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| /* |
| * Copyright © 2010 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. |
| * |
| * Authors: |
| * Eric Anholt <eric@anholt.net> |
| * |
| */ |
| |
| /** @file register_allocate.c |
| * |
| * Graph-coloring register allocator. |
| */ |
| |
| #include <ralloc.h> |
| |
| #include "main/imports.h" |
| #include "main/macros.h" |
| #include "main/mtypes.h" |
| #include "register_allocate.h" |
| |
| struct ra_reg { |
| char *name; |
| GLboolean *conflicts; |
| }; |
| |
| struct ra_regs { |
| struct ra_reg *regs; |
| unsigned int count; |
| |
| struct ra_class **classes; |
| unsigned int class_count; |
| }; |
| |
| struct ra_class { |
| GLboolean *regs; |
| |
| /** |
| * p_B in Runeson/Nyström paper. |
| * |
| * This is "how many regs are in the set." |
| */ |
| unsigned int p; |
| |
| /** |
| * q_B,C in Runeson/Nyström paper. |
| */ |
| unsigned int *q; |
| }; |
| |
| struct ra_node { |
| GLboolean *adjacency; |
| unsigned int class; |
| unsigned int adjacency_count; |
| unsigned int reg; |
| GLboolean in_stack; |
| float spill_cost; |
| }; |
| |
| struct ra_graph { |
| struct ra_regs *regs; |
| /** |
| * the variables that need register allocation. |
| */ |
| struct ra_node *nodes; |
| unsigned int count; /**< count of nodes. */ |
| |
| unsigned int *stack; |
| unsigned int stack_count; |
| }; |
| |
| struct ra_regs * |
| ra_alloc_reg_set(unsigned int count) |
| { |
| unsigned int i; |
| struct ra_regs *regs; |
| |
| regs = rzalloc(NULL, struct ra_regs); |
| regs->count = count; |
| regs->regs = rzalloc_array(regs, struct ra_reg, count); |
| |
| for (i = 0; i < count; i++) { |
| regs->regs[i].conflicts = rzalloc_array(regs->regs, GLboolean, count); |
| regs->regs[i].conflicts[i] = GL_TRUE; |
| } |
| |
| return regs; |
| } |
| |
| void |
| ra_add_reg_conflict(struct ra_regs *regs, unsigned int r1, unsigned int r2) |
| { |
| regs->regs[r1].conflicts[r2] = GL_TRUE; |
| regs->regs[r2].conflicts[r1] = GL_TRUE; |
| } |
| |
| unsigned int |
| ra_alloc_reg_class(struct ra_regs *regs) |
| { |
| struct ra_class *class; |
| |
| regs->classes = reralloc(regs->regs, regs->classes, struct ra_class *, |
| regs->class_count + 1); |
| |
| class = rzalloc(regs, struct ra_class); |
| regs->classes[regs->class_count] = class; |
| |
| class->regs = rzalloc_array(class, GLboolean, regs->count); |
| |
| return regs->class_count++; |
| } |
| |
| void |
| ra_class_add_reg(struct ra_regs *regs, unsigned int c, unsigned int r) |
| { |
| struct ra_class *class = regs->classes[c]; |
| |
| class->regs[r] = GL_TRUE; |
| class->p++; |
| } |
| |
| /** |
| * Must be called after all conflicts and register classes have been |
| * set up and before the register set is used for allocation. |
| */ |
| void |
| ra_set_finalize(struct ra_regs *regs) |
| { |
| unsigned int b, c; |
| |
| for (b = 0; b < regs->class_count; b++) { |
| regs->classes[b]->q = ralloc_array(regs, unsigned int, regs->class_count); |
| } |
| |
| /* Compute, for each class B and C, how many regs of B an |
| * allocation to C could conflict with. |
| */ |
| for (b = 0; b < regs->class_count; b++) { |
| for (c = 0; c < regs->class_count; c++) { |
