Jacques Lucke
1686979747
This implements an optimization pass for multi-function procedures. It optimizes memory reuse by moving destruct instructions up. For more details see the in-code comment. In very large fields with many short lived intermediate values, this change can improve performance 3-4x. Furthermore, in such cases, peak memory consumption is reduced significantly (e.g. 100x lower peak memory usage). Differential Revision: https://developer.blender.org/D13548
91 lines
3.6 KiB
C++
91 lines
3.6 KiB
C++
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "FN_multi_function_procedure_optimization.hh"
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namespace blender::fn::procedure_optimization {
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void move_destructs_up(MFProcedure &procedure, MFInstruction &block_end_instr)
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{
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/* A mapping from a variable to its destruct instruction. */
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Map<MFVariable *, MFDestructInstruction *> destruct_instructions;
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MFInstruction *current_instr = &block_end_instr;
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while (true) {
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MFInstructionType instr_type = current_instr->type();
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switch (instr_type) {
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case MFInstructionType::Destruct: {
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MFDestructInstruction &destruct_instr = static_cast<MFDestructInstruction &>(
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*current_instr);
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MFVariable *variable = destruct_instr.variable();
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if (variable == nullptr) {
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continue;
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}
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/* Remember this destruct instruction so that it can be moved up later on when the last use
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* of the variable is found. */
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destruct_instructions.add(variable, &destruct_instr);
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break;
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}
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case MFInstructionType::Call: {
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MFCallInstruction &call_instr = static_cast<MFCallInstruction &>(*current_instr);
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/* For each variable, place the corresponding remembered destruct instruction right after
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* this call instruction. */
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for (MFVariable *variable : call_instr.params()) {
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if (variable == nullptr) {
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continue;
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}
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MFDestructInstruction *destruct_instr = destruct_instructions.pop_default(variable,
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nullptr);
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if (destruct_instr == nullptr) {
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continue;
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}
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/* Unlink destruct instruction from previous position. */
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MFInstruction *after_destruct_instr = destruct_instr->next();
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while (!destruct_instr->prev().is_empty()) {
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/* Do a copy of the cursor here, because `destruct_instr->prev()` changes when
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* #set_next is called below. */
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const MFInstructionCursor cursor = destruct_instr->prev()[0];
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cursor.set_next(procedure, after_destruct_instr);
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}
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/* Insert destruct instruction in new position. */
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MFInstruction *next_instr = call_instr.next();
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call_instr.set_next(destruct_instr);
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destruct_instr->set_next(next_instr);
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}
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break;
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}
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default: {
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break;
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}
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}
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const Span<MFInstructionCursor> prev_cursors = current_instr->prev();
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if (prev_cursors.size() != 1) {
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/* Stop when there is some branching before this instruction. */
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break;
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}
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const MFInstructionCursor &prev_cursor = prev_cursors[0];
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current_instr = prev_cursor.instruction();
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if (current_instr == nullptr) {
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/* Stop when there is no previous instruction. E.g. when this is the first instruction. */
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break;
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}
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}
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}
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} // namespace blender::fn::procedure_optimization
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