr_bitmap, reg);
}