mesa/src/amd/compiler/aco_insert_NOPs.cpp

898 lines
35 KiB
C++

/*
* Copyright © 2019 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 <algorithm>
#include <bitset>
#include <stack>
#include <vector>
namespace aco {
namespace {
struct State {
Program* program;
Block* block;
std::vector<aco_ptr<Instruction>> old_instructions;
};
struct NOP_ctx_gfx6 {
void join(const NOP_ctx_gfx6& other)
{
set_vskip_mode_then_vector =
MAX2(set_vskip_mode_then_vector, other.set_vskip_mode_then_vector);
valu_wr_vcc_then_vccz = MAX2(valu_wr_vcc_then_vccz, other.valu_wr_vcc_then_vccz);
valu_wr_exec_then_execz = MAX2(valu_wr_exec_then_execz, other.valu_wr_exec_then_execz);
valu_wr_vcc_then_div_fmas = MAX2(valu_wr_vcc_then_div_fmas, other.valu_wr_vcc_then_div_fmas);
salu_wr_m0_then_gds_msg_ttrace =
MAX2(salu_wr_m0_then_gds_msg_ttrace, other.salu_wr_m0_then_gds_msg_ttrace);
valu_wr_exec_then_dpp = MAX2(valu_wr_exec_then_dpp, other.valu_wr_exec_then_dpp);
salu_wr_m0_then_lds = MAX2(salu_wr_m0_then_lds, other.salu_wr_m0_then_lds);
salu_wr_m0_then_moverel = MAX2(salu_wr_m0_then_moverel, other.salu_wr_m0_then_moverel);
setreg_then_getsetreg = MAX2(setreg_then_getsetreg, other.setreg_then_getsetreg);
vmem_store_then_wr_data |= other.vmem_store_then_wr_data;
smem_clause |= other.smem_clause;
smem_write |= other.smem_write;
for (unsigned i = 0; i < BITSET_WORDS(128); i++) {
smem_clause_read_write[i] |= other.smem_clause_read_write[i];
smem_clause_write[i] |= other.smem_clause_write[i];
}
}
bool operator==(const NOP_ctx_gfx6& other)
{
return set_vskip_mode_then_vector == other.set_vskip_mode_then_vector &&
valu_wr_vcc_then_vccz == other.valu_wr_vcc_then_vccz &&
valu_wr_exec_then_execz == other.valu_wr_exec_then_execz &&
valu_wr_vcc_then_div_fmas == other.valu_wr_vcc_then_div_fmas &&
vmem_store_then_wr_data == other.vmem_store_then_wr_data &&
salu_wr_m0_then_gds_msg_ttrace == other.salu_wr_m0_then_gds_msg_ttrace &&
valu_wr_exec_then_dpp == other.valu_wr_exec_then_dpp &&
salu_wr_m0_then_lds == other.salu_wr_m0_then_lds &&
salu_wr_m0_then_moverel == other.salu_wr_m0_then_moverel &&
setreg_then_getsetreg == other.setreg_then_getsetreg &&
smem_clause == other.smem_clause && smem_write == other.smem_write &&
BITSET_EQUAL(smem_clause_read_write, other.smem_clause_read_write) &&
BITSET_EQUAL(smem_clause_write, other.smem_clause_write);
}
void add_wait_states(unsigned amount)
{
if ((set_vskip_mode_then_vector -= amount) < 0)
set_vskip_mode_then_vector = 0;
if ((valu_wr_vcc_then_vccz -= amount) < 0)
valu_wr_vcc_then_vccz = 0;
if ((valu_wr_exec_then_execz -= amount) < 0)
valu_wr_exec_then_execz = 0;
if ((valu_wr_vcc_then_div_fmas -= amount) < 0)
valu_wr_vcc_then_div_fmas = 0;
if ((salu_wr_m0_then_gds_msg_ttrace -= amount) < 0)
salu_wr_m0_then_gds_msg_ttrace = 0;
if ((valu_wr_exec_then_dpp -= amount) < 0)
valu_wr_exec_then_dpp = 0;
if ((salu_wr_m0_then_lds -= amount) < 0)
salu_wr_m0_then_lds = 0;
if ((salu_wr_m0_then_moverel -= amount) < 0)
salu_wr_m0_then_moverel = 0;
if ((setreg_then_getsetreg -= amount) < 0)
setreg_then_getsetreg = 0;
vmem_store_then_wr_data.reset();
}
/* setting MODE.vskip and then any vector op requires 2 wait states */
int8_t set_vskip_mode_then_vector = 0;
/* VALU writing VCC/EXEC and then a VALU reading VCCZ/EXECZ requires 5 wait states */
int8_t valu_wr_vcc_then_vccz = 0;
int8_t valu_wr_exec_then_execz = 0;
/* VALU writing VCC followed by v_div_fmas require 4 wait states */
int8_t valu_wr_vcc_then_div_fmas = 0;
/* SALU writing M0 followed by GDS, s_sendmsg or s_ttrace_data requires 1 wait state */
int8_t salu_wr_m0_then_gds_msg_ttrace = 0;
/* VALU writing EXEC followed by DPP requires 5 wait states */
int8_t valu_wr_exec_then_dpp = 0;
/* SALU writing M0 followed by some LDS instructions requires 1 wait state on GFX10 */
