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ra: First cut at a graph-coloring register allocator for mesa.
Notably missing is choice of registers to spill.
This commit is contained in:
Eric Anholt
parent
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commit
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3 changed files with 431 additions and 0 deletions
361
src/mesa/program/register_allocate.c
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361
src/mesa/program/register_allocate.c
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/*
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* Copyright © 2010 Intel Corporation
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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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* Authors:
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* Eric Anholt <eric@anholt.net>
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*
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*/
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/** @file register_allocate.c
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*
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* Graph-coloring register allocator.
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*/
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#include <talloc.h>
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#include "main/imports.h"
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#include "main/macros.h"
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#include "main/mtypes.h"
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#include "register_allocate.h"
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struct ra_reg {
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char *name;
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GLboolean *conflicts;
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};
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struct ra_regs {
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struct ra_reg *regs;
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unsigned int count;
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struct ra_class **classes;
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unsigned int class_count;
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};
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struct ra_class {
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GLboolean *regs;
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/**
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* p_B in Runeson/Nyström paper.
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*
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* This is "how many regs are in the set."
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*/
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unsigned int p;
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/**
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* q_B,C in Runeson/Nyström paper.
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*/
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unsigned int *q;
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};
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struct ra_node {
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GLboolean *adjacency;
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unsigned int class;
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unsigned int adjacency_count;
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unsigned int reg;
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GLboolean in_stack;
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};
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struct ra_graph {
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struct ra_regs *regs;
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/**
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* the variables that need register allocation.
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*/
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struct ra_node *nodes;
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unsigned int count; /**< count of nodes. */
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unsigned int *stack;
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unsigned int stack_count;
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};
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struct ra_regs *
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ra_alloc_reg_set(unsigned int count)
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{
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unsigned int i;
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struct ra_regs *regs;
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regs = talloc_zero(NULL, struct ra_regs);
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regs->count = count;
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regs->regs = talloc_zero_array(regs, struct ra_reg, count);
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for (i = 0; i < count; i++) {
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regs->regs[i].conflicts = talloc_zero_array(regs->regs, GLboolean, count);
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regs->regs[i].conflicts[i] = GL_TRUE;
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}
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return regs;
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}
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void
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ra_add_reg_conflict(struct ra_regs *regs, unsigned int r1, unsigned int r2)
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{
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regs->regs[r1].conflicts[r2] = GL_TRUE;
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regs->regs[r2].conflicts[r1] = GL_TRUE;
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}
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unsigned int
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ra_alloc_reg_class(struct ra_regs *regs)
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{
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struct ra_class *class;
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regs->classes = talloc_realloc(regs, regs->classes,
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struct ra_class *,
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regs->class_count + 1);
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class = talloc_zero(regs, struct ra_class);
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regs->classes[regs->class_count] = class;
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class->regs = talloc_zero_array(class, GLboolean, regs->count);
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return regs->class_count++;
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}
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void
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ra_class_add_reg(struct ra_regs *regs, unsigned int c, unsigned int r)
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{
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struct ra_class *class = regs->classes[c];
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class->regs[r] = GL_TRUE;
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class->p++;
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}
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/**
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* Must be called after all conflicts and register classes have been
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* set up and before the register set is used for allocation.
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*/
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void
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ra_set_finalize(struct ra_regs *regs)
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{
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unsigned int b, c;
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for (b = 0; b < regs->class_count; b++) {
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regs->classes[b]->q = talloc_array(regs, unsigned int, regs->class_count);
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}
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/* Compute, for each class B and C, how many regs of B an
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* allocation to C could conflict with.
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*/
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for (b = 0; b < regs->class_count; b++) {
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for (c = 0; c < regs->class_count; c++) {
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unsigned int rc;
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int max_conflicts = 0;
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for (rc = 0; rc < regs->count; rc++) {
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unsigned int rb;
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int conflicts = 0;
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if (!regs->classes[c]->regs[rc])
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continue;
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for (rb = 0; rb < regs->count; rb++) {
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if (regs->classes[b]->regs[rb] &&
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regs->regs[rb].conflicts[rc])
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conflicts++;
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}
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max_conflicts = MAX2(max_conflicts, conflicts);
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}
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regs->classes[b]->q[c] = max_conflicts;
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}
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}
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}
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struct ra_graph *
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ra_alloc_interference_graph(struct ra_regs *regs, unsigned int count)
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{
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struct ra_graph *g;
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unsigned int i;
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g = talloc_zero(regs, struct ra_graph);
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g->regs = regs;
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g->nodes = talloc_zero_array(g, struct ra_node, count);
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g->count = count;
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g->stack = talloc_zero_array(g, unsigned int, count);
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for (i = 0; i < count; i++) {
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g->nodes[i].adjacency = talloc_zero_array(g, GLboolean, count);
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g->nodes[i].adjacency[i] = GL_TRUE;
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g->nodes[i].reg = ~0;
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}
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return g;
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}
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void
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ra_set_node_class(struct ra_graph *g,
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unsigned int n, unsigned int class)
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{
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g->nodes[n].class = class;
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}
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void
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ra_add_node_interference(struct ra_graph *g,
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unsigned int n1, unsigned int n2)
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{
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if (g->nodes[n1].adjacency[n2])
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return;
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g->nodes[n1].adjacency[n2] = GL_TRUE;
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g->nodes[n2].adjacency_count++;
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g->nodes[n2].adjacency[n1] = GL_TRUE;
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g->nodes[n2].adjacency_count++;
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}
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static GLboolean pq_test(struct ra_graph *g, unsigned int n)
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{
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unsigned int j;
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unsigned int q = 0;
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int n_class = g->nodes[n].class;
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for (j = 0; j < g->count; j++) {
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if (j == n || g->nodes[j].in_stack)
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continue;
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if (g->nodes[n].adjacency[j]) {
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unsigned int j_class = g->nodes[j].class;
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q += g->regs->classes[n_class]->q[j_class];
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}
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}
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return q < g->regs->classes[n_class]->p;
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}
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/**
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* Simplifies the interference graph by pushing all
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* trivially-colorable nodes into a stack of nodes to be colored,
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* removing them from the graph, and rinsing and repeating.
