Skip to content

Commit

Permalink
PPU LLVM: Reduce size of JIT-transition treampolines to 16
Browse files Browse the repository at this point in the history
  • Loading branch information
@elad335
elad335 committed Jan 23, 2025
1 parent dc6bae4 commit 6209c1e
Show file tree
Hide file tree
Showing 3 changed files with 153 additions and 4 deletions.
4 changes: 4 additions & 0 deletions Utilities/JIT.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,10 @@ struct jit_runtime final : jit_runtime_base
// Allocate memory
static u8* alloc(usz size, usz align, bool exec = true) noexcept;

// Allocate 0 bytes, observe memory location
// Same as alloc(0, 1, exec)
static u8* peek(bool exec = true) noexcept;

// Should be called at least once after global initialization
static void initialize();

Expand Down
18 changes: 18 additions & 0 deletions Utilities/JITASM.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,12 @@ static u8* add_jit_memory(usz size, usz align)
return pointer;
}

if (!size && align == 1)
{
// Return memory top address
return pointer + (Ctr.load() & 0xffff'ffff);
}

u64 olda, newa;

// Simple allocation by incrementing pointer to the next free data
Expand Down Expand Up @@ -273,6 +279,18 @@ u8* jit_runtime::alloc(usz size, usz align, bool exec) noexcept
}
}

u8* jit_runtime::peek(bool exec) noexcept
{
if (exec)
{
return add_jit_memory<s_code_pos, 0x0, utils::protection::wx>(0, 1);
}
else
{
return add_jit_memory<s_data_pos, 0x40000000, utils::protection::rw>(0, 1);
}
}

void jit_runtime::initialize()
{
if (!s_code_init.empty() || !s_data_init.empty())
Expand Down
135 changes: 131 additions & 4 deletions rpcs3/Emu/Cell/PPUThread.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4762,9 +4762,10 @@ bool ppu_initialize(const ppu_module<lv2_obj>& info, bool check_only, u64 file_s

const auto shared_runtime = make_shared<jit_runtime>();
const auto shared_map = make_shared<std::unordered_map<u32, u64>>();
const auto full_sample = make_shared<u64>(0);
const auto shared_mtx = make_shared<shared_mutex>();

auto symbols_cement = [runtime = shared_runtime, reloc, bound = info.segs[0].addr + info.segs[0].size - reloc, func_map = shared_map, shared_mtx](const std::string& name) -> u64
auto symbols_cement = [runtime = shared_runtime, reloc, seg0 = info.segs[0].addr, bound = info.segs[0].addr + info.segs[0].size - reloc, func_map = shared_map, shared_mtx, full_sample](const std::string& name) -> u64
{
u32 func_addr = umax;

Expand Down Expand Up @@ -4800,16 +4801,130 @@ bool ppu_initialize(const ppu_module<lv2_obj>& info, bool check_only, u64 file_s
return +code_ptr;
}

constexpr auto abs_diff = [](u64 a, u64 b) { return a <= b ? b - a : a - b; };

auto write_le = [](u8*& code, auto value)
{
write_to_ptr<le_t<std::remove_cvref_t<decltype(value)>>>(code, value);
code += sizeof(value);
};

#if defined(ARCH_X64)
// Try to make the code fit in 16 bytes, may fail and fallback
if (*full_sample && (*full_sample <= s32{smax} || abs_diff(*full_sample, reinterpret_cast<u64>(jit_runtime::peek(true))) <= s32{smax}))
{
u8* code = jit_runtime::alloc(16, 8, true);
code_ptr = reinterpret_cast<u64>(code);

// mov edx, func_addr
*code++ = 0xba;
write_le(code, func_addr - seg0);

const u64 diff_for_jump = abs_diff(reinterpret_cast<u64>(code + 5), *full_sample);

if (diff_for_jump <= s32{smax})
{
// jmp (rel32) full_sample
*code++ = 0xe9;

write_le(code, static_cast<s32>(*full_sample - reinterpret_cast<u64>(code + 4)));
return code_ptr;
}
else if (*full_sample <= s32{smax})
{
// mov eax, full_sample
*code++ = 0xb8;

write_le(code, static_cast<s32>(*full_sample));

// jmp rax
*code++ = 0xff;
*code++ = 0xea;
return code_ptr;
}
else // fallback (requiring more than 16 bytes)
{
// movabs rax, full_sample
// *code++ = 0x48;
// *code++ = 0xb8;