int8_t salu_wr_m0_then_lds = 0;
/* SALU writing M0 followed by s_moverel requires 1 wait state on GFX9 */
int8_t salu_wr_m0_then_moverel = 0;
/* s_setreg followed by a s_getreg/s_setreg of the same register needs 2 wait states
* currently we don't look at the actual register */
int8_t setreg_then_getsetreg = 0;
/* some memory instructions writing >64bit followed by a instructions
* writing the VGPRs holding the writedata requires 1 wait state */
std::bitset<256> vmem_store_then_wr_data;
/* we break up SMEM clauses that contain stores or overwrite an
* operand/definition of another instruction in the clause */
bool smem_clause = false;
bool smem_write = false;
BITSET_DECLARE(smem_clause_read_write, 128) = {0};
BITSET_DECLARE(smem_clause_write, 128) = {0};
};
struct NOP_ctx_gfx10 {
bool has_VOPC = false;
bool has_nonVALU_exec_read = false;
bool has_VMEM = false;
bool has_branch_after_VMEM = false;
bool has_DS = false;
bool has_branch_after_DS = false;
bool has_NSA_MIMG = false;
bool has_writelane = false;
std::bitset<128> sgprs_read_by_VMEM;
std::bitset<128> sgprs_read_by_SMEM;
void join(const NOP_ctx_gfx10& other)
{
has_VOPC |= other.has_VOPC;
has_nonVALU_exec_read |= other.has_nonVALU_exec_read;
has_VMEM |= other.has_VMEM;
has_branch_after_VMEM |= other.has_branch_after_VMEM;
has_DS |= other.has_DS;
has_branch_after_DS |= other.has_branch_after_DS;
has_NSA_MIMG |= other.has_NSA_MIMG;
has_writelane |= other.has_writelane;
sgprs_read_by_VMEM |= other.sgprs_read_by_VMEM;
sgprs_read_by_SMEM |= other.sgprs_read_by_SMEM;
}
bool operator==(const NOP_ctx_gfx10& other)
{
return has_VOPC == other.has_VOPC && has_nonVALU_exec_read == other.has_nonVALU_exec_read &&
has_VMEM == other.has_VMEM && has_branch_after_VMEM == other.has_branch_after_VMEM &&
has_DS == other.has_DS && has_branch_after_DS == other.has_branch_after_DS &&
has_NSA_MIMG == other.has_NSA_MIMG && has_writelane == other.has_writelane &&
sgprs_read_by_VMEM == other.sgprs_read_by_VMEM &&
sgprs_read_by_SMEM == other.sgprs_read_by_SMEM;
}
};
int
get_wait_states(aco_ptr<Instruction>& instr)
{
if (instr->opcode == aco_opcode::s_nop)
return instr->sopp().imm + 1;
else if (instr->opcode == aco_opcode::p_constaddr)
return 3; /* lowered to 3 instructions in the assembler */
else
return 1;
}
bool
regs_intersect(PhysReg a_reg, unsigned a_size, PhysReg b_reg, unsigned b_size)
{
return a_reg > b_reg ? (a_reg - b_reg < b_size) : (b_reg - a_reg < a_size);
}
template <bool Valu, bool Vintrp, bool Salu>
bool
handle_raw_hazard_instr(aco_ptr<Instruction>& pred, PhysReg reg, int* nops_needed, uint32_t* mask)
{
unsigned mask_size = util_last_bit(*mask);
uint32_t writemask = 0;
for (Definition& def : pred->definitions) {
if (regs_intersect(reg, mask_size, def.physReg(), def.size())) {
unsigned start = def.physReg() > reg ? def.physReg() - reg : 0;
unsigned end = MIN2(mask_size, start + def.size());
writemask |= u_bit_consecutive(start, end - start);
}
}
bool is_hazard = writemask != 0 && ((pred->isVALU() && Valu) || (pred->isVINTRP() && Vintrp) ||
(pred->isSALU() && Salu));
if (is_hazard)
return true;
*mask &= ~writemask;
*nops_needed = MAX2(*nops_needed - get_wait_states(pred), 0);
if (*mask == 0)
*nops_needed = 0;
return *nops_needed == 0;
}
template <bool Valu, bool Vintrp, bool Salu>
int
handle_raw_hazard_internal(State& state, Block* block, int nops_needed, PhysReg reg, uint32_t mask,
bool start_at_end)
{
if (block == state.block && start_at_end) {
/* If it's the current block, block->instructions is incomplete. */
for (int pred_idx = state.old_instructions.size() - 1; pred_idx >= 0; pred_idx--) {
aco_ptr<Instruction>& instr = state.old_instructions[pred_idx];
if (!instr)
break; /* Instruction has been moved to block->instructions. */
