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|
/*
* Copyright © 2010 Intel Corporation
* Copyright © 2014 Broadcom
*
* 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.
*/
/**
* @file vc4_qpu_schedule.c
*
* The basic model of the list scheduler is to take a basic block, compute a
* DAG of the dependencies, and make a list of the DAG heads. Heuristically
* pick a DAG head, then put all the children that are now DAG heads into the
* list of things to schedule.
*
* The goal of scheduling here is to pack pairs of operations together in a
* single QPU instruction.
*/
#include "vc4_qir.h"
#include "vc4_qpu.h"
#include "util/ralloc.h"
#include "util/dag.h"
static bool debug;
struct schedule_node_child;
struct schedule_node {
struct dag_node dag;
struct list_head link;
struct queued_qpu_inst *inst;
/* Longest cycles + instruction_latency() of any parent of this node. */
uint32_t unblocked_time;
/**
* Minimum number of cycles from scheduling this instruction until the
* end of the program, based on the slowest dependency chain through
* the children.
*/
uint32_t delay;
/**
* cycles between this instruction being scheduled and when its result
* can be consumed.
*/
uint32_t latency;
/**
* Which uniform from uniform_data[] this instruction read, or -1 if
* not reading a uniform.
*/
int uniform;
};
/* When walking the instructions in reverse, we need to swap before/after in
* add_dep().
*/
enum direction { F, R };
struct schedule_state {
struct dag *dag;
struct schedule_node *last_r[6];
struct schedule_node *last_ra[32];
struct schedule_node *last_rb[32];
struct schedule_node *last_sf;
struct schedule_node *last_vpm_read;
struct schedule_node *last_tmu_write;
struct schedule_node *last_tlb;
struct schedule_node *last_vpm;
struct schedule_node *last_uniforms_reset;
enum direction dir;
/* Estimated cycle when the current instruction would start. */
uint32_t time;
};
static void
add_dep(struct schedule_state *state,
struct schedule_node *before,
struct schedule_node *after,
bool write)
{
bool write_after_read = !write && state->dir == R;
void *edge_data = (void *)(uintptr_t)write_after_read;
if (!before || !after)
return;
assert(before != after);
if (state->dir == F)
dag_add_edge(&before->dag, &after->dag, edge_data);
else
dag_add_edge(&after->dag, &before->dag, edge_data);
}
static void
add_read_dep(struct schedule_state *state,
struct schedule_node *before,
struct schedule_node *after)
{
add_dep(state, before, after, false);
}
static void
add_write_dep(struct schedule_state *state,
struct schedule_node **before,
struct schedule_node *after)
{
add_dep(state, *before, after, true);
*before = after;
}
static bool
qpu_writes_r4(uint64_t inst)
{
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
switch(sig) {
case QPU_SIG_COLOR_LOAD:
case QPU_SIG_LOAD_TMU0:
case QPU_SIG_LOAD_TMU1:
case QPU_SIG_ALPHA_MASK_LOAD:
return true;
default:
return false;
}
}
static void
process_raddr_deps(struct schedule_state *state, struct schedule_node *n,
uint32_t raddr, bool is_a)
{
switch (raddr) {
case QPU_R_VARY:
add_write_dep(state, &state->last_r[5], n);
break;
case QPU_R_VPM:
add_write_dep(state, &state->last_vpm_read, n);
break;
case QPU_R_UNIF:
add_read_dep(state, state->last_uniforms_reset, n);
