248 lines
7.9 KiB
C
248 lines
7.9 KiB
C
/*
|
|
* 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 <stdio.h>
|
|
#include <assert.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <limits.h>
|
|
#include "util/macros.h"
|
|
#include "util/u_math.h"
|
|
#include "lcra.h"
|
|
|
|
/* This module is the reference implementation of "Linearly Constrained
|
|
* Register Allocation". The paper is available in PDF form
|
|
* (https://people.collabora.com/~alyssa/LCRA.pdf) as well as Markdown+LaTeX
|
|
* (https://gitlab.freedesktop.org/alyssa/lcra/blob/master/LCRA.md)
|
|
*/
|
|
|
|
struct lcra_state *
|
|
lcra_alloc_equations(
|
|
unsigned node_count, unsigned class_count)
|
|
{
|
|
struct lcra_state *l = calloc(1, sizeof(*l));
|
|
|
|
l->node_count = node_count;
|
|
l->class_count = class_count;
|
|
|
|
l->alignment = calloc(sizeof(l->alignment[0]), node_count);
|
|
l->linear = calloc(sizeof(l->linear[0]), node_count * node_count);
|
|
l->modulus = calloc(sizeof(l->modulus[0]), node_count);
|
|
l->class = calloc(sizeof(l->class[0]), node_count);
|
|
l->class_start = calloc(sizeof(l->class_start[0]), class_count);
|
|
l->class_disjoint = calloc(sizeof(l->class_disjoint[0]), class_count * class_count);
|
|
l->class_size = calloc(sizeof(l->class_size[0]), class_count);
|
|
l->spill_cost = calloc(sizeof(l->spill_cost[0]), node_count);
|
|
l->solutions = calloc(sizeof(l->solutions[0]), node_count);
|
|
|
|
memset(l->solutions, ~0, sizeof(l->solutions[0]) * node_count);
|
|
|
|
return l;
|
|
}
|
|
|
|
void
|
|
lcra_free(struct lcra_state *l)
|
|
{
|
|
if (!l)
|
|
return;
|
|
|
|
free(l->alignment);
|
|
free(l->linear);
|
|
free(l->modulus);
|
|
free(l->class);
|
|
free(l->class_start);
|
|
free(l->class_disjoint);
|
|
free(l->class_size);
|
|
free(l->spill_cost);
|
|
free(l->solutions);
|
|
|
|
free(l);
|
|
}
|
|
|
|
void
|
|
lcra_set_alignment(struct lcra_state *l, unsigned node, unsigned align_log2, unsigned bound)
|
|
{
|
|
l->alignment[node] = (align_log2 + 1) | (bound << 16);
|
|
}
|
|
|
|
void
|
|
lcra_set_disjoint_class(struct lcra_state *l, unsigned c1, unsigned c2)
|
|
{
|
|
l->class_disjoint[(c1 * l->class_count) + c2] = true;
|
|
l->class_disjoint[(c2 * l->class_count) + c1] = true;
|
|
}
|
|
|
|
void
|
|
lcra_restrict_range(struct lcra_state *l, unsigned node, unsigned len)
|
|
{
|
|
if (node < l->node_count && l->alignment[node]) {
|
|
unsigned BA = l->alignment[node];
|
|
unsigned alignment = (BA & 0xffff) - 1;
|
|
unsigned bound = BA >> 16;
|
|
l->modulus[node] = DIV_ROUND_UP(bound - len + 1, 1 << alignment);
|
|
}
|
|
}
|
|
|
|
void
|
|
lcra_add_node_interference(struct lcra_state *l, unsigned i, unsigned cmask_i, unsigned j, unsigned cmask_j)
|
|
{
|
|
if (i == j)
|
|
return;
|
|
|
|
if (l->class_disjoint[(l->class[i] * l->class_count) + l->class[j]])
|
|
return;
|
|
|
|
uint32_t constraint_fw = 0;
|
|
uint32_t constraint_bw = 0;
|
|
|
|
for (unsigned D = 0; D < 16; ++D) {
|
|
if (cmask_i & (cmask_j << D)) {
|
|
constraint_bw |= (1 << (15 + D));
|
|
constraint_fw |= (1 << (15 - D));
|
|
}
|
|
|
|
if (cmask_i & (cmask_j >> D)) {