if (handle_raw_hazard_instr<Valu, Vintrp, Salu>(instr, reg, &nops_needed, &mask))
return nops_needed;
}
}
for (int pred_idx = block->instructions.size() - 1; pred_idx >= 0; pred_idx--) {
if (handle_raw_hazard_instr<Valu, Vintrp, Salu>(block->instructions[pred_idx], reg,
&nops_needed, &mask))
return nops_needed;
}
int res = 0;
/* Loops require branch instructions, which count towards the wait
* states. So even with loops this should finish unless nops_needed is some
* huge value. */
for (unsigned lin_pred : block->linear_preds) {
res =
std::max(res, handle_raw_hazard_internal<Valu, Vintrp, Salu>(
state, &state.program->blocks[lin_pred], nops_needed, reg, mask, true));
}
return res;
}
template <bool Valu, bool Vintrp, bool Salu>
void
handle_raw_hazard(State& state, int* NOPs, int min_states, Operand op)
{
if (*NOPs >= min_states)
return;
int res = handle_raw_hazard_internal<Valu, Vintrp, Salu>(
state, state.block, min_states, op.physReg(), u_bit_consecutive(0, op.size()), false);
*NOPs = MAX2(*NOPs, res);
}
static auto handle_valu_then_read_hazard = handle_raw_hazard<true, true, false>;
static auto handle_vintrp_then_read_hazard = handle_raw_hazard<false, true, false>;
static auto handle_valu_salu_then_read_hazard = handle_raw_hazard<true, true, true>;
void
set_bitset_range(BITSET_WORD* words, unsigned start, unsigned size)
{
unsigned end = start + size - 1;
unsigned start_mod = start % BITSET_WORDBITS;
if (start_mod + size <= BITSET_WORDBITS) {
BITSET_SET_RANGE_INSIDE_WORD(words, start, end);
} else {
unsigned first_size = BITSET_WORDBITS - start_mod;
set_bitset_range(words, start, BITSET_WORDBITS - start_mod);
set_bitset_range(words, start + first_size, size - first_size);
}
}
bool
test_bitset_range(BITSET_WORD* words, unsigned start, unsigned size)
{
unsigned end = start + size - 1;
unsigned start_mod = start % BITSET_WORDBITS;
if (start_mod + size <= BITSET_WORDBITS) {
return BITSET_TEST_RANGE(words, start, end);
} else {
unsigned first_size = BITSET_WORDBITS - start_mod;
return test_bitset_range(words, start, BITSET_WORDBITS - start_mod) ||
test_bitset_range(words, start + first_size, size - first_size);
}
}
/* A SMEM clause is any group of consecutive SMEM instructions. The
* instructions in this group may return out of order and/or may be replayed.
*
* To fix this potential hazard correctly, we have to make sure that when a
* clause has more than one instruction, no instruction in the clause writes
* to a register that is read by another instruction in the clause (including
* itself). In this case, we have to break the SMEM clause by inserting non
* SMEM instructions.
*
* SMEM clauses are only present on GFX8+, and only matter when XNACK is set.
*/
void
handle_smem_clause_hazards(Program* program, NOP_ctx_gfx6& ctx, aco_ptr<Instruction>& instr,
int* NOPs)
{
/* break off from previous SMEM clause if needed */
if (!*NOPs & (ctx.smem_clause || ctx.smem_write)) {
/* Don't allow clauses with store instructions since the clause's
* instructions may use the same address. */
if (ctx.smem_write || instr->definitions.empty() ||
instr_info.is_atomic[(unsigned)instr->opcode]) {
*NOPs = 1;
} else if (program->dev.xnack_enabled) {
for (Operand op : instr->operands) {
if (!op.isConstant() &&
test_bitset_range(ctx.smem_clause_write, op.physReg(), op.size())) {
*NOPs = 1;
break;
}
}
Definition def = instr->definitions[0];
if (!*NOPs && test_bitset_range(ctx.smem_clause_read_write, def.physReg(), def.size()))
*NOPs = 1;
}
}
}
/* TODO: we don't handle accessing VCC using the actual SGPR instead of using the alias */
void
handle_instruction_gfx6(State& state, NOP_ctx_gfx6& ctx, aco_ptr<Instruction>& instr,
std::vector<aco_ptr<Instruction>>& new_instructions)
{
/* check hazards */
int NOPs = 0;
