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mesa/src/amd/compiler/aco_scheduler.cpp

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/*
* Copyright © 2018 Valve 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.
*
*/
#include "aco_builder.h"
#include "aco_ir.h"
#include "common/amdgfxregs.h"
#include <algorithm>
#include <unordered_set>
#include <vector>
#define SMEM_WINDOW_SIZE (350 - ctx.num_waves * 35)
#define VMEM_WINDOW_SIZE (1024 - ctx.num_waves * 64)
#define POS_EXP_WINDOW_SIZE 512
#define SMEM_MAX_MOVES (64 - ctx.num_waves * 4)
#define VMEM_MAX_MOVES (256 - ctx.num_waves * 16)
/* creating clauses decreases def-use distances, so make it less aggressive the lower num_waves is */
#define VMEM_CLAUSE_MAX_GRAB_DIST (ctx.num_waves * 2)
#define POS_EXP_MAX_MOVES 512
namespace aco {
enum MoveResult {
move_success,
move_fail_ssa,
move_fail_rar,
move_fail_pressure,
};
/**
* Cursor for downwards moves, where a single instruction is moved towards
* or below a group of instruction that hardware can execute as a clause.
*/
struct DownwardsCursor {
int source_idx; /* Current instruction to consider for moving */
int insert_idx_clause; /* First clause instruction */
int insert_idx; /* First instruction *after* the clause */
/* Maximum demand of all clause instructions,
* i.e. from insert_idx_clause (inclusive) to insert_idx (exclusive) */
RegisterDemand clause_demand;
/* Maximum demand of instructions from source_idx to insert_idx_clause (both exclusive) */
RegisterDemand total_demand;
DownwardsCursor(int current_idx, RegisterDemand initial_clause_demand)
: source_idx(current_idx - 1), insert_idx_clause(current_idx), insert_idx(current_idx + 1),
clause_demand(initial_clause_demand)
{}
void verify_invariants(const RegisterDemand* register_demand);
};
/**
* Cursor for upwards moves, where a single instruction is moved below
* another instruction.
*/
struct UpwardsCursor {
int source_idx; /* Current instruction to consider for moving */
int insert_idx; /* Instruction to move in front of */
/* Maximum demand of instructions from insert_idx (inclusive) to source_idx (exclusive) */
RegisterDemand total_demand;
UpwardsCursor(int source_idx_) : source_idx(source_idx_)
{
insert_idx = -1; /* to be initialized later */
}
bool has_insert_idx() const { return insert_idx != -1; }
void verify_invariants(const RegisterDemand* register_demand);
};
struct MoveState {
RegisterDemand max_registers;
Block* block;
Instruction* current;
RegisterDemand* register_demand; /* demand per instruction */
bool improved_rar;
std::vector<bool> depends_on;
/* Two are needed because, for downwards VMEM scheduling, one needs to
* exclude the instructions in the clause, since new instructions in the
* clause are not moved past any other instructions in the clause. */
std::vector<bool> RAR_dependencies;
std::vector<bool> RAR_dependencies_clause;
/* for moving instructions before the current instruction to after it */
DownwardsCursor downwards_init(int current_idx, bool improved_rar, bool may_form_clauses);
MoveResult downwards_move(DownwardsCursor&, bool clause);
void downwards_skip(DownwardsCursor&);
/* for moving instructions after the first use of the current instruction upwards */
UpwardsCursor upwards_init(int source_idx, bool improved_rar);
bool upwards_check_deps(UpwardsCursor&);
void upwards_update_insert_idx(UpwardsCursor&);
MoveResult upwards_move(UpwardsCursor&);
void upwards_skip(UpwardsCursor&);
};
struct sched_ctx {
amd_gfx_level gfx_level;
int16_t num_waves;
int16_t last_SMEM_stall;
int last_SMEM_dep_idx;
MoveState mv;
bool schedule_pos_exports = true;
unsigned schedule_pos_export_div = 1;
};
/* This scheduler is a simple bottom-up pass based on ideas from
* "A Novel Lightweight Instruction Scheduling Algorithm for Just-In-Time Compiler"
* from Xiaohua Shi and Peng Guo.
* The basic approach is to iterate over all instructions. When a memory instruction
* is encountered it tries to move independent instructions from above and below
* between the memory instruction and it's first user.
* The novelty is that this scheduler cares for the current register pressure:
* Instructions will only be moved if the register pressure won't exceed a certain bound.
