1414c7b049
This commit adds a bunch of passes, the most interesting of which is a pass that merges blocks together, and a pass that places blocks that flow into each other next to each other, and a very simply pass that removes duplicate basic blocks. Note that this does not remove the jump at the end of each block in that pass to avoid scope creep in the passes.
102 lines
3.9 KiB
C++
102 lines
3.9 KiB
C++
/*
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* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Bytecode/PassManager.h>
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namespace JS::Bytecode::Passes {
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void GenerateCFG::perform(PassPipelineExecutable& executable)
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{
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started();
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executable.cfg = HashMap<BasicBlock const*, HashTable<BasicBlock const*>> {};
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executable.inverted_cfg = HashMap<BasicBlock const*, HashTable<BasicBlock const*>> {};
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executable.exported_blocks = HashTable<BasicBlock const*> {};
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Vector<InstructionStreamIterator> iterators;
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Vector<BasicBlock const&> entered_blocks;
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HashTable<BasicBlock const*> seen_blocks;
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auto enter_label = [&](auto const& label, auto& entering_block, bool exported = false) {
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auto& entry = executable.cfg->ensure(&entering_block);
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entry.set(&label->block());
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auto& inverse_entry = executable.inverted_cfg->ensure(&label->block());
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inverse_entry.set(&entering_block);
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if (exported)
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executable.exported_blocks->set(&label->block());
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if (!seen_blocks.contains(&label->block())) {
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seen_blocks.set(&label->block());
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entered_blocks.append(label->block());
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iterators.empend(label->block().instruction_stream());
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}
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};
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seen_blocks.set(&executable.executable.basic_blocks.first());
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entered_blocks.append(executable.executable.basic_blocks.first());
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iterators.empend(executable.executable.basic_blocks.first().instruction_stream());
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while (!entered_blocks.is_empty()) {
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if (iterators.last().at_end()) {
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entered_blocks.take_last();
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iterators.take_last();
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continue;
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}
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auto& instruction = *iterators.last();
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++iterators.last();
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if (!instruction.is_terminator())
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continue;
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auto& current_block = entered_blocks.last();
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if (instruction.type() == Instruction::Type::Jump) {
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auto& true_target = static_cast<Op::Jump const&>(instruction).true_target();
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enter_label(true_target, current_block);
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continue;
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}
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if (instruction.type() == Instruction::Type::JumpConditional || instruction.type() == Instruction::Type::JumpNullish) {
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auto& true_target = static_cast<Op::Jump const&>(instruction).true_target();
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enter_label(true_target, current_block);
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auto& false_target = static_cast<Op::Jump const&>(instruction).false_target();
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enter_label(false_target, current_block);
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continue;
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}
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if (instruction.type() == Instruction::Type::Yield) {
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auto& continuation = static_cast<Op::Yield const&>(instruction).continuation();
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if (continuation.has_value())
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enter_label(continuation, current_block, true);
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continue;
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}
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if (instruction.type() == Instruction::Type::EnterUnwindContext) {
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auto& entry_point = static_cast<Op::EnterUnwindContext const&>(instruction).entry_point();
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auto& handler_target = static_cast<Op::EnterUnwindContext const&>(instruction).handler_target();
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auto& finalizer_target = static_cast<Op::EnterUnwindContext const&>(instruction).finalizer_target();
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enter_label(&entry_point, current_block);
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if (handler_target.has_value())
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enter_label(handler_target, current_block);
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if (finalizer_target.has_value())
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enter_label(finalizer_target, current_block);
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continue;
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}
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if (instruction.type() == Instruction::Type::ContinuePendingUnwind) {
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auto& resume_target = static_cast<Op::ContinuePendingUnwind const&>(instruction).resume_target();
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enter_label(&resume_target, current_block);
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continue;
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}
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// Otherwise, pop the current block off, it doesn't jump anywhere.
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iterators.take_last();
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entered_blocks.take_last();
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}
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finished();
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}
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}
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