* this during ra_set_finalize().
*/
-#include <ralloc.h>
+#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 {
- GLboolean *conflicts;
+ BITSET_WORD *conflicts;
unsigned int *conflict_list;
unsigned int conflict_list_size;
unsigned int num_conflicts;
struct ra_class **classes;
unsigned int class_count;
+
+ bool round_robin;
};
struct ra_class {
- GLboolean *regs;
+ /**
+ * 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.
* List of which nodes this node interferes with. This should be
* symmetric with the other node.
*/
- GLboolean *adjacency;
+ BITSET_WORD *adjacency;
unsigned int *adjacency_list;
+ unsigned int adjacency_list_size;
unsigned int adjacency_count;
/** @} */
* "remove the edge from the graph" in simplification without
* having to actually modify the adjacency_list.
*/
- GLboolean in_stack;
+ 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.
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(unsigned int count)
+ra_alloc_reg_set(void *mem_ctx, unsigned int count)
{
unsigned int i;
struct ra_regs *regs;
- regs = rzalloc(NULL, struct ra_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, GLboolean, count);
- regs->regs[i].conflicts[i] = GL_TRUE;
+ 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;
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)
{
unsigned int, reg1->conflict_list_size);
}
reg1->conflict_list[reg1->num_conflicts++] = r2;
- reg1->conflicts[r2] = GL_TRUE;
+ BITSET_SET(reg1->conflicts, r2);
}
void
ra_add_reg_conflict(struct ra_regs *regs, unsigned int r1, unsigned int r2)
{
- if (!regs->regs[r1].conflicts[r2]) {
+ if (!BITSET_TEST(regs->regs[r1].conflicts, r2)) {
ra_add_conflict_list(regs, r1, r2);
ra_add_conflict_list(regs, r2, r1);
}
class = rzalloc(regs, struct ra_class);
regs->classes[regs->class_count] = class;
- class->regs = rzalloc_array(class, GLboolean, regs->count);
+ class->regs = rzalloc_array(class, BITSET_WORD, BITSET_WORDS(regs->count));
return regs->class_count++;
}
{
struct ra_class *class = regs->classes[c];
- class->regs[r] = GL_TRUE;
+ 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)
+ra_set_finalize(struct ra_regs *regs, unsigned int **q_values)
{
unsigned int b, c;
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.
*/
int conflicts = 0;
int i;
- if (!regs->classes[c]->regs[rc])
+ 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 (regs->classes[b]->regs[rb])
+ if (BITSET_TEST(regs->classes[b]->regs, rb))
conflicts++;
}
max_conflicts = MAX2(max_conflicts, conflicts);
static void
ra_add_node_adjacency(struct ra_graph *g, unsigned int n1, unsigned int n2)
{
- g->nodes[n1].adjacency[n2] = GL_TRUE;
+ 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++;
}
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_list = ralloc_array(g, unsigned int, count);
+ 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;
}
ra_add_node_interference(struct ra_graph *g,
unsigned int n1, unsigned int n2)
{
- if (!g->nodes[n1].adjacency[n2]) {
+ if (!BITSET_TEST(g->nodes[n1].adjacency, n2)) {
ra_add_node_adjacency(g, n1, n2);
ra_add_node_adjacency(g, n2, n1);
}
}
-static GLboolean pq_test(struct ra_graph *g, unsigned int n)
+static bool
+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->nodes[n].adjacency_count; j++) {
- unsigned int n2 = g->nodes[n].adjacency_list[j];
+ 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) {
- q += g->regs->classes[n_class]->q[n2_class];
+ 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];
}
}
-
- return q < g->regs->classes[n_class]->p;
}
/**
* 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.
+ * 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.
*/
-GLboolean
+static void
ra_simplify(struct ra_graph *g)
{
- GLboolean progress = GL_TRUE;
+ bool progress = true;
int i;
while (progress) {
- progress = GL_FALSE;
+ 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 = GL_TRUE;
- progress = GL_TRUE;
+ 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;
+ }
}
}
- }
- for (i = 0; i < g->count; i++) {
- if (!g->nodes[i].in_stack)
- return GL_FALSE;
+ 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;
+ }
}
-
- return GL_TRUE;
}
/**
* registers as they go.
*
* If all nodes were trivially colorable, then this must succeed. If
- * not (optimistic coloring), then it may return GL_FALSE;
+ * not (optimistic coloring), then it may return false;
*/
-GLboolean
+static bool
ra_select(struct ra_graph *g)
{
int i;
+ int start_search_reg = 0;
while (g->stack_count != 0) {
- unsigned int r;
+ 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 (r = 0; r < g->regs->count; r++) {
- if (!c->regs[r])
+ 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. */
unsigned int n2 = g->nodes[n].adjacency_list[i];
if (!g->nodes[n2].in_stack &&
- g->regs->regs[r].conflicts[g->nodes[n2].reg]) {
+ BITSET_TEST(g->regs->regs[r].conflicts, g->nodes[n2].reg)) {
break;
}
}
if (i == g->nodes[n].adjacency_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;
-}
+ /* 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;
-/**
- * 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;
+ if (ri == g->regs->count)
+ return false;
- for (i = 0; i < g->count; i++) {
- if (g->nodes[i].in_stack || g->nodes[i].reg != NO_REG)
- continue;
+ g->nodes[n].reg = r;
+ g->stack_count--;
- g->stack[g->stack_count] = i;
- g->stack_count++;
- g->nodes[i].in_stack = GL_TRUE;
+ if (g->regs->round_robin)
+ start_search_reg = r + 1;
}
+
+ return true;
}
-GLboolean
-ra_allocate_no_spills(struct ra_graph *g)
+bool
+ra_allocate(struct ra_graph *g)
{
- if (!ra_simplify(g)) {
- ra_optimistic_color(g);
- }
+ ra_simplify(g);
return ra_select(g);
}
* 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().
*/
ra_set_node_reg(struct ra_graph *g, unsigned int n, unsigned int reg)
{
g->nodes[n].reg = reg;
- g->nodes[n].in_stack = GL_FALSE;
+ g->nodes[n].in_stack = false;
}
static float
ra_get_best_spill_node(struct ra_graph *g)
{
unsigned int best_node = -1;
- unsigned int best_benefit = 0.0;
+ 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) {
projects / mesa.git / blobdiff