mirror of
https://github.com/RGBCube/serenity
synced 2025-05-14 21:14:59 +00:00
12072dbac5
It removes empty `BasicBlock`s with an unconditional jump continuation and then removes unreferenced blocks from the graph.
85 lines
2.3 KiB
C++
85 lines
2.3 KiB
C++
/*
|
|
* Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#include "Compiler/Passes/CFGSimplificationPass.h"
|
|
#include "AST/AST.h"
|
|
#include "Function.h"
|
|
|
|
namespace JSSpecCompiler {
|
|
|
|
void CFGSimplificationPass::process_function()
|
|
{
|
|
auto& graph = *m_function->m_cfg;
|
|
|
|
m_replacement.clear();
|
|
m_replacement.resize(graph.blocks_count());
|
|
m_state.clear();
|
|
m_state.resize(graph.blocks_count());
|
|
|
|
for (auto const& block : graph.blocks) {
|
|
m_replacement[block->m_index] = block;
|
|
if (block->m_expressions.size() == 0)
|
|
if (auto jump = as<ControlFlowJump>(block->m_continuation); jump)
|
|
m_replacement[block->m_index] = jump->m_block;
|
|
}
|
|
|
|
for (size_t i = 0; i < graph.blocks_count(); ++i)
|
|
if (m_state[i] == State::NotUsed)
|
|
VERIFY(compute_replacement_block(i));
|
|
|
|
// Fixing references
|
|
graph.start_block = m_replacement[graph.start_block->m_index];
|
|
for (auto const& block : graph.blocks) {
|
|
for (auto* next_block : block->m_continuation->references())
|
|
*next_block = m_replacement[(*next_block)->m_index];
|
|
}
|
|
|
|
// Removing unused nodes
|
|
m_state.span().fill(State::NotUsed);
|
|
compute_referenced_blocks(graph.start_block);
|
|
|
|
size_t j = 0;
|
|
for (size_t i = 0; i < graph.blocks_count(); ++i) {
|
|
if (m_state[graph.blocks[i]->m_index] == State::Used) {
|
|
graph.blocks[j] = graph.blocks[i];
|
|
graph.blocks[j]->m_index = j;
|
|
++j;
|
|
}
|
|
}
|
|
graph.blocks.shrink(j);
|
|
}
|
|
|
|
bool CFGSimplificationPass::compute_replacement_block(size_t i)
|
|
{
|
|
if (m_state[i] == State::CurrentlyInside)
|
|
return false;
|
|
VERIFY(m_state[i] == State::NotUsed);
|
|
m_state[i] = State::CurrentlyInside;
|
|
|
|
size_t j = m_replacement[i]->m_index;
|
|
|
|
if (i == j)
|
|
return true;
|
|
if (m_state[j] == State::NotUsed)
|
|
if (!compute_replacement_block(j))
|
|
return false;
|
|
m_replacement[i] = m_replacement[j];
|
|
|
|
m_state[i] = State::Used;
|
|
return true;
|
|
}
|
|
|
|
void CFGSimplificationPass::compute_referenced_blocks(BasicBlockRef block)
|
|
{
|
|
if (m_state[block->m_index] == State::Used)
|
|
return;
|
|
m_state[block->m_index] = State::Used;
|
|
|
|
for (auto* next : block->m_continuation->references())
|
|
compute_referenced_blocks(*next);
|
|
}
|
|
|
|
}
|