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Diffstat (limited to 'mesalib/src/mesa/program/register_allocate.c')
| -rw-r--r-- | mesalib/src/mesa/program/register_allocate.c | 654 |
1 files changed, 0 insertions, 654 deletions
diff --git a/mesalib/src/mesa/program/register_allocate.c b/mesalib/src/mesa/program/register_allocate.c deleted file mode 100644 index 7faf67215..000000000 --- a/mesalib/src/mesa/program/register_allocate.c +++ /dev/null @@ -1,654 +0,0 @@ -/* - * 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. - * - * The basic idea of graph coloring is to make a node in a graph for - * every thing that needs a register (color) number assigned, and make - * edges in the graph between nodes that interfere (can't be allocated - * to the same register at the same time). - * - * During the "simplify" process, any any node with fewer edges than - * there are registers means that that edge can get assigned a - * register regardless of what its neighbors choose, so that node is - * pushed on a stack and removed (with its edges) from the graph. - * That likely causes other nodes to become trivially colorable as well. - * - * Then during the "select" process, nodes are popped off of that - * stack, their edges restored, and assigned a color different from - * their neighbors. Because they were pushed on the stack only when - * they were trivially colorable, any color chosen won't interfere - * with the registers to be popped later. - * - * The downside to most graph coloring is that real hardware often has - * limitations, like registers that need to be allocated to a node in - * pairs, or aligned on some boundary. This implementation follows - * the paper "Retargetable Graph-Coloring Register Allocation for - * Irregular Architectures" by Johan Runeson and Sven-Olof Nyström. - * - * In this system, there are register classes each containing various - * registers, and registers may interfere with other registers. For - * example, one might have a class of base registers, and a class of - * aligned register pairs that would each interfere with their pair of - * the base registers. Each node has a register class it needs to be - * assigned to. Define p(B) to be the size of register class B, and - * q(B,C) to be the number of registers in B that the worst choice - * register in C could conflict with. Then, this system replaces the - * basic graph coloring test of "fewer edges from this node than there - * are registers" with "For this node of class B, the sum of q(B,C) - * for each neighbor node of class C is less than pB". - * - * A nice feature of the pq test is that q(B,C) can be computed once - * up front and stored in a 2-dimensional array, so that the cost of - * coloring a node is constant with the number of registers. We do - * this during ra_set_finalize(). - */ - -#include <stdbool.h> - -#include "util/ralloc.h" -#include "main/imports.h" -#include "main/macros.h" -#include "main/mtypes.h" -#include "main/bitset.h" -#include "register_allocate.h" - -#define NO_REG ~0 - -struct ra_reg { - BITSET_WORD *conflicts; - unsigned int *conflict_list; - unsigned int conflict_list_size; - unsigned int num_conflicts; -}; - -struct ra_regs { - struct ra_reg *regs; - unsigned int count; - - struct ra_class **classes; - unsigned int class_count; - - bool round_robin; -}; - -struct ra_class { - /** - * Bitset indicating which registers belong to this class. - * - * (If bit N is set, then register N belongs to this class.) - */ - BITSET_WORD *regs; - - /** - * p(B) in Runeson/Nyström paper. - * - * This is "how many regs are in the set." - */ - unsigned int p; - - /** - * q(B,C) (indexed by C, B is this register class) in - * Runeson/Nyström paper. This is "how many registers of B could - * the worst choice register from C conflict with". - */ - unsigned int *q; -}; - -struct ra_node { - /** @{ - * - * List of which nodes this node interferes with. This should be - * symmetric with the other node. - */ - BITSET_WORD *adjacency; - unsigned int *adjacency_list; - unsigned int adjacency_list_size; - unsigned int adjacency_count; - /** @} */ - - unsigned int class; - - /* Register, if assigned, or NO_REG. */ - unsigned int reg; - - /** - * Set when the node is in the trivially colorable stack. When - * set, the adjacency to this node is ignored, to implement the - * "remove the edge from the graph" in simplification without - * having to actually modify the adjacency_list. - */ - bool in_stack; - - /** - * The q total, as defined in the Runeson/Nyström paper, for all the - * interfering nodes not in the stack. - */ - unsigned int q_total; - - /* For an implementation that needs register spilling, this is the - * approximate cost of spilling this node. - */ - 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; -}; - -/** - * Creates a set of registers for the allocator. - * - * mem_ctx is a ralloc context for the allocator. The reg set may be freed - * using ralloc_free(). - */ -struct ra_regs * -ra_alloc_reg_set(void *mem_ctx, unsigned int count) -{ - unsigned int i; - struct ra_regs *regs; - - regs = rzalloc(mem_ctx, 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, BITSET_WORD, - BITSET_WORDS(count)); - BITSET_SET(regs->regs[i].conflicts, i); - - regs->regs[i].conflict_list = ralloc_array(regs->regs, unsigned int, 4); - regs->regs[i].conflict_list_size = 4; - regs->regs[i].conflict_list[0] = i; - regs->regs[i].num_conflicts = 1; - } - - return regs; -} - -/** - * The register allocator by default prefers to allocate low register numbers, - * since it was written for hardware (gen4/5 Intel) that is limited in its - * multithreadedness by the number of registers used in a given shader. - * - * However, for hardware without that restriction, densely packed register - * allocation can put serious constraints on instruction scheduling. This - * function tells the allocator to rotate around the registers if possible as - * it allocates the nodes. - */ -void -ra_set_allocate_round_robin(struct ra_regs *regs) -{ - regs->round_robin = true; -} - -static void -ra_add_conflict_list(struct ra_regs *regs, unsigned int r1, unsigned int r2) -{ - struct ra_reg *reg1 = ®s->regs[r1]; - - if (reg1->conflict_list_size == reg1->num_conflicts) { - reg1->conflict_list_size *= 2; - reg1->conflict_list = reralloc(regs->regs, reg1->conflict_list, - unsigned int, reg1->conflict_list_size); - } - reg1->conflict_list[reg1->num_conflicts++] = r2; - BITSET_SET(reg1->conflicts, r2); -} - -void -ra_add_reg_conflict(struct ra_regs *regs, unsigned int r1, unsigned int r2) -{ - if (!BITSET_TEST(regs->regs[r1].conflicts, r2)) { - ra_add_conflict_list(regs, r1, r2); - ra_add_conflict_list(regs, r2, r1); - } -} - -/** - * Adds a conflict between base_reg and reg, and also between reg and - * anything that base_reg conflicts with. - * - * This can simplify code for setting up multiple register classes - * which are aggregates of some base hardware registers, compared to - * explicitly using ra_add_reg_conflict. - */ -void -ra_add_transitive_reg_conflict(struct ra_regs *regs, - unsigned int base_reg, unsigned int reg) -{ - int i; - - ra_add_reg_conflict(regs, reg, base_reg); - - for (i = 0; i < regs->regs[base_reg].num_conflicts; i++) { - ra_add_reg_conflict(regs, reg, regs->regs[base_reg].conflict_list[i]); - } -} - -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, BITSET_WORD, BITSET_WORDS(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]; - - BITSET_SET(class->regs, r); - class->p++; -} - -/** - * Returns true if the register belongs to the given class. - */ -static bool -reg_belongs_to_class(unsigned int r, struct ra_class *c) -{ - return BITSET_TEST(c->regs, r); -} - -/** - * Must be called after all conflicts and register classes have been - * set up and before the register set is used for allocation. - * To avoid costly q value computation, use the q_values paramater - * to pass precomputed q values to this function. - */ -void -ra_set_finalize(struct ra_regs *regs, unsigned int **q_values) -{ - unsigned int b, c; - - for (b = 0; b < regs->class_count; b++) { - regs->classes[b]->q = ralloc_array(regs, unsigned int, regs->class_count); - } - - if (q_values) { - for (b = 0; b < regs->class_count; b++) { - for (c = 0; c < regs->class_count; c++) { - regs->classes[b]->q[c] = q_values[b][c]; - } - } - return; - } - - /* 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++) { - int conflicts = 0; - int i; - - if (!reg_belongs_to_class(rc, regs->classes[c])) - continue; - - for (i = 0; i < regs->regs[rc].num_conflicts; i++) { - unsigned int rb = regs->regs[rc].conflict_list[i]; - if (BITSET_TEST(regs->classes[b]->regs, rb)) - conflicts++; - } - max_conflicts = MAX2(max_conflicts, conflicts); - } - regs->classes[b]->q[c] = max_conflicts; - } - } -} - -static void -ra_add_node_adjacency(struct ra_graph *g, unsigned int n1, unsigned int n2) -{ - BITSET_SET(g->nodes[n1].adjacency, n2); - - if (n1 != n2) { - int n1_class = g->nodes[n1].class; - int n2_class = g->nodes[n2].class; - g->nodes[n1].q_total += g->regs->classes[n1_class]->q[n2_class]; - } - - if (g->nodes[n1].adjacency_count >= - g->nodes[n1].adjacency_list_size) { - g->nodes[n1].adjacency_list_size *= 2; - g->nodes[n1].adjacency_list = reralloc(g, g->nodes[n1].adjacency_list, - unsigned int, - g->nodes[n1].adjacency_list_size); - } - - g->nodes[n1].adjacency_list[g->nodes[n1].adjacency_count] = n2; - g->nodes[n1].adjacency_count++; -} - -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++) { - int bitset_count = BITSET_WORDS(count); - g->nodes[i].adjacency = rzalloc_array(g, BITSET_WORD, bitset_count); - - g->nodes[i].adjacency_list_size = 4; - g->nodes[i].adjacency_list = - ralloc_array(g, unsigned int, g->nodes[i].adjacency_list_size); - g->nodes[i].adjacency_count = 0; - g->nodes[i].q_total = 0; - - ra_add_node_adjacency(g, i, i); - g->nodes[i].reg = NO_REG; - } - - 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 (!BITSET_TEST(g->nodes[n1].adjacency, n2)) { - ra_add_node_adjacency(g, n1, n2); - ra_add_node_adjacency(g, n2, n1); - } -} - -static bool -pq_test(struct ra_graph *g, unsigned int n) -{ - int n_class = g->nodes[n].class; - - return g->nodes[n].q_total < g->regs->classes[n_class]->p; -} - -static void -decrement_q(struct ra_graph *g, unsigned int n) -{ - unsigned int i; - int n_class = g->nodes[n].class; - - for (i = 0; i < g->nodes[n].adjacency_count; i++) { - unsigned int n2 = g->nodes[n].adjacency_list[i]; - unsigned int n2_class = g->nodes[n2].class; - - if (n != n2 && !g->nodes[n2].in_stack) { - assert(g->nodes[n2].q_total >= g->regs->classes[n2_class]->q[n_class]); - g->nodes[n2].q_total -= g->regs->classes[n2_class]->q[n_class]; - } - } -} - -/** - * 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. - * - * If we encounter a case where we can't push any nodes on the stack, then - * we optimistically choose a node and push it on the stack. We heuristically - * push the node with the lowest total q value, since it has the fewest - * neighbors and therefore is most likely to be allocated. - */ -static void -ra_simplify(struct ra_graph *g) -{ - bool progress = true; - int i; - - while (progress) { - unsigned int best_optimistic_node = ~0; - unsigned int lowest_q_total = ~0; - - progress = false; - - for (i = g->count - 1; i >= 0; i--) { - if (g->nodes[i].in_stack || g->nodes[i].reg != NO_REG) - continue; - - if (pq_test(g, i)) { - decrement_q(g, i); - g->stack[g->stack_count] = i; - g->stack_count++; - g->nodes[i].in_stack = true; - progress = true; - } else { - unsigned int new_q_total = g->nodes[i].q_total; - if (new_q_total < lowest_q_total) { - best_optimistic_node = i; - lowest_q_total = new_q_total; - } - } - } - - if (!progress && best_optimistic_node != ~0) { - decrement_q(g, best_optimistic_node); - g->stack[g->stack_count] = best_optimistic_node; - g->stack_count++; - g->nodes[best_optimistic_node].in_stack = true; - progress = 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 false; - */ -static bool -ra_select(struct ra_graph *g) -{ - int i; - int start_search_reg = 0; - - while (g->stack_count != 0) { - unsigned int ri; - unsigned int r = -1; - 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 (ri = 0; ri < g->regs->count; ri++) { - r = (start_search_reg + ri) % g->regs->count; - if (!reg_belongs_to_class(r, c)) - continue; - - /* Check if any of our neighbors conflict with this register choice. */ - for (i = 0; i < g->nodes[n].adjacency_count; i++) { - unsigned int n2 = g->nodes[n].adjacency_list[i]; - - if (!g->nodes[n2].in_stack && - BITSET_TEST(g->regs->regs[r].conflicts, g->nodes[n2].reg)) { - break; - } - } - if (i == g->nodes[n].adjacency_count) - break; - } - - /* set this to false even if we return here so that - * ra_get_best_spill_node() considers this node later. - */ - g->nodes[n].in_stack = false; - - if (ri == g->regs->count) - return false; - - g->nodes[n].reg = r; - g->stack_count--; - - if (g->regs->round_robin) - start_search_reg = r + 1; - } - - return true; -} - -bool -ra_allocate(struct ra_graph *g) -{ - ra_simplify(g); - return ra_select(g); -} - -unsigned int -ra_get_node_reg(struct ra_graph *g, unsigned int n) -{ - return g->nodes[n].reg; -} - -/** - * Forces a node to a specific register. This can be used to avoid - * creating a register class containing one node when handling data - * that must live in a fixed location and is known to not conflict - * with other forced register assignment (as is common with shader - * input data). These nodes do not end up in the stack during - * ra_simplify(), and thus at ra_select() time it is as if they were - * the first popped off the stack and assigned their fixed locations. - * Nodes that use this function do not need to be assigned a register - * class. - * - * Must be called before ra_simplify(). - */ -void -ra_set_node_reg(struct ra_graph *g, unsigned int n, unsigned int reg) -{ - g->nodes[n].reg = reg; - g->nodes[n].in_stack = false; -} - -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, n2 - * 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->nodes[n].adjacency_count; j++) { - unsigned int n2 = g->nodes[n].adjacency_list[j]; - if (n != n2) { - unsigned int n2_class = g->nodes[n2].class; - benefit += ((float)g->regs->classes[n_class]->q[n2_class] / - g->regs->classes[n_class]->p); - } - } - - 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; - float best_benefit = 0.0; - unsigned int n; - - /* Consider any nodes that we colored successfully or the node we failed to - * color for spilling. When we failed to color a node in ra_select(), we - * only considered these nodes, so spilling any other ones would not result - * in us making progress. - */ - for (n = 0; n < g->count; n++) { - float cost = g->nodes[n].spill_cost; - float benefit; - - if (cost <= 0.0) - continue; - - if (g->nodes[n].in_stack) - 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; -} |