|
|
constraint_fw |= (1 << (15 + D));
|
|
constraint_bw |= (1 << (15 - D));
|
|
}
|
|
}
|
|
|
|
l->linear[j * l->node_count + i] |= constraint_fw;
|
|
l->linear[i * l->node_count + j] |= constraint_bw;
|
|
}
|
|
|
|
static bool
|
|
lcra_test_linear(struct lcra_state *l, unsigned *solutions, unsigned i)
|
|
{
|
|
unsigned *row = &l->linear[i * l->node_count];
|
|
signed constant = solutions[i];
|
|
|
|
for (unsigned j = 0; j < l->node_count; ++j) {
|
|
if (solutions[j] == ~0) continue;
|
|
|
|
signed lhs = solutions[j] - constant;
|
|
|
|
if (lhs < -15 || lhs > 15)
|
|
continue;
|
|
|
|
if (row[j] & (1 << (lhs + 15)))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool
|
|
lcra_solve(struct lcra_state *l)
|
|
{
|
|
for (unsigned step = 0; step < l->node_count; ++step) {
|
|
if (l->solutions[step] != ~0) continue;
|
|
if (l->alignment[step] == 0) continue;
|
|
|
|
unsigned _class = l->class[step];
|
|
unsigned class_start = l->class_start[_class];
|
|
|
|
unsigned BA = l->alignment[step];
|
|
unsigned shift = (BA & 0xffff) - 1;
|
|
unsigned bound = BA >> 16;
|
|
|
|
unsigned P = bound >> shift;
|
|
unsigned Q = l->modulus[step];
|
|
unsigned r_max = l->class_size[_class];
|
|
unsigned k_max = r_max >> shift;
|
|
unsigned m_max = k_max / P;
|
|
bool succ = false;
|
|
|
|
for (unsigned m = 0; m < m_max; ++m) {
|
|
for (unsigned n = 0; n < Q; ++n) {
|
|
l->solutions[step] = ((m * P + n) << shift) + class_start;
|
|
succ = lcra_test_linear(l, l->solutions, step);
|
|
|
|
if (succ) break;
|
|
}
|
|
|
|
if (succ) break;
|
|
}
|
|
|
|
/* Out of registers - prepare to spill */
|
|
if (!succ) {
|
|
l->spill_class = l->class[step];
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Register spilling is implemented with a cost-benefit system. Costs are set
|
|
* by the user. Benefits are calculated from the constraints. */
|
|
|
|
void
|
|
lcra_set_node_spill_cost(struct lcra_state *l, unsigned node, signed cost)
|
|
{
|
|
if (node < l->node_count)
|
|
l->spill_cost[node] = cost;
|
|
}
|
|
|
|
static unsigned
|
|
lcra_count_constraints(struct lcra_state *l, unsigned i)
|
|
{
|
|
unsigned count = 0;
|
|
unsigned *constraints = &l->linear[i * l->node_count];
|
|
|
|
for (unsigned j = 0; j < l->node_count; ++j)
|
|
count += util_bitcount(constraints[j]);
|
|
|
|
return count;
|
|
}
|
|
|
|
signed
|
|
lcra_get_best_spill_node(struct lcra_state *l)
|
|
{
|
|
/* If there are no constraints on a node, do not pick it to spill under
|
|
* any circumstance, or else we would hang rather than fail RA */
|
|
float best_benefit = 0.0;
|
|
signed best_node = -1;
|
|
|
|
for (unsigned i = 0; i < l->node_count; ++i) {
|
|
/* Find spillable nodes */
|
|
if (l->class[i] != l->spill_class) continue;
|
|
if (l->spill_cost[i] < 0) continue;
|
|
|
|
/* Adapted from Chaitin's heuristic */
|
|
float constraints = lcra_count_constraints(l, i);
|
|
float cost = (l->spill_cost[i] + 1);
|
|
float benefit = constraints / cost;
|
|
|
|
if (benefit > best_benefit) {
|
|
best_benefit = benefit;
|
|
best_node = i;
|
|
}
|
|
}
|
|
|
|
return best_node;
|
|
}
|