break;
case QPU_R_NOP:
case QPU_R_ELEM_QPU:
case QPU_R_XY_PIXEL_COORD:
case QPU_R_MS_REV_FLAGS:
break;
default:
if (raddr < 32) {
if (is_a)
add_read_dep(state, state->last_ra[raddr], n);
else
add_read_dep(state, state->last_rb[raddr], n);
} else {
fprintf(stderr, "unknown raddr %d\n", raddr);
abort();
}
break;
}
}
static bool
is_tmu_write(uint32_t waddr)
{
switch (waddr) {
case QPU_W_TMU0_S:
case QPU_W_TMU0_T:
case QPU_W_TMU0_R:
case QPU_W_TMU0_B:
case QPU_W_TMU1_S:
case QPU_W_TMU1_T:
case QPU_W_TMU1_R:
case QPU_W_TMU1_B:
return true;
default:
return false;
}
}
static bool
reads_uniform(uint64_t inst)
{
if (QPU_GET_FIELD(inst, QPU_SIG) == QPU_SIG_LOAD_IMM)
return false;
return (QPU_GET_FIELD(inst, QPU_RADDR_A) == QPU_R_UNIF ||
(QPU_GET_FIELD(inst, QPU_RADDR_B) == QPU_R_UNIF &&
QPU_GET_FIELD(inst, QPU_SIG) != QPU_SIG_SMALL_IMM) ||
is_tmu_write(QPU_GET_FIELD(inst, QPU_WADDR_ADD)) ||
is_tmu_write(QPU_GET_FIELD(inst, QPU_WADDR_MUL)));
}
static void
process_mux_deps(struct schedule_state *state, struct schedule_node *n,
uint32_t mux)
{
if (mux != QPU_MUX_A && mux != QPU_MUX_B)
add_read_dep(state, state->last_r[mux], n);
}
static void
process_waddr_deps(struct schedule_state *state, struct schedule_node *n,
uint32_t waddr, bool is_add)
{
uint64_t inst = n->inst->inst;
bool is_a = is_add ^ ((inst & QPU_WS) != 0);
if (waddr < 32) {
if (is_a) {
add_write_dep(state, &state->last_ra[waddr], n);
} else {
add_write_dep(state, &state->last_rb[waddr], n);
}
} else if (is_tmu_write(waddr)) {
add_write_dep(state, &state->last_tmu_write, n);
add_read_dep(state, state->last_uniforms_reset, n);
} else if (qpu_waddr_is_tlb(waddr) ||
waddr == QPU_W_MS_FLAGS) {
add_write_dep(state, &state->last_tlb, n);
} else {
switch (waddr) {
case QPU_W_ACC0:
case QPU_W_ACC1:
case QPU_W_ACC2:
case QPU_W_ACC3:
case QPU_W_ACC5:
add_write_dep(state, &state->last_r[waddr - QPU_W_ACC0],
n);
break;
case QPU_W_VPM:
add_write_dep(state, &state->last_vpm, n);
break;
case QPU_W_VPMVCD_SETUP:
if (is_a)
add_write_dep(state, &state->last_vpm_read, n);
else
add_write_dep(state, &state->last_vpm, n);
break;
case QPU_W_SFU_RECIP:
case QPU_W_SFU_RECIPSQRT:
case QPU_W_SFU_EXP:
case QPU_W_SFU_LOG:
add_write_dep(state, &state->last_r[4], n);
break;
case QPU_W_TLB_STENCIL_SETUP:
/* This isn't a TLB operation that does things like
* implicitly lock the scoreboard, but it does have to
* appear before TLB_Z, and each of the TLB_STENCILs
* have to schedule in the same order relative to each
* other.
*/
add_write_dep(state, &state->last_tlb, n);
break;
case QPU_W_MS_FLAGS:
add_write_dep(state, &state->last_tlb, n);
break;
case QPU_W_UNIFORMS_ADDRESS:
add_write_dep(state, &state->last_uniforms_reset, n);
break;
case QPU_W_NOP:
break;
default:
fprintf(stderr, "Unknown waddr %d\n", waddr);
abort();
}
}
}
static void
process_cond_deps(struct schedule_state *state, struct schedule_node *n,
uint32_t cond)
{
switch (cond) {
case QPU_COND_NEVER:
case QPU_COND_ALWAYS:
break;
default:
add_read_dep(state, state->last_sf, n);
break;
}
}
/**
* Common code for dependencies that need to be tracked both forward and
* backward.
*
* This is for things like "all reads of r4 have to happen between the r4
* writes that surround them".
