-O2, -O3 -Ofast optimizations compiler is adding udf 255 instruction into the execution path which results in HF.
Example:
1154 pQueryChunk->pSrcDriver = pParser->pSourceDriver;
080157f4: ldr.w r3, [r9, #20]
080157f8: str.w r3, [r11, #12]
080157fc: b.n 0x801556e <httpG4WebPage+1130>
080157fe: movs r3, #0
08015800: ldr.w r2, [r9, #20]
08015804: str r2, [r3, #12]
08015806: udf #255 ; 0xff <---------- obviously wrong
if (pQueryChunk && ioIsValid(pRawChunk))
{
pQueryChunk->pSrcDriver = pRawChunk->pSrcDriver;
}
else if (pParser)
{
pQueryChunk->pSrcDriver = pParser->pSourceDriver;
}
GNU C11 (GNU Tools for STM32 10.3-2021.10.20211105-1100) version 10.3.1 20210824 (release) (arm-none-eabi)
compiled by GNU C version 7.3-win32 20180312, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
COLLECT_GCC_OPTIONS='-mcpu=cortex-m4' '-std=gnu11' '-g3' '-D' '_GNU_SOURCE=1' '-D' 'USE_HAL_DRIVER' '-D' '_DEBUG=1' '-D' 'DEBUG_RUN_WITHOUT_CHECKS=1' '-D' 'DEBUGFILEWRITE=0' '-D' 'DEBUG=0' '-D' 'SLOWSPIDEBUG=0' '-D' 'USE_FULL_ASSERT' '-D' '__USE_SIMPLE_SWO=0' '-D' 'USE_SWOTRACE=1' '-D' 'AMD64' '-D' 'HSE_VALUE=16000000UL' '-D' 'USE_FULL_LL_DRIVER=0' '-D' 'BOOTLOADER_VERSION=1' '-D' 'ALLOW_SOFTWARE_BKPTS=1' '-D' 'ARM_MATH_CM4' '-D' 'FORCE_CUBE_USB' '-D' 'USE_EMBEDDED_PHY=1' '-D' 'USE_USB_OTG_FS=1' '-D' 'BITMAP_LCD_ALLOWED=0' '-D' 'LCDGUI_ALLOWED=0' '-D' 'LCD_ALLOWED=0' '-D' 'GPS_ALLOWED=0' '-D' 'STM32L4S9xx' '-D' 'STM32L' '-D' 'INCLUDE_SLEEP_FUNCTIONS=1' '-D' 'COMPILE_FOR_EWB=1' '-D' 'COMPILE_USE_PL4S=1' '-c' '-Ofast' '-ffunction-sections' '-fdata-sections' '-Wall' '-v' '-fstack-usage' '-MMD' '-MP' '-MF' '-MT' '-specs=nano.specs' '-mfpu=fpv4-sp-d16' '-mfloat-abi=hard' '-mthumb' '-o' '-mlibarch=armv7e-m+fp' '-march=armv7e-m+fp'
-march=armv7e-m -mfloat-abi=hard -mfpu=fpv4-sp-d16 -meabi=5 -o Libraries/STM32L4xx_HAL_Driver/Src/stm32l4xx_hal_pwr.o C:\Users\Piotr\AppData\Local\Temp\ccHP5ygN.s
GNU assembler version 2.36.1 (arm-none-eabi) using BFD version (GNU Tools for STM32 10.3-2021.10.20211105-1100) 2.36.1.20210621
It is a quite big project (~800 source files) 800k generated code. It makes IDE unusable. Only -O0 and -Og prevent from udf instructions to be added.
