/*
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* Copyright © 2014 Broadcom
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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/**
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* @file vc4_qir_lower_uniforms.c
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*
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* This is the pre-code-generation pass for fixing up instructions that try to
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* read from multiple uniform values.
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*/
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#include "vc4_qir.h"
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#include "util/hash_table.h"
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#include "util/u_math.h"
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static inline uint32_t
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index_hash(const void *key)
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{
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return (uintptr_t)key;
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}
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static inline bool
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index_compare(const void *a, const void *b)
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{
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return a == b;
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}
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static void
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add_uniform(struct hash_table *ht, struct qreg reg)
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{
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struct hash_entry *entry;
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void *key = (void *)(uintptr_t)(reg.index + 1);
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entry = _mesa_hash_table_search(ht, key);
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if (entry) {
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entry->data++;
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} else {
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_mesa_hash_table_insert(ht, key, (void *)(uintptr_t)1);
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}
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}
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static void
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remove_uniform(struct hash_table *ht, struct qreg reg)
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{
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struct hash_entry *entry;
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void *key = (void *)(uintptr_t)(reg.index + 1);
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entry = _mesa_hash_table_search(ht, key);
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assert(entry);
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entry->data = (void *)(((uintptr_t) entry->data) - 1);
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if (entry->data == NULL)
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_mesa_hash_table_remove(ht, entry);
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}
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static bool
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is_lowerable_uniform(struct qinst *inst, int i)
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{
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if (inst->src[i].file != QFILE_UNIF)
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return false;
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if (qir_is_tex(inst))
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return i != qir_get_tex_uniform_src(inst);
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return true;
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}
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/* Returns the number of different uniform values referenced by the
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* instruction.
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*/
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static uint32_t
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qir_get_instruction_uniform_count(struct qinst *inst)
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{
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uint32_t count = 0;
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for (int i = 0; i < qir_get_nsrc(inst); i++) {
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if (inst->src[i].file != QFILE_UNIF)
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continue;
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bool is_duplicate = false;
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for (int j = 0; j < i; j++) {
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if (inst->src[j].file == QFILE_UNIF &&
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inst->src[j].index == inst->src[i].index) {
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is_duplicate = true;
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break;
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}
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}
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if (!is_duplicate)
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count++;
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}
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return count;
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}
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void
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qir_lower_uniforms(struct vc4_compile *c)
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{
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struct hash_table *ht =
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_mesa_hash_table_create(c, index_hash, index_compare);
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/* Walk the instruction list, finding which instructions have more
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* than one uniform referenced, and add those uniform values to the
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* ht.
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*/
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qir_for_each_inst_inorder(inst, c) {
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uint32_t nsrc = qir_get_nsrc(inst);
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if (qir_get_instruction_uniform_count(inst) <= 1)
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continue;
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for (int i = 0; i < nsrc; i++) {
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if (is_lowerable_uniform(inst, i))
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add_uniform(ht, inst->src[i]);
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}
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}
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while (ht->entries) {
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/* Find the most commonly used uniform in instructions that
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* need a uniform lowered.
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*/
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uint32_t max_count = 0;
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uint32_t max_index = 0;
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struct hash_entry *entry;
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hash_table_foreach(ht, entry) {
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uint32_t count = (uintptr_t)entry->data;
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uint32_t index = (uintptr_t)entry->key - 1;
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if (count > max_count) {
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max_count = count;
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max_index = index;
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}
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}
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struct qreg unif = qir_reg(QFILE_UNIF, max_index);
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/* Now, find the instructions using this uniform and make them
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* reference a temp instead.
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*/
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qir_for_each_block(block, c) {
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struct qinst *mov = NULL;
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qir_for_each_inst(inst, block) {
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uint32_t nsrc = qir_get_nsrc(inst);
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uint32_t count = qir_get_instruction_uniform_count(inst);
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if (count <= 1)
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continue;
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/* If the block doesn't have a load of hte
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* uniform yet, add it. We could potentially
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* do better and CSE MOVs from multiple blocks
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* into dominating blocks, except that may
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* cause troubles for register allocation.
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*/
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if (!mov) {
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mov = qir_inst(QOP_MOV, qir_get_temp(c),
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unif, c->undef);
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list_add(&mov->link,
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&block->instructions);
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c->defs[mov->dst.index] = mov;
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}
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bool removed = false;
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for (int i = 0; i < nsrc; i++) {
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if (is_lowerable_uniform(inst, i) &&
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inst->src[i].index == max_index) {
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inst->src[i] = mov->dst;
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remove_uniform(ht, unif);
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removed = true;
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}
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}
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if (removed)
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count--;
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/* If the instruction doesn't need lowering any more,
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* then drop it from the list.
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*/
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if (count <= 1) {
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for (int i = 0; i < nsrc; i++) {
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if (is_lowerable_uniform(inst, i))
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remove_uniform(ht, inst->src[i]);
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}
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}
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}
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}
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}
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_mesa_hash_table_destroy(ht, NULL);
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}
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