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mesa/src/freedreno/ir3/ir3_sched.c

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/*
* Copyright (C) 2014 Rob Clark <robclark@freedesktop.org>
*
* 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:
* Rob Clark <robclark@freedesktop.org>
*/
#include "util/dag.h"
#include "util/u_math.h"
#include "ir3.h"
#include "ir3_compiler.h"
#ifdef DEBUG
#define SCHED_DEBUG (ir3_shader_debug & IR3_DBG_SCHEDMSGS)
#else
#define SCHED_DEBUG 0
#endif
#define d(fmt, ...) \
do { \
if (SCHED_DEBUG) { \
mesa_logi("SCHED: " fmt, ##__VA_ARGS__); \
} \
} while (0)
#define di(instr, fmt, ...) \
do { \
if (SCHED_DEBUG) { \
struct log_stream *stream = mesa_log_streami(); \
mesa_log_stream_printf(stream, "SCHED: " fmt ": ", ##__VA_ARGS__); \
ir3_print_instr_stream(stream, instr); \
mesa_log_stream_destroy(stream); \
} \
} while (0)
/*
* Instruction Scheduling:
*
* A block-level pre-RA scheduler, which works by creating a DAG of
* instruction dependencies, and heuristically picking a DAG head
* (instruction with no unscheduled dependencies).
*
* Where possible, it tries to pick instructions that avoid nop delay
* slots, but it will prefer to pick instructions that reduce (or do
* not increase) the number of live values.
*
* If the only possible choices are instructions that increase the
* number of live values, it will try to pick the one with the earliest
* consumer (based on pre-sched program order).
*
* There are a few special cases that need to be handled, since sched
* is currently independent of register allocation. Usages of address
* register (a0.x) or predicate register (p0.x) must be serialized. Ie.
* if you have two pairs of instructions that write the same special
* register and then read it, then those pairs cannot be interleaved.
* To solve this, when we are in such a scheduling "critical section",
* and we encounter a conflicting write to a special register, we try
* to schedule any remaining instructions that use that value first.
*
* TODO we can detect too-large live_values here.. would be a good place
* to "spill" cheap things, like move from uniform/immed. (Constructing
* list of ssa def consumers before sched pass would make this easier.
* Also, in general it is general it might be best not to re-use load_immed
* across blocks.
*
* TODO we can use (abs)/(neg) src modifiers in a lot of cases to reduce
* the # of immediates in play (or at least that would help with
* dEQP-GLES31.functional.ubo.random.all_per_block_buffers.*).. probably
* do this in a nir pass that inserts fneg/etc? The cp pass should fold
* these into src modifiers..
*/
struct ir3_sched_ctx {
struct ir3_block *block; /* the current block */
struct dag *dag;
struct list_head unscheduled_list; /* unscheduled instructions */
struct ir3_instruction *scheduled; /* last scheduled instr */
struct ir3_instruction *addr0; /* current a0.x user, if any */
struct ir3_instruction *addr1; /* current a1.x user, if any */
struct ir3_instruction *pred; /* current p0.x user, if any */
struct ir3_instruction *split; /* most-recently-split a0/a1/p0 producer */
int remaining_kills;
int remaining_tex;
bool error;
unsigned ip;
int sy_delay;
int ss_delay;
/* We order the scheduled (sy)/(ss) producers, and keep track of the
* index of the last waited on instruction, so we can know which
* instructions are still outstanding (and therefore would require us to
* wait for all outstanding instructions before scheduling a use).
*/
int sy_index, first_outstanding_sy_index;
int ss_index, first_outstanding_ss_index;
};
struct ir3_sched_node {
struct dag_node dag; /* must be first for util_dynarray_foreach */
struct ir3_instruction *instr;
unsigned delay;
unsigned max_delay;
unsigned sy_index;
unsigned ss_index;
/* For ready instructions, the earliest possible ip that it could be
* scheduled.
*/
unsigned earliest_ip;
/* For instructions that are a meta:collect src, once we schedule
* the first src of the collect, the entire vecN is live (at least
* from the PoV of the first RA pass.. the 2nd scalar pass can fill
* in some of the gaps, but often not all). So we want to help out
* RA, and realize that as soon as we schedule the first collect
* src, there is no penalty to schedule the remainder (ie. they
* don't make additional values live). In fact we'd prefer to
* schedule the rest ASAP to minimize the live range of the vecN.
*
* For instructions that are the src of a collect, we track the
* corresponding collect, and mark them as partially live as soon
* as any one of the src's is scheduled.
*/
struct ir3_instruction *collect;
bool partially_live;
/* Is this instruction a direct or indirect dependency for a kill?
