Merge remote-tracking branch 'madcowswe/LTO' into devel

Firmware/Board/v3/Middlewares/Third_Party/FreeRTOS/Source/portable/GCC/ARM_CM4F/port.c

@@ -302,6 +302,7 @@ static void prvPortStartFirstTask( void )
 					" isb					\n"
 					" svc 0					\n" /* System call to start first task. */
 					" nop					\n"
+					" .ltorg                \n"
 				);
 }
 /*-----------------------------------------------------------*/
@@ -695,7 +696,8 @@ static void vPortEnableVFP( void )
 		"								\n"
 		"	orr r1, r1, #( 0xf << 20 )	\n" /* Enable CP10 and CP11 coprocessors, then save back. */
 		"	str r1, [r0]				\n"
-		"	bx r14						"
+		"	bx r14						\n"
+		"   .ltorg                        "
 	);
 }
 /*-----------------------------------------------------------*/

Firmware/Board/v3/Middlewares/Third_Party/FreeRTOS/Source/tasks.c

@@ -369,7 +369,7 @@ typedef tskTCB TCB_t;
 /*lint -e956 A manual analysis and inspection has been used to determine which
 static variables must be declared volatile. */
 
-PRIVILEGED_INITIALIZED_DATA TCB_t * volatile pxCurrentTCB = NULL;
+__attribute__((used)) PRIVILEGED_INITIALIZED_DATA TCB_t * volatile pxCurrentTCB = NULL;
 
 /* Lists for ready and blocked tasks. --------------------*/
 PRIVILEGED_DATA static List_t pxReadyTasksLists[ configMAX_PRIORITIES ];/*< Prioritised ready tasks. */
@@ -2758,6 +2758,7 @@ BaseType_t xSwitchRequired = pdFALSE;
 #endif /* configUSE_APPLICATION_TASK_TAG */
 /*-----------------------------------------------------------*/
 
+__attribute__((used))
 void vTaskSwitchContext( void )
 {
 	if( uxSchedulerSuspended != ( UBaseType_t ) pdFALSE )

Firmware/Board/v3/Src/stm32f4xx_it.c

@@ -75,6 +75,7 @@ void NMI_Handler(void)
   /* USER CODE END NonMaskableInt_IRQn 1 */
 }
 
+__attribute__((used)) 
 void get_regs(void** stack_ptr) {
   void* volatile r0 __attribute__((unused)) = stack_ptr[0];
   void* volatile r1 __attribute__((unused)) = stack_ptr[1];

Firmware/Tupfile.lua

@@ -137,7 +137,7 @@ FLAGS += '-g'
 
 -- linker flags
 LDFLAGS += board.ldflags
-LDFLAGS += '-lc -lm -lnosys' -- libs
+LDFLAGS += '-flto -lc -lm -lnosys' -- libs
 LDFLAGS += '-mthumb -mfloat-abi=hard -specs=nosys.specs -specs=nano.specs -u _printf_float -u _scanf_float -Wl,--cref -Wl,--gc-sections'
 LDFLAGS += '-Wl,--undefined=uxTopUsedPriority'
 
@@ -149,6 +149,11 @@ else
     OPT += '-O2'
 end
 
+if tup.getconfig("USE_LTO") == "true" then
+    OPT += '-flto'
+    LDFLAGS += '-flto'
+end
+
 -- common flags for ASM, C and C++
 OPT += '-ffast-math -fno-finite-math-only'
 tup.append_table(FLAGS, OPT)
@@ -159,7 +164,10 @@ toolchain = GCCToolchain('arm-none-eabi-', 'build', FLAGS, LDFLAGS)
 
 -- Load list of source files Makefile that was autogenerated by CubeMX
 vars = parse_makefile_vars(board.dir..'/Makefile')
-all_stm_sources = (vars['C_SOURCES'] or '')..' '..(vars['CPP_SOURCES'] or '')..' '..(vars['ASM_SOURCES'] or '')
+
+-- ASM sources must precede C sources due to LTO removing weak symbols which appear after strong symbols
+-- in the call to the linker:  https://bugs.launchpad.net/gcc-arm-embedded/+bug/1747966
+all_stm_sources = (vars['ASM_SOURCES'] or '')..' '..(vars['CPP_SOURCES'] or '')..' '..(vars['C_SOURCES'] or '')
 for src in string.gmatch(all_stm_sources, "%S+") do
     stm_sources += board.dir..'/'..src
 end

Firmware/communication/communication.cpp

@@ -57,7 +57,7 @@ void init_communication(void) {
 }
 
 extern "C" {
-int _write(int file, const char* data, int len);
+int _write(int file, const char* data, int len) __attribute__((used));
 }
 
 // @brief This is what printf calls internally

Firmware/tup.config.default

@@ -5,6 +5,7 @@ CONFIG_USB_PROTOCOL=native
 CONFIG_UART_PROTOCOL=ascii
 CONFIG_DEBUG=false
 CONFIG_DOCTEST=false
+CONFIG_USE_LTO=true
 
 # Uncomment this to error on compilation warnings
 #CONFIG_STRICT=true