src/amd/compiler/aco_lower_bool_phis.cpp

   1 /*
   2  * Copyright © 2019 Valve Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Rhys Perry (pendingchaos02@gmail.com)
  25  *
  26  */
  27
  28 #include <map>
  29
  30 #include "aco_ir.h"
  31 #include "aco_builder.h"
  32 #include <algorithm>
  33
  34
  35 namespace aco {
  36
  37 struct phi_use {
  38    Block *block;
  39    unsigned phi_def;
  40
  41    bool operator<(const phi_use& other) const {
  42       return std::make_tuple(block, phi_def) <
  43              std::make_tuple(other.block, other.phi_def);
  44    }
  45 };
  46
  47 struct ssa_state {
  48    std::map<unsigned, unsigned> latest;
  49    std::map<unsigned, std::map<phi_use, uint64_t>> phis;
  50 };
  51
  52 Operand get_ssa(Program *program, unsigned block_idx, ssa_state *state)
  53 {
  54    while (true) {
  55       auto pos = state->latest.find(block_idx);
  56       if (pos != state->latest.end())
  57          return Operand({pos->second, s2});
  58
  59       Block& block = program->blocks[block_idx];
  60       size_t pred = block.linear_preds.size();
  61       if (pred == 0) {
  62          return Operand(s2);
  63       } else if (pred == 1) {
  64          block_idx = block.linear_preds[0];
  65          continue;
  66       } else {
  67          unsigned res = program->allocateId();
  68          state->latest[block_idx] = res;
  69
  70          aco_ptr<Pseudo_instruction> phi{create_instruction<Pseudo_instruction>(aco_opcode::p_linear_phi, Format::PSEUDO, pred, 1)};
  71          for (unsigned i = 0; i < pred; i++) {
  72             phi->operands[i] = get_ssa(program, block.linear_preds[i], state);
  73             if (phi->operands[i].isTemp()) {
  74                assert(i < 64);
  75                state->phis[phi->operands[i].tempId()][(phi_use){&block, res}] |= (uint64_t)1 << i;
  76             }
  77          }
  78          phi->definitions[0] = Definition(Temp{res, s2});
  79          block.instructions.emplace(block.instructions.begin(), std::move(phi));
  80
  81          return Operand({res, s2});
  82       }
  83    }
  84 }
  85
  86 void update_phi(Program *program, ssa_state *state, Block *block, unsigned phi_def, uint64_t operand_mask) {
  87    for (auto& phi : block->instructions) {
  88       if (phi->opcode != aco_opcode::p_phi && phi->opcode != aco_opcode::p_linear_phi)
  89          break;
  90       if (phi->opcode != aco_opcode::p_linear_phi)
  91          continue;
  92       if (phi->definitions[0].tempId() != phi_def)
  93          continue;
  94       assert(ffsll(operand_mask) <= phi->operands.size());
  95
  96       uint64_t operands = operand_mask;
  97       while (operands) {
  98          unsigned operand = u_bit_scan64(&operands);
  99          Operand new_operand = get_ssa(program, block->linear_preds[operand], state);
 100          phi->operands[operand] = new_operand;
 101          if (!new_operand.isUndefined())
 102             state->phis[new_operand.tempId()][(phi_use){block, phi_def}] |= (uint64_t)1 << operand;
 103       }
 104       return;
 105    }
 106    assert(false);
 107 }
 108
 109 Temp write_ssa(Program *program, Block *block, ssa_state *state, unsigned previous) {
 110    unsigned id = program->allocateId();
 111    state->latest[block->index] = id;
 112
 113    /* update phis */
 114    if (previous) {
 115       std::map<phi_use, uint64_t> phis;
 116       phis.swap(state->phis[previous]);
 117       for (auto& phi : phis)
 118          update_phi(program, state, phi.first.block, phi.first.phi_def, phi.second);
 119    }
 120
 121    return {id, s2};
 122 }
 123
 124 void insert_before_logical_end(Block *block, aco_ptr<Instruction> instr)
 125 {
 126    auto IsLogicalEnd = [] (const aco_ptr<Instruction>& instr) -> bool {
 127       return instr->opcode == aco_opcode::p_logical_end;
 128    };
 129    auto it = std::find_if(block->instructions.crbegin(), block->instructions.crend(), IsLogicalEnd);
 130
 131    if (it == block->instructions.crend()) {
 132       assert(block->instructions.back()->format == Format::PSEUDO_BRANCH);
 133       block->instructions.insert(std::prev(block->instructions.end()), std::move(instr));