*/
static void
calculate_deps(struct schedule_state *state, struct schedule_node *n)
{
uint64_t inst = n->inst->inst;
uint32_t add_op = QPU_GET_FIELD(inst, QPU_OP_ADD);
uint32_t mul_op = QPU_GET_FIELD(inst, QPU_OP_MUL);
uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
uint32_t add_a = QPU_GET_FIELD(inst, QPU_ADD_A);
uint32_t add_b = QPU_GET_FIELD(inst, QPU_ADD_B);
uint32_t mul_a = QPU_GET_FIELD(inst, QPU_MUL_A);
uint32_t mul_b = QPU_GET_FIELD(inst, QPU_MUL_B);
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
if (sig != QPU_SIG_LOAD_IMM) {
process_raddr_deps(state, n, raddr_a, true);
if (sig != QPU_SIG_SMALL_IMM &&
sig != QPU_SIG_BRANCH)
process_raddr_deps(state, n, raddr_b, false);
}
if (add_op != QPU_A_NOP) {
process_mux_deps(state, n, add_a);
process_mux_deps(state, n, add_b);
}
if (mul_op != QPU_M_NOP) {
process_mux_deps(state, n, mul_a);
process_mux_deps(state, n, mul_b);
}
process_waddr_deps(state, n, waddr_add, true);
process_waddr_deps(state, n, waddr_mul, false);
if (qpu_writes_r4(inst))
add_write_dep(state, &state->last_r[4], n);
switch (sig) {
case QPU_SIG_SW_BREAKPOINT:
case QPU_SIG_NONE:
case QPU_SIG_SMALL_IMM:
case QPU_SIG_LOAD_IMM:
break;
case QPU_SIG_THREAD_SWITCH:
case QPU_SIG_LAST_THREAD_SWITCH:
/* All accumulator contents and flags are undefined after the
* switch.
*/
for (int i = 0; i < ARRAY_SIZE(state->last_r); i++)
add_write_dep(state, &state->last_r[i], n);
add_write_dep(state, &state->last_sf, n);
/* Scoreboard-locking operations have to stay after the last
* thread switch.
*/
add_write_dep(state, &state->last_tlb, n);
add_write_dep(state, &state->last_tmu_write, n);
break;
case QPU_SIG_LOAD_TMU0:
case QPU_SIG_LOAD_TMU1:
/* TMU loads are coming from a FIFO, so ordering is important.
*/
add_write_dep(state, &state->last_tmu_write, n);
break;
case QPU_SIG_COLOR_LOAD:
add_read_dep(state, state->last_tlb, n);
break;
case QPU_SIG_BRANCH:
add_read_dep(state, state->last_sf, n);
break;
case QPU_SIG_PROG_END:
case QPU_SIG_WAIT_FOR_SCOREBOARD:
case QPU_SIG_SCOREBOARD_UNLOCK:
case QPU_SIG_COVERAGE_LOAD:
case QPU_SIG_COLOR_LOAD_END:
case QPU_SIG_ALPHA_MASK_LOAD:
fprintf(stderr, "Unhandled signal bits %d\n", sig);
abort();
}
process_cond_deps(state, n, QPU_GET_FIELD(inst, QPU_COND_ADD));
process_cond_deps(state, n, QPU_GET_FIELD(inst, QPU_COND_MUL));
if ((inst & QPU_SF) && sig != QPU_SIG_BRANCH)
add_write_dep(state, &state->last_sf, n);
}
static void
calculate_forward_deps(struct vc4_compile *c, struct dag *dag,
struct list_head *schedule_list)
{
struct schedule_state state;
memset(&state, 0, sizeof(state));
state.dag = dag;
state.dir = F;
list_for_each_entry(struct schedule_node, node, schedule_list, link)
calculate_deps(&state, node);
}
static void
calculate_reverse_deps(struct vc4_compile *c, struct dag *dag,
struct list_head *schedule_list)
{
struct schedule_state state;
memset(&state, 0, sizeof(state));
state.dag = dag;
state.dir = R;
list_for_each_entry_rev(struct schedule_node, node, schedule_list,
link) {
calculate_deps(&state, (struct schedule_node *)node);
}
}
struct choose_scoreboard {
struct dag *dag;
int tick;
int last_sfu_write_tick;
int last_uniforms_reset_tick;
uint32_t last_waddr_a, last_waddr_b;
bool tlb_locked;
};
static bool
reads_too_soon_after_write(struct choose_scoreboard *scoreboard, uint64_t inst)
{
uint32_t raddr_a = QPU_GET_FIELD(inst, QPU_RADDR_A);
