Linker error only when compiling with -O0 (-Os works)

[Christian <lkml at janoff dot de>]

Hi there,

I want to use a (pre-existing) project for embedded ARM
(Cortex-M3 processor).

The 2 files will compile and link fine when compiling with -Os:

--- start ---
arm-softfloat-linux-gnueabi-gcc -fno-strict-aliasing -mcpu=cortex-m3
-mthumb -Wall -g -Os -msoft-float -Tstm32.ld -nostdlib -nostartfiles -c
../../../targets/olimex/main_olimex.cpp

arm-softfloat-linux-gnueabi-gcc -fno-strict-aliasing -mcpu=cortex-m3
-mthumb -Wall -g -Os -msoft-float -Tstm32.ld -nostdlib -nostartfiles -c
stm32f10x_vector.c

arm-softfloat-linux-gnueabi-gcc -fno-strict-aliasing -mcpu=cortex-m3
-mthumb -Wall -g -Os -msoft-float -Tstm32.ld -nostdlib -nostartfiles -o
target.elf -Wl,--gc-sections,-Map=all.map,-cref,-u,Reset_Handler
main_olimex.o stm32f10x_vector.o
--- end ---

If I use -O0 (for debugging reasons) the files will still compile
but they won't link:

--- start ---
arm-softfloat-linux-gnueabi-gcc -fno-strict-aliasing -mcpu=cortex-m3
-mthumb -Wall -g -O0 -msoft-float -Tstm32.ld -nostdlib -nostartfiles -o
target.elf -Wl,--gc-sections,-Map=all.map,-cref,-u,Reset_Handler
main_olimex.o stm32f10x_vector.o
main_olimex.o:(.ARM.exidx+0x28): undefined reference to
`__aeabi_unwind_cpp_pr1'
main_olimex.o:(.ARM.exidx+0xc0): undefined reference to
`__aeabi_unwind_cpp_pr0'
main_olimex.o:(.ARM.exidx.text._ZN14name_citlUsage9name_Citl15name_debugTools10DebugToolsIN7guclLib12uart_stm32fxINS3_3allINS0_4CitlINS0_8name_STD17PlatformCfgPresetEE4MmplEE9cfgPreset4uartESA_E4bodyIN7stm32fx11app_stm32fxI10appAdapterE7guclCfgIN18platformDispatcherISI_E7depBodyEN3ind3appISI_E7guclCfgINSM_7indBodyENS3_11all_stm32fxISC_SA_E9cfgPresetEEEE4uartENSU_4bodyISX_NSB_4bodyISX_EEE12indBody_uartENS3_12gpio_stm32fxINSC_4gpioESA_E4bodyINS16_9cfgPresetENS12_12indBody_gpioENS3_11sys_stm32fxINSC_3sysESA_E4bodyINS1C_9cfgPresetENS12_11indBody_sysEEEEES1G_E4portILi0EEELi100ELb1ENSI_3EnvEE13writeDebugStrEPh[_ZN14name_citlUsage9name_Citl15name_debugTools10DebugToolsIN7guclLib12uart_stm32fxINS3_3allINS0_4CitlINS0_8name_STD17PlatformCfgPresetEE4MmplEE9cfgPreset4uartESA_E4bodyIN7stm32fx11app_stm32fxI10appAdapterE7guclCfgIN18platformDispatcherISI_E7depBodyEN3ind3appISI_E7guclCfgINSM_7indBodyENS3_11all_stm32fxISC_SA_E9cfgPresetEEEE4uartENSU_4bodyISX_NSB_4bodyISX_EEE12indBody_uartENS3_12gpio_stm32fxINSC_4gpioESA_E4bodyINS16_9cfgPresetENS12_12indBody_gpioENS3_11sys_stm32fxINSC_3sysESA_E4bodyINS1C_9cfgPresetENS12_11indBody_sysEEEEES1G_E4portILi0EEELi100ELb1ENSI_3EnvEE13writeDebugStrEPh]+0x0):
undefined reference to `__aeabi_unwind_cpp_pr1'
main_olimex.o: In function `name_citlUsage::name_Citl::na...

<and so on ...>

--- end ---

=> -Os links. -O0 doesn't.

Any idea what's going on here?

Christian