 134    }
 135    else
 136       block->instructions.insert(std::prev(it.base()), std::move(instr));
 137 }
 138
 139 void lower_divergent_bool_phi(Program *program, Block *block, aco_ptr<Instruction>& phi)
 140 {
 141    Builder bld(program);
 142
 143    ssa_state state;
 144    state.latest[block->index] = phi->definitions[0].tempId();
 145    for (unsigned i = 0; i < phi->operands.size(); i++) {
 146       Block *pred = &program->blocks[block->logical_preds[i]];
 147
 148       if (phi->operands[i].isUndefined())
 149          continue;
 150
 151       assert(phi->operands[i].isTemp());
 152       Temp phi_src = phi->operands[i].getTemp();
 153       if (phi_src.regClass() == s1) {
 154          Temp new_phi_src = bld.tmp(s2);
 155          insert_before_logical_end(pred,
 156             bld.sop2(aco_opcode::s_cselect_b64, Definition(new_phi_src),
 157                      Operand((uint32_t)-1), Operand(0u), bld.scc(phi_src)).get_ptr());
 158          phi_src = new_phi_src;
 159       }
 160       assert(phi_src.regClass() == s2);
 161
 162       Operand cur = get_ssa(program, pred->index, &state);
 163       Temp new_cur = write_ssa(program, pred, &state, cur.isTemp() ? cur.tempId() : 0);
 164
 165       if (cur.isUndefined()) {
 166          insert_before_logical_end(pred, bld.sop1(aco_opcode::s_mov_b64, Definition(new_cur), phi_src).get_ptr());
 167       } else {
 168          Temp tmp1 = bld.tmp(s2), tmp2 = bld.tmp(s2);
 169          insert_before_logical_end(pred,
 170             bld.sop2(aco_opcode::s_andn2_b64, Definition(tmp1), bld.def(s1, scc),
 171                      cur, Operand(exec, s2)).get_ptr());
 172          insert_before_logical_end(pred,
 173             bld.sop2(aco_opcode::s_and_b64, Definition(tmp2), bld.def(s1, scc),
 174                      phi_src, Operand(exec, s2)).get_ptr());
 175          insert_before_logical_end(pred,
 176             bld.sop2(aco_opcode::s_or_b64, Definition(new_cur), bld.def(s1, scc),
 177                      tmp1, tmp2).get_ptr());
 178       }
 179    }
 180
 181    unsigned num_preds = block->linear_preds.size();
 182    if (phi->operands.size() != num_preds) {
 183       Pseudo_instruction* new_phi{create_instruction<Pseudo_instruction>(aco_opcode::p_linear_phi, Format::PSEUDO, num_preds, 1)};
 184       new_phi->definitions[0] = phi->definitions[0];
 185       phi.reset(new_phi);
 186    } else {
 187       phi->opcode = aco_opcode::p_linear_phi;
 188    }
 189    assert(phi->operands.size() == num_preds);
 190
 191    for (unsigned i = 0; i < num_preds; i++)
 192       phi->operands[i] = get_ssa(program, block->linear_preds[i], &state);
 193
 194    return;
 195 }
 196
 197 void lower_linear_bool_phi(Program *program, Block *block, aco_ptr<Instruction>& phi)
 198 {
 199    Builder bld(program);
 200
 201    for (unsigned i = 0; i < phi->operands.size(); i++) {
 202       if (!phi->operands[i].isTemp())
 203          continue;
 204
 205       Temp phi_src = phi->operands[i].getTemp();
 206       if (phi_src.regClass() == s2) {
 207          Temp new_phi_src = bld.tmp(s1);
 208          insert_before_logical_end(&program->blocks[block->linear_preds[i]],
 209             bld.sopc(aco_opcode::s_cmp_lg_u64, bld.scc(Definition(new_phi_src)),
 210                      Operand(0u), phi_src).get_ptr());
 211          phi->operands[i].setTemp(new_phi_src);
 212       }
 213    }
 214 }
 215
 216 void lower_bool_phis(Program* program)
 217 {
 218    for (Block& block : program->blocks) {
 219       for (aco_ptr<Instruction>& phi : block.instructions) {
 220          if (phi->opcode == aco_opcode::p_phi) {
 221             if (phi->definitions[0].regClass() == s2)
 222                lower_divergent_bool_phi(program, &block, phi);
 223          } else if (phi->opcode == aco_opcode::p_linear_phi) {
 224             /* if it's a valid non-boolean phi, this should be a no-op */
 225             if (phi->definitions[0].regClass() == s1)
 226                lower_linear_bool_phi(program, &block, phi);
 227          } else {
 228             break;
 229          }
 230       }
 231    }
 232 }
 233
 234 }