*/
template <typename T>
void
move_element(T begin_it, size_t idx, size_t before)
{
if (idx < before) {
auto begin = std::next(begin_it, idx);
auto end = std::next(begin_it, before);
std::rotate(begin, begin + 1, end);
} else if (idx > before) {
auto begin = std::next(begin_it, before);
auto end = std::next(begin_it, idx + 1);
std::rotate(begin, end - 1, end);
}
}
void
DownwardsCursor::verify_invariants(const RegisterDemand* register_demand)
{
assert(source_idx < insert_idx_clause);
assert(insert_idx_clause < insert_idx);
#ifndef NDEBUG
RegisterDemand reference_demand;
for (int i = source_idx + 1; i < insert_idx_clause; ++i) {
reference_demand.update(register_demand[i]);
}
assert(total_demand == reference_demand);
reference_demand = {};
for (int i = insert_idx_clause; i < insert_idx; ++i) {
reference_demand.update(register_demand[i]);
}
assert(clause_demand == reference_demand);
#endif
}
DownwardsCursor
MoveState::downwards_init(int current_idx, bool improved_rar_, bool may_form_clauses)
{
improved_rar = improved_rar_;
std::fill(depends_on.begin(), depends_on.end(), false);
if (improved_rar) {
std::fill(RAR_dependencies.begin(), RAR_dependencies.end(), false);
if (may_form_clauses)
std::fill(RAR_dependencies_clause.begin(), RAR_dependencies_clause.end(), false);
}
for (const Operand& op : current->operands) {
if (op.isTemp()) {
depends_on[op.tempId()] = true;
if (improved_rar && op.isFirstKill())
RAR_dependencies[op.tempId()] = true;
}
}
DownwardsCursor cursor(current_idx, register_demand[current_idx]);
cursor.verify_invariants(register_demand);
return cursor;
}
/* If add_to_clause is true, the current clause is extended by moving the
* instruction at source_idx in front of the clause. Otherwise, the instruction
* is moved past the end of the clause without extending it */
MoveResult
MoveState::downwards_move(DownwardsCursor& cursor, bool add_to_clause)
{
aco_ptr<Instruction>& instr = block->instructions[cursor.source_idx];
for (const Definition& def : instr->definitions)
if (def.isTemp() && depends_on[def.tempId()])
return move_fail_ssa;
/* check if one of candidate's operands is killed by depending instruction */
std::vector<bool>& RAR_deps =
improved_rar ? (add_to_clause ? RAR_dependencies_clause : RAR_dependencies) : depends_on;
for (const Operand& op : instr->operands) {
if (op.isTemp() && RAR_deps[op.tempId()]) {
// FIXME: account for difference in register pressure
return move_fail_rar;
}
}
if (add_to_clause) {
for (const Operand& op : instr->operands) {
if (op.isTemp()) {
depends_on[op.tempId()] = true;
if (op.isFirstKill())
RAR_dependencies[op.tempId()] = true;
}
}
}
const int dest_insert_idx = add_to_clause ? cursor.insert_idx_clause : cursor.insert_idx;
RegisterDemand register_pressure = cursor.total_demand;
if (!add_to_clause) {
register_pressure.update(cursor.clause_demand);
}
/* Check the new demand of the instructions being moved over */
const RegisterDemand candidate_diff = get_live_changes(instr);
if (RegisterDemand(register_pressure - candidate_diff).exceeds(max_registers))
return move_fail_pressure;
/* New demand for the moved instruction */
const RegisterDemand temp = get_temp_registers(instr);
const RegisterDemand temp2 = get_temp_registers(block->instructions[dest_insert_idx - 1]);
const RegisterDemand new_demand = register_demand[dest_insert_idx - 1] - temp2 + temp;
if (new_demand.exceeds(max_registers))
return move_fail_pressure;
/* move the candidate below the memory load */
move_element(block->instructions.begin(), cursor.source_idx, dest_insert_idx);
/* update register pressure */
move_element(register_demand, cursor.source_idx, dest_insert_idx);
for (int i = cursor.source_idx; i < dest_insert_idx - 1; i++)
register_demand[i] -= candidate_diff;
register_demand[dest_insert_idx - 1] = new_demand;
cursor.insert_idx_clause--;
if (cursor.source_idx != cursor.insert_idx_clause) {
/* Update demand if we moved over any instructions before the clause */
cursor.total_demand -= candidate_diff;
} else {
assert(cursor.total_demand == RegisterDemand{});
}
if (add_to_clause) {
cursor.clause_demand.update(new_demand);
} else {
cursor.clause_demand -= candidate_diff;
cursor.insert_idx--;
}
cursor.source_idx--;
cursor.verify_invariants(register_demand);
return move_success;
}
void
MoveState::downwards_skip(DownwardsCursor& cursor)
{
aco_ptr<Instruction>& instr = block->instructions[cursor.source_idx];