* If so, we should prioritize it when possible
*/
bool kill_path;
/* This node represents a shader output. A semi-common pattern in
* shaders is something along the lines of:
*
* fragcolor.w = 1.0
*
* Which we'd prefer to schedule as late as possible, since it
* produces a live value that is never killed/consumed. So detect
* outputs up-front, and avoid scheduling them unless the reduce
* register pressure (or at least are neutral)
*/
bool output;
};
#define foreach_sched_node(__n, __list) \
list_for_each_entry (struct ir3_sched_node, __n, __list, dag.link)
static void sched_node_init(struct ir3_sched_ctx *ctx,
struct ir3_instruction *instr);
static void sched_node_add_dep(struct ir3_instruction *instr,
struct ir3_instruction *src, int i);
static bool
is_scheduled(struct ir3_instruction *instr)
{
return !!(instr->flags & IR3_INSTR_MARK);
}
/* check_src_cond() passing a ir3_sched_ctx. */
static bool
sched_check_src_cond(struct ir3_instruction *instr,
bool (*cond)(struct ir3_instruction *,
struct ir3_sched_ctx *),
struct ir3_sched_ctx *ctx)
{
foreach_ssa_src (src, instr) {
/* meta:split/collect aren't real instructions, the thing that
* we actually care about is *their* srcs
*/
if ((src->opc == OPC_META_SPLIT) || (src->opc == OPC_META_COLLECT)) {
if (sched_check_src_cond(src, cond, ctx))
return true;
} else {
if (cond(src, ctx))
return true;
}
}
return false;
}
/* Is this a sy producer that hasn't been waited on yet? */
static bool
is_outstanding_sy(struct ir3_instruction *instr, struct ir3_sched_ctx *ctx)
{
if (!is_sy_producer(instr))
return false;
/* The sched node is only valid within the same block, we cannot
* really say anything about src's from other blocks
*/
if (instr->block != ctx->block)
return true;
struct ir3_sched_node *n = instr->data;
return n->sy_index >= ctx->first_outstanding_sy_index;
}
static bool
is_outstanding_ss(struct ir3_instruction *instr, struct ir3_sched_ctx *ctx)
{
if (!is_ss_producer(instr))
return false;
/* The sched node is only valid within the same block, we cannot
* really say anything about src's from other blocks
*/
if (instr->block != ctx->block)
return true;
struct ir3_sched_node *n = instr->data;
return n->ss_index >= ctx->first_outstanding_ss_index;
}
static unsigned
cycle_count(struct ir3_instruction *instr)
{
if (instr->opc == OPC_META_COLLECT) {
/* Assume that only immed/const sources produce moves */
unsigned n = 0;
foreach_src (src, instr) {
if (src->flags & (IR3_REG_IMMED | IR3_REG_CONST))
n++;
}
return n;
} else if (is_meta(instr)) {
return 0;
} else {
return 1;
}
}
static void
schedule(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
{
assert(ctx->block == instr->block);
/* remove from depth list:
*/
list_delinit(&instr->node);
if (writes_addr0(instr)) {
assert(ctx->addr0 == NULL);
ctx->addr0 = instr;
}
if (writes_addr1(instr)) {
assert(ctx->addr1 == NULL);
ctx->addr1 = instr;
}
if (writes_pred(instr)) {
assert(ctx->pred == NULL);
ctx->pred = instr;
}
instr->flags |= IR3_INSTR_MARK;
di(instr, "schedule");
list_addtail(&instr->node, &instr->block->instr_list);
ctx->scheduled = instr;
if (is_kill_or_demote(instr)) {
assert(ctx->remaining_kills > 0);
ctx->remaining_kills--;
}
struct ir3_sched_node *n = instr->data;
/* If this instruction is a meta:collect src, mark the remaining
* collect srcs as partially live.
*/
if (n->collect) {
foreach_ssa_src (src, n->collect) {
if (src->block != instr->block)
continue;
struct ir3_sched_node *sn = src->data;
sn->partially_live = true;
}
}
bool counts_for_delay = is_alu(instr) || is_flow(instr);
/* TODO: switch to "cycles". For now try to match ir3_delay. */
unsigned delay_cycles = counts_for_delay ? 1 + instr->repeat : 0;
/* We insert any nop's needed to get to earliest_ip, then advance
* delay_cycles by scheduling the instruction.
*/
ctx->ip = MAX2(ctx->ip, n->earliest_ip) + delay_cycles;
util_dynarray_foreach (&n->dag.edges, struct dag_edge, edge) {
unsigned delay = (unsigned)(uintptr_t)edge->data;
struct ir3_sched_node *child =
container_of(edge->child, struct ir3_sched_node, dag);
child->earliest_ip = MAX2(child->earliest_ip, ctx->ip + delay);
}
dag_prune_head(ctx->dag, &n->dag);
unsigned cycles = cycle_count(instr);
if (is_ss_producer(instr)) {
ctx->ss_delay = soft_ss_delay(instr);
n->ss_index = ctx->ss_index++;
} else if (!is_meta(instr) &&
sched_check_src_cond(instr, is_outstanding_ss, ctx)) {
ctx->ss_delay = 0;
ctx->first_outstanding_ss_index = ctx->ss_index;
} else if (ctx->ss_delay > 0) {
ctx->ss_delay -= MIN2(cycles, ctx->ss_delay);
}
if (is_sy_producer(instr)) {
/* NOTE that this isn't an attempt to hide texture fetch latency,
* but an attempt to hide the cost of switching to another warp.
