LivePlusPlus_O3DE_Gem

An integration of Live++ for Open 3D Engine (GitHub) (Windows only).

Important: Live++ is NOT open source. See its website for details: Pricing and Legal.

Example Project

Refer to the included example project with Live++ enabled and configured:

• https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/tree/main/ExampleProject

I left out the actual Live++ package due to copyright, of course!

Compatibility with Live++ versions

• Use 'main' branch for Live++ 2.0.x
• Use 'v1' branch for Live++ 1.x: https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/tree/v1

Installation

1. Let's assume O3DE engine is at C:\git\o3de and your project is at C:\git\YourProject.
2. Pull down this repository, for example to C:\git\Gems\LivePlusPlus_O3DE_Gem\LivePlusPlus.
3. Register it as a gem for your O3DE project (see Register Gems for details). For example:
   • C:\git\o3de> .\scripts\o3de.bat register --gem-path C:\git\Gems\LivePlusPlus_O3DE_Gem\LivePlusPlus --external-subdirectory-project-path C:\git\YourProject.
4. Enable the LivePlusPlus gem in your project
   • This can be achieved by adding LivePlusPlus to enabled_gems.json in the C:\git\YourProject directory.
   • Or by using O3DE Project Manager.
5. Get your copy of Live++.
6. Unzip it into C:\git\Gems\LivePlusPlus_O3DE_Gem\LivePlusPlus\3rdParty\LivePP.
7. Compile your project and run.

Modifying Compiler/Linker Settings for Hotpatching C++ code

Enable Hotpatching for your project and your gems

For each project/gem you wish to hotpatch, do the following:

• create a PAL file for windows, such as: Gems\MyGem\Code\Platform\Windows\enable_hotpatch_link_options_windows.cmake with the following content: https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/blob/f0eea72f356d3e9e84a663e915316607b8d42b93/ExampleProject/Gem/Platform/Windows/platform_windows.cmake#L2-L17
• other platforms should have this file as empty, for example: Gems\MyGem\Code\Platform\Linux\enable_hotpatch_linux.cmake

• for a Gem/Project target in CMake include the above PAL file as:

  ly_add_target(
      NAME MyGem.Static STATIC
      ...
      PLATFORM_INCLUDE_FILES
          ${pal_dir}/enable_hotpatch_${PAL_PLATFORM_NAME_LOWERCASE}.cmake
      ...
  )
  > For example: https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/blob/f0eea72f356d3e9e84a663e915316607b8d42b93/ExampleProject/Gem/CMakeLists.txt#L28-L35
  
  ly_add_target(
      NAME MyGem ${PAL_TRAIT_MONOLITHIC_DRIVEN_MODULE_TYPE}
      ...
      PLATFORM_INCLUDE_FILES
          ${pal_dir}/enable_hotpatch_${PAL_PLATFORM_NAME_LOWERCASE}.cmake
      ...
  )
  

  For example: https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/blob/f0eea72f356d3e9e84a663e915316607b8d42b93/ExampleProject/Gem/CMakeLists.txt#L45-L52

This will enable hotpatching just for gems and projects that you wish to hotpatch. You do need to make this change for each ${PAL_TRAIT_MONOLITHIC_DRIVEN_MODULE_TYPE} target, though. An additional improvement would be to create a common place for enable_hotpatch_windows.cmake PAL files and re-use them across Gems.

Configuration

1. Refer to Live++ documentation.

2. By default, all gems registered for your O3DE project will be hot patched.

3. Optionally, you can set a regex filter to choose which O3DE gems by using O3DE registry.

   Note: This can significantly improve performance of Live++ and is highly encouraged to improve iteration times.

   https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/blob/f0eea72f356d3e9e84a663e915316607b8d42b93/ExampleProject/Registry/liveplusplus.setreg#L1-L9

   Here are some other examples:

   • ".*" - Matches any path
   • ".ImGui." - Matches ImGui gems
   • ".ImGui.|.ScriptCanvas." - Matches ImGui and ScriptCanvas gem

That is it! You are done!

