Implemented the trace reconstruction + bugs fixed

Core/MIPS/IR/IRFrontend.cpp

@@ -307,8 +307,10 @@ void IRFrontend::DoJit(u32 em_address, std::vector<IRInst> &instructions, u32 &m
 	else {
 		std::vector<IRInst> block_instructions = code->GetInstructions();
 		instructions.reserve(block_instructions.capacity());
-		block_instructions.push_back({ IROp::LogBlockHash, 0, 0, 0, 0 });
-		std::copy(block_instructions.begin(), block_instructions.end(), std::back_inserter(instructions));
+		// The first instruction is "Downcount"
+		instructions.push_back(block_instructions.front());
+		instructions.push_back({ IROp::LogBlockHash, 0, 0, 0, 0 });
+		std::copy(block_instructions.begin() + 1, block_instructions.end(), std::back_inserter(instructions));
 	}
 
 	if (logBlocks > 0 && dontLogBlocks == 0) {

Core/MIPS/MIPSTracer.cpp

@@ -53,7 +53,8 @@ void MIPSTracer::prepare_block(MIPSComp::IRBlock* block, MIPSComp::IRBlockCache&
 	if (it != mipsTracer.hash_to_index.end()) {
 		u32 index = it->second;
 		auto ir_ptr = (IRInst*)blocks.GetBlockInstructionPtr(*block);
-		ir_ptr->constant = index;
+
+		ir_ptr[1].constant = index;
 		return;
 	}
 
@@ -80,16 +81,46 @@ void MIPSTracer::prepare_block(MIPSComp::IRBlock* block, MIPSComp::IRBlockCache&
 	hash_to_index.emplace(hash, index);
 
 	auto ir_ptr = (IRInst*)blocks.GetBlockInstructionPtr(*block);
-	ir_ptr->constant = index;
+	ir_ptr[1].constant = index;
 }
 
 bool MIPSTracer::flush_to_file() {
 	INFO_LOG(Log::JIT, "MIPSTracer ordered to flush the trace to a file...");
-	// Do nothing for now
+
+	output.open(logging_path, std::ios::out);
+	if (!output) {
+		WARN_LOG(Log::JIT, "MIPSTracer failed to open the file '%s'", logging_path);
+		return false;
+	}
+	auto trace = executed_blocks.get_content();
+	for (auto index : trace) {
+		auto& block_info = trace_info[index];
+		flush_block_to_file(block_info);
+	}
+
+	INFO_LOG(Log::JIT, "Trace flushed, closing the file...");
+	output.close();
 	clear();
 	return true;
 }
 
+void MIPSTracer::flush_block_to_file(TraceBlockInfo& block_info) {
+	static char buffer[1024];
+
+	// The log format is '0x{8 hex digits of the address}: {disassembled line}'
+	const auto prefix_size = 2 + 8 + 2;
+
+	u32 addr = block_info.virt_address;
+	u32 index = block_info.storage_index;
+	u32 end_addr = addr + block_info.size;
+
+	for (; addr < end_addr; addr += 4, ++index) {
+		snprintf(buffer, sizeof(buffer), "0x%08x: ", addr);
+		MIPSDisAsm(storage[index], addr, buffer + prefix_size, sizeof(buffer) - prefix_size, true);
+		output << std::string(buffer) << "\n";
+	}
+}
+
 void MIPSTracer::start_tracing() {
 	tracing_enabled = true;
 	INFO_LOG(Log::JIT, "MIPSTracer enabled");

Core/MIPS/MIPSTracer.h

@@ -21,6 +21,7 @@
 #include <vector>
 #include <string>
 #include <iterator>
+#include <fstream>
 
 #include "Common/CommonTypes.h"
 #include "Core/Opcode.h"
@@ -135,6 +136,7 @@ struct MIPSTracer {
 	TraceBlockStorage storage;
 
 	std::string logging_path;
+	std::ofstream output;
 	bool tracing_enabled = false;
 
 	int in_storage_capacity = 0;
@@ -152,6 +154,8 @@ struct MIPSTracer {
 	}
 
 	bool flush_to_file();
+	void flush_block_to_file(TraceBlockInfo& block);
+
 	void initialize(u32 storage_capacity, u32 max_trace_size);
 	void clear();
 

UI/GameSettingsScreen.cpp

@@ -2148,7 +2148,7 @@ UI::EventReturn DeveloperToolsScreen::OnMIPSTracerEnabled(UI::EventParams &e) {
 		u32 trace_size = mipsTracer.in_max_trace_size;
 
 		mipsTracer.initialize(capacity, trace_size);
-		// mipsTracer.start_tracing();
+		mipsTracer.start_tracing();
 	}
 	else {
 		mipsTracer.stop_tracing();