uint32_t raddr_b = QPU_GET_FIELD(inst, QPU_RADDR_B);
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
/* Full immediate loads don't read any registers. */
if (sig == QPU_SIG_LOAD_IMM)
return false;
uint32_t src_muxes[] = {
QPU_GET_FIELD(inst, QPU_ADD_A),
QPU_GET_FIELD(inst, QPU_ADD_B),
QPU_GET_FIELD(inst, QPU_MUL_A),
QPU_GET_FIELD(inst, QPU_MUL_B),
};
for (int i = 0; i < ARRAY_SIZE(src_muxes); i++) {
if ((src_muxes[i] == QPU_MUX_A &&
raddr_a < 32 &&
scoreboard->last_waddr_a == raddr_a) ||
(src_muxes[i] == QPU_MUX_B &&
sig != QPU_SIG_SMALL_IMM &&
raddr_b < 32 &&
scoreboard->last_waddr_b == raddr_b)) {
return true;
}
if (src_muxes[i] == QPU_MUX_R4) {
if (scoreboard->tick -
scoreboard->last_sfu_write_tick <= 2) {
return true;
}
}
}
if (sig == QPU_SIG_SMALL_IMM &&
QPU_GET_FIELD(inst, QPU_SMALL_IMM) >= QPU_SMALL_IMM_MUL_ROT) {
uint32_t mux_a = QPU_GET_FIELD(inst, QPU_MUL_A);
uint32_t mux_b = QPU_GET_FIELD(inst, QPU_MUL_B);
if (scoreboard->last_waddr_a == mux_a + QPU_W_ACC0 ||
scoreboard->last_waddr_a == mux_b + QPU_W_ACC0 ||
scoreboard->last_waddr_b == mux_a + QPU_W_ACC0 ||
scoreboard->last_waddr_b == mux_b + QPU_W_ACC0) {
return true;
}
}
if (reads_uniform(inst) &&
scoreboard->tick - scoreboard->last_uniforms_reset_tick <= 2) {
return true;
}
return false;
}
static bool
pixel_scoreboard_too_soon(struct choose_scoreboard *scoreboard, uint64_t inst)
{
return (scoreboard->tick < 2 && qpu_inst_is_tlb(inst));
}
static int
get_instruction_priority(uint64_t inst)
{
uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
uint32_t baseline_score;
uint32_t next_score = 0;
/* Schedule TLB operations as late as possible, to get more
* parallelism between shaders.
*/
if (qpu_inst_is_tlb(inst))
return next_score;
next_score++;
/* Schedule texture read results collection late to hide latency. */
if (sig == QPU_SIG_LOAD_TMU0 || sig == QPU_SIG_LOAD_TMU1)
return next_score;
next_score++;
/* Default score for things that aren't otherwise special. */
baseline_score = next_score;
next_score++;
/* Schedule texture read setup early to hide their latency better. */
if (is_tmu_write(waddr_add) || is_tmu_write(waddr_mul))
return next_score;
next_score++;
return baseline_score;
}
static struct schedule_node *
choose_instruction_to_schedule(struct choose_scoreboard *scoreboard,
struct list_head *schedule_list,
struct schedule_node *prev_inst)
{
struct schedule_node *chosen = NULL;
int chosen_prio = 0;
/* Don't pair up anything with a thread switch signal -- emit_thrsw()
* will handle pairing it along with filling the delay slots.
*/
if (prev_inst) {
uint32_t prev_sig = QPU_GET_FIELD(prev_inst->inst->inst,
QPU_SIG);
if (prev_sig == QPU_SIG_THREAD_SWITCH ||
prev_sig == QPU_SIG_LAST_THREAD_SWITCH) {
return NULL;
}
}
list_for_each_entry(struct schedule_node, n, &scoreboard->dag->heads,
dag.link) {
uint64_t inst = n->inst->inst;
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
/* Don't choose the branch instruction until it's the last one
* left. XXX: We could potentially choose it before it's the
* last one, if the remaining instructions fit in the delay
* slots.
*/
if (sig == QPU_SIG_BRANCH &&
!list_is_singular(&scoreboard->dag->heads)) {
continue;
}
/* "An instruction must not read from a location in physical
* regfile A or B that was written to by the previous
* instruction."
