A code optimization (-O2) break MCU when call the function EEPROM_ReadWord() (GCC 5)

GCC 4.9 was working fine.

$ arm-none-eabi-gcc  -DUSE_MDR1986VE9x -D__START=main -D__STARTUP_CLEAR_BSS
  -mcpu=cortex-m3 -mthumb -O2 -ffunction-sections -fdata-sections
  -Wall -Wextra -Wshadow -Wredundant-decls -pipe 
  -I CMSIS/CM3/CoreSupport -I CMSIS/CM3/DeviceSupport/MDR32F9Qx/inc 
  -I CMSIS/CM3/DeviceSupport/MDR32F9Qx/startup/gcc -I MDR32F9Qx_StdPeriph_Driver/inc    
  -o CMakeFiles/xz.dir/thdparty/MDR32F9Qx_StdPeriph_Driver/src/MDR32F9Qx_eeprom.c.obj  
  -c MDR32F9Qx_StdPeriph_Driver/src/MDR32F9Qx_eeprom.c

When I'll have a time I try to see that issue.

eldarkg / emdr1986x-std-per-lib

A code optimization (-O2) break MCU when call the function EEPROM_ReadWord() (GCC 5) #2