JitArm64: Far Code Cache

Source/Core/Common/Arm64Emitter.cpp

@@ -271,7 +271,7 @@ bool IsImmLogical(uint64_t value, unsigned int width, unsigned int *n, unsigned
 void ARM64XEmitter::SetCodePtr(u8* ptr)
 {
 	m_code = ptr;
-	m_startcode = m_code;
+	if (!m_lastCacheFlushEnd)
 		m_lastCacheFlushEnd = ptr;
 }
 
@@ -315,6 +315,9 @@ void ARM64XEmitter::FlushIcache()
 
 void ARM64XEmitter::FlushIcacheSection(u8* start, u8* end)
 {
+	if (start == end)
+		return;
+
 #if defined(IOS)
 	// Header file says this is equivalent to: sys_icache_invalidate(start, end - start);
 	sys_cache_control(kCacheFunctionPrepareForExecution, start, end - start);

Source/Core/Common/Arm64Emitter.h

@@ -324,7 +324,6 @@ class ARM64XEmitter
 
 private:
 	u8* m_code;
-	u8* m_startcode;
 	u8* m_lastCacheFlushEnd;
 
 	void EncodeCompareBranchInst(u32 op, ARM64Reg Rt, const void* ptr);
@@ -365,14 +364,13 @@ protected:
 
 public:
 	ARM64XEmitter()
-		: m_code(nullptr), m_startcode(nullptr), m_lastCacheFlushEnd(nullptr)
+		: m_code(nullptr), m_lastCacheFlushEnd(nullptr)
 	{
 	}
 
 	ARM64XEmitter(u8* code_ptr) {
 		m_code = code_ptr;
 		m_lastCacheFlushEnd = code_ptr;
-		m_startcode = code_ptr;
 	}
 
 	virtual ~ARM64XEmitter()

Source/Core/Core/PowerPC/JitArm64/Jit.cpp

@@ -17,6 +17,7 @@ using namespace Arm64Gen;
 void JitArm64::Init()
 {
 	AllocCodeSpace(CODE_SIZE);
+	farcode.Init(SConfig::GetInstance().bMMU ? FARCODE_SIZE_MMU : FARCODE_SIZE);
 	jo.enableBlocklink = true;
 	jo.optimizeGatherPipe = true;
 	UpdateMemoryOptions();
@@ -36,6 +37,7 @@ void JitArm64::Init()
 void JitArm64::ClearCache()
 {
 	ClearCodeSpace();
+	farcode.ClearCodeSpace();
 	blocks.Clear();
 	UpdateMemoryOptions();
 }
@@ -43,6 +45,7 @@ void JitArm64::ClearCache()
 void JitArm64::Shutdown()
 {
 	FreeCodeSpace();
+	farcode.Shutdown();
 	blocks.Shutdown();
 	asm_routines.Shutdown();
 }
@@ -276,7 +279,8 @@ void JitArm64::SingleStep()
 
 void JitArm64::Jit(u32)
 {
-	if (GetSpaceLeft() < 0x10000 || blocks.IsFull() || SConfig::GetInstance().bJITNoBlockCache)
+	if (GetSpaceLeft() < 0x10000 || farcode.GetSpaceLeft() < 0x10000 || blocks.IsFull() ||
+		SConfig::GetInstance().bJITNoBlockCache)
 	{
 		ClearCache();
 	}
@@ -450,5 +454,6 @@ const u8* JitArm64::DoJit(u32 em_address, PPCAnalyst::CodeBuffer *code_buf, JitB
 	b->originalSize = code_block.m_num_instructions;
 
 	FlushIcache();
+	farcode.FlushIcache();
 	return start;
 }

Source/Core/Core/PowerPC/JitArm64/Jit.h

@@ -18,6 +18,15 @@
 
 #define PPCSTATE_OFF(elem) (offsetof(PowerPC::PowerPCState, elem))
 
+// A place to throw blocks of code we don't want polluting the cache, e.g. rarely taken
+// exception branches.
+class FarCodeCacheArm64 : public Arm64Gen::ARM64CodeBlock
+{
+public:
+	void Init(int size) { AllocCodeSpace(size); }
+	void Shutdown() { FreeCodeSpace(); }
+};
+
 // Some asserts to make sure we will be able to load everything
 static_assert(PPCSTATE_OFF(spr[1023]) <= 16380, "LDR(32bit) can't reach the last SPR");
 static_assert((PPCSTATE_OFF(ps[0][0]) % 8) == 0, "LDR(64bit VFP) requires FPRs to be 8 byte aligned");
@@ -185,6 +194,22 @@ private:
 
 	ARM64FloatEmitter m_float_emit;
 
+	FarCodeCacheArm64 farcode;
+	u8* nearcode; // Backed up when we switch to far code.
+
+	// Simple functions to switch between near and far code emitting
+	void SwitchToFarCode()
+	{
+		nearcode = GetWritableCodePtr();
+		SetCodePtr(farcode.GetWritableCodePtr());
+	}
+
+	void SwitchToNearCode()
+	{
+		farcode.SetCodePtr(GetWritableCodePtr());
+		SetCodePtr(nearcode);
+	}
+
 	// Dump a memory range of code
 	void DumpCode(const u8* start, const u8* end);