for (const Operand& op : instr->operands) {
if (op.isTemp()) {
depends_on[op.tempId()] = true;
if (improved_rar && op.isFirstKill()) {
RAR_dependencies[op.tempId()] = true;
RAR_dependencies_clause[op.tempId()] = true;
}
}
}
cursor.total_demand.update(register_demand[cursor.source_idx]);
cursor.source_idx--;
cursor.verify_invariants(register_demand);
}
void
UpwardsCursor::verify_invariants(const RegisterDemand* register_demand)
{
#ifndef NDEBUG
if (!has_insert_idx()) {
return;
}
assert(insert_idx < source_idx);
RegisterDemand reference_demand;
for (int i = insert_idx; i < source_idx; ++i) {
reference_demand.update(register_demand[i]);
}
assert(total_demand == reference_demand);
#endif
}
UpwardsCursor
MoveState::upwards_init(int source_idx, bool improved_rar_)
{
improved_rar = improved_rar_;
std::fill(depends_on.begin(), depends_on.end(), false);
std::fill(RAR_dependencies.begin(), RAR_dependencies.end(), false);
for (const Definition& def : current->definitions) {
if (def.isTemp())
depends_on[def.tempId()] = true;
}
return UpwardsCursor(source_idx);
}
bool
MoveState::upwards_check_deps(UpwardsCursor& cursor)
{
aco_ptr<Instruction>& instr = block->instructions[cursor.source_idx];
for (const Operand& op : instr->operands) {
if (op.isTemp() && depends_on[op.tempId()])
return false;
}
return true;
}
void
MoveState::upwards_update_insert_idx(UpwardsCursor& cursor)
{
cursor.insert_idx = cursor.source_idx;
cursor.total_demand = register_demand[cursor.insert_idx];
}
MoveResult
MoveState::upwards_move(UpwardsCursor& cursor)
{
assert(cursor.has_insert_idx());
aco_ptr<Instruction>& instr = block->instructions[cursor.source_idx];
for (const Operand& op : instr->operands) {
if (op.isTemp() && depends_on[op.tempId()])
return move_fail_ssa;
}
/* check if candidate uses/kills an operand which is used by a dependency */
for (const Operand& op : instr->operands) {
if (op.isTemp() && (!improved_rar || op.isFirstKill()) && RAR_dependencies[op.tempId()])
return move_fail_rar;
}
/* check if register pressure is low enough: the diff is negative if register pressure is
* decreased */
const RegisterDemand candidate_diff = get_live_changes(instr);
const RegisterDemand temp = get_temp_registers(instr);
if (RegisterDemand(cursor.total_demand + candidate_diff).exceeds(max_registers))
return move_fail_pressure;
const RegisterDemand temp2 = get_temp_registers(block->instructions[cursor.insert_idx - 1]);
const RegisterDemand new_demand =
register_demand[cursor.insert_idx - 1] - temp2 + candidate_diff + temp;
if (new_demand.exceeds(max_registers))
return move_fail_pressure;
/* move the candidate above the insert_idx */
move_element(block->instructions.begin(), cursor.source_idx, cursor.insert_idx);
/* update register pressure */
move_element(register_demand, cursor.source_idx, cursor.insert_idx);
register_demand[cursor.insert_idx] = new_demand;
for (int i = cursor.insert_idx + 1; i <= cursor.source_idx; i++)
register_demand[i] += candidate_diff;
cursor.total_demand += candidate_diff;
cursor.total_demand.update(register_demand[cursor.source_idx]);
cursor.insert_idx++;
cursor.source_idx++;
cursor.verify_invariants(register_demand);
return move_success;
}
void
MoveState::upwards_skip(UpwardsCursor& cursor)
{
if (cursor.has_insert_idx()) {
aco_ptr<Instruction>& instr = block->instructions[cursor.source_idx];
for (const Definition& def : instr->definitions) {
if (def.isTemp())
depends_on[def.tempId()] = true;
}
for (const Operand& op : instr->operands) {
if (op.isTemp())
RAR_dependencies[op.tempId()] = true;
}
cursor.total_demand.update(register_demand[cursor.source_idx]);
}
cursor.source_idx++;
cursor.verify_invariants(register_demand);
}
bool
is_done_sendmsg(amd_gfx_level gfx_level, const Instruction* instr)
{
if (gfx_level <= GFX10_3 && instr->opcode == aco_opcode::s_sendmsg)
return (instr->sopp().imm & sendmsg_id_mask) == _sendmsg_gs_done;
return false;
}
memory_sync_info
get_sync_info_with_hack(const Instruction* instr)
{
memory_sync_info sync = get_sync_info(instr);
if (instr->isSMEM() && !instr->operands.empty() && instr->operands[0].bytes() == 16) {
// FIXME: currently, it doesn't seem beneficial to omit this due to how our scheduler works
sync.storage = (storage_class)(sync.storage | storage_buffer);
sync.semantics =
(memory_semantics)((sync.semantics | semantic_private) & ~semantic_can_reorder);