// write_le(code, *full_sample);

// // jmp rax
// *code++ = 0xff;
// *code++ = 0xea;
// return code_ptr;
ppu_log.error("JIT symbol trampoline failed.");
}
}
#else
// Try to make the code fit in 16 bytes, may fail and fallback
if (*full_sample && abs_diff(*full_sample, reinterpret_cast<u64>(jit_runtime::peek(true) + 3 * 4)) < (128u << 20))
{
#ifdef __APPLE__
pthread_jit_write_protect_np(false);
#endif
u8* code = jit_runtime::alloc(12, 4, true);
code_ptr = reinterpret_cast<u64>(code);

union arm_op
{
u32 op;
bf_t<u32, 0, 26> b_target;
bf_t<u32, 5, 16> mov_imm16;
};

const u64 diff_for_jump = abs_diff(reinterpret_cast<u64>(code + 3 * 4), *full_sample);

if (diff_for_jump < (128u << 20))
{
// MOVZ w15, func_addr
arm_op mov_pcl{0x5280000F};
mov_pcl.mov_imm16 = func_addr & 0xffff;

write_le(code, mov_pcl.op);

// MOVK w15, func_addr >> 16, LSL #16
arm_op mov_pch{0x72A0000F};
mov_pch.mov_imm16 = func_addr >> 16;

write_le(code, mov_pch.op);

const s64 branch_offset = (*full_sample - reinterpret_cast<u64>(code + 4));

// B full_sample
arm_op b_sample{0x14000000};
b_sample.b_target = static_cast<s32>(branch_offset / 4);

write_le(code, b_sample.op);
return code_ptr;
}
else // fallback
{
ppu_log.error("JIT symbol trampoline failed.");
}
}
#endif

using namespace asmjit;

usz code_size_until_jump = umax;

auto func = build_function_asm<u8*(*)(ppu_thread&, u64, u8*, u64, u64, u64)>(name, [&](native_asm& c, auto& args)
{
#if defined(ARCH_X64)
c.mov(x86::edx, func_addr - seg0); // Load PC

const auto buf_start = reinterpret_cast<const u8*>(c.bufferData());
const auto buf_end = reinterpret_cast<const u8*>(c.bufferPtr());

code_size_until_jump = buf_end - buf_start;

c.add(x86::edx, seg0);
c.mov(x86::rax, x86::qword_ptr(reinterpret_cast<u64>(&vm::g_exec_addr)));
c.mov(x86::edx, func_addr); // Load PC
c.mov(x86::dword_ptr(x86::rbp, ::offset32(&ppu_thread::cia)), x86::edx);

c.mov(x86::rax, x86::qword_ptr(x86::rax, x86::edx, 1, 0)); // Load call target
c.mov(x86::rax, x86::qword_ptr(x86::rax, x86::rdx, 1, 0)); // Load call target
c.mov(x86::rdx, x86::rax);
c.shl(x86::rax, 16);
c.shr(x86::rax, 16);
Expand All @@ -4829,11 +4944,18 @@ bool ppu_initialize(const ppu_module<lv2_obj>& info, bool check_only, u64 file_s
const arm::GpX pc = a64::x15;
const arm::GpX cia_addr_reg = a64::x11;

// Load CIA
c.mov(pc.w(), func_addr);

const auto buf_start = reinterpret_cast<const u8*>(c.bufferData());
const auto buf_end = reinterpret_cast<const u8*>(c.bufferPtr());

code_size_until_jump = buf_end - buf_start;

// Load offset value
c.mov(cia_addr_reg, static_cast<u64>(::offset32(&ppu_thread::cia)));

// Update CIA
c.mov(pc.w(), func_addr);
c.str(pc.w(), arm::Mem(ppu_t_base, cia_addr_reg));

// Multiply by 2 to index into ptr table
Expand All @@ -4858,6 +4980,11 @@ bool ppu_initialize(const ppu_module<lv2_obj>& info, bool check_only, u64 file_s
#endif
}, runtime.get(), true);

// Full sample may exist already, but is very far away
// So in this case, a new sample is written
ensure(code_size_until_jump != umax);
*full_sample = reinterpret_cast<u64>(func) + code_size_until_jump;

code_ptr = reinterpret_cast<u64>(func);
return code_ptr;
};
Expand Down

0 comments on commit 6209c1e

Please sign in to comment.