fdlibm is not C99 conformant

>
> On Wed, Dec 29, 2010 at 09:21:29PM +0100, Nicolas Cellier wrote:
>>
>> Hi,
>> I suggest using replacements for __HI() and __LO() without illegal
>> pointer dereferencing.
>> One stupid possibility is to use an explicit memory copy, like in this
>> example: (see test_fdlibm.c attachment)
>>
>> I've tested with:
>>     gcc -m64 -Wall -02 -D__LITTLE_ENDIAN test_fdlibm.c
>>     ./a.out
>> and obtained
>>     x=-3.14159
>>
>> Of course, it'll be a bit slower, but we don't care.
>> More problematic is that we would have to change all the fdlibm sources...
>
> Thanks Nicolas,
>
> But the __HI and __LO macros look fine to me, and they seem to work as
> expected (see attached update to your test). Is there an alignment issue
> here that I'm missing?
>
> Dave
>

> PLUGIN_DEFINITIONS (-DNO_ISNAN=1)
> TEST_BIG_ENDIAN(IS_BIGENDER)
> IF (NOT IS_BIGENDER)
> # fdlibm.h does not handle x86_64, so set it here for all platforms
> PLUGIN_DEFINITIONS (-D__LITTLE_ENDIAN=1)
> ENDIF()
> # The fdlibm library must be compiled with no gcc optimization. Add -O0 to
> # the CFLAGS string to override the optimization setting.
> SET (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0")

>
> On Thu, Dec 30, 2010 at 01:48:55AM +0100, Nicolas Cellier wrote:
>>
>> >
>> > OK, got it, you have to compile with -D__LITTLE_ENDIAN
>> > This macro is set automatically in fdlibm.h when compiled ith -m32 but
>> > not when compiled with -m64
>> >
>> > Nicolas
>> >
>>
>> We can add something like
>>   || defined(__x86_64)
>> in fdlibm.h
>>
>> your macro definitions can be obtained via
>> gcc -E -dM - < /dev/null
>>
>> Nicolas
>
> Bravo, good catch! This solves the problem, and all KernelTests-Numbers
> are now green with a 64-bit Linux VM.
>
> Patching fdlibm.h solves the problem, but it is probably not good policy
> to be making local patches to the library, so I think a more general fix
> is to set __LITTLE_ENDIAN properly in the build system.
>
> Attached is a platforms/unix/plugins/FloatMathPlugin/config.cmake that
> addresses this, and that also sets the -O0 flag to disable gcc optimization.
>
> I'll forward this to Ian also for the platforms/unix update.
>
> Igor and Esteban, you may need to do something similar if you build a
> 32/64 bit Mac VM.
>