* If we can, we'd like to try to schedule another texture fetch
* before scheduling something that would sync.
*/
ctx->sy_delay = soft_sy_delay(instr, ctx->block->shader);
assert(ctx->remaining_tex > 0);
ctx->remaining_tex--;
n->sy_index = ctx->sy_index++;
} else if (!is_meta(instr) &&
sched_check_src_cond(instr, is_outstanding_sy, ctx)) {
ctx->sy_delay = 0;
ctx->first_outstanding_sy_index = ctx->sy_index;
} else if (ctx->sy_delay > 0) {
ctx->sy_delay -= MIN2(cycles, ctx->sy_delay);
}
}
struct ir3_sched_notes {
/* there is at least one kill which could be scheduled, except
* for unscheduled bary.f's:
*/
bool blocked_kill;
/* there is at least one instruction that could be scheduled,
* except for conflicting address/predicate register usage:
*/
bool addr0_conflict, addr1_conflict, pred_conflict;
};
static bool
should_skip(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
{
if (ctx->remaining_kills && (is_tex(instr) || is_mem(instr))) {
/* avoid texture/memory access if we have unscheduled kills
* that could make the expensive operation unnecessary. By
* definition, if there are remaining kills, and this instr
* is not a dependency of a kill, there are other instructions
* that we can choose from.
*/
struct ir3_sched_node *n = instr->data;
if (!n->kill_path)
return true;
}
return false;
}
/* could an instruction be scheduled if specified ssa src was scheduled? */
static bool
could_sched(struct ir3_sched_ctx *ctx,
struct ir3_instruction *instr, struct ir3_instruction *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;
}
}
/* Instructions not in the current block can never be scheduled.
*/
if (instr->block != src->block)
return false;
return !should_skip(ctx, instr);
}
/* Check if instruction is ok to schedule. Make sure it is not blocked
* by use of addr/predicate register, etc.
*/
static bool
check_instr(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
struct ir3_instruction *instr)
{
assert(!is_scheduled(instr));
if (instr == ctx->split) {
/* Don't schedule instructions created by splitting a a0.x/a1.x/p0.x
* write until another "normal" instruction has been scheduled.
*/
return false;
}
if (should_skip(ctx, instr))
return false;
/* 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.
*
* NOTE if any instructions use pred register and have other
* src args, we would need to do the same for writes_pred()..
*/
if (writes_addr0(instr)) {
struct ir3 *ir = instr->block->shader;
bool ready = false;
for (unsigned i = 0; (i < ir->a0_users_count) && !ready; i++) {
struct ir3_instruction *indirect = ir->a0_users[i];
if (!indirect)
continue;
if (indirect->address->def != instr->dsts[0])
continue;
ready = could_sched(ctx, indirect, instr);
}
/* nothing could be scheduled, so keep looking: */
if (!ready)
return false;
}
if (writes_addr1(instr)) {
struct ir3 *ir = instr->block->shader;
bool ready = false;
for (unsigned i = 0; (i < ir->a1_users_count) && !ready; i++) {
struct ir3_instruction *indirect = ir->a1_users[i];
if (!indirect)
continue;
if (indirect->address->def != instr->dsts[0])
continue;
ready = could_sched(ctx, 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_addr0(instr) && ctx->addr0) {
assert(ctx->addr0 != instr);
notes->addr0_conflict = true;
return false;
}
if (writes_addr1(instr) && ctx->addr1) {
assert(ctx->addr1 != instr);
notes->addr1_conflict = true;
return false;
}
if (writes_pred(instr) && ctx->pred) {
assert(ctx->pred != instr);
notes->pred_conflict = true;
return false;
}
/* 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.
*
* We could do this by adding each bary.f instruction as
* virtual ssa src for the kill instruction. But we have
* fixed length instr->srcs[].
*
* TODO we could handle this by false-deps now, probably.
