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Re: Linker error only when compiling with -O0 (-Os works)
- From: Oleg Endo <oleg dot endo at t-online dot de>
- To: Christian <lkml at janoff dot de>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Sun, 10 Feb 2013 21:50:11 +0100
- Subject: Re: Linker error only when compiling with -O0 (-Os works)
- References: <511805CB.2050600@janoff.de>
On Sun, 2013-02-10 at 21:40 +0100, Christian wrote:
> 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?
I'm just guessing here...
When compiling for -Os the calls to the unwinding code are optimized
away and for -O0 they remain. The unwinder code is usually part of
libgcc which seems to be not included in your linking step.
Probably because of '-nostdlib'...
Cheers,
Oleg