/*
* Instruction Scheduling:
*
- * A priority-queue based scheduling algo. Add eligible instructions,
- * ie. ones with all their dependencies scheduled, to the priority
- * (depth) sorted queue (list). Pop highest priority instruction off
- * the queue and schedule it, add newly eligible instructions to the
- * priority queue, rinse, repeat.
+ * A recursive depth based scheduling algo. Recursively find an eligible
+ * instruction to schedule from the deepest instruction (recursing through
+ * it's unscheduled src instructions). Normally this would result in a
+ * lot of re-traversal of the same instructions, so we cache results in
+ * instr->data (and clear cached results that would be no longer valid
+ * after scheduling an instruction).
*
* There are a few special cases that need to be handled, since sched
* is currently independent of register allocation. Usages of address
struct ir3_sched_ctx {
struct ir3_block *block; /* the current block */
+ struct list_head depth_list; /* depth sorted unscheduled instrs */
struct ir3_instruction *scheduled; /* last scheduled instr XXX remove*/
struct ir3_instruction *addr; /* current a0.x user, if any */
struct ir3_instruction *pred; /* current p0.x user, if any */
return is_sfu(instr) || is_mem(instr);
}
+#define NULL_INSTR ((void *)~0)
+
+static void
+clear_cache(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
+{
+ list_for_each_entry (struct ir3_instruction, instr2, &ctx->depth_list, node) {
+ if ((instr2->data == instr) || (instr2->data == NULL_INSTR) || !instr)
+ instr2->data = NULL;
+ }
+}
+
static void
schedule(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
{
list_addtail(&instr->node, &instr->block->instr_list);
ctx->scheduled = instr;
+
+ if (writes_addr(instr) || writes_pred(instr) || is_input(instr)) {
+ clear_cache(ctx, NULL);
+ } else {
+ /* invalidate only the necessary entries.. */
+ clear_cache(ctx, instr);
+ }
+}
+
+static struct ir3_instruction *
+deepest(struct ir3_instruction **srcs, unsigned nsrcs)
+{
+ struct ir3_instruction *d = NULL;
+ unsigned i = 0, id = 0;
+
+ while ((i < nsrcs) && !(d = srcs[id = i]))
+ i++;
+
+ if (!d)
+ return NULL;
+
+ for (; i < nsrcs; i++)
+ if (srcs[i] && (srcs[i]->depth > d->depth))
+ d = srcs[id = i];
+
+ srcs[id] = NULL;
+
+ return d;
}
static unsigned
return !!(instr->flags & IR3_INSTR_MARK);
}
+/* could an instruction be scheduled if specified ssa src was scheduled? */
+static bool
+could_sched(struct ir3_instruction *instr, struct ir3_instruction *src)
+{
+ struct ir3_instruction *other_src;
+ foreach_ssa_src(other_src, instr) {
+ /* if dependency not scheduled, we aren't ready yet: */
+ if ((src != other_src) && !is_scheduled(other_src)) {
+ return false;
+ }
+ }
+ return true;
+}
+
+/* Check if instruction is ok to schedule. Make sure it is not blocked
+ * by use of addr/predicate register, etc.
+ */
static bool
-check_conflict(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
+check_instr(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
struct ir3_instruction *instr)
{
+ /* For instructions that write address register we need to
+ * make sure there is at least one instruction that uses the
+ * addr value which is otherwise ready.
+ *
+ * TODO if any instructions use pred register and have other
+ * src args, we would need to do the same for writes_pred()..
+ */
+ if (writes_addr(instr)) {
+ struct ir3 *ir = instr->block->shader;
+ bool ready = false;
+ for (unsigned i = 0; (i < ir->indirects_count) && !ready; i++) {
+ struct ir3_instruction *indirect = ir->indirects[i];
+ if (!indirect)
+ continue;
+ if (indirect->address != instr)
+ continue;
+ ready = could_sched(indirect, instr);
+ }
+
+ /* nothing could be scheduled, so keep looking: */
+ if (!ready)
+ return false;
+ }
+
/* if this is a write to address/predicate register, and that
* register is currently in use, we need to defer until it is
* free:
if (writes_addr(instr) && ctx->addr) {
debug_assert(ctx->addr != instr);
notes->addr_conflict = true;
- return true;
+ return false;
}
if (writes_pred(instr) && ctx->pred) {
debug_assert(ctx->pred != instr);
notes->pred_conflict = true;
- return true;
+ return false;
}
- return false;
-}
-
-/* is this instruction ready to be scheduled? Return negative for not
- * ready (updating notes if needed), or >= 0 to indicate number of
- * delay slots needed.