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*
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* Returns GL_TRUE if all nodes were removed from the graph. GL_FALSE
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* means that either spilling will be required, or optimistic coloring
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* should be applied.
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*/
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GLboolean
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ra_simplify(struct ra_graph *g)
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{
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GLboolean progress = GL_TRUE;
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int i;
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while (progress) {
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progress = GL_FALSE;
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for (i = g->count - 1; i >= 0; i--) {
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if (g->nodes[i].in_stack)
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continue;
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if (pq_test(g, i)) {
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g->stack[g->stack_count] = i;
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g->stack_count++;
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g->nodes[i].in_stack = GL_TRUE;
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progress = GL_TRUE;
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}
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}
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}
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for (i = 0; i < g->count; i++) {
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if (!g->nodes[i].in_stack)
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return GL_FALSE;
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}
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return GL_TRUE;
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}
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/**
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* Pops nodes from the stack back into the graph, coloring them with
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* registers as they go.
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*
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* If all nodes were trivially colorable, then this must succeed. If
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* not (optimistic coloring), then it may return GL_FALSE;
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*/
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GLboolean
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ra_select(struct ra_graph *g)
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{
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int i;
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while (g->stack_count != 0) {
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unsigned int r;
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int n = g->stack[g->stack_count - 1];
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struct ra_class *c = g->regs->classes[g->nodes[n].class];
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/* Find the lowest-numbered reg which is not used by a member
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* of the graph adjacent to us.
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*/
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for (r = 0; r < g->regs->count; r++) {
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if (!c->regs[r])
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continue;
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/* Check if any of our neighbors conflict with this register choice. */
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for (i = 0; i < g->count; i++) {
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if (g->nodes[n].adjacency[i] &&
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!g->nodes[i].in_stack &&
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g->regs->regs[r].conflicts[g->nodes[i].reg]) {
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break;
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}
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}
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if (i == g->count)
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break;
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}
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if (r == g->regs->count)
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return GL_FALSE;
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g->nodes[n].reg = r;
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g->nodes[n].in_stack = GL_FALSE;
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g->stack_count--;
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}
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return GL_TRUE;
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}
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/**
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* Optimistic register coloring: Just push the remaining nodes
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* on the stack. They'll be colored first in ra_select(), and
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* if they succeed then the locally-colorable nodes are still
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* locally-colorable and the rest of the register allocation
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* will succeed.
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*/
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void
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ra_optimistic_color(struct ra_graph *g)
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{
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unsigned int i;
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for (i = 0; i < g->count; i++) {
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if (g->nodes[i].in_stack)
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continue;
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g->stack[g->stack_count] = i;
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g->stack_count++;
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g->nodes[i].in_stack = GL_TRUE;
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}
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}
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GLboolean
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ra_allocate_no_spills(struct ra_graph *g)
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{
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if (!ra_simplify(g)) {
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ra_optimistic_color(g);
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}
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return ra_select(g);
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}
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unsigned int
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ra_get_node_reg(struct ra_graph *g, unsigned int n)
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{
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return g->nodes[n].reg;
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}
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69
src/mesa/program/register_allocate.h
Normal file
69
src/mesa/program/register_allocate.h
Normal file
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@ -0,0 +1,69 @@
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/*
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* Copyright © 2010 Intel Corporation
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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
|
||||
* 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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* Authors:
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* Eric Anholt <eric@anholt.net>
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*
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*/
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struct ra_class;
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struct ra_regs;
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/* @{
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* Register set setup.
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*
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* This should be done once at backend initializaion, as
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* ra_set_finalize is O(r^2*c^2). The registers may be virtual
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* registers, such as aligned register pairs that conflict with the
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* two real registers from which they are composed.
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*/
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struct ra_regs *ra_alloc_reg_set(unsigned int count);
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unsigned int ra_alloc_reg_class(struct ra_regs *regs);
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void ra_add_reg_conflict(struct ra_regs *regs,
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unsigned int r1, unsigned int r2);
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void ra_class_add_reg(struct ra_regs *regs, unsigned int c, unsigned int reg);
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void ra_set_finalize(struct ra_regs *regs);
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/** @} */
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/** @{ Interference graph setup.
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*
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* Each interference graph node is a virtual variable in the IL. It
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* is up to the user to ra_set_node_class() for the virtual variable,
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* and compute live ranges and ra_node_interfere() between conflicting
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* live ranges.
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*/
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struct ra_graph *ra_alloc_interference_graph(struct ra_regs *regs,
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unsigned int count);
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void ra_set_node_class(struct ra_graph *g, unsigned int n, unsigned int c);
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void ra_add_node_interference(struct ra_graph *g,
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unsigned int n1, unsigned int n2);
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/** @} */
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/** @{ Graph-coloring register allocation */
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GLboolean ra_simplify(struct ra_graph *g);
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void ra_optimistic_color(struct ra_graph *g);
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GLboolean ra_select(struct ra_graph *g);
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GLboolean ra_allocate_no_spills(struct ra_graph *g);
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unsigned int ra_get_node_reg(struct ra_graph *g, unsigned int n);
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/** @} */
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@ -247,6 +247,7 @@ PROGRAM_SOURCES = \
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program/prog_statevars.c \
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program/prog_uniform.c \
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program/programopt.c \
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program/register_allocate.c \
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program/symbol_table.c
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SHADER_CXX_SOURCES = \
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