*/
if (reads_too_soon_after_write(scoreboard, inst))
continue;
/* "A scoreboard wait must not occur in the first two
* instructions of a fragment shader. This is either the
* explicit Wait for Scoreboard signal or an implicit wait
* with the first tile-buffer read or write instruction."
*/
if (pixel_scoreboard_too_soon(scoreboard, inst))
continue;
/* If we're trying to pair with another instruction, check
* that they're compatible.
*/
if (prev_inst) {
/* Don't pair up a thread switch signal -- we'll
* handle pairing it when we pick it on its own.
*/
if (sig == QPU_SIG_THREAD_SWITCH ||
sig == QPU_SIG_LAST_THREAD_SWITCH) {
continue;
}
if (prev_inst->uniform != -1 && n->uniform != -1)
continue;
/* Don't merge in something that will lock the TLB.
* Hopwefully what we have in inst will release some
* other instructions, allowing us to delay the
* TLB-locking instruction until later.
*/
if (!scoreboard->tlb_locked && qpu_inst_is_tlb(inst))
continue;
inst = qpu_merge_inst(prev_inst->inst->inst, inst);
if (!inst)
continue;
}
int prio = get_instruction_priority(inst);
/* Found a valid instruction. If nothing better comes along,
* this one works.
*/
if (!chosen) {
chosen = n;
chosen_prio = prio;
continue;
}
if (prio > chosen_prio) {
chosen = n;
chosen_prio = prio;
} else if (prio < chosen_prio) {
continue;
}
if (n->delay > chosen->delay) {
chosen = n;
chosen_prio = prio;
} else if (n->delay < chosen->delay) {
continue;
}
}
return chosen;
}
static void
update_scoreboard_for_chosen(struct choose_scoreboard *scoreboard,
uint64_t inst)
{
uint32_t waddr_add = QPU_GET_FIELD(inst, QPU_WADDR_ADD);
uint32_t waddr_mul = QPU_GET_FIELD(inst, QPU_WADDR_MUL);
if (!(inst & QPU_WS)) {
scoreboard->last_waddr_a = waddr_add;
scoreboard->last_waddr_b = waddr_mul;
} else {
scoreboard->last_waddr_b = waddr_add;
scoreboard->last_waddr_a = waddr_mul;
}
if ((waddr_add >= QPU_W_SFU_RECIP && waddr_add <= QPU_W_SFU_LOG) ||
(waddr_mul >= QPU_W_SFU_RECIP && waddr_mul <= QPU_W_SFU_LOG)) {
scoreboard->last_sfu_write_tick = scoreboard->tick;
}
if (waddr_add == QPU_W_UNIFORMS_ADDRESS ||
waddr_mul == QPU_W_UNIFORMS_ADDRESS) {
scoreboard->last_uniforms_reset_tick = scoreboard->tick;
}
if (qpu_inst_is_tlb(inst))
scoreboard->tlb_locked = true;
}
static void
dump_state(struct dag *dag)
{
list_for_each_entry(struct schedule_node, n, &dag->heads, dag.link) {
fprintf(stderr, " t=%4d: ", n->unblocked_time);
vc4_qpu_disasm(&n->inst->inst, 1);
fprintf(stderr, "\n");
util_dynarray_foreach(&n->dag.edges, struct dag_edge, edge) {
struct schedule_node *child =
(struct schedule_node *)edge->child;
if (!child)
continue;
fprintf(stderr, " - ");
vc4_qpu_disasm(&child->inst->inst, 1);
fprintf(stderr, " (%d parents, %c)\n",
child->dag.parent_count,
edge->data ? 'w' : 'r');
}
}
}
static uint32_t waddr_latency(uint32_t waddr, uint64_t after)
{
if (waddr < 32)
return 2;
/* Apply some huge latency between texture fetch requests and getting
* their results back.
*
* FIXME: This is actually pretty bogus. If we do:
*
* mov tmu0_s, a
* <a bit of math>
* mov tmu0_s, b
* load_tmu0
* <more math>
* load_tmu0
*
* we count that as worse than
*
* mov tmu0_s, a
* mov tmu0_s, b
* <lots of math>
* load_tmu0
* <more math>
* load_tmu0
*
* because we associate the first load_tmu0 with the *second* tmu0_s.
