From 390b6da0b84cf54a1b8d19947c6578076b3f07bf Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Thu, 26 Dec 2019 00:02:15 +1000
Subject: [PATCH] CPU/Recompiler: Add unconditional EmitBranch

---
 src/core/cpu_recompiler_code_generator.h       |  3 +++
 .../cpu_recompiler_code_generator_aarch64.cpp  | 18 ++++++++++++++++++
 src/core/cpu_recompiler_code_generator_x64.cpp | 15 +++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/src/core/cpu_recompiler_code_generator.h b/src/core/cpu_recompiler_code_generator.h
index 3364407b6..85cd223c6 100644
--- a/src/core/cpu_recompiler_code_generator.h
+++ b/src/core/cpu_recompiler_code_generator.h
@@ -78,6 +78,9 @@ public:
   Value EmitLoadGuestMemory(const Value& address, RegSize size);
   void EmitStoreGuestMemory(const Value& address, const Value& value);
 
+  // Unconditional branch to pointer. May allocate a scratch register.
+  void EmitBranch(const void* address, bool allow_scratch = true);
+
   // Branching, generates two paths.
   void EmitBranch(Condition condition, Reg lr_reg, Value&& branch_target);
   void EmitBranchIfBitClear(HostReg reg, RegSize size, u8 bit, LabelType* label);
diff --git a/src/core/cpu_recompiler_code_generator_aarch64.cpp b/src/core/cpu_recompiler_code_generator_aarch64.cpp
index 0e85b0ae7..d3b7c8e5e 100644
--- a/src/core/cpu_recompiler_code_generator_aarch64.cpp
+++ b/src/core/cpu_recompiler_code_generator_aarch64.cpp
@@ -1390,6 +1390,24 @@ void CodeGenerator::EmitCancelInterpreterLoadDelayForReg(Reg reg)
   m_emit->Bind(&skip_cancel);
 }
 
+void CodeGenerator::EmitBranch(const void* address, bool allow_scratch)
+{
+  const s64 jump_distance =
+    static_cast<s64>(reinterpret_cast<intptr_t>(address) - reinterpret_cast<intptr_t>(GetCurrentCodePointer()));
+  Assert(Common::IsAligned(jump_distance, 4));
+  if (a64::Instruction::IsValidImmPCOffset(a64::UncondBranchType, jump_distance >> 2))
+  {
+    m_emit->b(jump_distance >> 2);
+    return;
+  }
+
+  Assert(allow_scratch);
+
+  Value temp = m_register_cache.AllocateScratch(RegSize_64);
+  m_emit->Mov(GetHostReg64(temp), reinterpret_cast<uintptr_t>(address));
+  m_emit->br(GetHostReg64(temp));
+}
+
 template<typename T>
 static void EmitConditionalJump(Condition condition, bool invert, a64::MacroAssembler* emit, const T& label)
 {
diff --git a/src/core/cpu_recompiler_code_generator_x64.cpp b/src/core/cpu_recompiler_code_generator_x64.cpp
index fb377775f..2203116d8 100644
--- a/src/core/cpu_recompiler_code_generator_x64.cpp
+++ b/src/core/cpu_recompiler_code_generator_x64.cpp
@@ -1792,6 +1792,21 @@ void CodeGenerator::EmitCancelInterpreterLoadDelayForReg(Reg reg)
   m_emit->L(skip_cancel);
 }
 
+void CodeGenerator::EmitBranch(const void* address, bool allow_scratch)
+{
+  if (Xbyak::inner::IsInInt32(reinterpret_cast<uintptr_t>(address)))
+  {
+    m_emit->jmp(address);
+    return;
+  }
+
+  Assert(allow_scratch);
+
+  Value temp = m_register_cache.AllocateScratch(RegSize_64);
+  m_emit->mov(GetHostReg64(temp), reinterpret_cast<uintptr_t>(address));
+  m_emit->jmp(GetHostReg64(temp));
+}
+
 template<typename T>
 static void EmitConditionalJump(Condition condition, bool invert, Xbyak::CodeGenerator* emit, const T& label)
 {