amd/compiler/aco_insert_NOPs.cpp

/*
 * 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->chip_class == 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->chip_class == 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->chip_class == 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->chip_class == 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->chip_class >= GFX10_3)
      ; /* no hazards/bugs to mitigate */
   else if (program->chip_class >= GFX10)
      mitigate_hazards<NOP_ctx_gfx10, handle_instruction_gfx10>(program);
   else
      mitigate_hazards<NOP_ctx_gfx6, handle_instruction_gfx6>(program);
}

} // namespace aco