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PPU LLVM: Fix optimization of branch string
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@elad335
elad335 committed Sep 6, 2023
1 parent 52495c1 commit cf89048
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Showing 2 changed files with 40 additions and 17 deletions.
53 changes: 38 additions & 15 deletions rpcs3/Emu/Cell/PPUTranslator.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -266,7 +266,7 @@ Function* PPUTranslator::Translate(const ppu_function& info)
if (!m_ir->GetInsertBlock()->getTerminator())
{
FlushRegisters();
CallFunction(m_addr);
CallFunction(m_addr, nullptr, m_ir->GetInsertBlock());
}
}

Expand Down Expand Up @@ -354,7 +354,7 @@ Value* PPUTranslator::RotateLeft(Value* arg, Value* n)
return m_ir->CreateOr(m_ir->CreateShl(arg, m_ir->CreateAnd(n, mask)), m_ir->CreateLShr(arg, m_ir->CreateAnd(m_ir->CreateNeg(n), mask)));
}

void PPUTranslator::CallFunction(u64 target, Value* indirect)
void PPUTranslator::CallFunction(u64 target, Value* indirect, BasicBlock* prev_block)
{
const auto type = m_function->getFunctionType();
const auto block = m_ir->GetInsertBlock();
Expand All @@ -372,21 +372,27 @@ void PPUTranslator::CallFunction(u64 target, Value* indirect)

if (_target >= caddr && _target <= cend)
{
std::unordered_set<u64> passed_targets{_target};
std::unordered_set<u64> passed_targets;

u32 target_last = _target;

// Try to follow unconditional branches as long as there is no infinite loop
while (target_last != _target)
while (target_last != m_addr + base)
{
if (passed_targets.empty())
{
passed_targets.emplace(_target);
passed_targets.emplace(m_addr + base);
}

const ppu_opcode_t op{*ensure(m_info.get_ptr<u32>(target_last))};
const ppu_itype::type itype = g_ppu_itype.decode(op.opcode);

if (((itype == ppu_itype::BC && (op.bo & 0x14) == 0x14) || itype == ppu_itype::B) && !op.lk)
{
const u32 new_target = (op.aa ? 0 : target_last) + (itype == ppu_itype::B ? +op.bt24 : +op.bt14);

if (target_last >= caddr && target_last <= cend)
if (new_target >= caddr && new_target <= cend)
{
if (passed_targets.emplace(new_target).second)
{
Expand All @@ -401,11 +407,21 @@ void PPUTranslator::CallFunction(u64 target, Value* indirect)

// Odd destination
}
else if (itype == ppu_itype::BCLR && (op.bo & 0x14) == 0x14 && !op.lk)
else if (itype == ppu_itype::BCLR && (op.bo & 0x14) == 0x14 && !op.lk && (prev_block || m_lr))
{
// Special case: empty function
// In this case the branch can be treated as BCLR because previous CIA does not matter
indirect = RegLoad(m_lr);
indirect = m_lr;

if (!indirect)
{
// Emit register load in the beginning of the common block
m_ir->SetInsertPoint(prev_block, prev_block->getFirstInsertionPt());
indirect = RegLoad(m_lr);

// Restore current insert point
m_ir->SetInsertPoint(block);
}
}

break;
Expand Down Expand Up @@ -629,7 +645,7 @@ Value* PPUTranslator::Trunc(Value* value, Type* type)
return type != value->getType() ? m_ir->CreateTrunc(value, type) : value;
}

void PPUTranslator::UseCondition(MDNode* hint, Value* cond)
void PPUTranslator::UseCondition(MDNode* hint, Value* cond, BasicBlock* prev_block)
{
FlushRegisters();

