From a0e9417912e0dd552f54a7b00e19fafe4017b7c5 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Mon, 30 Jan 2017 21:43:40 +0000
Subject: [PATCH] ir_opt: Initial constant propagation pass implementation

---
 src/CMakeLists.txt                       |  1 +
 src/backend_x64/interface_x64.cpp        |  1 +
 src/ir_opt/constant_propagation_pass.cpp | 73 ++++++++++++++++++++++++
 src/ir_opt/passes.h                      |  3 +
 4 files changed, 78 insertions(+)
 create mode 100644 src/ir_opt/constant_propagation_pass.cpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 879eca9c..0cb4ccd8 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -27,6 +27,7 @@ set(SRCS
     frontend/translate/translate_arm/synchronization.cpp
     frontend/translate/translate_arm/vfp2.cpp
     frontend/translate/translate_thumb.cpp
+    ir_opt/constant_propagation_pass.cpp
     ir_opt/dead_code_elimination_pass.cpp
     ir_opt/get_set_elimination_pass.cpp
     ir_opt/verification_pass.cpp
diff --git a/src/backend_x64/interface_x64.cpp b/src/backend_x64/interface_x64.cpp
index 78123370..5511a019 100644
--- a/src/backend_x64/interface_x64.cpp
+++ b/src/backend_x64/interface_x64.cpp
@@ -105,6 +105,7 @@ private:
 
         IR::Block ir_block = Arm::Translate(descriptor, callbacks.memory.ReadCode);
         Optimization::GetSetElimination(ir_block);
+        Optimization::ConstantPropagation(ir_block, callbacks.memory);
         Optimization::DeadCodeElimination(ir_block);
         Optimization::VerificationPass(ir_block);
         return emitter.Emit(ir_block);
diff --git a/src/ir_opt/constant_propagation_pass.cpp b/src/ir_opt/constant_propagation_pass.cpp
new file mode 100644
index 00000000..cb925f9a
--- /dev/null
+++ b/src/ir_opt/constant_propagation_pass.cpp
@@ -0,0 +1,73 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2016 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#include <dynarmic/callbacks.h>
+
+#include "frontend/ir/basic_block.h"
+#include "frontend/ir/opcodes.h"
+#include "ir_opt/passes.h"
+
+namespace Dynarmic {
+namespace Optimization {
+
+void ConstantPropagation(IR::Block& block, const UserCallbacks::Memory& memory_callbacks) {
+    for (auto& inst : block) {
+        if (!inst.AreAllArgsImmediates())
+            continue;
+
+        switch (inst.GetOpcode()) {
+        case IR::Opcode::ReadMemory8: {
+            u32 vaddr = inst.GetArg(0).GetU32();
+            if (memory_callbacks.IsReadOnlyMemory(vaddr)) {
+                u8 value_from_memory = memory_callbacks.Read8(vaddr);
+                inst.ReplaceUsesWith(IR::Value{value_from_memory});
+            }
+            break;
+        }
+        case IR::Opcode::ReadMemory16: {
+            u32 vaddr = inst.GetArg(0).GetU32();
+            if (memory_callbacks.IsReadOnlyMemory(vaddr)) {
+                u16 value_from_memory = memory_callbacks.Read16(vaddr);
+                inst.ReplaceUsesWith(IR::Value{value_from_memory});
+            }
+            break;
+        }
+        case IR::Opcode::ReadMemory32: {
+            u32 vaddr = inst.GetArg(0).GetU32();
+            if (memory_callbacks.IsReadOnlyMemory(vaddr)) {
+                u32 value_from_memory = memory_callbacks.Read32(vaddr);
+                inst.ReplaceUsesWith(IR::Value{value_from_memory});
+            }
+            break;
+        }
+        case IR::Opcode::ReadMemory64: {
+            u32 vaddr = inst.GetArg(0).GetU32();
+            if (memory_callbacks.IsReadOnlyMemory(vaddr)) {
+                u64 value_from_memory = memory_callbacks.Read64(vaddr);
+                inst.ReplaceUsesWith(IR::Value{value_from_memory});
+            }
+            break;
+        }
+        case IR::Opcode::ZeroExtendByteToWord: {
+            u8 byte = inst.GetArg(0).GetU8();
+            u32 value = static_cast<u32>(byte);
+            inst.ReplaceUsesWith(IR::Value{value});
+            break;
+        }
+        case IR::Opcode::ZeroExtendHalfToWord: {
+            u16 half = inst.GetArg(0).GetU16();
+            u32 value = static_cast<u32>(half);
+            inst.ReplaceUsesWith(IR::Value{value});
+            break;
+        }
+        default:
+            break;
+        }
+    }
+}
+
+} // namespace Optimization
+} // namespace Dynarmic
diff --git a/src/ir_opt/passes.h b/src/ir_opt/passes.h
index 8d06509c..c861c876 100644
--- a/src/ir_opt/passes.h
+++ b/src/ir_opt/passes.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <dynarmic/callbacks.h>
+
 namespace Dynarmic {
 namespace IR {
 class Block;
@@ -16,6 +18,7 @@ namespace Dynarmic {
 namespace Optimization {
 
 void GetSetElimination(IR::Block& block);
+void ConstantPropagation(IR::Block& block, const UserCallbacks::Memory& memory_callbacks);
 void DeadCodeElimination(IR::Block& block);
 void VerificationPass(const IR::Block& block);