if (instr->isSMEM()) {
if (state.program->gfx_level == GFX6) {
/* A read of an SGPR by SMRD instruction requires 4 wait states
* when the SGPR was written by a VALU instruction. According to LLVM,
* there is also an undocumented hardware behavior when the buffer
* descriptor is written by a SALU instruction */
for (unsigned i = 0; i < instr->operands.size(); i++) {
Operand op = instr->operands[i];
if (op.isConstant())
continue;
bool is_buffer_desc = i == 0 && op.size() > 2;
if (is_buffer_desc)
handle_valu_salu_then_read_hazard(state, &NOPs, 4, op);
else
handle_valu_then_read_hazard(state, &NOPs, 4, op);
}
}
handle_smem_clause_hazards(state.program, ctx, instr, &NOPs);
} else if (instr->isSALU()) {
if (instr->opcode == aco_opcode::s_setreg_b32 ||
instr->opcode == aco_opcode::s_setreg_imm32_b32 ||
instr->opcode == aco_opcode::s_getreg_b32) {
NOPs = MAX2(NOPs, ctx.setreg_then_getsetreg);
}
if (state.program->gfx_level == GFX9) {
if (instr->opcode == aco_opcode::s_movrels_b32 ||
instr->opcode == aco_opcode::s_movrels_b64 ||
instr->opcode == aco_opcode::s_movreld_b32 ||
instr->opcode == aco_opcode::s_movreld_b64) {
NOPs = MAX2(NOPs, ctx.salu_wr_m0_then_moverel);
}
}
if (instr->opcode == aco_opcode::s_sendmsg || instr->opcode == aco_opcode::s_ttracedata)
NOPs = MAX2(NOPs, ctx.salu_wr_m0_then_gds_msg_ttrace);
} else if (instr->isDS() && instr->ds().gds) {
NOPs = MAX2(NOPs, ctx.salu_wr_m0_then_gds_msg_ttrace);
} else if (instr->isVALU() || instr->isVINTRP()) {
for (Operand op : instr->operands) {
if (op.physReg() == vccz)
NOPs = MAX2(NOPs, ctx.valu_wr_vcc_then_vccz);
if (op.physReg() == execz)
NOPs = MAX2(NOPs, ctx.valu_wr_exec_then_execz);
}
if (instr->isDPP()) {
NOPs = MAX2(NOPs, ctx.valu_wr_exec_then_dpp);
handle_valu_then_read_hazard(state, &NOPs, 2, instr->operands[0]);
}
for (Definition def : instr->definitions) {
if (def.regClass().type() != RegType::sgpr) {
for (unsigned i = 0; i < def.size(); i++)
NOPs = MAX2(NOPs, ctx.vmem_store_then_wr_data[(def.physReg() & 0xff) + i]);
}
}
if ((instr->opcode == aco_opcode::v_readlane_b32 ||
instr->opcode == aco_opcode::v_readlane_b32_e64 ||
instr->opcode == aco_opcode::v_writelane_b32 ||
instr->opcode == aco_opcode::v_writelane_b32_e64) &&
!instr->operands[1].isConstant()) {
handle_valu_then_read_hazard(state, &NOPs, 4, instr->operands[1]);
}
/* It's required to insert 1 wait state if the dst VGPR of any v_interp_*
* is followed by a read with v_readfirstlane or v_readlane to fix GPU
* hangs on GFX6. Note that v_writelane_* is apparently not affected.
* This hazard isn't documented anywhere but AMD confirmed that hazard.
*/
if (state.program->gfx_level == GFX6 &&
(instr->opcode == aco_opcode::v_readlane_b32 || /* GFX6 doesn't have v_readlane_b32_e64 */
instr->opcode == aco_opcode::v_readfirstlane_b32)) {
handle_vintrp_then_read_hazard(state, &NOPs, 1, instr->operands[0]);
}
if (instr->opcode == aco_opcode::v_div_fmas_f32 ||
instr->opcode == aco_opcode::v_div_fmas_f64)
NOPs = MAX2(NOPs, ctx.valu_wr_vcc_then_div_fmas);
} else if (instr->isVMEM() || instr->isFlatLike()) {
/* If the VALU writes the SGPR that is used by a VMEM, the user must add five wait states. */
for (Operand op : instr->operands) {
if (!op.isConstant() && !op.isUndefined() && op.regClass().type() == RegType::sgpr)
handle_valu_then_read_hazard(state, &NOPs, 5, op);
}
}
if (!instr->isSALU() && instr->format != Format::SMEM)
NOPs = MAX2(NOPs, ctx.set_vskip_mode_then_vector);
if (state.program->gfx_level == GFX9) {
bool lds_scratch_global = (instr->isScratch() || instr->isGlobal()) && instr->flatlike().lds;
if (instr->isVINTRP() || lds_scratch_global ||
instr->opcode == aco_opcode::ds_read_addtid_b32 ||
instr->opcode == aco_opcode::ds_write_addtid_b32 ||
instr->opcode == aco_opcode::buffer_store_lds_dword) {
