Added experimental LTO kconfig option

CMakeLists.txt

@@ -99,7 +99,7 @@
 #
 #=============================================================================
 
-cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.9 FATAL_ERROR)
 
 set(PX4_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}" CACHE FILEPATH "PX4 source directory" FORCE)
 set(PX4_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}" CACHE FILEPATH "PX4 binary directory" FORCE)
@@ -234,6 +234,14 @@ message(STATUS "cmake build type: ${CMAKE_BUILD_TYPE}")
 #
 project(px4 CXX C ASM)
 
+# Check if LTO option and check if toolchain supports it
+if(LTO)
+    include(CheckIPOSupported)
+    check_ipo_supported()
+    message(AUTHOR_WARNING "LTO enabled: LTO is highly experimental and should not be used in production")
+    set(CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
+endif()
+
 set(package-contact "px4users@googlegroups.com")
 
 set(CMAKE_CXX_STANDARD 14)

Kconfig

@@ -51,6 +51,13 @@ menu "Toolchain"
         string "Architecture"
         default ""
 
+    config BOARD_LTO
+        bool "(EXPERIMENTAL) Link Time Optimization (LTO)"
+        default n
+        help
+            Enables LTO flag in linker
+            Note: Highly EXPERIMENTAL, furthermore make sure you're using a modern compiler GCC 9 or later
+
     config BOARD_FULL_OPTIMIZATION
         bool "Full optmization (O3)"
         default n

src/modules/mc_pos_control/MulticopterPositionControl.hpp

@@ -88,7 +88,7 @@ public:
 private:
 	void Run() override;
 
-	Takeoff _takeoff; /**< state machine and ramp to bring the vehicle off the ground without jumps */
+	TakeoffHandling _takeoff; /**< state machine and ramp to bring the vehicle off the ground without jumps */
 
 	orb_advert_t _mavlink_log_pub{nullptr};
 

src/modules/mc_pos_control/Takeoff/Takeoff.cpp

@@ -39,14 +39,14 @@
 #include <mathlib/mathlib.h>
 #include <lib/geo/geo.h>
 
-void Takeoff::generateInitialRampValue(float velocity_p_gain)
+void TakeoffHandling::generateInitialRampValue(float velocity_p_gain)
 {
 	velocity_p_gain = math::max(velocity_p_gain, 0.01f);
 	_takeoff_ramp_vz_init = -CONSTANTS_ONE_G / velocity_p_gain;
 }
 
-void Takeoff::updateTakeoffState(const bool armed, const bool landed, const bool want_takeoff,
-				 const float takeoff_desired_vz, const bool skip_takeoff, const hrt_abstime &now_us)
+void TakeoffHandling::updateTakeoffState(const bool armed, const bool landed, const bool want_takeoff,
+		const float takeoff_desired_vz, const bool skip_takeoff, const hrt_abstime &now_us)
 {
 	_spoolup_time_hysteresis.set_state_and_update(armed, now_us);
 
@@ -109,7 +109,7 @@ void Takeoff::updateTakeoffState(const bool armed, const bool landed, const bool
 	}
 }
 
-float Takeoff::updateRamp(const float dt, const float takeoff_desired_vz)
+float TakeoffHandling::updateRamp(const float dt, const float takeoff_desired_vz)
 {
 	float upwards_velocity_limit = takeoff_desired_vz;
 

src/modules/mc_pos_control/Takeoff/Takeoff.hpp

@@ -53,11 +53,11 @@ enum class TakeoffState {
 	flight = takeoff_status_s::TAKEOFF_STATE_FLIGHT
 };
 
-class Takeoff
+class TakeoffHandling
 {
 public:
-	Takeoff() = default;
-	~Takeoff() = default;
+	TakeoffHandling() = default;
+	~TakeoffHandling() = default;
 
 	// initialize parameters
 	void setSpoolupTime(const float seconds) { _spoolup_time_hysteresis.set_hysteresis_time_from(false, seconds * 1_s); }

src/modules/mc_pos_control/Takeoff/TakeoffTest.cpp

@@ -38,13 +38,13 @@
 
 TEST(TakeoffTest, Initialization)
 {
-	Takeoff takeoff;
+	TakeoffHandling takeoff;
 	EXPECT_EQ(takeoff.getTakeoffState(), TakeoffState::disarmed);
 }
 
 TEST(TakeoffTest, RegularTakeoffRamp)
 {
-	Takeoff takeoff;
+	TakeoffHandling takeoff;
 	takeoff.setSpoolupTime(1.f);
 	takeoff.setTakeoffRampTime(2.0);
 	takeoff.generateInitialRampValue(CONSTANTS_ONE_G / 0.5f);