*/
if (is_kill_or_demote(instr)) {
struct ir3 *ir = instr->block->shader;
for (unsigned i = 0; i < ir->baryfs_count; i++) {
struct ir3_instruction *baryf = ir->baryfs[i];
if (baryf->flags & IR3_INSTR_UNUSED)
continue;
if (!is_scheduled(baryf)) {
notes->blocked_kill = true;
return false;
}
}
}
return true;
}
/* Find the instr->ip of the closest use of an instruction, in
* pre-sched order. This isn't going to be the same as post-sched
* order, but it is a reasonable approximation to limit scheduling
* instructions *too* early. This is mostly to prevent bad behavior
* in cases where we have a large number of possible instructions
* to choose, to avoid creating too much parallelism (ie. blowing
* up register pressure)
*
* See
* dEQP-GLES31.functional.atomic_counter.layout.reverse_offset.inc_dec.8_counters_5_calls_1_thread
*/
static int
nearest_use(struct ir3_instruction *instr)
{
unsigned nearest = ~0;
foreach_ssa_use (use, instr)
if (!is_scheduled(use))
nearest = MIN2(nearest, use->ip);
/* slight hack.. this heuristic tends to push bary.f's to later
* in the shader, closer to their uses. But we actually would
* prefer to get these scheduled earlier, to unlock varying
* storage for more VS jobs:
*/
if (is_input(instr))
nearest /= 2;
return nearest;
}
static bool
is_only_nonscheduled_use(struct ir3_instruction *instr,
struct ir3_instruction *use)
{
foreach_ssa_use (other_use, instr) {
if (other_use != use && !is_scheduled(other_use))
return false;
}
return true;
}
static unsigned
new_regs(struct ir3_instruction *instr)
{
unsigned regs = 0;
foreach_dst (dst, instr) {
if (!is_dest_gpr(dst))
continue;
regs += reg_elems(dst);
}
return regs;
}
/* find net change to live values if instruction were scheduled: */
static int
live_effect(struct ir3_instruction *instr)
{
struct ir3_sched_node *n = instr->data;
int new_live =
(n->partially_live || !instr->uses || instr->uses->entries == 0)
? 0
: new_regs(instr);
int freed_live = 0;
/* if we schedule something that causes a vecN to be live,
* then count all it's other components too:
*/
if (n->collect)
new_live *= n->collect->srcs_count;
foreach_ssa_src_n (src, n, instr) {
if (__is_false_dep(instr, n))
continue;
if (instr->block != src->block)
continue;
if (is_only_nonscheduled_use(src, instr))
freed_live += new_regs(src);
}
return new_live - freed_live;
}
/* Determine if this is an instruction that we'd prefer not to schedule
* yet, in order to avoid an (ss)/(sy) sync. This is limited by the
* ss_delay/sy_delay counters, ie. the more cycles it has been since
* the last SFU/tex, the less costly a sync would be, and the number of
* outstanding SFU/tex instructions to prevent a blowup in register pressure.
*/
static bool
should_defer(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
{
if (ctx->ss_delay) {
if (sched_check_src_cond(instr, is_outstanding_ss, ctx))
return true;
}
/* We mostly just want to try to schedule another texture fetch
* before scheduling something that would (sy) sync, so we can
* limit this rule to cases where there are remaining texture
* fetches
*/
if (ctx->sy_delay && ctx->remaining_tex) {
if (sched_check_src_cond(instr, is_outstanding_sy, ctx))
return true;
}
/* Avoid scheduling too many outstanding texture or sfu instructions at
* once by deferring further tex/SFU instructions. This both prevents
* stalls when the queue of texture/sfu instructions becomes too large,
* and prevents unacceptably large increases in register pressure from too
* many outstanding texture instructions.
*/
if (ctx->sy_index - ctx->first_outstanding_sy_index >= 8 && is_sy_producer(instr))
return true;
if (ctx->ss_index - ctx->first_outstanding_ss_index >= 8 && is_ss_producer(instr))
return true;
return false;
}
static struct ir3_sched_node *choose_instr_inc(struct ir3_sched_ctx *ctx,
struct ir3_sched_notes *notes,
bool defer, bool avoid_output);
enum choose_instr_dec_rank {
DEC_NEUTRAL,
DEC_NEUTRAL_READY,
DEC_FREED,
DEC_FREED_READY,
};
static const char *
dec_rank_name(enum choose_instr_dec_rank rank)
{
switch (rank) {
case DEC_NEUTRAL:
return "neutral";
case DEC_NEUTRAL_READY:
return "neutral+ready";
case DEC_FREED:
return "freed";
case DEC_FREED_READY:
return "freed+ready";
default:
return NULL;
}
}
static unsigned
node_delay(struct ir3_sched_ctx *ctx, struct ir3_sched_node *n)
{
return MAX2(n->earliest_ip, ctx->ip) - ctx->ip;
}
/**
* Chooses an instruction to schedule using the Goodman/Hsu (1988) CSR (Code
* Scheduling for Register pressure) heuristic.
*
* Only handles the case of choosing instructions that reduce register pressure
* or are even.
*/
static struct ir3_sched_node *
choose_instr_dec(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
bool defer)
{
const char *mode = defer ? "-d" : "";
struct ir3_sched_node *chosen = NULL;
enum choose_instr_dec_rank chosen_rank = DEC_NEUTRAL;
foreach_sched_node (n, &ctx->dag->heads) {
if (defer && should_defer(ctx, n->instr))
continue;
unsigned d = node_delay(ctx, n);
int live = live_effect(n->instr);
if (live > 0)
continue;
if (!check_instr(ctx, notes, n->instr))
continue;
enum choose_instr_dec_rank rank;
if (live < 0) {
/* Prioritize instrs which free up regs and can be scheduled with no
* delay.
