lcra.h

/*
 * Copyright (C) 2019 Collabora, Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Authors (Collabora):
 *      Alyssa Rosenzweig <[email protected]>
 */

#ifndef __LCRA_H
#define __LCRA_H

#include <stdbool.h>
#include <stdint.h>

struct lcra_state {
        unsigned node_count;

        /* Alignment for node in log2(bytes)+1. Since alignment must be
         * non-negative power-of-two, the elements are strictly positive
         * integers. Zero is the sentinel for a missing node. In upper word,
         * bound. */
        unsigned *alignment;

        /* Linear constraints imposed. Nested array sized upfront, organized as
         * linear[node_left][node_right]. That is, calculate indices as:
         *
         * Each element is itself a bit field denoting whether (c_j - c_i) bias
         * is present or not, including negative biases.
         *
         * Note for Midgard, there are 16 components so the bias is in range
         * [-15, 15] so encoded by 32-bit field. */

        uint32_t *linear;

        /* Per node max modulus constraints */
        uint8_t *modulus;

        /* Classes allow nodes to be partitioned with a starting register.
         * Classes cannot interfere; that is, they are true partitions in the
         * usual sense of the word. class_count is the number of classes.
         * class[] is indexed by a node to get the mapped class. class_start is
         * biased to all solutions in the class. */

        unsigned class_count;
        unsigned *class;
        unsigned *class_start;
        unsigned *class_size;
        bool *class_disjoint;

        /* Before solving, forced registers; after solving, solutions. */
        unsigned *solutions;

        /* For register spilling, the costs to spill nodes (as set by the user)
         * are in spill_cost[], negative if a node is unspillable. Internally,
         * spill_class specifies which class to spill (whichever class failed
         * to allocate) */

        signed *spill_cost;
        unsigned spill_class;
};

struct lcra_state *
lcra_alloc_equations(
                unsigned node_count, unsigned class_count);

void
lcra_free(struct lcra_state *l);

void
lcra_set_disjoint_class(struct lcra_state *l, unsigned c1, unsigned c2);

void
lcra_set_alignment(struct lcra_state *l, unsigned node, unsigned align_log2, unsigned bound);

void
lcra_restrict_range(struct lcra_state *l, unsigned node, unsigned len);

void
lcra_add_node_interference(struct lcra_state *l, unsigned i, unsigned cmask_i, unsigned j, unsigned cmask_j);

bool
lcra_solve(struct lcra_state *l);

void
lcra_set_node_spill_cost(struct lcra_state *l, unsigned node, signed cost);

signed
lcra_get_best_spill_node(struct lcra_state *l);

#endif