Bug 206588: devel/powerpc64-gcc on amd64 defines _LITTLE_ENDIAN, __NO_STRICT_ALIGNMENT, etc.

[Mark Millard]

I've submitted Bug 206588 from which the below is quoted (but is not all the text). First I list my later comment then the beginning of the description.

> This is likely more an issue of not having a proper set of headers to use with powerpc64-gcc when cross compiling from other architectures, such as little endian ones.
> 
> It is still a cross compiler usage difficulty that is not handled or documented.


> I used the following program and compiler command line options to dump macro definitions from devel/powerpc64-gcc and discovered some nasty ones: LITTLE_ENDIAN usage on amd64 despite targeting a big endian powerpc64. Differing __NO_STRICT_ALIGNMENT status and __GCC_HAVE_DWARF2_CFI_ASM status as well. The details follow.
> 
> # more with_libc++__config.cpp 
> #include <__config>
> int main(void)
> { return 0; }
> 
> used via:
> 
> /usr/local/bin/powerpc64-portbld-freebsd11.0-g++ -std=c++11 -I/usr/include -I/usr/include/c++/v1/ -dM -E func.cpp | sort > ~/powerpc64-gcc_52_macros.txt
> 
> on a native powerpc64 (Powermac G5) context and on a amd64 context (inside Virtual Box on Mac OS X). The "<"'s below are from the G5 context and the ">" below are from the amd64 context.
> 
> There is also a related __NO_STRICT_ALIGNMENT difference and a __GCC_HAVE_DWARF2_CFI_ASM difference.
> 
> # diff /media/root/powerpc64_gcc_52_macros.txt ~/powerpc64_gcc_52_macros.txt | more
> 16c16
> < #define _BYTE_ORDER _BIG_ENDIAN
> ---
> 
> > #define _BYTE_ORDER _LITTLE_ENDIAN
> 
> 27c27
> < #define _LIBCPP_BIG_ENDIAN 1
> ---
> 
> > #define _LIBCPP_BIG_ENDIAN 0
> 
> 60c60
> < #define _LIBCPP_LITTLE_ENDIAN 0
> ---
> 
> > #define _LIBCPP_LITTLE_ENDIAN 1
> 
> 84,85c84,85
> < #define _QUAD_HIGHWORD 0
> < #define _QUAD_LOWWORD 1
> ---
> 
> > #define _QUAD_HIGHWORD 1
> > #define _QUAD_LOWWORD 0
> 
> 
> 200d199
> < #define __GCC_HAVE_DWARF2_CFI_ASM 1
> 289a289
> 
> > #define __NO_STRICT_ALIGNMENT 
. . .

===
Mark Millard
markmi at dsl-only.net