| unsigned int rc; |
| int max_conflicts = 0; |
| |
| for (rc = 0; rc < regs->count; rc++) { |
| unsigned int rb; |
| int conflicts = 0; |
| |
| if (!regs->classes[c]->regs[rc]) |
| continue; |
| |
| for (rb = 0; rb < regs->count; rb++) { |
| if (regs->classes[b]->regs[rb] && |
| regs->regs[rb].conflicts[rc]) |
| conflicts++; |
| } |
| max_conflicts = MAX2(max_conflicts, conflicts); |
| } |
| regs->classes[b]->q[c] = max_conflicts; |
| } |
| } |
| } |
| |
| struct ra_graph * |
| ra_alloc_interference_graph(struct ra_regs *regs, unsigned int count) |
| { |
| struct ra_graph *g; |
| unsigned int i; |
| |
| g = rzalloc(regs, struct ra_graph); |
| g->regs = regs; |
| g->nodes = rzalloc_array(g, struct ra_node, count); |
| g->count = count; |
| |
| g->stack = rzalloc_array(g, unsigned int, count); |
| |
| for (i = 0; i < count; i++) { |
| g->nodes[i].adjacency = rzalloc_array(g, GLboolean, count); |
| g->nodes[i].adjacency[i] = GL_TRUE; |
| g->nodes[i].reg = ~0; |
| } |
| |
| return g; |
| } |
| |
| void |
| ra_set_node_class(struct ra_graph *g, |
| unsigned int n, unsigned int class) |
| { |
| g->nodes[n].class = class; |
| } |
| |
| void |
| ra_add_node_interference(struct ra_graph *g, |
| unsigned int n1, unsigned int n2) |
| { |
| if (g->nodes[n1].adjacency[n2]) |
| return; |
| |
| g->nodes[n1].adjacency[n2] = GL_TRUE; |
| g->nodes[n2].adjacency_count++; |
| g->nodes[n2].adjacency[n1] = GL_TRUE; |
| g->nodes[n2].adjacency_count++; |
| } |
| |
| static GLboolean pq_test(struct ra_graph *g, unsigned int n) |
| { |
| unsigned int j; |
| unsigned int q = 0; |
| int n_class = g->nodes[n].class; |
| |
| for (j = 0; j < g->count; j++) { |
| if (j == n || g->nodes[j].in_stack) |
| continue; |
| |
| if (g->nodes[n].adjacency[j]) { |
| unsigned int j_class = g->nodes[j].class; |
| q += g->regs->classes[n_class]->q[j_class]; |
| } |
| } |
| |
| return q < g->regs->classes[n_class]->p; |
| } |
| |
| /** |
| * Simplifies the interference graph by pushing all |
| * trivially-colorable nodes into a stack of nodes to be colored, |
| * removing them from the graph, and rinsing and repeating. |
| * |
| * Returns GL_TRUE if all nodes were removed from the graph. GL_FALSE |
| * means that either spilling will be required, or optimistic coloring |
| * should be applied. |
| */ |
| GLboolean |
| ra_simplify(struct ra_graph *g) |
| { |
| GLboolean progress = GL_TRUE; |
| int i; |
| |
| while (progress) { |
| progress = GL_FALSE; |
| |
| for (i = g->count - 1; i >= 0; i--) { |
| if (g->nodes[i].in_stack) |
| continue; |
| |
| if (pq_test(g, i)) { |
| g->stack[g->stack_count] = i; |
| g->stack_count++; |
| g->nodes[i].in_stack = GL_TRUE; |
| progress = GL_TRUE; |
| } |
| } |
| } |
| |
| for (i = 0; i < g->count; i++) { |
| if (!g->nodes[i].in_stack) |
| return GL_FALSE; |
| } |
| |
| return GL_TRUE; |
| } |
| |
| /** |
| * Pops nodes from the stack back into the graph, coloring them with |
| * registers as they go. |
| * |
| * If all nodes were trivially colorable, then this must succeed. If |
| * not (optimistic coloring), then it may return GL_FALSE; |
| */ |
| GLboolean |
| ra_select(struct ra_graph *g) |
| { |
| int i; |
| |
| while (g->stack_count != 0) { |
| unsigned int r; |