Optional Advanced Configurations

(Optional) Enable Hotpatching for the the entire engine

1. Go to o3de\cmake\Platform\Common\MSVC\Configurations_msvc.cmake
2. Make the following changes: a. Profile Builds

   PS C:\git\o3de> git diff C:\git\o3de\cmake\Platform\Common\MSVC\Configurations_msvc.cmake
   diff --git a/cmake/Platform/Common/MSVC/Configurations_msvc.cmake b/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   index 9353e4eb1c..3ae8796b3c 100644
   --- a/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   +++ b/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   @@ -68,6 +68,8 @@ ly_append_configurations_options(
           /Zc:inline      # Removes unreferenced functions or data that are COMDATs or only have internal linkage
           /Zc:wchar_t     # Use compiler native wchar_t
           /Zi             # Generate debugging information (no Edit/Continue)
   +        /Z7             # for hot patching C++ code
   +        /Gw             # for hot patching C++ code
       COMPILATION_RELEASE
           /Ox             # Full optimization
           /Ob2            # Inline any suitable function
   @@ -78,8 +80,9 @@ ly_append_configurations_options(
           /NOLOGO             # Suppress Copyright and version number message
           /IGNORE:4099        # 3rdParty linking produces noise with LNK4099
       LINK_NON_STATIC_PROFILE
   -        /OPT:REF            # Eliminates functions and data that are never referenced
   -        /OPT:ICF            # Perform identical COMDAT folding. Redundant COMDATs can be removed from the linker output
   +        /OPT:NOREF            # for hot patching C++ code
   +        /OPT:NOICF            # for hot patching C++ code
   +        /FUNCTIONPADMIN       # for hot patching C++ code
           /INCREMENTAL:NO
           /DEBUG              # Generate pdbs
       LINK_NON_STATIC_RELEASE

   b. Debug Builds

   PS E:\o3de> git diff cmake\Platform\Common\MSVC\Configurations_msvc.cmake
   diff --git a/cmake/Platform/Common/MSVC/Configurations_msvc.cmake b/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   index 66a5b7b01f..221d813e08 100644
   --- a/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   +++ b/cmake/Platform/Common/MSVC/Configurations_msvc.cmake
   @@ -70,6 +70,8 @@ ly_append_configurations_options(
                           # It also causes the compiler to place the library name MSVCRTD.lib into the .obj file.
           /Ob0            # Disables inline expansions
           /Od             # Disables optimization
   +       /Z7             # for hot patching C++ code
   +       /Gw             # for hot patching C++ code
       COMPILATION_PROFILE
           /GF             # Enable string pooling
           /Gy             # Function level linking
   @@ -88,9 +90,11 @@ ly_append_configurations_options(
       LINK
           /NOLOGO             # Suppress Copyright and version number message
           /IGNORE:4099        # 3rdParty linking produces noise with LNK4099
   +        /OPT:NOREF         # for hot patching C++ code
   +        /OPT:NOICF         # for hot patching C++ code
   +        /FUNCTIONPADMIN    # for hot patching C++ code
   +
       LINK_NON_STATIC_PROFILE
   -        /OPT:REF            # Eliminates functions and data that are never referenced
   -        /OPT:ICF            # Perform identical COMDAT folding. Redundant COMDATs can be removed from the linker output
        /INCREMENTAL:NO

Enabling Live++ for other dynamic libraries

1. By default only AZ Modules are loaded for use with Live++. There are some dynamic libraries that are themselves not AZ Modules. It is possible to load these explicitly in LivePlusPlusSystemComponent_Windows.cpp with:

   const char* library = <full-path-to-dll>; // e.g. <path/to>/EditorLib.dll
   m_lppAgent.EnableModuleANSI(library, lpp::LPP_MODULES_OPTION_NONE);

   In the following section: https://github.com/AMZN-Olex/LivePlusPlus_O3DE_Gem/blob/f0eea72f356d3e9e84a663e915316607b8d42b93/LivePlusPlus/Code/Platform/Windows/LivePlusPlusSystemComponent_Windows.cpp#L169-L176

Enjoy!