}
return sync;
}
struct memory_event_set {
bool has_control_barrier;
unsigned bar_acquire;
unsigned bar_release;
unsigned bar_classes;
unsigned access_acquire;
unsigned access_release;
unsigned access_relaxed;
unsigned access_atomic;
};
struct hazard_query {
amd_gfx_level gfx_level;
bool contains_spill;
bool contains_sendmsg;
bool uses_exec;
bool writes_exec;
memory_event_set mem_events;
unsigned aliasing_storage; /* storage classes which are accessed (non-SMEM) */
unsigned aliasing_storage_smem; /* storage classes which are accessed (SMEM) */
};
void
init_hazard_query(const sched_ctx& ctx, hazard_query* query)
{
query->gfx_level = ctx.gfx_level;
query->contains_spill = false;
query->contains_sendmsg = false;
query->uses_exec = false;
query->writes_exec = false;
memset(&query->mem_events, 0, sizeof(query->mem_events));
query->aliasing_storage = 0;
query->aliasing_storage_smem = 0;
}
void
add_memory_event(amd_gfx_level gfx_level, memory_event_set* set, Instruction* instr,
memory_sync_info* sync)
{
set->has_control_barrier |= is_done_sendmsg(gfx_level, instr);
if (instr->opcode == aco_opcode::p_barrier) {
Pseudo_barrier_instruction& bar = instr->barrier();
if (bar.sync.semantics & semantic_acquire)
set->bar_acquire |= bar.sync.storage;
if (bar.sync.semantics & semantic_release)
set->bar_release |= bar.sync.storage;
set->bar_classes |= bar.sync.storage;
set->has_control_barrier |= bar.exec_scope > scope_invocation;
}
if (!sync->storage)
return;
if (sync->semantics & semantic_acquire)
set->access_acquire |= sync->storage;
if (sync->semantics & semantic_release)
set->access_release |= sync->storage;
if (!(sync->semantics & semantic_private)) {
if (sync->semantics & semantic_atomic)
set->access_atomic |= sync->storage;
else
set->access_relaxed |= sync->storage;
}
}
void
add_to_hazard_query(hazard_query* query, Instruction* instr)
{
if (instr->opcode == aco_opcode::p_spill || instr->opcode == aco_opcode::p_reload)
query->contains_spill = true;
query->contains_sendmsg |= instr->opcode == aco_opcode::s_sendmsg;
query->uses_exec |= needs_exec_mask(instr);
for (const Definition& def : instr->definitions) {
if (def.isFixed() && def.physReg() == exec)
query->writes_exec = true;
}
memory_sync_info sync = get_sync_info_with_hack(instr);
add_memory_event(query->gfx_level, &query->mem_events, instr, &sync);
if (!(sync.semantics & semantic_can_reorder)) {
unsigned storage = sync.storage;
/* images and buffer/global memory can alias */ // TODO: more precisely, buffer images and
// buffer/global memory can alias
if (storage & (storage_buffer | storage_image))
storage |= storage_buffer | storage_image;
if (instr->isSMEM())
query->aliasing_storage_smem |= storage;
else
query->aliasing_storage |= storage;
}
}
enum HazardResult {
hazard_success,
hazard_fail_reorder_vmem_smem,
hazard_fail_reorder_ds,
hazard_fail_reorder_sendmsg,
hazard_fail_spill,
hazard_fail_export,
hazard_fail_barrier,
/* Must stop at these failures. The hazard query code doesn't consider them
* when added. */
hazard_fail_exec,
hazard_fail_unreorderable,
};
HazardResult
perform_hazard_query(hazard_query* query, Instruction* instr, bool upwards)
{
/* don't schedule discards downwards */
if (!upwards && instr->opcode == aco_opcode::p_exit_early_if)
return hazard_fail_unreorderable;
if (query->uses_exec) {
for (const Definition& def : instr->definitions) {
if (def.isFixed() && def.physReg() == exec)
return hazard_fail_exec;
}
}
if (query->writes_exec && needs_exec_mask(instr))
return hazard_fail_exec;
/* don't move exports so that they stay closer together */
if (instr->isEXP())
return hazard_fail_export;
/* don't move non-reorderable instructions */
if (instr->opcode == aco_opcode::s_memtime || instr->opcode == aco_opcode::s_memrealtime ||
instr->opcode == aco_opcode::s_setprio || instr->opcode == aco_opcode::s_getreg_b32 ||
instr->opcode == aco_opcode::p_init_scratch || instr->opcode == aco_opcode::p_jump_to_epilog ||
instr->opcode == aco_opcode::s_sendmsg_rtn_b32 || instr->opcode == aco_opcode::s_sendmsg_rtn_b64)
return hazard_fail_unreorderable;
memory_event_set instr_set;
memset(&instr_set, 0, sizeof(instr_set));
memory_sync_info sync = get_sync_info_with_hack(instr);
add_memory_event(query->gfx_level, &instr_set, instr, &sync);
memory_event_set* first = &instr_set;
memory_event_set* second = &query->mem_events;
if (upwards)
std::swap(first, second);