NOPs = MAX2(NOPs, ctx.salu_wr_m0_then_lds);
}
}
ctx.add_wait_states(NOPs + get_wait_states(instr));
// TODO: try to schedule the NOP-causing instruction up to reduce the number of stall cycles
if (NOPs) {
/* create NOP */
aco_ptr<SOPP_instruction> nop{
create_instruction<SOPP_instruction>(aco_opcode::s_nop, Format::SOPP, 0, 0)};
nop->imm = NOPs - 1;
nop->block = -1;
new_instructions.emplace_back(std::move(nop));
}
/* update information to check for later hazards */
if ((ctx.smem_clause || ctx.smem_write) && (NOPs || instr->format != Format::SMEM)) {
ctx.smem_clause = false;
ctx.smem_write = false;
if (state.program->dev.xnack_enabled) {
BITSET_ZERO(ctx.smem_clause_read_write);
BITSET_ZERO(ctx.smem_clause_write);
}
}
if (instr->isSMEM()) {
if (instr->definitions.empty() || instr_info.is_atomic[(unsigned)instr->opcode]) {
ctx.smem_write = true;
} else {
ctx.smem_clause = true;
if (state.program->dev.xnack_enabled) {
for (Operand op : instr->operands) {
if (!op.isConstant()) {
set_bitset_range(ctx.smem_clause_read_write, op.physReg(), op.size());
}
}
Definition def = instr->definitions[0];
set_bitset_range(ctx.smem_clause_read_write, def.physReg(), def.size());
set_bitset_range(ctx.smem_clause_write, def.physReg(), def.size());
}
}
} else if (instr->isVALU()) {
for (Definition def : instr->definitions) {
if (def.regClass().type() == RegType::sgpr) {
if (def.physReg() == vcc || def.physReg() == vcc_hi) {
ctx.valu_wr_vcc_then_vccz = 5;
ctx.valu_wr_vcc_then_div_fmas = 4;
}
if (def.physReg() == exec || def.physReg() == exec_hi) {
ctx.valu_wr_exec_then_execz = 5;
ctx.valu_wr_exec_then_dpp = 5;
}
}
}
} else if (instr->isSALU() && !instr->definitions.empty()) {
if (!instr->definitions.empty()) {
/* all other definitions should be SCC */
Definition def = instr->definitions[0];
if (def.physReg() == m0) {
ctx.salu_wr_m0_then_gds_msg_ttrace = 1;
ctx.salu_wr_m0_then_lds = 1;
ctx.salu_wr_m0_then_moverel = 1;
}
} else if (instr->opcode == aco_opcode::s_setreg_b32 ||
instr->opcode == aco_opcode::s_setreg_imm32_b32) {
SOPK_instruction& sopk = instr->sopk();
unsigned offset = (sopk.imm >> 6) & 0x1f;
unsigned size = ((sopk.imm >> 11) & 0x1f) + 1;
unsigned reg = sopk.imm & 0x3f;
ctx.setreg_then_getsetreg = 2;
if (reg == 1 && offset >= 28 && size > (28 - offset))
ctx.set_vskip_mode_then_vector = 2;
}
} else if (instr->isVMEM() || instr->isFlatLike()) {
/* >64-bit MUBUF/MTBUF store with a constant in SOFFSET */
bool consider_buf = (instr->isMUBUF() || instr->isMTBUF()) && instr->operands.size() == 4 &&
instr->operands[3].size() > 2 && instr->operands[2].physReg() >= 128;
/* MIMG store with a 128-bit T# with more than two bits set in dmask (making it a >64-bit
* store) */
bool consider_mimg = instr->isMIMG() &&
instr->operands[1].regClass().type() == RegType::vgpr &&
instr->operands[1].size() > 2 && instr->operands[0].size() == 4;
/* FLAT/GLOBAL/SCRATCH store with >64-bit data */
bool consider_flat =
instr->isFlatLike() && instr->operands.size() == 3 && instr->operands[2].size() > 2;
if (consider_buf || consider_mimg || consider_flat) {
PhysReg wrdata = instr->operands[consider_flat ? 2 : 3].physReg();
unsigned size = instr->operands[consider_flat ? 2 : 3].size();
for (unsigned i = 0; i < size; i++)
ctx.vmem_store_then_wr_data[(wrdata & 0xff) + i] = 1;
}
}
}
template <std::size_t N>
bool
check_written_regs(const aco_ptr<Instruction>& instr, const std::bitset<N>& check_regs)
{
return std::any_of(instr->definitions.begin(), instr->definitions.end(),
[&check_regs](const Definition& def) -> bool
{
bool writes_any = false;
for (unsigned i = 0; i < def.size(); i++) {
unsigned def_reg = def.physReg() + i;
writes_any |= def_reg < check_regs.size() && check_regs[def_reg];
}
return writes_any;
});
}
