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/* SPDX-License-Identifier: GPL-2.0-or-later */
#include "FN_multi_function_procedure_optimization.hh"
namespace blender::fn::procedure_optimization {
void move_destructs_up(MFProcedure &procedure, MFInstruction &block_end_instr)
{
/* A mapping from a variable to its destruct instruction. */
Map<MFVariable *, MFDestructInstruction *> destruct_instructions;
MFInstruction *current_instr = &block_end_instr;
while (true) {
MFInstructionType instr_type = current_instr->type();
switch (instr_type) {
case MFInstructionType::Destruct: {
MFDestructInstruction &destruct_instr = static_cast<MFDestructInstruction &>(
*current_instr);
MFVariable *variable = destruct_instr.variable();
if (variable == nullptr) {
continue;
}
/* Remember this destruct instruction so that it can be moved up later on when the last use
* of the variable is found. */
destruct_instructions.add(variable, &destruct_instr);
break;
}
case MFInstructionType::Call: {
MFCallInstruction &call_instr = static_cast<MFCallInstruction &>(*current_instr);
/* For each variable, place the corresponding remembered destruct instruction right after
* this call instruction. */
for (MFVariable *variable : call_instr.params()) {
if (variable == nullptr) {
continue;
}
MFDestructInstruction *destruct_instr = destruct_instructions.pop_default(variable,
nullptr);
if (destruct_instr == nullptr) {
continue;
}
/* Unlink destruct instruction from previous position. */
MFInstruction *after_destruct_instr = destruct_instr->next();
while (!destruct_instr->prev().is_empty()) {
/* Do a copy of the cursor here, because `destruct_instr->prev()` changes when
* #set_next is called below. */
const MFInstructionCursor cursor = destruct_instr->prev()[0];
cursor.set_next(procedure, after_destruct_instr);
}
/* Insert destruct instruction in new position. */
MFInstruction *next_instr = call_instr.next();
call_instr.set_next(destruct_instr);
destruct_instr->set_next(next_instr);
}
break;
}
default: {
break;
}
}
const Span<MFInstructionCursor> prev_cursors = current_instr->prev();
if (prev_cursors.size() != 1) {
/* Stop when there is some branching before this instruction. */
break;
}
const MFInstructionCursor &prev_cursor = prev_cursors[0];
current_instr = prev_cursor.instruction();
if (current_instr == nullptr) {
/* Stop when there is no previous instruction. E.g. when this is the first instruction. */
break;
}
}
}
} // namespace blender::fn::procedure_optimization
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