Re: [ARM/FDPIC v5 02/21] [ARM] FDPIC: Handle arm*-*-uclinuxfdpiceabi in configure scripts

[Richard Sandiford <richard.sandiford@arm.com>]

Christophe Lyon <christophe.lyon@linaro.org> writes:
> On Fri, 30 Aug 2019 at 11:00, Richard Sandiford
> <richard.sandiford@arm.com> wrote:
>>
>> Christophe Lyon <christophe.lyon@st.com> writes:
>> > @@ -785,7 +785,7 @@ case ${target} in
>> >    esac
>> >    tmake_file="t-slibgcc"
>> >    case $target in
>> > -    *-*-linux* | frv-*-*linux* | *-*-kfreebsd*-gnu | *-*-kopensolaris*-gnu)
>> > +    *-*-linux* | frv-*-*linux* | *-*-kfreebsd*-gnu | *-*-kopensolaris*-gnu  | *-*-uclinuxfdpiceabi)
>> >        :;;
>> >      *-*-gnu*)
>> >        native_system_header_dir=/include
>>
>> I don't think this is necessary, since this target will never match the
>> following *-*-gnu*) stanza anyway.
> OK (I thought it was clearer to add the fdpic config where we already
> have linux that would not match)

I think the idea is to match pure GNU systems only in the second stanza
(i.e. GNU/Hurd).  So we need the first stanza to exclude hybrid-GNU
systems like GNU/Linux, GNU/Solaris, GNU/FreeBSD, etc.

Since uclinuxfdpiceabi isn't a GNU-based system, I don't think it
needs to appear at all.

>> > diff --git a/libtool.m4 b/libtool.m4
>> > index 8966762..64e507a 100644
>> > --- a/libtool.m4
>> > +++ b/libtool.m4
>> > @@ -3734,7 +3739,7 @@ m4_if([$1], [CXX], [
>> >           ;;
>> >       esac
>> >       ;;
>> > -      linux* | k*bsd*-gnu | kopensolaris*-gnu)
>> > +      linux* | k*bsd*-gnu | kopensolaris*-gnu | uclinux*)
>> >       case $cc_basename in
>> >         KCC*)
>> >           # KAI C++ Compiler
>>
>> Is this needed?  It seems to be in the !GCC branch of an if/else.
> I must admit I didn't test this case. I thought it was needed because
> this target does not match "linux*", in case someone tries to compile
> with another compiler...
>
>
>>
>> If it is needed, the default:
>>
>>         _LT_TAGVAR(lt_prog_compiler_can_build_shared, $1)=no
>>
>> seems correct for non-FDPIC uclinux.
>>
> So, either use uclinuxfdpiceabi above, or do nothing and do not try to
> support other compilers?

Yeah.  I think the latter's better, since in this context we only
need libtool.m4 to support building with GCC.  The decision might
be different for upstream libtool, but do any commercial compilers
support Arm FDPIC yet?

>> > @@ -4032,7 +4037,7 @@ m4_if([$1], [CXX], [
>> >        _LT_TAGVAR(lt_prog_compiler_static, $1)='-non_shared'
>> >        ;;
>> >
>> > -    linux* | k*bsd*-gnu | kopensolaris*-gnu)
>> > +    linux* | k*bsd*-gnu | kopensolaris*-gnu | uclinux*)
>> >        case $cc_basename in
>> >        # old Intel for x86_64 which still supported -KPIC.
>> >        ecc*)
>>
>> Same here.
>>
>> > @@ -5946,7 +5951,7 @@ if test "$_lt_caught_CXX_error" != yes; then
>> >          _LT_TAGVAR(inherit_rpath, $1)=yes
>> >          ;;
>> >
>> > -      linux* | k*bsd*-gnu | kopensolaris*-gnu)
>> > +      linux* | k*bsd*-gnu | kopensolaris*-gnu | uclinuxfdpiceabi)
>> >          case $cc_basename in
>> >            KCC*)
>> >           # Kuck and Associates, Inc. (KAI) C++ Compiler
>>
>> Here too the code seems to be dealing specifically with non-GCC compilers.
>>
>> > @@ -6598,7 +6603,7 @@ interix[[3-9]]*)
>> >    _LT_TAGVAR(postdeps,$1)=
>> >    ;;
>> >
>> > -linux*)
>> > +linux* | uclinux*)
>> >    case `$CC -V 2>&1 | sed 5q` in
>> >    *Sun\ C*)
>> >      # Sun C++ 5.9
>>
>> Here too.  (It only seems to do anything for Sun's C compiler.)
>>
>> The fewer hunks we have to maintain downstream the better :-)
>>
> Sure.
>
> I thought safer/cleaner to prepare the cases for non-GCC compilers, I
> guess it's better not to add that until proven useful?

Yeah, I think so.  I guess it depends on your POV.  To me, it seems
cleaner to add uclinux* and uclinuxfdpiceabi only where we know there's
a specific need, since that's also how we decide which of uclinux* and
uclinuxfdpiceabi to use.

Thanks,
Richard