On Wed, Sep 06, 2023 at 06:38:25PM +0800, Xi Ruoyao wrote:
> On Wed, 2023-09-06 at 18:06 +0800, Yang Yujie wrote:
> > When multilib is enabled, the c++ header directory of the default multilib
> > variant needs to be linked to the toplevel since g++ does not search the
> > toplevel in this case.
> >
> > libstdc++-v3/ChangeLog:
> >
> > * configure.host: Register t-loongarch in tmake_file.
> > * config/cpu/loongarch/t-loongarch: New file. Link c++ header
> > directory in the default ABI to the toplevel.
> > ---
> > libstdc++-v3/config/cpu/loongarch/t-loongarch | 12 ++++++++++++
> > libstdc++-v3/configure.host | 5 ++++-
> > 2 files changed, 16 insertions(+), 1 deletion(-)
> > create mode 100644 libstdc++-v3/config/cpu/loongarch/t-loongarch
> >
> > diff --git a/libstdc++-v3/config/cpu/loongarch/t-loongarch
> > b/libstdc++-v3/config/cpu/loongarch/t-loongarch
> > new file mode 100644
> > index 00000000000..942eddeb3be
> > --- /dev/null
> > +++ b/libstdc++-v3/config/cpu/loongarch/t-loongarch
> > @@ -0,0 +1,12 @@
> > +LA_DEFAULT_MULTIDIR = $(shell $(CXX) --print-multi-directory)
> > +TOPLEV_HEADERS =
> > $(DESTDIR)${gxx_include_dir}/${host_alias}/$(LA_DEFAULT_MULTIDIR)
> > +
> > +.PHONY: install-toplevel-link
> > +install: install-toplevel-link
> > +install-toplevel-link:
> > + if test x$(MULTIDO) != xtrue && \
> > + test x$(LA_DEFAULT_MULTIDIR) != x.; then \
> > + $(MKDIR_P) "$(dir $(TOPLEV_HEADERS))"; \
> > + rm -rf "$(TOPLEV_HEADERS)"; \
> > + $(LN_S) ../ "$(TOPLEV_HEADERS)"; \
>
> From autoconf info page:
>
> -- Macro: AC_PROG_LN_S
> If ‘ln -s’ works on the current file system (the operating system
> and file system support symbolic links), set the output variable
> ‘LN_S’ to ‘ln -s’; otherwise, if ‘ln’ works, set ‘LN_S’ to ‘ln’,
> and otherwise set it to ‘cp -pR’.
>
> If you make a link in a directory other than the current directory,
> its meaning depends on whether ‘ln’ or ‘ln -s’ is used. To safely
> create links using ‘$(LN_S)’, either find out which form is used
> and adjust the arguments, or always invoke ‘ln’ in the directory
> where the link is to be created.
>
> In other words, it does not work to do:
> $(LN_S) foo /x/bar
>
> Instead, do:
>
> (cd /x && $(LN_S) foo bar)
>
> But for this special case we cannot "cp -pR ../ $(TOPLEV_HEADERS)"
> either:
>
> $ cp ../* -pR something
> cp: cannot copy a directory, '../g', into itself, 'h/g'
>
> So I guess we'll need something like
>
> if ln -s ../ "$(TOPLEV_HEADERS)"; then
> # OK!
> true
> else
> # system does not support symlink :(
> # install another copy of toplevel headers into default multilib subdir
> TODO: ????????
> fi
>
> And all libstdc++ patches should Cc: libstd...@gcc.gnu.org.
>
> > + fi
> > diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
> > index 9e7c7f02dfd..9dc42ad3edb 100644
> > --- a/libstdc++-v3/configure.host
> > +++ b/libstdc++-v3/configure.host
> > @@ -315,7 +315,10 @@ esac
> > # Set any OS-dependent and CPU-dependent bits.
> > # THIS TABLE IS SORTED. KEEP IT THAT WAY.
> > case "${host}" in
> > - *-*-linux* | *-*-uclinux*)
> > + loongarch*)
> > + tmake_file="cpu/loongarch/t-loongarch"
> > + ;;
> > + *-*-linux* | *-*-uclinux*)
> > case "${host_cpu}" in
> > i[567]86)
> > abi_baseline_pair=i486-linux-gnu
>
> --
> Xi Ruoyao <xry...@xry111.site>
> School of Aerospace Science and Technology, Xidian University
Thanks for the review!
After some tweaking, it appeared that we can simply override
${multisubdir} in configure.host and achieve the same.
I will upload another patch soon.
Yujie
