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LibJS: Generate bytecode in basic blocks instead of one big block

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This limits the size of each block (currently set to 1K), and gets us
closer to a canonical, more easily analysable bytecode format.
As a result of this, "Labels" are now simply entries to basic blocks.
Since there is no more 'conditional' jump (as all jumps are always
taken), JumpIf{True,False} are unified to JumpConditional, and
JumpIfNullish is renamed to JumpNullish.
Also fixes #7914 as a result of reimplementing the loop logic.
This commit is contained in:
Ali Mohammad Pur 2021-06-09 06:49:58 +04:30 • committed by Andreas Kling
parent d7a25cdb82
commit 01e8f0889a
16 changed files with 392 additions and 174 deletions
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45
Userland/Libraries/LibJS/Bytecode/Generator.h
View file

@ -6,43 +6,73 @@
#pragma once
#include <AK/NonnullOwnPtrVector.h>
#include <AK/OwnPtr.h>
#include <AK/SinglyLinkedList.h>
#include <LibJS/Bytecode/BasicBlock.h>
#include <LibJS/Bytecode/Label.h>
#include <LibJS/Bytecode/Register.h>
#include <LibJS/Forward.h>
namespace JS::Bytecode {
struct ExecutionUnit {
NonnullOwnPtrVector<BasicBlock> basic_blocks;
size_t number_of_registers { 0 };
};
class Generator {
public:
static OwnPtr<Block> generate(ASTNode const&);
static ExecutionUnit generate(ASTNode const&);
Register allocate_register();
template<typename OpType, typename... Args>
OpType& emit(Args&&... args)
{
VERIFY(!is_current_block_terminated());
void* slot = next_slot();
grow(sizeof(OpType));
new (slot) OpType(forward<Args>(args)...);
if constexpr (OpType::IsTerminator)
m_current_basic_block->terminate({});
return *static_cast<OpType*>(slot);
}
template<typename OpType, typename... Args>
OpType& emit_with_extra_register_slots(size_t extra_register_slots, Args&&... args)
{
VERIFY(!is_current_block_terminated());
void* slot = next_slot();
grow(sizeof(OpType) + extra_register_slots * sizeof(Register));
new (slot) OpType(forward<Args>(args)...);
if constexpr (OpType::IsTerminator)
m_current_basic_block->terminate({});
return *static_cast<OpType*>(slot);
}
Label make_label() const;
void begin_continuable_scope();
void begin_continuable_scope(Label continue_target);
void end_continuable_scope();
Label nearest_continuable_scope() const;
[[nodiscard]] Label nearest_continuable_scope() const;
void switch_to_basic_block(BasicBlock& block)
{
m_current_basic_block = &block;
}
BasicBlock& make_block(String name = {})
{
if (name.is_empty())
name = String::number(m_next_block++);
m_root_basic_blocks.append(BasicBlock::create(name));
return m_root_basic_blocks.last();
}
bool is_current_block_terminated() const
{
return m_current_basic_block->is_terminated();
}
private:
Generator();
@ -51,8 +81,11 @@ private:
void grow(size_t);
void* next_slot();
OwnPtr<Block> m_block;
BasicBlock* m_current_basic_block { nullptr };
NonnullOwnPtrVector<BasicBlock> m_root_basic_blocks;
u32 m_next_register { 1 };
u32 m_next_block { 1 };
Vector<Label> m_continuable_scopes;
};