template <std::size_t N>
void
mark_read_regs(const aco_ptr<Instruction>& instr, std::bitset<N>& reg_reads)
{
for (const Operand& op : instr->operands) {
for (unsigned i = 0; i < op.size(); i++) {
unsigned reg = op.physReg() + i;
if (reg < reg_reads.size())
reg_reads.set(reg);
}
}
}
bool
VALU_writes_sgpr(aco_ptr<Instruction>& instr)
{
if (instr->isVOPC())
return true;
if (instr->isVOP3() && instr->definitions.size() == 2)
return true;
if (instr->opcode == aco_opcode::v_readfirstlane_b32 ||
instr->opcode == aco_opcode::v_readlane_b32 ||
instr->opcode == aco_opcode::v_readlane_b32_e64)
return true;
return false;
}
bool
instr_writes_exec(const aco_ptr<Instruction>& instr)
{
return std::any_of(instr->definitions.begin(), instr->definitions.end(),
[](const Definition& def) -> bool
{ return def.physReg() == exec_lo || def.physReg() == exec_hi; });
}
bool
instr_writes_sgpr(const aco_ptr<Instruction>& instr)
{
return std::any_of(instr->definitions.begin(), instr->definitions.end(),
[](const Definition& def) -> bool
{ return def.getTemp().type() == RegType::sgpr; });
}
inline bool
instr_is_branch(const aco_ptr<Instruction>& instr)
{
return instr->opcode == aco_opcode::s_branch || instr->opcode == aco_opcode::s_cbranch_scc0 ||
instr->opcode == aco_opcode::s_cbranch_scc1 ||
instr->opcode == aco_opcode::s_cbranch_vccz ||
instr->opcode == aco_opcode::s_cbranch_vccnz ||
instr->opcode == aco_opcode::s_cbranch_execz ||
instr->opcode == aco_opcode::s_cbranch_execnz ||
instr->opcode == aco_opcode::s_cbranch_cdbgsys ||
instr->opcode == aco_opcode::s_cbranch_cdbguser ||
instr->opcode == aco_opcode::s_cbranch_cdbgsys_or_user ||
instr->opcode == aco_opcode::s_cbranch_cdbgsys_and_user ||
instr->opcode == aco_opcode::s_subvector_loop_begin ||
instr->opcode == aco_opcode::s_subvector_loop_end ||
instr->opcode == aco_opcode::s_setpc_b64 || instr->opcode == aco_opcode::s_swappc_b64 ||
instr->opcode == aco_opcode::s_getpc_b64 || instr->opcode == aco_opcode::s_call_b64;
}
void
handle_instruction_gfx10(State& state, NOP_ctx_gfx10& ctx, aco_ptr<Instruction>& instr,
std::vector<aco_ptr<Instruction>>& new_instructions)
{
// TODO: s_dcache_inv needs to be in it's own group on GFX10
/* VMEMtoScalarWriteHazard
* Handle EXEC/M0/SGPR write following a VMEM instruction without a VALU or "waitcnt vmcnt(0)"
* in-between.
*/
if (instr->isVMEM() || instr->isFlatLike() || instr->isDS()) {
/* Remember all SGPRs that are read by the VMEM instruction */
mark_read_regs(instr, ctx.sgprs_read_by_VMEM);
ctx.sgprs_read_by_VMEM.set(exec);
if (state.program->wave_size == 64)
ctx.sgprs_read_by_VMEM.set(exec_hi);
} else if (instr->isSALU() || instr->isSMEM()) {
if (instr->opcode == aco_opcode::s_waitcnt) {
/* Hazard is mitigated by "s_waitcnt vmcnt(0)" */
uint16_t imm = instr->sopp().imm;
unsigned vmcnt = (imm & 0xF) | ((imm & (0x3 << 14)) >> 10);
if (vmcnt == 0)
ctx.sgprs_read_by_VMEM.reset();
} else if (instr->opcode == aco_opcode::s_waitcnt_depctr) {
/* Hazard is mitigated by a s_waitcnt_depctr with a magic imm */
if (instr->sopp().imm == 0xffe3)
ctx.sgprs_read_by_VMEM.reset();
}
/* Check if SALU writes an SGPR that was previously read by the VALU */
if (check_written_regs(instr, ctx.sgprs_read_by_VMEM)) {
ctx.sgprs_read_by_VMEM.reset();
/* Insert s_waitcnt_depctr instruction with magic imm to mitigate the problem */
aco_ptr<SOPP_instruction> depctr{
create_instruction<SOPP_instruction>(aco_opcode::s_waitcnt_depctr, Format::SOPP, 0, 0)};
depctr->imm = 0xffe3;
depctr->block = -1;
new_instructions.emplace_back(std::move(depctr));
}
} else if (instr->isVALU()) {
/* Hazard is mitigated by any VALU instruction */
ctx.sgprs_read_by_VMEM.reset();
}
/* VcmpxPermlaneHazard
* Handle any permlane following a VOPC instruction, insert v_mov between them.