/* everything after barrier(acquire) happens after the atomics/control_barriers before
* everything after load(acquire) happens after the load
*/
if ((first->has_control_barrier || first->access_atomic) && second->bar_acquire)
return hazard_fail_barrier;
if (((first->access_acquire || first->bar_acquire) && second->bar_classes) ||
((first->access_acquire | first->bar_acquire) &
(second->access_relaxed | second->access_atomic)))
return hazard_fail_barrier;
/* everything before barrier(release) happens before the atomics/control_barriers after *
* everything before store(release) happens before the store
*/
if (first->bar_release && (second->has_control_barrier || second->access_atomic))
return hazard_fail_barrier;
if ((first->bar_classes && (second->bar_release || second->access_release)) ||
((first->access_relaxed | first->access_atomic) &
(second->bar_release | second->access_release)))
return hazard_fail_barrier;
/* don't move memory barriers around other memory barriers */
if (first->bar_classes && second->bar_classes)
return hazard_fail_barrier;
/* Don't move memory accesses to before control barriers. I don't think
* this is necessary for the Vulkan memory model, but it might be for GLSL450. */
unsigned control_classes =
storage_buffer | storage_image | storage_shared | storage_task_payload;
if (first->has_control_barrier &&
((second->access_atomic | second->access_relaxed) & control_classes))
return hazard_fail_barrier;
/* don't move memory loads/stores past potentially aliasing loads/stores */
unsigned aliasing_storage =
instr->isSMEM() ? query->aliasing_storage_smem : query->aliasing_storage;
if ((sync.storage & aliasing_storage) && !(sync.semantics & semantic_can_reorder)) {
unsigned intersect = sync.storage & aliasing_storage;
if (intersect & storage_shared)
return hazard_fail_reorder_ds;
return hazard_fail_reorder_vmem_smem;
}
if ((instr->opcode == aco_opcode::p_spill || instr->opcode == aco_opcode::p_reload) &&
query->contains_spill)
return hazard_fail_spill;
if (instr->opcode == aco_opcode::s_sendmsg && query->contains_sendmsg)
return hazard_fail_reorder_sendmsg;
return hazard_success;
}
void
schedule_SMEM(sched_ctx& ctx, Block* block, std::vector<RegisterDemand>& register_demand,
Instruction* current, int idx)
{
assert(idx != 0);
int window_size = SMEM_WINDOW_SIZE;
int max_moves = SMEM_MAX_MOVES;
int16_t k = 0;
/* don't move s_memtime/s_memrealtime */
if (current->opcode == aco_opcode::s_memtime ||
current->opcode == aco_opcode::s_memrealtime ||
current->opcode == aco_opcode::s_sendmsg_rtn_b32 ||
current->opcode == aco_opcode::s_sendmsg_rtn_b64)
return;
/* first, check if we have instructions before current to move down */
hazard_query hq;
init_hazard_query(ctx, &hq);
add_to_hazard_query(&hq, current);
DownwardsCursor cursor = ctx.mv.downwards_init(idx, false, false);
for (int candidate_idx = idx - 1; k < max_moves && candidate_idx > (int)idx - window_size;
candidate_idx--) {
assert(candidate_idx >= 0);
assert(candidate_idx == cursor.source_idx);
aco_ptr<Instruction>& candidate = block->instructions[candidate_idx];
/* break if we'd make the previous SMEM instruction stall */
bool can_stall_prev_smem =
idx <= ctx.last_SMEM_dep_idx && candidate_idx < ctx.last_SMEM_dep_idx;
if (can_stall_prev_smem && ctx.last_SMEM_stall >= 0)
break;
/* break when encountering another MEM instruction, logical_start or barriers */
if (candidate->opcode == aco_opcode::p_logical_start)
break;
/* only move VMEM instructions below descriptor loads. be more aggressive at higher num_waves
* to help create more vmem clauses */
if ((candidate->isVMEM() || candidate->isFlatLike()) &&
(cursor.insert_idx - cursor.source_idx > (ctx.num_waves * 4) ||
current->operands[0].size() == 4))
break;
/* don't move descriptor loads below buffer loads */
if (candidate->isSMEM() && !candidate->operands.empty() && current->operands[0].size() == 4 &&
candidate->operands[0].size() == 2)
break;
bool can_move_down = true;
HazardResult haz = perform_hazard_query(&hq, candidate.get(), false);
if (haz == hazard_fail_reorder_ds || haz == hazard_fail_spill ||
haz == hazard_fail_reorder_sendmsg || haz == hazard_fail_barrier ||
haz == hazard_fail_export)
can_move_down = false;
else if (haz != hazard_success)
break;
/* don't use LDS/GDS instructions to hide latency since it can
* significanly worsen LDS scheduling */