*/
if (d == 0)
rank = DEC_FREED_READY;
else
rank = DEC_FREED;
} else {
/* Contra the paper, pick a leader with no effect on used regs. This
* may open up new opportunities, as otherwise a single-operand instr
* consuming a value will tend to block finding freeing that value.
* This had a massive effect on reducing spilling on V3D.
*
* XXX: Should this prioritize ready?
*/
if (d == 0)
rank = DEC_NEUTRAL_READY;
else
rank = DEC_NEUTRAL;
}
/* Prefer higher-ranked instructions, or in the case of a rank tie, the
* highest latency-to-end-of-program instruction.
*/
if (!chosen || rank > chosen_rank ||
(rank == chosen_rank && chosen->max_delay < n->max_delay)) {
chosen = n;
chosen_rank = rank;
}
}
if (chosen) {
di(chosen->instr, "dec%s: chose (%s)", mode, dec_rank_name(chosen_rank));
return chosen;
}
return choose_instr_inc(ctx, notes, defer, true);
}
enum choose_instr_inc_rank {
INC_DISTANCE,
INC_DISTANCE_READY,
};
static const char *
inc_rank_name(enum choose_instr_inc_rank rank)
{
switch (rank) {
case INC_DISTANCE:
return "distance";
case INC_DISTANCE_READY:
return "distance+ready";
default:
return NULL;
}
}
/**
* When we can't choose an instruction that reduces register pressure or
* is neutral, we end up here to try and pick the least bad option.
*/
static struct ir3_sched_node *
choose_instr_inc(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes,
bool defer, bool avoid_output)
{
const char *mode = defer ? "-d" : "";
struct ir3_sched_node *chosen = NULL;
enum choose_instr_inc_rank chosen_rank = INC_DISTANCE;
/*
* From hear on out, we are picking something that increases
* register pressure. So try to pick something which will
* be consumed soon:
*/
unsigned chosen_distance = 0;
/* Pick the max delay of the remaining ready set. */
foreach_sched_node (n, &ctx->dag->heads) {
if (avoid_output && n->output)
continue;
if (defer && should_defer(ctx, n->instr))
continue;
if (!check_instr(ctx, notes, n->instr))
continue;
unsigned d = node_delay(ctx, n);
enum choose_instr_inc_rank rank;
if (d == 0)
rank = INC_DISTANCE_READY;
else
rank = INC_DISTANCE;
unsigned distance = nearest_use(n->instr);
if (!chosen || rank > chosen_rank ||
(rank == chosen_rank && distance < chosen_distance)) {
chosen = n;
chosen_distance = distance;
chosen_rank = rank;
}
}
if (chosen) {
di(chosen->instr, "inc%s: chose (%s)", mode, inc_rank_name(chosen_rank));
return chosen;
}
return NULL;
}
/* Handles instruction selections for instructions we want to prioritize
* even if csp/csr would not pick them.
*/
static struct ir3_sched_node *
choose_instr_prio(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes)
{
struct ir3_sched_node *chosen = NULL;
foreach_sched_node (n, &ctx->dag->heads) {
/*
* - phi nodes and inputs must be scheduled first
* - split should be scheduled first, so that the vector value is
* killed as soon as possible. RA cannot split up the vector and
* reuse components that have been killed until it's been killed.
* - collect, on the other hand, should be treated as a "normal"
* instruction, and may add to register pressure if its sources are
* part of another vector or immediates.
*/
if (!is_meta(n->instr) || n->instr->opc == OPC_META_COLLECT)
continue;
if (!chosen || (chosen->max_delay < n->max_delay))
chosen = n;
}
if (chosen) {
di(chosen->instr, "prio: chose (meta)");
return chosen;
}
return NULL;
}
static void
dump_state(struct ir3_sched_ctx *ctx)
{
if (!SCHED_DEBUG)
return;
foreach_sched_node (n, &ctx->dag->heads) {
di(n->instr, "maxdel=%3d le=%d del=%u ", n->max_delay,
live_effect(n->instr), node_delay(ctx, n));
util_dynarray_foreach (&n->dag.edges, struct dag_edge, edge) {
struct ir3_sched_node *child = (struct ir3_sched_node *)edge->child;
di(child->instr, " -> (%d parents) ", child->dag.parent_count);
}
}
}
/* find instruction to schedule: */
static struct ir3_instruction *
choose_instr(struct ir3_sched_ctx *ctx, struct ir3_sched_notes *notes)
{
struct ir3_sched_node *chosen;
dump_state(ctx);
chosen = choose_instr_prio(ctx, notes);
if (chosen)
return chosen->instr;
chosen = choose_instr_dec(ctx, notes, true);
if (chosen)
return chosen->instr;
chosen = choose_instr_dec(ctx, notes, false);
if (chosen)
return chosen->instr;
chosen = choose_instr_inc(ctx, notes, false, false);
if (chosen)
return chosen->instr;
return NULL;
}
static struct ir3_instruction *
split_instr(struct ir3_sched_ctx *ctx, struct ir3_instruction *orig_instr)
{
struct ir3_instruction *new_instr = ir3_instr_clone(orig_instr);
di(new_instr, "split instruction");
sched_node_init(ctx, new_instr);
return new_instr;
}
/* "spill" the address registers by remapping any unscheduled
* instructions which depend on the current address register
* to a clone of the instruction which wrote the address reg.