| int n = g->stack[g->stack_count - 1]; |
| struct ra_class *c = g->regs->classes[g->nodes[n].class]; |
| |
| /* Find the lowest-numbered reg which is not used by a member |
| * of the graph adjacent to us. |
| */ |
| for (r = 0; r < g->regs->count; r++) { |
| if (!c->regs[r]) |
| continue; |
| |
| /* Check if any of our neighbors conflict with this register choice. */ |
| for (i = 0; i < g->count; i++) { |
| if (g->nodes[n].adjacency[i] && |
| !g->nodes[i].in_stack && |
| g->regs->regs[r].conflicts[g->nodes[i].reg]) { |
| break; |
| } |
| } |
| if (i == g->count) |
| break; |
| } |
| if (r == g->regs->count) |
| return GL_FALSE; |
| |
| g->nodes[n].reg = r; |
| g->nodes[n].in_stack = GL_FALSE; |
| g->stack_count--; |
| } |
| |
| return GL_TRUE; |
| } |
| |
| /** |
| * Optimistic register coloring: Just push the remaining nodes |
| * on the stack. They'll be colored first in ra_select(), and |
| * if they succeed then the locally-colorable nodes are still |
| * locally-colorable and the rest of the register allocation |
| * will succeed. |
| */ |
| void |
| ra_optimistic_color(struct ra_graph *g) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < g->count; i++) { |
| if (g->nodes[i].in_stack) |
| continue; |
| |
| g->stack[g->stack_count] = i; |
| g->stack_count++; |
| g->nodes[i].in_stack = GL_TRUE; |
| } |
| } |
| |
| GLboolean |
| ra_allocate_no_spills(struct ra_graph *g) |
| { |
| if (!ra_simplify(g)) { |
| ra_optimistic_color(g); |
| } |
| return ra_select(g); |
| } |
| |
| unsigned int |
| ra_get_node_reg(struct ra_graph *g, unsigned int n) |
| { |
| return g->nodes[n].reg; |
| } |
| |
| static float |
| ra_get_spill_benefit(struct ra_graph *g, unsigned int n) |
| { |
| int j; |
| float benefit = 0; |
| int n_class = g->nodes[n].class; |
| |
| /* Define the benefit of eliminating an interference between n, j |
| * through spilling as q(C, B) / p(C). This is similar to the |
| * "count number of edges" approach of traditional graph coloring, |
| * but takes classes into account. |
| */ |
| for (j = 0; j < g->count; j++) { |
| if (j != n && g->nodes[n].adjacency[j]) { |
| unsigned int j_class = g->nodes[j].class; |
| benefit += ((float)g->regs->classes[n_class]->q[j_class] / |
| g->regs->classes[n_class]->p); |
| break; |
| } |
| } |
| |
| return benefit; |
| } |
| |
| /** |
| * Returns a node number to be spilled according to the cost/benefit using |
| * the pq test, or -1 if there are no spillable nodes. |
| */ |
| int |
| ra_get_best_spill_node(struct ra_graph *g) |
| { |
| unsigned int best_node = -1; |
| unsigned int best_benefit = 0.0; |
| unsigned int n; |
| |
| for (n = 0; n < g->count; n++) { |
| float cost = g->nodes[n].spill_cost; |
| float benefit; |
| |
| if (cost <= 0.0) |
| continue; |
| |
| benefit = ra_get_spill_benefit(g, n); |
| |
| if (benefit / cost > best_benefit) { |
| best_benefit = benefit / cost; |
| best_node = n; |
| } |
| } |
| |
| return best_node; |
| } |
| |
| /** |
| * Only nodes with a spill cost set (cost != 0.0) will be considered |
| * for register spilling. |
| */ |
| void |
| ra_set_node_spill_cost(struct ra_graph *g, unsigned int n, float cost) |
| { |
| g->nodes[n].spill_cost = cost; |
| } |