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/*
* Copyright © 2011 Intel Corporation
*
* 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.
*/
#include "main/macros.h"
#include "util/register_allocate.h"
#include "brw_vec4.h"
#include "brw_vs.h"
#include "brw_cfg.h"
using namespace brw;
namespace brw {
static void
assign(unsigned int *reg_hw_locations, backend_reg *reg)
{
if (reg->file == GRF) {
reg->reg = reg_hw_locations[reg->reg] + reg->reg_offset;
reg->reg_offset = 0;
}
}
bool
vec4_visitor::reg_allocate_trivial()
{
unsigned int hw_reg_mapping[this->alloc.count];
bool virtual_grf_used[this->alloc.count];
int next;
/* Calculate which virtual GRFs are actually in use after whatever
* optimization passes have occurred.
*/
for (unsigned i = 0; i < this->alloc.count; i++) {
virtual_grf_used[i] = false;
}
foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
if (inst->dst.file == GRF)
virtual_grf_used[inst->dst.reg] = true;
for (unsigned i = 0; i < 3; i++) {
if (inst->src[i].file == GRF)
virtual_grf_used[inst->src[i].reg] = true;
}
}
hw_reg_mapping[0] = this->first_non_payload_grf;
next = hw_reg_mapping[0] + this->alloc.sizes[0];
for (unsigned i = 1; i < this->alloc.count; i++) {
if (virtual_grf_used[i]) {
hw_reg_mapping[i] = next;
next += this->alloc.sizes[i];
}
}
prog_data->total_grf = next;
foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
assign(hw_reg_mapping, &inst->dst);
assign(hw_reg_mapping, &inst->src[0]);
assign(hw_reg_mapping, &inst->src[1]);
assign(hw_reg_mapping, &inst->src[2]);
}
if (prog_data->total_grf > max_grf) {
fail("Ran out of regs on trivial allocator (%d/%d)\n",
prog_data->total_grf, max_grf);
return false;
}
return true;
}
extern "C" void
brw_vec4_alloc_reg_set(struct brw_compiler *compiler)
{
int base_reg_count =
compiler->devinfo->gen >= 7 ? GEN7_MRF_HACK_START : BRW_MAX_GRF;
/* After running split_virtual_grfs(), almost all VGRFs will be of size 1.
* SEND-from-GRF sources cannot be split, so we also need classes for each
* potential message length.
*/
const int class_count = MAX_VGRF_SIZE;
int class_sizes[MAX_VGRF_SIZE];
for (int i = 0; i < class_count; i++)
class_sizes[i] = i + 1;
/* Compute the total number of registers across all classes. */
int ra_reg_count = 0;
for (int i = 0; i < class_count; i++) {
ra_reg_count += base_reg_count - (class_sizes[i] - 1);
}
ralloc_free(compiler->vec4_reg_set.ra_reg_to_grf);
compiler->vec4_reg_set.ra_reg_to_grf = ralloc_array(compiler, uint8_t, ra_reg_count);
ralloc_free(compiler->vec4_reg_set.regs);
compiler->vec4_reg_set.regs = ra_alloc_reg_set(compiler, ra_reg_count);
if (compiler->devinfo->gen >= 6)
ra_set_allocate_round_robin(compiler->vec4_reg_set.regs);
ralloc_free(compiler->vec4_reg_set.classes);
compiler->vec4_reg_set.classes = ralloc_array(compiler, int, class_count);
/* Now, add the registers to their classes, and add the conflicts
* between them and the base GRF registers (and also each other).
*/
int reg = 0;
unsigned *q_values[MAX_VGRF_SIZE];
for (int i = 0; i < class_count; i++) {
int class_reg_count = base_reg_count - (class_sizes[i] - 1);
compiler->vec4_reg_set.classes[i] = ra_alloc_reg_class(compiler->vec4_reg_set.regs);
q_values[i] = new unsigned[MAX_VGRF_SIZE];
for (int j = 0; j < class_reg_count; j++) {
ra_class_add_reg(compiler->vec4_reg_set.regs, compiler->vec4_reg_set.classes[i], reg);
compiler->vec4_reg_set.ra_reg_to_grf[reg] = j;
for (int base_reg = j;
base_reg < j + class_sizes[i];
base_reg++) {
ra_add_transitive_reg_conflict(compiler->vec4_reg_set.regs, base_reg, reg);
}
reg++;
}
for (int j = 0; j < class_count; j++) {
/* Calculate the q values manually because the algorithm used by
* ra_set_finalize() to do it has higher complexity affecting the
* start-up time of some applications. q(i, j) is just the maximum
* number of registers from class i a register from class j can
* conflict with.
*/
q_values[i][j] = class_sizes[i] + class_sizes[j] - 1;
}
}
assert(reg == ra_reg_count);
ra_set_finalize(compiler->vec4_reg_set.regs, q_values);
for (int i = 0; i < MAX_VGRF_SIZE; i++)
delete[] q_values[i];
}
void
vec4_visitor::setup_payload_interference(struct ra_graph *g,
int first_payload_node,
int reg_node_count)
{
int payload_node_count = this->first_non_payload_grf;
for (int i = 0; i < payload_node_count; i++) {
/* Mark each payload reg node as being allocated to its physical register.
*
* The alternative would be to have per-physical register classes, which
* would just be silly.