*/
if (instr->isVOPC()) {
ctx.has_VOPC = true;
} else if (ctx.has_VOPC && (instr->opcode == aco_opcode::v_permlane16_b32 ||
instr->opcode == aco_opcode::v_permlanex16_b32)) {
ctx.has_VOPC = false;
/* v_nop would be discarded by SQ, so use v_mov with the first operand of the permlane */
aco_ptr<VOP1_instruction> v_mov{
create_instruction<VOP1_instruction>(aco_opcode::v_mov_b32, Format::VOP1, 1, 1)};
v_mov->definitions[0] = Definition(instr->operands[0].physReg(), v1);
v_mov->operands[0] = Operand(instr->operands[0].physReg(), v1);
new_instructions.emplace_back(std::move(v_mov));
} else if (instr->isVALU() && instr->opcode != aco_opcode::v_nop) {
ctx.has_VOPC = false;
}
/* VcmpxExecWARHazard
* Handle any VALU instruction writing the exec mask after it was read by a non-VALU instruction.
*/
if (!instr->isVALU() && instr->reads_exec()) {
ctx.has_nonVALU_exec_read = true;
} else if (instr->isVALU()) {
if (instr_writes_exec(instr)) {
ctx.has_nonVALU_exec_read = false;
/* Insert s_waitcnt_depctr instruction with magic imm to mitigate the problem */
aco_ptr<SOPP_instruction> depctr{
create_instruction<SOPP_instruction>(aco_opcode::s_waitcnt_depctr, Format::SOPP, 0, 0)};
depctr->imm = 0xfffe;
depctr->block = -1;
new_instructions.emplace_back(std::move(depctr));
} else if (instr_writes_sgpr(instr)) {
/* Any VALU instruction that writes an SGPR mitigates the problem */
ctx.has_nonVALU_exec_read = false;
}
} else if (instr->opcode == aco_opcode::s_waitcnt_depctr) {
/* s_waitcnt_depctr can mitigate the problem if it has a magic imm */
if ((instr->sopp().imm & 0xfffe) == 0xfffe)
ctx.has_nonVALU_exec_read = false;
}
/* SMEMtoVectorWriteHazard
* Handle any VALU instruction writing an SGPR after an SMEM reads it.
*/
if (instr->isSMEM()) {
/* Remember all SGPRs that are read by the SMEM instruction */
mark_read_regs(instr, ctx.sgprs_read_by_SMEM);
} else if (VALU_writes_sgpr(instr)) {
/* Check if VALU writes an SGPR that was previously read by SMEM */
if (check_written_regs(instr, ctx.sgprs_read_by_SMEM)) {
ctx.sgprs_read_by_SMEM.reset();
/* Insert s_mov to mitigate the problem */
aco_ptr<SOP1_instruction> s_mov{
create_instruction<SOP1_instruction>(aco_opcode::s_mov_b32, Format::SOP1, 1, 1)};
s_mov->definitions[0] = Definition(sgpr_null, s1);
s_mov->operands[0] = Operand::zero();
new_instructions.emplace_back(std::move(s_mov));
}
} else if (instr->isSALU()) {
if (instr->format != Format::SOPP) {
/* SALU can mitigate the hazard */
ctx.sgprs_read_by_SMEM.reset();
} else {
/* Reducing lgkmcnt count to 0 always mitigates the hazard. */
const SOPP_instruction& sopp = instr->sopp();
if (sopp.opcode == aco_opcode::s_waitcnt_lgkmcnt) {
if (sopp.imm == 0 && sopp.definitions[0].physReg() == sgpr_null)
ctx.sgprs_read_by_SMEM.reset();
} else if (sopp.opcode == aco_opcode::s_waitcnt) {
unsigned lgkm = (sopp.imm >> 8) & 0x3f;
if (lgkm == 0)
ctx.sgprs_read_by_SMEM.reset();
}
}
}
/* LdsBranchVmemWARHazard
* Handle VMEM/GLOBAL/SCRATCH->branch->DS and DS->branch->VMEM/GLOBAL/SCRATCH patterns.
