Adds a JitSymbols interface

This allows linux perf to see execution inside of JIT functions.
This could be extended in the future to support something like vtune or
oprofile.

CMakeLists.txt

@@ -6,6 +6,7 @@ project(${PROJECT_NAME}
 
 option(ENABLE_CLANG_FORMAT "Run clang format over the source" FALSE)
 option(FORCE_AARCH64 "Force AArch64 Target for testing" FALSE)
+option(ENABLE_JITSYMBOLS "Enable visibility of JITSymbols in profiling tools" FALSE)
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 

Source/CMakeLists.txt

@@ -47,6 +47,7 @@ endif()
 
 set (SRCS
   Common/Paths.cpp
+  Common/JitSymbols.cpp
   Interface/Config/Config.cpp
   Interface/Context/Context.cpp
   Interface/Core/BlockCache.cpp
@@ -89,6 +90,10 @@ if (ENABLE_JIT)
   endif()
 endif()
 
+if (ENABLE_JITSYMBOLS)
+  add_definitions(-DENABLE_JITSYMBOLS=1)
+endif()
+
 # Generate IR include file
 set(OUTPUT_NAME "${CMAKE_CURRENT_BINARY_DIR}/IRDefines.inc")
 set(INPUT_NAME "${CMAKE_CURRENT_SOURCE_DIR}/Interface/IR/IR.json")

Source/Common/JitSymbols.cpp

@@ -0,0 +1,35 @@
+#include "Common/JitSymbols.h"
+
+#include <string>
+#include <sstream>
+#include <unistd.h>
+
+namespace FEXCore {
+  JITSymbols::JITSymbols() {
+    std::stringstream PerfMap;
+    PerfMap << "/tmp/perf-" << getpid() << ".map";
+
+    fp = fopen(PerfMap.str().c_str(), "wb");
+    if (fp) {
+      // Disable buffering on this file
+      setvbuf(fp, nullptr, _IONBF, 0);
+    }
+  }
+
+  JITSymbols::~JITSymbols() {
+    if (fp) {
+      fclose(fp);
+    }
+  }
+
+  void JITSymbols::Register(void *HostAddr, uint64_t GuestAddr, uint32_t CodeSize) {
+    if (!fp) return;
+
+    // Linux perf format is very straightforward
+    // `<HostPtr> <Size> <Name>\n`
+    std::stringstream String;
+    String << std::hex << HostAddr << " " << CodeSize << " " << "JIT_0x" << GuestAddr << std::endl;
+    fwrite(String.str().c_str(), 1, String.str().size(), fp);
+  }
+}
+

Source/Common/JitSymbols.h

@@ -0,0 +1,14 @@
+#pragma once
+#include <cstdint>
+#include <cstdio>
+
+namespace FEXCore {
+class JITSymbols final {
+public:
+  JITSymbols();
+  ~JITSymbols();
+  void Register(void *HostAddr, uint64_t GuestAddr, uint32_t CodeSize);
+private:
+  FILE* fp{};
+};
+}

Source/Interface/Context/Context.h

@@ -1,4 +1,5 @@
 #pragma once
+#include "Common/JitSymbols.h"
 #include "Event.h"
 #include "Interface/Core/CPUID.h"
 #include "Interface/Core/Frontend.h"
@@ -115,5 +116,9 @@ namespace FEXCore::Context {
     std::vector<uint64_t> InitLocations;
     uint64_t StartingRIP;
     IR::RegisterAllocationPass *RAPass {};
+#if ENABLE_JITSYMBOLS
+    FEXCore::JITSymbols Symbols;
+#endif
+
   };
 }

Source/Interface/Core/Core.cpp

@@ -1,5 +1,6 @@
 #include "Common/MathUtils.h"
 #include "Common/Paths.h"
+
 #include "Interface/Context/Context.h"
 #include "Interface/Core/BlockCache.h"
 #include "Interface/Core/Core.h"
@@ -563,6 +564,10 @@ namespace FEXCore::Context {
 
     if (CodePtr != nullptr) {
       // The core managed to compile the code.
+#if ENABLE_JITSYMBOLS
+      Symbols.Register(CodePtr, GuestRIP, DebugData->HostCodeSize);
+#endif
+
       return AddBlockMapping(Thread, GuestRIP, CodePtr);
     }
 

Source/Interface/Core/JIT/x86_64/JIT.cpp

@@ -2863,8 +2863,12 @@ void *JITCore::CompileCode([[maybe_unused]] FEXCore::IR::IRListView<true> const
     }
   }
 
+  void *Exit = getCurr<void*>();
+
   ready();
 
+  DebugData->HostCodeSize = reinterpret_cast<uintptr_t>(Exit) - reinterpret_cast<uintptr_t>(Entry);
+
   return Entry;
 }