*/
static struct ir3_instruction *
split_addr(struct ir3_sched_ctx *ctx, struct ir3_instruction **addr,
struct ir3_instruction **users, unsigned users_count)
{
struct ir3_instruction *new_addr = NULL;
unsigned i;
assert(*addr);
for (i = 0; i < users_count; i++) {
struct ir3_instruction *indirect = users[i];
if (!indirect)
continue;
/* skip instructions already scheduled: */
if (is_scheduled(indirect))
continue;
/* remap remaining instructions using current addr
* to new addr:
*/
if (indirect->address->def == (*addr)->dsts[0]) {
if (!new_addr) {
new_addr = split_instr(ctx, *addr);
/* original addr is scheduled, but new one isn't: */
new_addr->flags &= ~IR3_INSTR_MARK;
}
indirect->address->def = new_addr->dsts[0];
/* don't need to remove old dag edge since old addr is
* already scheduled:
*/
sched_node_add_dep(indirect, new_addr, 0);
di(indirect, "new address");
}
}
/* all remaining indirects remapped to new addr: */
*addr = NULL;
return new_addr;
}
/* "spill" the predicate register by remapping any unscheduled
* instructions which depend on the current predicate register
* to a clone of the instruction which wrote the address reg.
*/
static struct ir3_instruction *
split_pred(struct ir3_sched_ctx *ctx)
{
struct ir3 *ir;
struct ir3_instruction *new_pred = NULL;
unsigned i;
assert(ctx->pred);
ir = ctx->pred->block->shader;
for (i = 0; i < ir->predicates_count; i++) {
struct ir3_instruction *predicated = ir->predicates[i];
if (!predicated)
continue;
/* skip instructions already scheduled: */
if (is_scheduled(predicated))
continue;
/* remap remaining instructions using current pred
* to new pred:
*
* TODO is there ever a case when pred isn't first
* (and only) src?
*/
if (ssa(predicated->srcs[0]) == ctx->pred) {
if (!new_pred) {
new_pred = split_instr(ctx, ctx->pred);
/* original pred is scheduled, but new one isn't: */
new_pred->flags &= ~IR3_INSTR_MARK;
}
predicated->srcs[0]->instr = new_pred;
/* don't need to remove old dag edge since old pred is
* already scheduled:
*/
sched_node_add_dep(predicated, new_pred, 0);
di(predicated, "new predicate");
}
}
if (ctx->block->condition == ctx->pred) {
if (!new_pred) {
new_pred = split_instr(ctx, ctx->pred);
/* original pred is scheduled, but new one isn't: */
new_pred->flags &= ~IR3_INSTR_MARK;
}
ctx->block->condition = new_pred;
d("new branch condition");
}
/* all remaining predicated remapped to new pred: */
ctx->pred = NULL;
return new_pred;
}
static void
sched_node_init(struct ir3_sched_ctx *ctx, struct ir3_instruction *instr)
{
struct ir3_sched_node *n = rzalloc(ctx->dag, struct ir3_sched_node);
dag_init_node(ctx->dag, &n->dag);
n->instr = instr;
instr->data = n;
}
static void
sched_node_add_dep(struct ir3_instruction *instr, struct ir3_instruction *src,
int i)
{
/* don't consider dependencies in other blocks: */
if (src->block != instr->block)
return;
/* we could have false-dep's that end up unused: */
if (src->flags & IR3_INSTR_UNUSED) {
assert(__is_false_dep(instr, i));
return;
}
struct ir3_sched_node *n = instr->data;
struct ir3_sched_node *sn = src->data;
/* If src is consumed by a collect, track that to realize that once
* any of the collect srcs are live, we should hurry up and schedule
* the rest.
*/
if (instr->opc == OPC_META_COLLECT)
sn->collect = instr;
unsigned d_soft = ir3_delayslots(src, instr, i, true);
unsigned d = ir3_delayslots(src, instr, i, false);
/* delays from (ss) and (sy) are considered separately and more accurately in
* the scheduling heuristic, so ignore it when calculating the ip of
* instructions, but do consider it when prioritizing which instructions to
* schedule.