if (candidate->isDS() || !can_move_down) {
add_to_hazard_query(&hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
}
MoveResult res = ctx.mv.downwards_move(cursor, false);
if (res == move_fail_ssa || res == move_fail_rar) {
add_to_hazard_query(&hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
} else if (res == move_fail_pressure) {
break;
}
if (candidate_idx < ctx.last_SMEM_dep_idx)
ctx.last_SMEM_stall++;
k++;
}
/* find the first instruction depending on current or find another MEM */
UpwardsCursor up_cursor = ctx.mv.upwards_init(idx + 1, false);
bool found_dependency = false;
/* second, check if we have instructions after current to move up */
for (int candidate_idx = idx + 1; k < max_moves && candidate_idx < (int)idx + window_size;
candidate_idx++) {
assert(candidate_idx == up_cursor.source_idx);
assert(candidate_idx < (int)block->instructions.size());
aco_ptr<Instruction>& candidate = block->instructions[candidate_idx];
if (candidate->opcode == aco_opcode::p_logical_end)
break;
/* check if candidate depends on current */
bool is_dependency = !found_dependency && !ctx.mv.upwards_check_deps(up_cursor);
/* no need to steal from following VMEM instructions */
if (is_dependency && (candidate->isVMEM() || candidate->isFlatLike()))
break;
if (found_dependency) {
HazardResult haz = perform_hazard_query(&hq, candidate.get(), true);
if (haz == hazard_fail_reorder_ds || haz == hazard_fail_spill ||
haz == hazard_fail_reorder_sendmsg || haz == hazard_fail_barrier ||
haz == hazard_fail_export)
is_dependency = true;
else if (haz != hazard_success)
break;
}
if (is_dependency) {
if (!found_dependency) {
ctx.mv.upwards_update_insert_idx(up_cursor);
init_hazard_query(ctx, &hq);
found_dependency = true;
}
}
if (is_dependency || !found_dependency) {
if (found_dependency)
add_to_hazard_query(&hq, candidate.get());
else
k++;
ctx.mv.upwards_skip(up_cursor);
continue;
}
MoveResult res = ctx.mv.upwards_move(up_cursor);
if (res == move_fail_ssa || res == move_fail_rar) {
/* no need to steal from following VMEM instructions */
if (res == move_fail_ssa && (candidate->isVMEM() || candidate->isFlatLike()))
break;
add_to_hazard_query(&hq, candidate.get());
ctx.mv.upwards_skip(up_cursor);
continue;
} else if (res == move_fail_pressure) {
break;
}
k++;
}
ctx.last_SMEM_dep_idx = found_dependency ? up_cursor.insert_idx : 0;
ctx.last_SMEM_stall = 10 - ctx.num_waves - k;
}
void
schedule_VMEM(sched_ctx& ctx, Block* block, std::vector<RegisterDemand>& register_demand,
Instruction* current, int idx)
{
assert(idx != 0);
int window_size = VMEM_WINDOW_SIZE;
int max_moves = VMEM_MAX_MOVES;
int clause_max_grab_dist = VMEM_CLAUSE_MAX_GRAB_DIST;
bool only_clauses = false;
int16_t k = 0;
/* first, check if we have instructions before current to move down */
hazard_query indep_hq;
hazard_query clause_hq;
init_hazard_query(ctx, &indep_hq);
init_hazard_query(ctx, &clause_hq);
add_to_hazard_query(&indep_hq, current);
DownwardsCursor cursor = ctx.mv.downwards_init(idx, true, true);
for (int candidate_idx = idx - 1; k < max_moves && candidate_idx > (int)idx - window_size;
candidate_idx--) {
assert(candidate_idx == cursor.source_idx);
assert(candidate_idx >= 0);
aco_ptr<Instruction>& candidate = block->instructions[candidate_idx];
bool is_vmem = candidate->isVMEM() || candidate->isFlatLike();
/* break when encountering another VMEM instruction, logical_start or barriers */
if (candidate->opcode == aco_opcode::p_logical_start)
break;
/* break if we'd make the previous SMEM instruction stall */
bool can_stall_prev_smem =
idx <= ctx.last_SMEM_dep_idx && candidate_idx < ctx.last_SMEM_dep_idx;
if (can_stall_prev_smem && ctx.last_SMEM_stall >= 0)
break;
bool part_of_clause = false;
if (current->isVMEM() == candidate->isVMEM()) {
int grab_dist = cursor.insert_idx_clause - candidate_idx;
/* We can't easily tell how much this will decrease the def-to-use
* distances, so just use how far it will be moved as a heuristic. */
part_of_clause =
grab_dist < clause_max_grab_dist + k && should_form_clause(current, candidate.get());
}
/* if current depends on candidate, add additional dependencies and continue */
bool can_move_down = !is_vmem || part_of_clause || candidate->definitions.empty();
if (only_clauses) {
/* In case of high register pressure, only try to form clauses,
* and only if the previous clause is not larger
* than the current one will be.