*/
if (waddr == QPU_W_TMU0_S) {
if (QPU_GET_FIELD(after, QPU_SIG) == QPU_SIG_LOAD_TMU0)
return 100;
}
if (waddr == QPU_W_TMU1_S) {
if (QPU_GET_FIELD(after, QPU_SIG) == QPU_SIG_LOAD_TMU1)
return 100;
}
switch(waddr) {
case QPU_W_SFU_RECIP:
case QPU_W_SFU_RECIPSQRT:
case QPU_W_SFU_EXP:
case QPU_W_SFU_LOG:
return 3;
default:
return 1;
}
}
static uint32_t
instruction_latency(struct schedule_node *before, struct schedule_node *after)
{
uint64_t before_inst = before->inst->inst;
uint64_t after_inst = after->inst->inst;
return MAX2(waddr_latency(QPU_GET_FIELD(before_inst, QPU_WADDR_ADD),
after_inst),
waddr_latency(QPU_GET_FIELD(before_inst, QPU_WADDR_MUL),
after_inst));
}
/** Recursive computation of the delay member of a node. */
static void
compute_delay(struct dag_node *node, void *state)
{
struct schedule_node *n = (struct schedule_node *)node;
n->delay = 1;
util_dynarray_foreach(&n->dag.edges, struct dag_edge, edge) {
struct schedule_node *child =
(struct schedule_node *)edge->child;
n->delay = MAX2(n->delay, (child->delay +
instruction_latency(n, child)));
}
}
/* Removes a DAG head, but removing only the WAR edges. (dag_prune_head()
* should be called on it later to finish pruning the other edges).
*/
static void
pre_remove_head(struct dag *dag, struct schedule_node *n)
{
list_delinit(&n->dag.link);
util_dynarray_foreach(&n->dag.edges, struct dag_edge, edge) {
if (edge->data)
dag_remove_edge(dag, edge);
}
}
static void
mark_instruction_scheduled(struct dag *dag,
uint32_t time,
struct schedule_node *node)
{
if (!node)
return;
util_dynarray_foreach(&node->dag.edges, struct dag_edge, edge) {
struct schedule_node *child =
(struct schedule_node *)edge->child;
if (!child)
continue;
uint32_t latency = instruction_latency(node, child);
child->unblocked_time = MAX2(child->unblocked_time,
time + latency);
}
dag_prune_head(dag, &node->dag);
}
/**
* Emits a THRSW/LTHRSW signal in the stream, trying to move it up to pair
* with another instruction.
*/
static void
emit_thrsw(struct vc4_compile *c,
struct choose_scoreboard *scoreboard,
uint64_t inst)
{
uint32_t sig = QPU_GET_FIELD(inst, QPU_SIG);
/* There should be nothing in a thrsw inst being scheduled other than
* the signal bits.
*/
assert(QPU_GET_FIELD(inst, QPU_OP_ADD) == QPU_A_NOP);
assert(QPU_GET_FIELD(inst, QPU_OP_MUL) == QPU_M_NOP);
/* Try to find an earlier scheduled instruction that we can merge the
* thrsw into.
*/
int thrsw_ip = c->qpu_inst_count;
for (int i = 1; i <= MIN2(c->qpu_inst_count, 3); i++) {
uint64_t prev_instr = c->qpu_insts[c->qpu_inst_count - i];
uint32_t prev_sig = QPU_GET_FIELD(prev_instr, QPU_SIG);
if (prev_sig == QPU_SIG_NONE)
thrsw_ip = c->qpu_inst_count - i;
}
if (thrsw_ip != c->qpu_inst_count) {
/* Merge the thrsw into the existing instruction. */
c->qpu_insts[thrsw_ip] =
QPU_UPDATE_FIELD(c->qpu_insts[thrsw_ip], sig, QPU_SIG);
} else {
qpu_serialize_one_inst(c, inst);
update_scoreboard_for_chosen(scoreboard, inst);
}
/* Fill the delay slots. */
while (c->qpu_inst_count < thrsw_ip + 3) {
update_scoreboard_for_chosen(scoreboard, qpu_NOP());
qpu_serialize_one_inst(c, qpu_NOP());
}
}
static uint32_t
schedule_instructions(struct vc4_compile *c,
struct choose_scoreboard *scoreboard,
struct qblock *block,
struct list_head *schedule_list,
enum quniform_contents *orig_uniform_contents,
uint32_t *orig_uniform_data,
uint32_t *next_uniform)
{
uint32_t time = 0;
while (!list_empty(&scoreboard->dag->heads)) {
struct schedule_node *chosen =
choose_instruction_to_schedule(scoreboard,
schedule_list,
NULL);
struct schedule_node *merge = NULL;
/* If there are no valid instructions to schedule, drop a NOP
* in.