- */
-static int
-instr_eligibility(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
- struct ir3_instruction *instr)
-{
- struct ir3_instruction *src;
- unsigned delay = 0;
-
- /* Phi instructions can have a dependency on something not
- * scheduled yet (for ex, loops). But OTOH we don't really
- * care. By definition phi's should appear at the top of
- * the block, and it's sources should be values from the
- * previously executing block, so they are always ready to
- * be scheduled:
- */
- if (is_meta(instr) && (instr->opc == OPC_META_PHI))
- return 0;
-
- foreach_ssa_src(src, instr) {
- /* if dependency not scheduled, we aren't ready yet: */
- if (!is_scheduled(src))
- return -1;
- }
-
- /* all our dependents are scheduled, figure out if
- * we have enough delay slots to schedule ourself:
- */
- delay = delay_calc(ctx, instr);
- if (delay)
- return delay;
-
/* if the instruction is a kill, we need to ensure *every*
* bary.f is scheduled. The hw seems unhappy if the thread
* gets killed before the end-input (ei) flag is hit.
continue;
if (!is_scheduled(baryf)) {
notes->blocked_kill = true;
- return -1;
+ return false;
}
}
}
- if (check_conflict(ctx, notes, instr))
- return -1;
-
- return 0;
+ return true;
}
-/* could an instruction be scheduled if specified ssa src was scheduled? */
-static bool
-could_sched(struct ir3_instruction *instr, struct ir3_instruction *src)
+/* Find the best instruction to schedule from specified instruction or
+ * recursively it's ssa sources.
+ */
+static struct ir3_instruction *
+find_instr_recursive(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
+ struct ir3_instruction *instr)
{
- struct ir3_instruction *other_src;
- foreach_ssa_src(other_src, instr) {
- /* if dependency not scheduled, we aren't ready yet: */
- if ((src != other_src) && !is_scheduled(other_src)) {
- return false;
+ struct ir3_instruction *srcs[__ssa_src_cnt(instr)];
+ struct ir3_instruction *src;
+ unsigned nsrcs = 0;
+
+ if (is_scheduled(instr))
+ return NULL;
+
+ /* use instr->data to cache the results of recursing up the
+ * instr src's. Otherwise the recursive algo can scale quite
+ * badly w/ shader size. But this takes some care to clear
+ * the cache appropriately when instructions are scheduled.
+ */
+ if (instr->data) {
+ if (instr->data == NULL_INSTR)
+ return NULL;
+ return instr->data;
+ }
+
+ /* find unscheduled srcs: */
+ foreach_ssa_src(src, instr) {
+ if (!is_scheduled(src)) {
+ debug_assert(nsrcs < ARRAY_SIZE(srcs));
+ srcs[nsrcs++] = src;
}
}
- return true;
+
+ /* if all our src's are already scheduled: */
+ if (nsrcs == 0) {
+ if (check_instr(ctx, notes, instr)) {
+ instr->data = instr;
+ return instr;
+ }
+ return NULL;
+ }
+
+ while ((src = deepest(srcs, nsrcs))) {
+ struct ir3_instruction *candidate;
+
+ candidate = find_instr_recursive(ctx, notes, src);
+ if (!candidate)
+ continue;
+
+ if (check_instr(ctx, notes, candidate)) {
+ instr->data = candidate;
+ return candidate;
+ }
+ }
+
+ instr->data = NULL_INSTR;
+ return NULL;
}
-/* move eligible instructions to the priority list: */
-static unsigned
-add_eligible_instrs(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
- struct list_head *prio_queue, struct list_head *unscheduled_list)
+/* find instruction to schedule: */
+static struct ir3_instruction *
+find_eligible_instr(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes)
{
+ struct ir3_instruction *best_instr = NULL;
unsigned min_delay = ~0;
- list_for_each_entry_safe (struct ir3_instruction, instr, unscheduled_list, node) {
- int e = instr_eligibility(ctx, notes, instr);
- if (e < 0)
- continue;
+ /* TODO we'd really rather use the list/array of block outputs. But we
+ * don't have such a thing. Recursing *every* instruction in the list
+ * will result in a lot of repeated traversal, since instructions will
+ * get traversed both when they appear as ssa src to a later instruction
+ * as well as where they appear in the depth_list.
+ */
+ list_for_each_entry_rev (struct ir3_instruction, instr, &ctx->depth_list, node) {
+ struct ir3_instruction *candidate;
+ unsigned delay;
- /* For instructions that write address register we need to
- * make sure there is at least one instruction that uses the
- * addr value which is otherwise ready.