*/
dag_add_edge_max_data(&sn->dag, &n->dag, (uintptr_t)d);
n->delay = MAX2(n->delay, d_soft);
}
static void
mark_kill_path(struct ir3_instruction *instr)
{
struct ir3_sched_node *n = instr->data;
if (n->kill_path) {
return;
}
n->kill_path = true;
foreach_ssa_src (src, instr) {
if (src->block != instr->block)
continue;
mark_kill_path(src);
}
}
/* Is it an output? */
static bool
is_output_collect(struct ir3_instruction *instr)
{
if (instr->opc != OPC_META_COLLECT)
return false;
foreach_ssa_use (use, instr) {
if (use->opc != OPC_END && use->opc != OPC_CHMASK)
return false;
}
return true;
}
/* Is it's only use as output? */
static bool
is_output_only(struct ir3_instruction *instr)
{
foreach_ssa_use (use, instr)
if (!is_output_collect(use))
return false;
return true;
}
static void
sched_node_add_deps(struct ir3_instruction *instr)
{
/* There's nothing to do for phi nodes, since they always go first. And
* phi nodes can reference sources later in the same block, so handling
* sources is not only unnecessary but could cause problems.
*/
if (instr->opc == OPC_META_PHI)
return;
/* Since foreach_ssa_src() already handles false-dep's we can construct
* the DAG easily in a single pass.
*/
foreach_ssa_src_n (src, i, instr) {
sched_node_add_dep(instr, src, i);
}
/* NOTE that all inputs must be scheduled before a kill, so
* mark these to be prioritized as well:
*/
if (is_kill_or_demote(instr) || is_input(instr)) {
mark_kill_path(instr);
}
if (is_output_only(instr)) {
struct ir3_sched_node *n = instr->data;
n->output = true;
}
}
static void
sched_dag_max_delay_cb(struct dag_node *node, void *state)
{
struct ir3_sched_node *n = (struct ir3_sched_node *)node;
uint32_t max_delay = 0;
util_dynarray_foreach (&n->dag.edges, struct dag_edge, edge) {
struct ir3_sched_node *child = (struct ir3_sched_node *)edge->child;
max_delay = MAX2(child->max_delay, max_delay);
}
n->max_delay = MAX2(n->max_delay, max_delay + n->delay);
}
static void
sched_dag_init(struct ir3_sched_ctx *ctx)
{
ctx->dag = dag_create(ctx);
foreach_instr (instr, &ctx->unscheduled_list)
sched_node_init(ctx, instr);
foreach_instr (instr, &ctx->unscheduled_list)
sched_node_add_deps(instr);
dag_traverse_bottom_up(ctx->dag, sched_dag_max_delay_cb, NULL);
}
static void
sched_dag_destroy(struct ir3_sched_ctx *ctx)
{
ralloc_free(ctx->dag);
ctx->dag = NULL;
}
static void
sched_block(struct ir3_sched_ctx *ctx, struct ir3_block *block)
{
ctx->block = block;
/* addr/pred writes are per-block: */
ctx->addr0 = NULL;
ctx->addr1 = NULL;
ctx->pred = NULL;
ctx->sy_delay = 0;
ctx->ss_delay = 0;
ctx->sy_index = ctx->first_outstanding_sy_index = 0;
ctx->ss_index = ctx->first_outstanding_ss_index = 0;
/* move all instructions to the unscheduled list, and
* empty the block's instruction list (to which we will
* be inserting).
*/
list_replace(&block->instr_list, &ctx->unscheduled_list);
list_inithead(&block->instr_list);
sched_dag_init(ctx);
ctx->remaining_kills = 0;
ctx->remaining_tex = 0;
foreach_instr_safe (instr, &ctx->unscheduled_list) {
if (is_kill_or_demote(instr))
ctx->remaining_kills++;
if (is_sy_producer(instr))
ctx->remaining_tex++;
}
/* First schedule all meta:input and meta:phi instructions, followed by
* tex-prefetch. We want all of the instructions that load values into
* registers before the shader starts to go before any other instructions.
* But in particular we want inputs to come before prefetches. This is
* because a FS's bary_ij input may not actually be live in the shader,
* but it should not be scheduled on top of any other input (but can be
* overwritten by a tex prefetch)
*
* Note: Because the first block cannot have predecessors, meta:input and
* meta:phi cannot exist in the same block.
*/
foreach_instr_safe (instr, &ctx->unscheduled_list)
if (instr->opc == OPC_META_INPUT || instr->opc == OPC_META_PHI)
schedule(ctx, instr);
foreach_instr_safe (instr, &ctx->unscheduled_list)
if (instr->opc == OPC_META_TEX_PREFETCH)
schedule(ctx, instr);
while (!list_is_empty(&ctx->unscheduled_list)) {
struct ir3_sched_notes notes = {0};
struct ir3_instruction *instr;
instr = choose_instr(ctx, &notes);
if (instr) {
unsigned delay = node_delay(ctx, instr->data);
d("delay=%u", delay);
assert(delay <= 6);
schedule(ctx, instr);
/* Since we've scheduled a "real" instruction, we can now
* schedule any split instruction created by the scheduler again.