*/
uint64_t inst = chosen ? chosen->inst->inst : qpu_NOP();
if (debug) {
fprintf(stderr, "t=%4d: current list:\n",
time);
dump_state(scoreboard->dag);
fprintf(stderr, "t=%4d: chose: ", time);
vc4_qpu_disasm(&inst, 1);
fprintf(stderr, "\n");
}
/* Schedule this instruction onto the QPU list. Also try to
* find an instruction to pair with it.
*/
if (chosen) {
time = MAX2(chosen->unblocked_time, time);
pre_remove_head(scoreboard->dag, chosen);
if (chosen->uniform != -1) {
c->uniform_data[*next_uniform] =
orig_uniform_data[chosen->uniform];
c->uniform_contents[*next_uniform] =
orig_uniform_contents[chosen->uniform];
(*next_uniform)++;
}
merge = choose_instruction_to_schedule(scoreboard,
schedule_list,
chosen);
if (merge) {
time = MAX2(merge->unblocked_time, time);
inst = qpu_merge_inst(inst, merge->inst->inst);
assert(inst != 0);
if (merge->uniform != -1) {
c->uniform_data[*next_uniform] =
orig_uniform_data[merge->uniform];
c->uniform_contents[*next_uniform] =
orig_uniform_contents[merge->uniform];
(*next_uniform)++;
}
if (debug) {
fprintf(stderr, "t=%4d: merging: ",
time);
vc4_qpu_disasm(&merge->inst->inst, 1);
fprintf(stderr, "\n");
fprintf(stderr, " resulting in: ");
vc4_qpu_disasm(&inst, 1);
fprintf(stderr, "\n");
}
}
}
if (debug) {
fprintf(stderr, "\n");
}
/* Now that we've scheduled a new instruction, some of its
* children can be promoted to the list of instructions ready to
* be scheduled. Update the children's unblocked time for this
* DAG edge as we do so.
*/
mark_instruction_scheduled(scoreboard->dag, time, chosen);
mark_instruction_scheduled(scoreboard->dag, time, merge);
if (QPU_GET_FIELD(inst, QPU_SIG) == QPU_SIG_THREAD_SWITCH ||
QPU_GET_FIELD(inst, QPU_SIG) == QPU_SIG_LAST_THREAD_SWITCH) {
emit_thrsw(c, scoreboard, inst);
} else {
qpu_serialize_one_inst(c, inst);
update_scoreboard_for_chosen(scoreboard, inst);
}
scoreboard->tick++;
time++;
if (QPU_GET_FIELD(inst, QPU_SIG) == QPU_SIG_BRANCH) {
block->branch_qpu_ip = c->qpu_inst_count - 1;
/* Fill the delay slots.
