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LibJS: Work-in-progress JIT compiler :^)

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This commit is contained in:
Andreas Kling 2023-10-14 14:37:48 +02:00
parent f52e4fa5c2
commit babdc0a25b
11 changed files with 634 additions and 4 deletions
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267
Userland/Libraries/LibJS/JIT/Assembler.h Normal file
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/*
* Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Vector.h>
#include <LibJS/Bytecode/BasicBlock.h>
namespace JS::JIT {
struct Assembler {
Assembler(Vector<u8>& output)
: m_output(output)
{
}
Vector<u8>& m_output;
enum class Reg {
GPR0 = 0, // RAX
GPR1 = 1, // RCX
Arg0 = 7, // RDI
Arg1 = 6, // RSI
Arg2 = 2, // RDX
Ret = 0, // RAX
// FIXME: These are LibJS specific.
RegisterArrayBase = 8, // R8
LocalsArrayBase = 9, // R9
};
struct Operand {
enum class Type {
Reg,
Imm64,
Mem64BaseAndOffset,
};
Type type {};
Reg reg {};
u64 offset_or_immediate { 0 };
static Operand Register(Reg reg)
{
Operand operand;
operand.type = Type::Reg;
operand.reg = reg;
return operand;
}
static Operand Imm64(u64 imm64)
{
Operand operand;
operand.type = Type::Imm64;
operand.offset_or_immediate = imm64;
return operand;
}
static Operand Mem64BaseAndOffset(Reg base, u64 offset)
{
Operand operand;
operand.type = Type::Mem64BaseAndOffset;
operand.reg = base;
operand.offset_or_immediate = offset;
return operand;
}
};
static constexpr u8 encode_reg(Reg reg)
{
return to_underlying(reg) & 0x7;
}
void mov(Operand dst, Operand src)
{
if (dst.type == Operand::Type::Reg && src.type == Operand::Type::Reg) {
if (src.reg == dst.reg)
return;
emit8(0x48
| ((to_underlying(src.reg) >= 8) ? 1 << 2 : 0)
| ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0));
emit8(0x89);
emit8(0xc0 | (encode_reg(src.reg) << 3) | encode_reg(dst.reg));
return;
}
if (dst.type == Operand::Type::Reg && src.type == Operand::Type::Imm64) {
emit8(0x48 | ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0));
emit8(0xb8 | encode_reg(dst.reg));
emit64(src.offset_or_immediate);
return;
}
if (dst.type == Operand::Type::Mem64BaseAndOffset && src.type == Operand::Type::Reg) {
emit8(0x48
| ((to_underlying(src.reg) >= 8) ? 1 << 2 : 0)
| ((to_underlying(dst.reg) >= 8) ? 1 << 0 : 0));
emit8(0x89);
emit8(0x80 | (encode_reg(src.reg) << 3) | encode_reg(dst.reg));
emit32(dst.offset_or_immediate);
return;
}
if (dst.type == Operand::Type::Reg && src.type == Operand::Type::Mem64BaseAndOffset) {
emit8(0x48
| ((to_underlying(dst.reg) >= 8) ? 1 << 2 : 0)
| ((to_underlying(src.reg) >= 8) ? 1 << 0 : 0));
emit8(0x8b);
emit8(0x80 | (encode_reg(dst.reg) << 3) | encode_reg(src.reg));
emit32(src.offset_or_immediate);
return;
}
VERIFY_NOT_REACHED();
}
void emit8(u8 value)
{
m_output.append(value);
}
void emit32(u32 value)
{
m_output.append((value >> 0) & 0xff);
m_output.append((value >> 8) & 0xff);
m_output.append((value >> 16) & 0xff);
m_output.append((value >> 24) & 0xff);
}
void emit64(u64 value)
{
m_output.append((value >> 0) & 0xff);
m_output.append((value >> 8) & 0xff);
m_output.append((value >> 16) & 0xff);
m_output.append((value >> 24) & 0xff);
m_output.append((value >> 32) & 0xff);
m_output.append((value >> 40) & 0xff);
m_output.append((value >> 48) & 0xff);
m_output.append((value >> 56) & 0xff);
}
void load_immediate64(Reg dst, u64 imm)
{
mov(Operand::Register(dst), Operand::Imm64(imm));
}
void increment(Reg dst)
{
emit8(0x48);
emit8(0xff);
emit8(0xc0 | to_underlying(dst));
}
void less_than(Reg dst, Reg src)
{
// cmp src, dst
emit8(0x48);
emit8(0x39);
emit8(0xc0 | (to_underlying(src) << 3) | to_underlying(dst));
// setl dst
emit8(0x0f);
emit8(0x9c);
emit8(0xc0 | to_underlying(dst));
// movzx dst, dst
emit8(0x48);
emit8(0x0f);
emit8(0xb6);
emit8(0xc0 | (to_underlying(dst) << 3) | to_underlying(dst));
}
void jump(Bytecode::BasicBlock& target)
{
// jmp target (RIP-relative 32-bit offset)
emit8(0xe9);
target.jumps_to_here.append(m_output.size());
emit32(0xdeadbeef);
}
void jump_conditional(Reg reg, Bytecode::BasicBlock& true_target, Bytecode::BasicBlock& false_target)
{
// if (reg & 1) is 0, jump to false_target, else jump to true_target
// test reg, 1
emit8(0x48 | ((to_underlying(reg) >= 8) ? 1 << 2 : 0));
emit8(0xf7);
emit8(0xc0 | encode_reg(reg));
emit32(0x01);
// jz false_target (RIP-relative 32-bit offset)
emit8(0x0f);
emit8(0x84);
false_target.jumps_to_here.append(m_output.size());
emit32(0xdeadbeef);
// jmp true_target (RIP-relative 32-bit offset)
jump(true_target);
}
void exit()
{
// ret
emit8(0xc3);
}
void native_call(void* callee)
{
// push caller-saved registers on the stack
// (callee-saved registers: RBX, RSP, RBP, and R12–R15)
// push RCX, RDX, RSI, RDI, R8, R9, R10, R11
emit8(0x51);
emit8(0x52);
emit8(0x56);
emit8(0x57);
emit8(0x41);
emit8(0x50);
emit8(0x41);
emit8(0x51);
emit8(0x41);
emit8(0x52);
emit8(0x41);
emit8(0x53);
// align the stack to 16-byte boundary
emit8(0x48);
emit8(0x83);
emit8(0xec);
emit8(0x08);
// load callee into RAX and make indirect call
emit8(0x48);
emit8(0xb8);
emit64((u64)callee);
emit8(0xff);
emit8(0xd0);
// adjust stack pointer
emit8(0x48);
emit8(0x83);
emit8(0xc4);
emit8(0x08);
// restore caller-saved registers from the stack
// pop R11, R10, R9, R8, RDI, RSI, RDX, RCX
emit8(0x41);
emit8(0x5b);
emit8(0x41);
emit8(0x5a);
emit8(0x41);
emit8(0x59);
emit8(0x41);
emit8(0x58);
emit8(0x5f);
emit8(0x5e);
emit8(0x5a);
emit8(0x59);
}
};
}