*/
if (part_of_clause) {
int clause_size = cursor.insert_idx - cursor.insert_idx_clause;
int prev_clause_size = 1;
while (should_form_clause(current,
block->instructions[candidate_idx - prev_clause_size].get()))
prev_clause_size++;
if (prev_clause_size > clause_size + 1)
break;
} else {
can_move_down = false;
}
}
HazardResult haz =
perform_hazard_query(part_of_clause ? &clause_hq : &indep_hq, candidate.get(), false);
if (haz == hazard_fail_reorder_ds || haz == hazard_fail_spill ||
haz == hazard_fail_reorder_sendmsg || haz == hazard_fail_barrier ||
haz == hazard_fail_export)
can_move_down = false;
else if (haz != hazard_success)
break;
if (!can_move_down) {
if (part_of_clause)
break;
add_to_hazard_query(&indep_hq, candidate.get());
add_to_hazard_query(&clause_hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
}
Instruction* candidate_ptr = candidate.get();
MoveResult res = ctx.mv.downwards_move(cursor, part_of_clause);
if (res == move_fail_ssa || res == move_fail_rar) {
if (part_of_clause)
break;
add_to_hazard_query(&indep_hq, candidate.get());
add_to_hazard_query(&clause_hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
} else if (res == move_fail_pressure) {
only_clauses = true;
if (part_of_clause)
break;
add_to_hazard_query(&indep_hq, candidate.get());
add_to_hazard_query(&clause_hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
}
if (part_of_clause)
add_to_hazard_query(&indep_hq, candidate_ptr);
else
k++;
if (candidate_idx < ctx.last_SMEM_dep_idx)
ctx.last_SMEM_stall++;
}
/* find the first instruction depending on current or find another VMEM */
UpwardsCursor up_cursor = ctx.mv.upwards_init(idx + 1, true);
bool found_dependency = false;
/* second, check if we have instructions after current to move up */
for (int candidate_idx = idx + 1; k < max_moves && candidate_idx < (int)idx + window_size;
candidate_idx++) {
assert(candidate_idx == up_cursor.source_idx);
assert(candidate_idx < (int)block->instructions.size());
aco_ptr<Instruction>& candidate = block->instructions[candidate_idx];
bool is_vmem = candidate->isVMEM() || candidate->isFlatLike();
if (candidate->opcode == aco_opcode::p_logical_end)
break;
/* check if candidate depends on current */
bool is_dependency = false;
if (found_dependency) {
HazardResult haz = perform_hazard_query(&indep_hq, candidate.get(), true);
if (haz == hazard_fail_reorder_ds || haz == hazard_fail_spill ||
haz == hazard_fail_reorder_vmem_smem || haz == hazard_fail_reorder_sendmsg ||
haz == hazard_fail_barrier || haz == hazard_fail_export)
is_dependency = true;
else if (haz != hazard_success)
break;
}
is_dependency |= !found_dependency && !ctx.mv.upwards_check_deps(up_cursor);
if (is_dependency) {
if (!found_dependency) {
ctx.mv.upwards_update_insert_idx(up_cursor);
init_hazard_query(ctx, &indep_hq);
found_dependency = true;
}
} else if (is_vmem) {
/* don't move up dependencies of other VMEM instructions */
for (const Definition& def : candidate->definitions) {
if (def.isTemp())
ctx.mv.depends_on[def.tempId()] = true;
}
}
if (is_dependency || !found_dependency) {
if (found_dependency)
add_to_hazard_query(&indep_hq, candidate.get());
else
k++;
ctx.mv.upwards_skip(up_cursor);
continue;
}
MoveResult res = ctx.mv.upwards_move(up_cursor);
if (res == move_fail_ssa || res == move_fail_rar) {
add_to_hazard_query(&indep_hq, candidate.get());
ctx.mv.upwards_skip(up_cursor);
continue;
} else if (res == move_fail_pressure) {
break;
}
k++;
}
}
void
schedule_position_export(sched_ctx& ctx, Block* block, std::vector<RegisterDemand>& register_demand,
Instruction* current, int idx)
{
assert(idx != 0);
int window_size = POS_EXP_WINDOW_SIZE / ctx.schedule_pos_export_div;
int max_moves = POS_EXP_MAX_MOVES / ctx.schedule_pos_export_div;
int16_t k = 0;
DownwardsCursor cursor = ctx.mv.downwards_init(idx, true, false);
hazard_query hq;
init_hazard_query(ctx, &hq);
add_to_hazard_query(&hq, current);
for (int candidate_idx = idx - 1; k < max_moves && candidate_idx > (int)idx - window_size;
candidate_idx--) {
assert(candidate_idx >= 0);
aco_ptr<Instruction>& candidate = block->instructions[candidate_idx];
if (candidate->opcode == aco_opcode::p_logical_start)
break;
if (candidate->isVMEM() || candidate->isSMEM() || candidate->isFlatLike())
break;
HazardResult haz = perform_hazard_query(&hq, candidate.get(), false);
if (haz == hazard_fail_exec || haz == hazard_fail_unreorderable)
break;
if (haz != hazard_success) {
add_to_hazard_query(&hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
}
MoveResult res = ctx.mv.downwards_move(cursor, false);
if (res == move_fail_ssa || res == move_fail_rar) {
