From 9a0a5a1735d8f3cbfa95287ead33763effd8383f Mon Sep 17 00:00:00 2001
From: Elad <18193363+elad335@users.noreply.github.com>
Date: Mon, 16 Mar 2026 08:18:53 +0200
Subject: [PATCH] LLVM: Try to reuse BitCasts

---
 rpcs3/Emu/CPU/CPUTranslator.cpp      | 58 +++++++++++++++++++++++++++-
 rpcs3/Emu/Cell/SPULLVMRecompiler.cpp |  2 +-
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/rpcs3/Emu/CPU/CPUTranslator.cpp b/rpcs3/Emu/CPU/CPUTranslator.cpp
index 08e8e9ad30..22413f62b8 100644
--- a/rpcs3/Emu/CPU/CPUTranslator.cpp
+++ b/rpcs3/Emu/CPU/CPUTranslator.cpp
@@ -225,12 +225,66 @@ llvm::Value* cpu_translator::bitcast(llvm::Value* val, llvm::Type* type) const
 		fmt::throw_exception("cpu_translator::bitcast(): incompatible type sizes (%u vs %u)", s1, s2);
 	}
 
-	if (const auto c1 = llvm::dyn_cast<llvm::Constant>(val))
+	if (val->getType() == type)
+	{
+		return val;
+	}
+
+	llvm::CastInst* i;
+	llvm::Value* source_val = val;
+
+	// Try to reuse older bitcasts
+	while ((i = llvm::dyn_cast_or_null<llvm::CastInst>(source_val)) && i->getOpcode() == llvm::Instruction::BitCast)
+	{
+		source_val = i->getOperand(0);
+
+		if (source_val->getType() == type)
+		{
+			return source_val;
+		}
+	}
+
+	for (auto it = source_val->use_begin(); it != source_val->use_end(); ++it)
+	{
+		llvm::Value* it_val = *it;
+
+		if (!it_val)
+		{
+			continue;
+		}
+
+		llvm::CastInst* bci = llvm::dyn_cast_or_null<llvm::CastInst>(it_val);
+
+		// Walk through bitcasts
+		while (bci && bci->getOpcode() == llvm::Instruction::BitCast)
+		{
+			if (bci->getParent() != m_ir->GetInsertBlock())
+			{
+				break;
+			}
+
+			if (bci->getType() == type)
+			{
+				return bci;
+			}
+
+			if (bci->use_begin() == bci->use_end())
+			{
+				break;
+			}
+
+			bci = llvm::dyn_cast_or_null<llvm::CastInst>(*bci->use_begin());
+		}
+	}
+
+	// Do bitcast on the source
+
+	if (const auto c1 = llvm::dyn_cast<llvm::Constant>(source_val))
 	{
 		return ensure(llvm::ConstantFoldCastOperand(llvm::Instruction::BitCast, c1, type, m_module->getDataLayout()));
 	}
 
-	return m_ir->CreateBitCast(val, type);
+	return m_ir->CreateBitCast(source_val, type);
 }
 
 template <>
diff --git a/rpcs3/Emu/Cell/SPULLVMRecompiler.cpp b/rpcs3/Emu/Cell/SPULLVMRecompiler.cpp
index 9c543915bf..7511b2ae7b 100644
--- a/rpcs3/Emu/Cell/SPULLVMRecompiler.cpp
+++ b/rpcs3/Emu/Cell/SPULLVMRecompiler.cpp
@@ -991,7 +991,7 @@ class spu_llvm_recompiler : public spu_recompiler_base, public cpu_translator
 		}
 
 		// Write register to the context
-		_store = m_ir->CreateStore(is_xfloat ? double_to_xfloat(saved_value) : m_ir->CreateBitCast(value, get_reg_type(index)), addr);
+		_store = m_ir->CreateStore(is_xfloat ? double_to_xfloat(saved_value) : bitcast(value, get_reg_type(index)), addr);
 
 		spu_context_attr(_store);
 	}