Expand All @@ -639,7 +655,7 @@ void PPUTranslator::UseCondition(MDNode* hint, Value* cond)
const auto next = BasicBlock::Create(m_context, "__next", m_function);
m_ir->CreateCondBr(cond, local, next, hint);
m_ir->SetInsertPoint(next);
CallFunction(m_addr + 4);
CallFunction(m_addr + 4, nullptr, prev_block);
m_ir->SetInsertPoint(local);
}
}
Expand Down Expand Up @@ -2024,19 +2040,22 @@ void PPUTranslator::BC(ppu_opcode_t op)
const s32 bt14 = op.bt14; // Workaround for VS 16.5
const u64 target = (op.aa ? 0 : m_addr) + bt14;

const auto block = m_ir->GetInsertBlock();

if (op.aa && m_reloc)
{
CompilationError("Branch with absolute address");
}

if (op.lk)
{
m_ir->CreateStore(GetAddr(+4), m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
m_lr = GetAddr(+4);
m_ir->CreateStore(m_lr, m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
}

UseCondition(CheckBranchProbability(op.bo), CheckBranchCondition(op.bo, op.bi));
UseCondition(CheckBranchProbability(op.bo), CheckBranchCondition(op.bo, op.bi), block);

CallFunction(target);
CallFunction(target, nullptr, block);
}

void PPUTranslator::SC(ppu_opcode_t op)
Expand Down Expand Up @@ -2074,6 +2093,8 @@ void PPUTranslator::B(ppu_opcode_t op)
const s32 bt24 = op.bt24; // Workaround for VS 16.5
const u64 target = (op.aa ? 0 : m_addr) + bt24;

const auto block = m_ir->GetInsertBlock();

if (op.aa && m_reloc)
{
CompilationError("Branch with absolute address");
Expand All @@ -2085,7 +2106,7 @@ void PPUTranslator::B(ppu_opcode_t op)
}

FlushRegisters();
CallFunction(target);
CallFunction(target, nullptr, block);
}

void PPUTranslator::MCRF(ppu_opcode_t op)
Expand All @@ -2103,7 +2124,8 @@ void PPUTranslator::BCLR(ppu_opcode_t op)

if (op.lk)
{
m_ir->CreateStore(GetAddr(+4), m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
m_lr = GetAddr(+4);
m_ir->CreateStore(m_lr, m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
}

UseCondition(CheckBranchProbability(op.bo), CheckBranchCondition(op.bo, op.bi));
Expand Down Expand Up @@ -2166,7 +2188,8 @@ void PPUTranslator::BCCTR(ppu_opcode_t op)

if (op.lk)
{
m_ir->CreateStore(GetAddr(+4), m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
m_lr = GetAddr(+4);
m_ir->CreateStore(m_lr, m_ir->CreateStructGEP(m_thread_type, m_thread, static_cast<uint>(&m_lr - m_locals)));
}

UseCondition(CheckBranchProbability(op.bo | 0x4), CheckBranchCondition(op.bo | 0x4, op.bi));
Expand Down
4 changes: 2 additions & 2 deletions rpcs3/Emu/Cell/PPUTranslator.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ class PPUTranslator final : public cpu_translator
llvm::Value* RotateLeft(llvm::Value* arg, llvm::Value* n);

// Emit function call
void CallFunction(u64 target, llvm::Value* indirect = nullptr);
void CallFunction(u64 target, llvm::Value* indirect = nullptr, llvm::BasicBlock* prev_block = nullptr);

// Initialize global for writing
llvm::Value* RegInit(llvm::Value*& local);
Expand Down Expand Up @@ -292,7 +292,7 @@ class PPUTranslator final : public cpu_translator
llvm::MDNode* CheckBranchProbability(u32 bo);

// Branch to next instruction if condition failed, never branch on nullptr
void UseCondition(llvm::MDNode* hint, llvm::Value* = nullptr);
void UseCondition(llvm::MDNode* hint, llvm::Value* = nullptr, llvm::BasicBlock* prev_block = nullptr);

// Get memory pointer
llvm::Value* GetMemory(llvm::Value* addr);
Expand Down

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