[cmake] Allow enabling LTO for Qt frontend and libcelestia.so

.github/workflows/ci.yml

@@ -85,6 +85,7 @@ jobs:
             -DENABLE_QT6=ON       `
             -DENABLE_FFMPEG=ON    `
             -DENABLE_MINIAUDIO=ON `
+            -DENABLE_LTO=ON       `
             -DUSE_ICU=ON          `
             -DUSE_WIN_ICU=OFF
 

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.9)
 
 option(LEGACY_OPENGL_LIBS "Use legacy OpenGL libraries instead of glvnd library (Default: off)" OFF)
 
@@ -58,9 +58,10 @@ option(ENABLE_WIN           "Build Windows native frontend? (Default: on)" ON)
 option(ENABLE_FFMPEG        "Support video capture using FFMPEG (Default: off)" OFF)
 option(ENABLE_MINIAUDIO     "Support audio playback using miniaudio (Default: off)" OFF)
 option(ENABLE_TOOLS         "Build different tools? (Default: off)" OFF)
-option(FAST_MATH            "Build with unsafe fast-math compiller option (Default: off)" OFF)
+option(ENABLE_FAST_MATH     "Build with unsafe fast-math compiller option (Default: off)" OFF)
 option(ENABLE_TESTS         "Enable unit tests? (Default: off)" OFF)
 option(ENABLE_GLES          "Build for OpenGL ES 2.0 instead of OpenGL 2.1 (Default: off)" OFF)
+option(ENABLE_LTO           "Enable link time optimizations (Default: off)" OFF)
 option(USE_GTKGLEXT         "Use libgtkglext1 for GTK2 frontend (Default: on)" ON)
 option(USE_GTK3             "Use Gtk3 in GTK2 frontend (Default: off)" OFF)
 option(USE_WAYLAND          "Use Wayland in Qt frontend (Default: off)" OFF)
@@ -172,7 +173,7 @@ if(USE_WEFFCPP AND CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   endif()
 endif()
 
-EnableFastMath(${FAST_MATH})
+EnableFastMath(${ENABLE_FAST_MATH})
 
 #
 # NLS (Gettext) support
@@ -408,6 +409,22 @@ else()
   endif()
 endif()
 
+if(ENABLE_LTO)
+  if(WIN32)
+    message(WARNING "LTO is not supported yet when building for Windows")
+    set(ENABLE_LTO OFF)
+  else()
+    include(CheckIPOSupported)
+    check_ipo_supported(RESULT lto_supported)
+    if(lto_supported)
+      message(STATUS "LTO is supported")
+    else()
+      message(WARNING "LTO is not supported")
+      set(ENABLE_LTO OFF)
+    endif()
+  endif()
+endif()
+
 # Turning all debug on dramatically decreases performance
 if(OCTREE_DEBUG)
   add_definitions(-DOCTREE_DEBUG)

src/celestia/CMakeLists.txt

@@ -101,10 +101,14 @@ if(ENABLE_FFMPEG)
   target_link_libraries(celestia ${FFMPEG_LIBRARIES})
 endif()
 
-if (HAVE_MESHOPTIMIZER)
+if(HAVE_MESHOPTIMIZER)
   target_link_libraries(celestia meshoptimizer::meshoptimizer)
 endif()
 
+if(ENABLE_LTO)
+  set_target_properties(celestia PROPERTIES INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 if(WIN32)
   install(
     TARGETS celestia

src/celestia/qt/qtsolarsystembrowser.cpp

@@ -342,18 +342,15 @@ SolarSystemBrowser::SolarSystemTreeModel::addTreeItemChildrenFiltered(TreeItem*
     }
 
     // Calculate the total number of children
-    if ((item->nChildren = bodies.size()) == 0)
+    // WARN: max(size_t) > max(int) so in theory it's possible to have a negative value
+    if ((item->nChildren = static_cast<int>(bodies.size())) <= 0)
         return;
 
-    int childIndex = 0;
     item->children = new TreeItem*[item->nChildren];
 
     // Add the direct children
     for (int i = 0; i < (int) bodies.size(); i++)
-    {
-        item->children[childIndex] = createTreeItem(bodies[i], item, childIndex);
-        childIndex++;
-    }
+        item->children[i] = createTreeItem(bodies[i], item, i);
 }
 
 

src/celestia/qt5/CMakeLists.txt

@@ -46,6 +46,10 @@ if(APPLE)
   set_property(TARGET celestia-qt5 APPEND_STRING PROPERTY LINK_FLAGS " -framework CoreServices")
 endif()
 
+if(ENABLE_LTO)
+  set_target_properties(celestia-qt5 PROPERTIES INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 install(
   TARGETS celestia-qt5
   RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}

src/celestia/qt6/CMakeLists.txt

@@ -45,6 +45,10 @@ install(
   COMPONENT qt6gui
 )
 
+if(ENABLE_LTO)
+  set_target_properties(celestia-qt6 PROPERTIES INTERPROCEDURAL_OPTIMIZATION ON)
+endif()
+
 if(WIN32)
   qt6_generate_deploy_app_script(TARGET celestia-qt6
     OUTPUT_SCRIPT deploy-celestia-qt6