stm32/mboot: Use additional CFLAGS to compile string0.c.
This is the same as but applied to
mboot's Makefile.
@@ -57,6 +57,10 @@ CFLAGS_MCU_h7 = $(CFLAGS_CORTEX_M) -mtune=cortex-m7 -mcpu=cortex-m7
CFLAGS_MCU_l4 = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
CFLAGS_MCU_wb = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
+# Standard C functions like memset need to be compiled with special flags so
+# the compiler does not optimise these functions in terms of themselves.
+CFLAGS_BUILTIN ?= -ffreestanding -fno-builtin -fno-lto
+
CFLAGS = $(INC) -Wall -Wpointer-arith -Wdouble-promotion -Wfloat-conversion -Werror -std=gnu99 -nostdlib $(CFLAGS_MOD) $(CFLAGS_EXTRA)
CFLAGS += -D$(CMSIS_MCU)
CFLAGS += $(CFLAGS_MCU_$(MCU_SERIES))
@@ -84,6 +88,7 @@ else
COPT += -Os -DNDEBUG
endif
+$(BUILD)/lib/libc/string0.o: CFLAGS += $(CFLAGS_BUILTIN)
LIB_SRC_C = \
lib/libc/string0.c \
lib/oofatfs/ff.c \
