Re: GCC 4.4 cross compiler and issue with __floatdidf

[Kai Ruottu <kai dot ruottu at wippies dot com>]

Vincent R. wrote:

> > > > > > > When compiling the following code with a gcc 4.4 cross-compiler 
> > > > > > > targetting
> > > > > > > arm wince platform I get a problem with undefined reference
> > > __floatdidf
> > > > When using nm with gcc-4.4:
> > > >
> > > > $ arm-mingw32ce-nm libgcc.a | grep float
> > > > _floatundidf.o:
> > > > 00000000 T __floatundidf
> > > >          U __floatunsidf

Somewhere is the source for this module '_floatundidf.o'...

> > > > with an old working version (4.1.2):
> > > >
> > > > 0000038c T __floatdidf
> > > > 00000310 T __floatsidf
> > > > 00000378 T __floatundidf
> > > > 000002ec T __floatunsidf
> > > > 00000200 T __floatdisf
> > > > 000001d0 T __floatsisf
> > > > 000001f0 T __floatundisf
> > > > 000001c8 T __floatunsisf

These symbols then being in module '_arm_addsubdf3.o' (which
was not produced)

> > > I found why it's because of the following test :
> > >
> > > #ifdef L_arm_addsubdf3
> > > ...
> > > #endif
> > >
> > > Now I need to find why L_arm_addsubdf3 is defined.

"Not defined" maybe was the aim to write...

> So I am still stuck with this missing symbol.
> What I don't understand is the fact that __floatundidf is available but not
>  __floatdidf.

Something else seems to add this although it too should
be in the '_arm_addsubdf3.o' module...

>  If I look in gcc/config/arm/t-wince-pe here is what is declared for my
>  target:
>  LIB1ASMSRC = arm/lib1funcs.asm
>  
>  LIB1ASMFUNCS = _udivsi3 _divsi3 _umodsi3 _modsi3 _dvmd_tls _call_via_rX
>  _interwork_call_via_rX _clzsi2 _clzdi2 \
>  	_bb_init_func _lshrdi3 _ashrdi3 _ashldi3 \
>  	_negdf2 _addsubdf3 _muldivdf3 _cmpdf2 _unorddf2 _fixdfsi _fixunsdfsi \
>  	_truncdfsf2 _negsf2 _addsubsf3 _muldivsf3 _cmpsf2 _unordsf2 \
>  	_fixsfsi _fixunssfsi _floatdidf _floatdisf \
>  	_arm_fixunsdfsi
>  
>  and I can see that _floatdidf is declared but is not available in libgcc

These should be object module names, so a '_floatdidf.o' should be
the result from something but the symbol names in it could be totally
different... The 'L_arm_addsubdf3' isn't defined so nothing in that
module will appear...

> Does it mean I need to remove _floatdidf _floatdisf from the list ?

No, you could try editing the '_addsubdf3' to '_arm_addsubdf3' and see
what happens...

> Maybe the problem comes from the patch I am applying against vanilla gcc :
>
> Index: gcc/config/arm/t-wince-pe
> ===================================================================
> --- gcc/config/arm/t-wince-pe	(rÃvision 144104)
> +++ gcc/config/arm/t-wince-pe	(copie de travail)
> @@ -1,6 +1,26 @@
>  LIB1ASMSRC = arm/lib1funcs.asm
> -LIB1ASMFUNCS = _udivsi3 _divsi3 _umodsi3 _modsi3 _dvmd_tls _call_via_rX
> _interwork_call_via_rX _clzsi2 _clzdi2
>  
> +LIB1ASMFUNCS = _udivsi3 _divsi3 _umodsi3 _modsi3 _dvmd_tls _call_via_rX
> _interwork_call_via_rX _clzsi2 _clzdi2 \
> +	_bb_init_func _lshrdi3 _ashrdi3 _ashldi3 \
> +	_negdf2 _addsubdf3 _muldivdf3 _cmpdf2 _unorddf2 _fixdfsi _fixunsdfsi \
> +	_truncdfsf2 _negsf2 _addsubsf3 _muldivsf3 _cmpsf2 _unordsf2 \
> +	_fixsfsi _fixunssfsi _floatdidf _floatdisf \
> +	_arm_fixunsdfsi
> +
> +# For most CPUs we have an assembly soft-float implementations.
> +# However this is not true for ARMv6M.  Here we want to use the soft-fp C
> +# implementation.  The soft-fp code is only build for ARMv6M.  This pulls
> +# in the asm implementation for other CPUs.
> +#LIB1ASMFUNCS = _udivsi3 _divsi3 _umodsi3 _modsi3 _dvmd_tls _bb_init_func
> \
> +#	_call_via_rX _interwork_call_via_rX \
> +#	_lshrdi3 _ashrdi3 _ashldi3 \
> +#	_arm_negdf2 _arm_addsubdf3 _arm_muldivdf3 _arm_cmpdf2 _arm_unorddf2 \
> +#	_arm_fixdfsi _arm_fixunsdfsi \
> +#	_arm_truncdfsf2 _arm_negsf2 _arm_addsubsf3 _arm_muldivsf3 \
> +#	_arm_cmpsf2 _arm_unordsf2 _arm_fixsfsi _arm_fixunssfsi \
> +#	_arm_floatdidf _arm_floatdisf _arm_floatundidf _arm_floatundisf \
> +#	_clzsi2 _clzdi2
> +

Yes, this removes producing those '_arm_*' modules in 'ieee754-df.S' !
There is no module sources for '_addsubdf3' available in my gcc-4.4
sources :

[root@Dell arm]# grep addsubdf3 *
bpabi-v6m.S:#ifdef L_arm_addsubdf3
bpabi-v6m.S:#endif /* L_arm_addsubdf3 */
ieee754-df.S:#ifdef L_arm_addsubdf3
ieee754-df.S:#endif /* L_addsubdf3 */
t-arm-elf:      _arm_negdf2 _arm_addsubdf3 _arm_muldivdf3 _arm_cmpdf2 
_arm_unorddf2 \
t-linux:        _arm_addsubdf3 _arm_addsubsf3
t-symbian:      _negdf2 _addsubdf3 _muldivdf3 _cmpdf2 _unorddf2 _fixdfsi 
_fixunsdfsi \

only for '_arm_addsubdf3'... So the purpose for the 'patch' is quite
unclear, WHY all those '_arm_*' modules were removed from libgcc ?

Did the old gcc-4.1.2 use these modules?  Maybe the naming there was
different? Let's see :

#ifdef L_addsubdf3

ARM_FUNC_START aeabi_drsub

        eor     xh, xh, #0x80000000     @ flip sign bit of first arg
        b       1f

ARM_FUNC_START subdf3
ARM_FUNC_ALIAS aeabi_dsub subdf3

        eor     yh, yh, #0x80000000     @ flip sign bit of second arg
#if defined(__INTERWORKING_STUBS__)
        b       1f                      @ Skip Thumb-code prologue
#endif

Yes, the naming was changed and gcc-4.4 has added that '_arm' into the
module names...

So my advice is that you would fix the symbol names to have that '_arm'
prefix in LIB1ASMFUNCS !  Where there originally was that, let's have
it still !