- *
- * TODO if any instructions use pred register and have other
- * src args, we would need to do the same for writes_pred()..
- */
- if (unlikely(writes_addr(instr))) {
- struct ir3 *ir = instr->block->shader;
- bool ready = false;
- for (unsigned i = 0; (i < ir->indirects_count) && !ready; i++) {
- struct ir3_instruction *indirect = ir->indirects[i];
- if (!indirect)
- continue;
- if (indirect->address != instr)
- continue;
- ready = could_sched(indirect, instr);
- }
+ candidate = find_instr_recursive(ctx, notes, instr);
+ if (!candidate)
+ continue;
- /* nothing could be scheduled, so keep looking: */
- if (!ready)
- continue;
+ delay = delay_calc(ctx, candidate);
+ if (delay < min_delay) {
+ best_instr = candidate;
+ min_delay = delay;
}
- min_delay = MIN2(min_delay, e);
- if (e == 0) {
- /* remove from unscheduled list and into priority queue: */
- list_delinit(&instr->node);
- ir3_insert_by_depth(instr, prio_queue);
- }
+ if (min_delay == 0)
+ break;
}
- return min_delay;
+ return best_instr;
}
/* "spill" the address register by remapping any unscheduled
static void
sched_block(struct ir3_sched_ctx *ctx, struct ir3_block *block)
{
- struct list_head unscheduled_list, prio_queue;
+ struct list_head unscheduled_list;
ctx->block = block;
+ /* addr/pred writes are per-block: */
+ ctx->addr = NULL;
+ ctx->pred = NULL;
+
/* move all instructions to the unscheduled list, and
* empty the block's instruction list (to which we will
- * be inserting.
+ * be inserting).
*/
list_replace(&block->instr_list, &unscheduled_list);
list_inithead(&block->instr_list);
- list_inithead(&prio_queue);
+ list_inithead(&ctx->depth_list);
/* first a pre-pass to schedule all meta:input/phi instructions
* (which need to appear first so that RA knows the register is
- * occupied:
+ * occupied), and move remaining to depth sorted list:
*/
list_for_each_entry_safe (struct ir3_instruction, instr, &unscheduled_list, node) {
if (is_meta(instr) && ((instr->opc == OPC_META_INPUT) ||
- (instr->opc == OPC_META_PHI)))
+ (instr->opc == OPC_META_PHI))) {
schedule(ctx, instr);
+ } else {
+ ir3_insert_by_depth(instr, &ctx->depth_list);
+ }
}
- while (!(list_empty(&unscheduled_list) &&
- list_empty(&prio_queue))) {
+ while (!list_empty(&ctx->depth_list)) {
struct ir3_sched_notes notes = {0};
- unsigned delay;
+ struct ir3_instruction *instr;
+
+ instr = find_eligible_instr(ctx, ¬es);
- delay = add_eligible_instrs(ctx, ¬es, &prio_queue, &unscheduled_list);
+ if (instr) {
+ unsigned delay = delay_calc(ctx, instr);
- if (!list_empty(&prio_queue)) {
- struct ir3_instruction *instr = list_last_entry(&prio_queue,
- struct ir3_instruction, node);
- /* ugg, this is a bit ugly, but between the time when
- * the instruction became eligible and now, a new
- * conflict may have arose..
+ /* and if we run out of instructions that can be scheduled,
+ * then it is time for nop's:
*/
- if (check_conflict(ctx, ¬es, instr)) {
- list_del(&instr->node);
- list_addtail(&instr->node, &unscheduled_list);
- continue;
+ debug_assert(delay <= 6);
+ while (delay > 0) {
+ ir3_NOP(block);
+ delay--;
}
schedule(ctx, instr);
- } else if (delay == ~0) {
+ } else {
struct ir3_instruction *new_instr = NULL;
/* nothing available to schedule.. if we are blocked on
}
if (new_instr) {
- list_del(&new_instr->node);
- list_addtail(&new_instr->node, &unscheduled_list);
+ /* clearing current addr/pred can change what is
+ * available to schedule, so clear cache..
+ */
+ clear_cache(ctx, NULL);
+
+ ir3_insert_by_depth(new_instr, &ctx->depth_list);
/* the original instr that wrote addr/pred may have
* originated from a different block:
*/
new_instr->block = block;
}
-
- } else {
- /* and if we run out of instructions that can be scheduled,
- * then it is time for nop's:
- */
- debug_assert(delay <= 6);
- while (delay > 0) {
- ir3_NOP(block);
- delay--;
- }
}
}
projects / mesa.git / commitdiff