[Bug target/64953] Compiling sourcecode for STM32F103 causes USB errors with some optimization settings

[manuel.reimer at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64953

--- Comment #6 from manuel.reimer at gmx dot de ---
The exact command line is:

arm-none-eabi-gcc -c -mthumb -mcpu=cortex-m3 -mthumb-interwork -I.  -Os
-ffunction-sections -fdata-sections -Wall -Wimplicit -Wcast-align
-Wpointer-arith -Wswitch -Wredundant-decls -Wreturn-type -Wshadow -Wunused
-Wa,-adhlns=build/usb.lst -I./stm32_lib -I./usb_lib -DMAPLE --save-temps -MD
-MP -MF .dep/usb.o.d usb.c -o build/usb.o