add_to_hazard_query(&hq, candidate.get());
ctx.mv.downwards_skip(cursor);
continue;
} else if (res == move_fail_pressure) {
break;
}
k++;
}
}
void
schedule_block(sched_ctx& ctx, Program* program, Block* block, live& live_vars)
{
ctx.last_SMEM_dep_idx = 0;
ctx.last_SMEM_stall = INT16_MIN;
ctx.mv.block = block;
ctx.mv.register_demand = live_vars.register_demand[block->index].data();
/* go through all instructions and find memory loads */
for (unsigned idx = 0; idx < block->instructions.size(); idx++) {
Instruction* current = block->instructions[idx].get();
if (block->kind & block_kind_export_end && current->isEXP() && ctx.schedule_pos_exports) {
unsigned target = current->exp().dest;
if (target >= V_008DFC_SQ_EXP_POS && target < V_008DFC_SQ_EXP_PRIM) {
ctx.mv.current = current;
schedule_position_export(ctx, block, live_vars.register_demand[block->index], current,
idx);
}
}
if (current->definitions.empty())
continue;
if (current->isVMEM() || current->isFlatLike()) {
ctx.mv.current = current;
schedule_VMEM(ctx, block, live_vars.register_demand[block->index], current, idx);
}
if (current->isSMEM()) {
ctx.mv.current = current;
schedule_SMEM(ctx, block, live_vars.register_demand[block->index], current, idx);
}
}
/* resummarize the block's register demand */
block->register_demand = RegisterDemand();
for (unsigned idx = 0; idx < block->instructions.size(); idx++) {
block->register_demand.update(live_vars.register_demand[block->index][idx]);
}
}
void
schedule_program(Program* program, live& live_vars)
{
/* don't use program->max_reg_demand because that is affected by max_waves_per_simd */
RegisterDemand demand;
for (Block& block : program->blocks)
demand.update(block.register_demand);
demand.vgpr += program->config->num_shared_vgprs / 2;
sched_ctx ctx;
ctx.gfx_level = program->gfx_level;
ctx.mv.depends_on.resize(program->peekAllocationId());
ctx.mv.RAR_dependencies.resize(program->peekAllocationId());
ctx.mv.RAR_dependencies_clause.resize(program->peekAllocationId());
/* Allowing the scheduler to reduce the number of waves to as low as 5
* improves performance of Thrones of Britannia significantly and doesn't
* seem to hurt anything else. */
// TODO: account for possible uneven num_waves on GFX10+
unsigned wave_fac = program->dev.physical_vgprs / 256;
if (program->num_waves <= 5 * wave_fac)
ctx.num_waves = program->num_waves;
else if (demand.vgpr >= 29)
ctx.num_waves = 5 * wave_fac;
else if (demand.vgpr >= 25)
ctx.num_waves = 6 * wave_fac;
else
ctx.num_waves = 7 * wave_fac;
ctx.num_waves = std::max<uint16_t>(ctx.num_waves, program->min_waves);
ctx.num_waves = std::min<uint16_t>(ctx.num_waves, program->num_waves);
ctx.num_waves = max_suitable_waves(program, ctx.num_waves);
/* VMEM_MAX_MOVES and such assume pre-GFX10 wave count */
ctx.num_waves = std::max<uint16_t>(ctx.num_waves / wave_fac, 1);
assert(ctx.num_waves > 0);
ctx.mv.max_registers = {int16_t(get_addr_vgpr_from_waves(program, ctx.num_waves * wave_fac) - 2),
int16_t(get_addr_sgpr_from_waves(program, ctx.num_waves * wave_fac))};
/* NGG culling shaders are very sensitive to position export scheduling.
* Schedule less aggressively when early primitive export is used, and
* keep the position export at the very bottom when late primitive export is used.
*/
if (program->info.has_ngg_culling && program->stage.num_sw_stages() == 1) {
if (!program->info.has_ngg_early_prim_export)
ctx.schedule_pos_exports = false;
else
ctx.schedule_pos_export_div = 4;
}
for (Block& block : program->blocks)
schedule_block(ctx, program, &block, live_vars);
/* update max_reg_demand and num_waves */
RegisterDemand new_demand;
for (Block& block : program->blocks) {
new_demand.update(block.register_demand);
}
update_vgpr_sgpr_demand(program, new_demand);
/* if enabled, this code asserts that register_demand is updated correctly */
#if 0
int prev_num_waves = program->num_waves;
const RegisterDemand prev_max_demand = program->max_reg_demand;
std::vector<RegisterDemand> demands(program->blocks.size());
for (unsigned j = 0; j < program->blocks.size(); j++) {
demands[j] = program->blocks[j].register_demand;
}
live live_vars2 = aco::live_var_analysis(program);
for (unsigned j = 0; j < program->blocks.size(); j++) {
Block &b = program->blocks[j];
for (unsigned i = 0; i < b.instructions.size(); i++)
assert(live_vars.register_demand[b.index][i] == live_vars2.register_demand[b.index][i]);
assert(b.register_demand == demands[j]);
}
assert(program->max_reg_demand == prev_max_demand);
assert(program->num_waves == prev_num_waves);
#endif
}
} // namespace aco
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