*/
if (instr->isVMEM() || instr->isGlobal() || instr->isScratch()) {
ctx.has_VMEM = true;
ctx.has_branch_after_VMEM = false;
/* Mitigation for DS is needed only if there was already a branch after */
ctx.has_DS = ctx.has_branch_after_DS;
} else if (instr->isDS()) {
ctx.has_DS = true;
ctx.has_branch_after_DS = false;
/* Mitigation for VMEM is needed only if there was already a branch after */
ctx.has_VMEM = ctx.has_branch_after_VMEM;
} else if (instr_is_branch(instr)) {
ctx.has_branch_after_VMEM = ctx.has_VMEM;
ctx.has_branch_after_DS = ctx.has_DS;
} else if (instr->opcode == aco_opcode::s_waitcnt_vscnt) {
/* Only s_waitcnt_vscnt can mitigate the hazard */
const SOPK_instruction& sopk = instr->sopk();
if (sopk.definitions[0].physReg() == sgpr_null && sopk.imm == 0)
ctx.has_VMEM = ctx.has_branch_after_VMEM = ctx.has_DS = ctx.has_branch_after_DS = false;
}
if ((ctx.has_VMEM && ctx.has_branch_after_DS) || (ctx.has_DS && ctx.has_branch_after_VMEM)) {
ctx.has_VMEM = ctx.has_branch_after_VMEM = ctx.has_DS = ctx.has_branch_after_DS = false;
/* Insert s_waitcnt_vscnt to mitigate the problem */
aco_ptr<SOPK_instruction> wait{
create_instruction<SOPK_instruction>(aco_opcode::s_waitcnt_vscnt, Format::SOPK, 0, 1)};
wait->definitions[0] = Definition(sgpr_null, s1);
wait->imm = 0;
new_instructions.emplace_back(std::move(wait));
}
/* NSAToVMEMBug
* Handles NSA MIMG (4 or more dwords) immediately followed by MUBUF/MTBUF (with offset[2:1] !=
* 0).
*/
if (instr->isMIMG() && get_mimg_nsa_dwords(instr.get()) > 1) {
ctx.has_NSA_MIMG = true;
} else if (ctx.has_NSA_MIMG) {
ctx.has_NSA_MIMG = false;
if (instr->isMUBUF() || instr->isMTBUF()) {
uint32_t offset = instr->isMUBUF() ? instr->mubuf().offset : instr->mtbuf().offset;
if (offset & 6)
Builder(state.program, &new_instructions).sopp(aco_opcode::s_nop, -1, 0);
}
}
/* waNsaCannotFollowWritelane
* Handles NSA MIMG immediately following a v_writelane_b32.
*/
if (instr->opcode == aco_opcode::v_writelane_b32_e64) {
ctx.has_writelane = true;
} else if (ctx.has_writelane) {
ctx.has_writelane = false;
if (instr->isMIMG() && get_mimg_nsa_dwords(instr.get()) > 0)
Builder(state.program, &new_instructions).sopp(aco_opcode::s_nop, -1, 0);
}
}
template <typename Ctx>
using HandleInstr = void (*)(State& state, Ctx&, aco_ptr<Instruction>&,
std::vector<aco_ptr<Instruction>>&);
template <typename Ctx, HandleInstr<Ctx> Handle>
void
handle_block(Program* program, Ctx& ctx, Block& block)
{
if (block.instructions.empty())
return;
State state;
state.program = program;
state.block = &block;
state.old_instructions = std::move(block.instructions);
block.instructions.clear(); // Silence clang-analyzer-cplusplus.Move warning
block.instructions.reserve(state.old_instructions.size());
for (aco_ptr<Instruction>& instr : state.old_instructions) {
Handle(state, ctx, instr, block.instructions);
block.instructions.emplace_back(std::move(instr));
}
}
template <typename Ctx, HandleInstr<Ctx> Handle>
void
mitigate_hazards(Program* program)
{
std::vector<Ctx> all_ctx(program->blocks.size());
std::stack<unsigned, std::vector<unsigned>> loop_header_indices;
for (unsigned i = 0; i < program->blocks.size(); i++) {
Block& block = program->blocks[i];
Ctx& ctx = all_ctx[i];
if (block.kind & block_kind_loop_header) {
loop_header_indices.push(i);
} else if (block.kind & block_kind_loop_exit) {
/* Go through the whole loop again */
for (unsigned idx = loop_header_indices.top(); idx < i; idx++) {
Ctx loop_block_ctx;
for (unsigned b : program->blocks[idx].linear_preds)
loop_block_ctx.join(all_ctx[b]);
handle_block<Ctx, Handle>(program, loop_block_ctx, program->blocks[idx]);
/* We only need to continue if the loop header context changed */
if (idx == loop_header_indices.top() && loop_block_ctx == all_ctx[idx])
break;
all_ctx[idx] = loop_block_ctx;
}
loop_header_indices.pop();
}
for (unsigned b : block.linear_preds)
ctx.join(all_ctx[b]);
handle_block<Ctx, Handle>(program, ctx, block);
}
}
} /* end namespace */
void
insert_NOPs(Program* program)
{
if (program->gfx_level >= GFX10_3)
; /* no hazards/bugs to mitigate */
else if (program->gfx_level >= GFX10)
mitigate_hazards<NOP_ctx_gfx10, handle_instruction_gfx10>(program);
else
mitigate_hazards<NOP_ctx_gfx6, handle_instruction_gfx6>(program);
}
} // namespace aco