*
* We should fill these with actual instructions,
* instead, but that will probably need to be done
* after this, once we know what the leading
* instructions of the successors are (so we can
* handle A/B register file write latency)
*/
inst = qpu_NOP();
update_scoreboard_for_chosen(scoreboard, inst);
qpu_serialize_one_inst(c, inst);
qpu_serialize_one_inst(c, inst);
qpu_serialize_one_inst(c, inst);
}
}
return time;
}
static uint32_t
qpu_schedule_instructions_block(struct vc4_compile *c,
struct choose_scoreboard *scoreboard,
struct qblock *block,
enum quniform_contents *orig_uniform_contents,
uint32_t *orig_uniform_data,
uint32_t *next_uniform)
{
scoreboard->dag = dag_create(NULL);
struct list_head setup_list;
list_inithead(&setup_list);
/* Wrap each instruction in a scheduler structure. */
uint32_t next_sched_uniform = *next_uniform;
while (!list_empty(&block->qpu_inst_list)) {
struct queued_qpu_inst *inst =
(struct queued_qpu_inst *)block->qpu_inst_list.next;
struct schedule_node *n = rzalloc(scoreboard->dag,
struct schedule_node);
dag_init_node(scoreboard->dag, &n->dag);
n->inst = inst;
if (reads_uniform(inst->inst)) {
n->uniform = next_sched_uniform++;
} else {
n->uniform = -1;
}
list_del(&inst->link);
list_addtail(&n->link, &setup_list);
}
calculate_forward_deps(c, scoreboard->dag, &setup_list);
calculate_reverse_deps(c, scoreboard->dag, &setup_list);
dag_traverse_bottom_up(scoreboard->dag, compute_delay, NULL);
uint32_t cycles = schedule_instructions(c, scoreboard, block,
&setup_list,
orig_uniform_contents,
orig_uniform_data,
next_uniform);
ralloc_free(scoreboard->dag);
scoreboard->dag = NULL;
return cycles;
}
static void
qpu_set_branch_targets(struct vc4_compile *c)
{
qir_for_each_block(block, c) {
/* The end block of the program has no branch. */
if (!block->successors[0])
continue;
/* If there was no branch instruction, then the successor
* block must follow immediately after this one.
*/
if (block->branch_qpu_ip == ~0) {
assert(block->end_qpu_ip + 1 ==
block->successors[0]->start_qpu_ip);
continue;
}
/* Set the branch target for the block that doesn't follow
* immediately after ours.
*/
uint64_t *branch_inst = &c->qpu_insts[block->branch_qpu_ip];
assert(QPU_GET_FIELD(*branch_inst, QPU_SIG) == QPU_SIG_BRANCH);
assert(QPU_GET_FIELD(*branch_inst, QPU_BRANCH_TARGET) == 0);
uint32_t branch_target =
(block->successors[0]->start_qpu_ip -
(block->branch_qpu_ip + 4)) * sizeof(uint64_t);
*branch_inst = (*branch_inst |
QPU_SET_FIELD(branch_target, QPU_BRANCH_TARGET));
/* Make sure that the if-we-don't-jump successor was scheduled
* just after the delay slots.
*/
if (block->successors[1]) {
assert(block->successors[1]->start_qpu_ip ==
block->branch_qpu_ip + 4);
}
}
}
uint32_t
qpu_schedule_instructions(struct vc4_compile *c)
{
/* We reorder the uniforms as we schedule instructions, so save the
* old data off and replace it.
*/
uint32_t *uniform_data = c->uniform_data;
enum quniform_contents *uniform_contents = c->uniform_contents;
c->uniform_contents = ralloc_array(c, enum quniform_contents,
c->num_uniforms);
c->uniform_data = ralloc_array(c, uint32_t, c->num_uniforms);
c->uniform_array_size = c->num_uniforms;
uint32_t next_uniform = 0;
struct choose_scoreboard scoreboard;
memset(&scoreboard, 0, sizeof(scoreboard));
scoreboard.last_waddr_a = ~0;
scoreboard.last_waddr_b = ~0;
scoreboard.last_sfu_write_tick = -10;
scoreboard.last_uniforms_reset_tick = -10;
if (debug) {
fprintf(stderr, "Pre-schedule instructions\n");
qir_for_each_block(block, c) {
fprintf(stderr, "BLOCK %d\n", block->index);
list_for_each_entry(struct queued_qpu_inst, q,
&block->qpu_inst_list, link) {
vc4_qpu_disasm(&q->inst, 1);
fprintf(stderr, "\n");
}
}
fprintf(stderr, "\n");
}
uint32_t cycles = 0;
qir_for_each_block(block, c) {
block->start_qpu_ip = c->qpu_inst_count;
block->branch_qpu_ip = ~0;
cycles += qpu_schedule_instructions_block(c,
&scoreboard,
block,
uniform_contents,
uniform_data,
&next_uniform);
block->end_qpu_ip = c->qpu_inst_count - 1;
}
qpu_set_branch_targets(c);
assert(next_uniform == c->num_uniforms);
if (debug) {
fprintf(stderr, "Post-schedule instructions\n");
vc4_qpu_disasm(c->qpu_insts, c->qpu_inst_count);
fprintf(stderr, "\n");
}
return cycles;
}
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