*/
ctx->split = NULL;
} else {
struct ir3_instruction *new_instr = NULL;
struct ir3 *ir = block->shader;
/* nothing available to schedule.. if we are blocked on
* address/predicate register conflict, then break the
* deadlock by cloning the instruction that wrote that
* reg:
*/
if (notes.addr0_conflict) {
new_instr =
split_addr(ctx, &ctx->addr0, ir->a0_users, ir->a0_users_count);
} else if (notes.addr1_conflict) {
new_instr =
split_addr(ctx, &ctx->addr1, ir->a1_users, ir->a1_users_count);
} else if (notes.pred_conflict) {
new_instr = split_pred(ctx);
} else {
d("unscheduled_list:");
foreach_instr (instr, &ctx->unscheduled_list)
di(instr, "unscheduled: ");
assert(0);
ctx->error = true;
return;
}
if (new_instr) {
list_delinit(&new_instr->node);
list_addtail(&new_instr->node, &ctx->unscheduled_list);
}
/* If we produced a new instruction, do not schedule it next to
* guarantee progress.
*/
ctx->split = new_instr;
}
}
sched_dag_destroy(ctx);
}
int
ir3_sched(struct ir3 *ir)
{
struct ir3_sched_ctx *ctx = rzalloc(NULL, struct ir3_sched_ctx);
foreach_block (block, &ir->block_list) {
foreach_instr (instr, &block->instr_list) {
instr->data = NULL;
}
}
ir3_count_instructions(ir);
ir3_clear_mark(ir);
ir3_find_ssa_uses(ir, ctx, false);
foreach_block (block, &ir->block_list) {
sched_block(ctx, block);
}
int ret = ctx->error ? -1 : 0;
ralloc_free(ctx);
return ret;
}
static unsigned
get_array_id(struct ir3_instruction *instr)
{
/* The expectation is that there is only a single array
* src or dst, ir3_cp should enforce this.
*/
foreach_dst (dst, instr)
if (dst->flags & IR3_REG_ARRAY)
return dst->array.id;
foreach_src (src, instr)
if (src->flags & IR3_REG_ARRAY)
return src->array.id;
unreachable("this was unexpected");
}
/* does instruction 'prior' need to be scheduled before 'instr'? */
static bool
depends_on(struct ir3_instruction *instr, struct ir3_instruction *prior)
{
/* TODO for dependencies that are related to a specific object, ie
* a specific SSBO/image/array, we could relax this constraint to
* make accesses to unrelated objects not depend on each other (at
* least as long as not declared coherent)
*/
if (((instr->barrier_class & IR3_BARRIER_EVERYTHING) &&
prior->barrier_class) ||
((prior->barrier_class & IR3_BARRIER_EVERYTHING) &&
instr->barrier_class))
return true;
if (instr->barrier_class & prior->barrier_conflict) {
if (!(instr->barrier_class &
~(IR3_BARRIER_ARRAY_R | IR3_BARRIER_ARRAY_W))) {
/* if only array barrier, then we can further limit false-deps
* by considering the array-id, ie reads/writes to different
* arrays do not depend on each other (no aliasing)
*/
if (get_array_id(instr) != get_array_id(prior)) {
return false;
}
}
return true;
}
return false;
}
static void
add_barrier_deps(struct ir3_block *block, struct ir3_instruction *instr)
{
struct list_head *prev = instr->node.prev;
struct list_head *next = instr->node.next;
/* add dependencies on previous instructions that must be scheduled
* prior to the current instruction
*/
while (prev != &block->instr_list) {
struct ir3_instruction *pi =
list_entry(prev, struct ir3_instruction, node);
prev = prev->prev;
if (is_meta(pi))
continue;
if (instr->barrier_class == pi->barrier_class) {
ir3_instr_add_dep(instr, pi);
break;
}
if (depends_on(instr, pi))
ir3_instr_add_dep(instr, pi);
}
/* add dependencies on this instruction to following instructions
* that must be scheduled after the current instruction:
*/
while (next != &block->instr_list) {
struct ir3_instruction *ni =
list_entry(next, struct ir3_instruction, node);
next = next->next;
if (is_meta(ni))
continue;
if (instr->barrier_class == ni->barrier_class) {
ir3_instr_add_dep(ni, instr);
break;
}
if (depends_on(ni, instr))
ir3_instr_add_dep(ni, instr);
}
}
/* before scheduling a block, we need to add any necessary false-dependencies
* to ensure that:
*
* (1) barriers are scheduled in the right order wrt instructions related
* to the barrier
*
* (2) reads that come before a write actually get scheduled before the
* write
*/
bool
ir3_sched_add_deps(struct ir3 *ir)
{
bool progress = false;
foreach_block (block, &ir->block_list) {
foreach_instr (instr, &block->instr_list) {
if (instr->barrier_class) {
add_barrier_deps(block, instr);
progress = true;
}
}
}
return progress;
}
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