*/
ra_set_node_reg(g, first_payload_node + i, i);
/* For now, just mark each payload node as interfering with every other
* node to be allocated.
*/
for (int j = 0; j < reg_node_count; j++) {
ra_add_node_interference(g, first_payload_node + i, j);
}
}
}
bool
vec4_visitor::reg_allocate()
{
struct brw_compiler *compiler = brw->intelScreen->compiler;
unsigned int hw_reg_mapping[alloc.count];
int payload_reg_count = this->first_non_payload_grf;
/* Using the trivial allocator can be useful in debugging undefined
* register access as a result of broken optimization passes.
*/
if (0)
return reg_allocate_trivial();
calculate_live_intervals();
int node_count = alloc.count;
int first_payload_node = node_count;
node_count += payload_reg_count;
struct ra_graph *g =
ra_alloc_interference_graph(compiler->vec4_reg_set.regs, node_count);
for (unsigned i = 0; i < alloc.count; i++) {
int size = this->alloc.sizes[i];
assert(size >= 1 && size <= MAX_VGRF_SIZE);
ra_set_node_class(g, i, compiler->vec4_reg_set.classes[size - 1]);
for (unsigned j = 0; j < i; j++) {
if (virtual_grf_interferes(i, j)) {
ra_add_node_interference(g, i, j);
}
}
}
setup_payload_interference(g, first_payload_node, node_count);
if (!ra_allocate(g)) {
/* Failed to allocate registers. Spill a reg, and the caller will
* loop back into here to try again.
*/
int reg = choose_spill_reg(g);
if (this->no_spills) {
fail("Failure to register allocate. Reduce number of live "
"values to avoid this.");
} else if (reg == -1) {
fail("no register to spill\n");
} else {
spill_reg(reg);
}
ralloc_free(g);
return false;
}
/* Get the chosen virtual registers for each node, and map virtual
* regs in the register classes back down to real hardware reg
* numbers.
*/
prog_data->total_grf = payload_reg_count;
for (unsigned i = 0; i < alloc.count; i++) {
int reg = ra_get_node_reg(g, i);
hw_reg_mapping[i] = compiler->vec4_reg_set.ra_reg_to_grf[reg];
prog_data->total_grf = MAX2(prog_data->total_grf,
hw_reg_mapping[i] + alloc.sizes[i]);
}
foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
assign(hw_reg_mapping, &inst->dst);
assign(hw_reg_mapping, &inst->src[0]);
assign(hw_reg_mapping, &inst->src[1]);
assign(hw_reg_mapping, &inst->src[2]);
}
ralloc_free(g);
return true;
}
void
vec4_visitor::evaluate_spill_costs(float *spill_costs, bool *no_spill)
{
float loop_scale = 1.0;
for (unsigned i = 0; i < this->alloc.count; i++) {
spill_costs[i] = 0.0;
no_spill[i] = alloc.sizes[i] != 1;
}
/* Calculate costs for spilling nodes. Call it a cost of 1 per
* spill/unspill we'll have to do, and guess that the insides of
* loops run 10 times.
*/
foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
for (unsigned int i = 0; i < 3; i++) {
if (inst->src[i].file == GRF) {
spill_costs[inst->src[i].reg] += loop_scale;
if (inst->src[i].reladdr)
no_spill[inst->src[i].reg] = true;
}
}
if (inst->dst.file == GRF) {
spill_costs[inst->dst.reg] += loop_scale;
if (inst->dst.reladdr)
no_spill[inst->dst.reg] = true;
}
switch (inst->opcode) {
case BRW_OPCODE_DO:
loop_scale *= 10;
break;
case BRW_OPCODE_WHILE:
loop_scale /= 10;
break;
case SHADER_OPCODE_GEN4_SCRATCH_READ:
case SHADER_OPCODE_GEN4_SCRATCH_WRITE:
for (int i = 0; i < 3; i++) {
if (inst->src[i].file == GRF)
no_spill[inst->src[i].reg] = true;
}
if (inst->dst.file == GRF)
no_spill[inst->dst.reg] = true;
break;
default:
break;
}
}
}
int
vec4_visitor::choose_spill_reg(struct ra_graph *g)
{
float spill_costs[this->alloc.count];
bool no_spill[this->alloc.count];
evaluate_spill_costs(spill_costs, no_spill);
for (unsigned i = 0; i < this->alloc.count; i++) {
if (!no_spill[i])
ra_set_node_spill_cost(g, i, spill_costs[i]);
}
return ra_get_best_spill_node(g);
}
void
vec4_visitor::spill_reg(int spill_reg_nr)
{
assert(alloc.sizes[spill_reg_nr] == 1);
unsigned int spill_offset = c->last_scratch++;
/* Generate spill/unspill instructions for the objects being spilled. */
foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
for (unsigned int i = 0; i < 3; i++) {
if (inst->src[i].file == GRF && inst->src[i].reg == spill_reg_nr) {
src_reg spill_reg = inst->src[i];
inst->src[i].reg = alloc.allocate(1);
dst_reg temp = dst_reg(inst->src[i]);
emit_scratch_read(block, inst, temp, spill_reg, spill_offset);
}
}
if (inst->dst.file == GRF && inst->dst.reg == spill_reg_nr) {
emit_scratch_write(block, inst, spill_offset);
}
}
invalidate_live_intervals();
}
} /* namespace brw */
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