From d28b0ba2faf72ebc41a53059de17f3285b374e53 Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Tue, 7 Sep 2021 19:42:05 +0300
Subject: [PATCH] SPU LLVM: implement spu_re, spu_rsqrte

Improve matching with peek_through_bitcasts() helper.
Implement erase_stores() helper.
---
 rpcs3/Emu/CPU/CPUTranslator.cpp  | 35 +++++++++++++++++++++
 rpcs3/Emu/CPU/CPUTranslator.h    | 15 ++++++++-
 rpcs3/Emu/Cell/SPURecompiler.cpp | 53 ++++++++++++++++++++++++++++----
 3 files changed, 96 insertions(+), 7 deletions(-)

diff --git a/rpcs3/Emu/CPU/CPUTranslator.cpp b/rpcs3/Emu/CPU/CPUTranslator.cpp
index 4262a87b94..52f67e7569 100644
--- a/rpcs3/Emu/CPU/CPUTranslator.cpp
+++ b/rpcs3/Emu/CPU/CPUTranslator.cpp
@@ -7,6 +7,18 @@
 
 llvm::LLVMContext g_llvm_ctx;
 
+llvm::Value* peek_through_bitcasts(llvm::Value* arg)
+{
+	llvm::CastInst* i;
+
+	while ((i = llvm::dyn_cast_or_null<llvm::CastInst>(arg)) && i->getOpcode() == llvm::Instruction::BitCast)
+	{
+		arg = i->getOperand(0);
+	}
+
+	return arg;
+}
+
 cpu_translator::cpu_translator(llvm::Module* _module, bool is_be)
     : m_context(g_llvm_ctx)
 	, m_module(_module)
@@ -312,4 +324,27 @@ void cpu_translator::replace_intrinsics(llvm::Function& f)
 	}
 }
 
+void cpu_translator::erase_stores(llvm::ArrayRef<llvm::Value*> args)
+{
+	for (auto v : args)
+	{
+		for (auto it = v->use_begin(); it != v->use_end(); ++it)
+		{
+			llvm::Value* i = *it;
+			llvm::CastInst* bci = nullptr;
+
+			// Walk through bitcasts
+			while (i && (bci = llvm::dyn_cast<llvm::CastInst>(i)) && bci->getOpcode() == llvm::Instruction::BitCast)
+			{
+				i = *bci->use_begin();
+			}
+
+			if (auto si = llvm::dyn_cast_or_null<llvm::StoreInst>(i))
+			{
+				si->eraseFromParent();
+			}
+		}
+	}
+}
+
 #endif
diff --git a/rpcs3/Emu/CPU/CPUTranslator.h b/rpcs3/Emu/CPU/CPUTranslator.h
index ee644ce0c4..52d3f690d0 100644
--- a/rpcs3/Emu/CPU/CPUTranslator.h
+++ b/rpcs3/Emu/CPU/CPUTranslator.h
@@ -427,6 +427,9 @@ using llvm_common_t = std::enable_if_t<(is_llvm_expr_of<T, Types>::ok && ...), t
 template <typename... Args>
 using llvm_match_tuple = decltype(std::tuple_cat(std::declval<llvm_expr_t<Args>&>().match(std::declval<llvm::Value*&>(), nullptr)...));
 
+// Helper function
+llvm::Value* peek_through_bitcasts(llvm::Value*);
+
 template <typename T, typename U = llvm_common_t<llvm_value_t<T>>>
 struct llvm_match_t
 {
@@ -442,7 +445,8 @@ struct llvm_match_t
 	template <typename... Args>
 	bool eq(const Args&... args) const
 	{
-		return value && ((value == args.value) && ...);
+		llvm::Value* lhs = nullptr;
+		return value && (lhs = peek_through_bitcasts(value)) && ((lhs == peek_through_bitcasts(args.value)) && ...);
 	}
 
 	llvm::Value* eval(llvm::IRBuilder<>*) const
@@ -3491,6 +3495,15 @@ public:
 	// Finalize processing custom intrinsics
 	void replace_intrinsics(llvm::Function&);
 
+	// Erase store instructions of provided
+	void erase_stores(llvm::ArrayRef<llvm::Value*> args);
+
+	template <typename... Args>
+	void erase_stores(Args... args)
+	{
+		erase_stores({args.value...});
+	}
+
 	template <typename T, typename U>
 	static auto pshufb(T&& a, U&& b)
 	{
diff --git a/rpcs3/Emu/Cell/SPURecompiler.cpp b/rpcs3/Emu/Cell/SPURecompiler.cpp
index 79410b3fa4..b3236a3031 100644
--- a/rpcs3/Emu/Cell/SPURecompiler.cpp
+++ b/rpcs3/Emu/Cell/SPURecompiler.cpp
@@ -7778,12 +7778,9 @@ public:
 
 	bool is_input_positive(value_t<f32[4]> a)
 	{
-		if (auto [ok, v0, v1] = match_expr(a, match<f32[4]>() * match<f32[4]>()); ok)
+		if (auto [ok, v0, v1] = match_expr(a, match<f32[4]>() * match<f32[4]>()); ok && v0.eq(v1))
 		{
-			if (v0.value == v1.value)
-			{
-				return true;
-			}
+			return true;
 		}
 
 		return false;
@@ -8496,6 +8493,18 @@ public:
 		return {"spu_fi", {std::forward<T>(a), std::forward<U>(b)}};
 	}
 
+	template <typename T>
+	static llvm_calli<f32[4], T> spu_re(T&& a)
+	{
+		return {"spu_re", {std::forward<T>(a)}};
+	}
+
+	template <typename T>
+	static llvm_calli<f32[4], T> spu_rsqrte(T&& a)
+	{
+		return {"spu_rsqrte", {std::forward<T>(a)}};
+	}
+
 	void FI(spu_opcode_t op)
 	{
 		// TODO
@@ -8527,7 +8536,39 @@ public:
 			return bitcast<f32[4]>((b & 0xff800000u) | (bitcast<u32[4]>(fpcast<f32[4]>(bnew)) & ~0xff800000u)); // Inject old sign and exponent
 		});
 
-		set_vr(op.rt, fi(get_vr<f32[4]>(op.ra), get_vr<f32[4]>(op.rb)));
+		register_intrinsic("spu_re", [&](llvm::CallInst* ci)
+		{
+			const auto a = value<f32[4]>(ci->getOperand(0));
+			return fre(a);
+		});
+
+		register_intrinsic("spu_rsqrte", [&](llvm::CallInst* ci)
+		{
+			const auto a = value<f32[4]>(ci->getOperand(0));
+			return frsqe(fabs(a));
+		});
+
+		const auto [a, b] = get_vrs<f32[4]>(op.ra, op.rb);
+
+		if (const auto [ok, mb] = match_expr(b, frest(match<f32[4]>())); ok && mb.eq(a))
+		{
+			erase_stores(b);
+			set_vr(op.rt, spu_re(a));
+			return;
+		}
+
+		if (const auto [ok, mb] = match_expr(b, frsqest(match<f32[4]>())); ok && mb.eq(a))
+		{
+			erase_stores(b);
+			set_vr(op.rt, spu_rsqrte(a));
+			return;
+		}
+
+		const auto r = eval(fi(a, b));
+		if (!m_interp_magn)
+			spu_log.todo("[%s:0x%05x] Unmatched spu_fi found", m_hash, m_pos);
+
+		set_vr(op.rt, r);
 	}
 
 	void CFLTS(spu_opcode_t op)