/*
 * 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 <alyssa.rosenzweig@collabora.com>
 */

#include "compiler.h"

/* When we're 'squeezing down' the values in the IR, we maintain a hash
 * as such */

static unsigned
find_or_allocate_temp(compiler_context *ctx, unsigned hash)
{
        if (hash >= SSA_FIXED_MINIMUM)
                return hash;

        unsigned temp = (uintptr_t) _mesa_hash_table_u64_search(
                                ctx->hash_to_temp, hash + 1);

        if (temp)
                return temp - 1;

        /* If no temp is find, allocate one */
        temp = ctx->temp_count++;
        ctx->max_hash = MAX2(ctx->max_hash, hash);

        _mesa_hash_table_u64_insert(ctx->hash_to_temp,
                                    hash + 1, (void *) ((uintptr_t) temp + 1));

        return temp;
}

/* Reassigns numbering to get rid of gaps in the indices and to prioritize
 * smaller register classes */

void
mir_squeeze_index(compiler_context *ctx)
{
        /* Reset */
        ctx->temp_count = 0;
        /* TODO don't leak old hash_to_temp */
        ctx->hash_to_temp = _mesa_hash_table_u64_create(NULL);

        /* We need to prioritize texture registers on older GPUs so we don't
         * fail RA trying to assign to work registers r0/r1 when a work
         * register is already there */

        mir_foreach_instr_global(ctx, ins) {
                if (ins->type == TAG_TEXTURE_4)
                        ins->dest = find_or_allocate_temp(ctx, ins->dest);
        }

        mir_foreach_instr_global(ctx, ins) {
                if (ins->type != TAG_TEXTURE_4)
                        ins->dest = find_or_allocate_temp(ctx, ins->dest);

                for (unsigned i = 0; i < ARRAY_SIZE(ins->src); ++i)
                        ins->src[i] = find_or_allocate_temp(ctx, ins->src[i]);
        }
}
