diff mbox series

lto-plugin: Add path to libatomic for riscv64

Message ID 31c1c05e-79c6-01d5-4fc1-d401f8b52384@suse.cz
State New
Headers
Series lto-plugin: Add path to libatomic for riscv64 |

Commit Message

Martin Liška July 4, 2022, 11:32 a.m. UTC 
  Similarly to libgo, we need to provide -L for targets where
libpthread does depends on libatomic.

Ready for master?

	PR bootstrap/106156

lto-plugin/ChangeLog:

	* Makefile.am: Use PTHREAD_CFLAGS.
	* Makefile.in: Regenerate.
	* configure.ac: Detect if PTHREAD_CFLAGS should contain path
	to libatomic.
	* configure: Regenerate.
---
 lto-plugin/Makefile.am  |  2 +-
 lto-plugin/Makefile.in  |  3 ++-
 lto-plugin/configure    | 34 ++++++++++++++++++++++++++++++++--
 lto-plugin/configure.ac | 17 +++++++++++++++++
 4 files changed, 52 insertions(+), 4 deletions(-)

Comments

Richard Biener July 4, 2022, 12:28 p.m. UTC | #1 
On Mon, Jul 4, 2022 at 1:32 PM Martin Liška <mliska@suse.cz> wrote:
>
> Similarly to libgo, we need to provide -L for targets where
> libpthread does depends on libatomic.
>
> Ready for master?

OK

>         PR bootstrap/106156
>
> lto-plugin/ChangeLog:
>
>         * Makefile.am: Use PTHREAD_CFLAGS.
>         * Makefile.in: Regenerate.
>         * configure.ac: Detect if PTHREAD_CFLAGS should contain path
>         to libatomic.
>         * configure: Regenerate.
> ---
>  lto-plugin/Makefile.am  |  2 +-
>  lto-plugin/Makefile.in  |  3 ++-
>  lto-plugin/configure    | 34 ++++++++++++++++++++++++++++++++--
>  lto-plugin/configure.ac | 17 +++++++++++++++++
>  4 files changed, 52 insertions(+), 4 deletions(-)
>
> diff --git a/lto-plugin/Makefile.am b/lto-plugin/Makefile.am
> index 81362eafc36..64a6bc8c943 100644
> --- a/lto-plugin/Makefile.am
> +++ b/lto-plugin/Makefile.am
> @@ -10,7 +10,7 @@ libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
>  AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
>  AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
>  # The plug-in depends on pthreads.
> -AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
> +AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
>  AM_LIBTOOLFLAGS = --tag=disable-static
>  override CFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(CFLAGS))
>  override LDFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(LDFLAGS))
> diff --git a/lto-plugin/Makefile.in b/lto-plugin/Makefile.in
> index 2033dd9b7c2..de19c8873de 100644
> --- a/lto-plugin/Makefile.in
> +++ b/lto-plugin/Makefile.in
> @@ -264,6 +264,7 @@ PACKAGE_TARNAME = @PACKAGE_TARNAME@
>  PACKAGE_URL = @PACKAGE_URL@
>  PACKAGE_VERSION = @PACKAGE_VERSION@
>  PATH_SEPARATOR = @PATH_SEPARATOR@
> +PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
>  RANLIB = @RANLIB@
>  SED = @SED@
>  SET_MAKE = @SET_MAKE@
> @@ -345,7 +346,7 @@ libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
>  AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
>  AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
>  # The plug-in depends on pthreads.
> -AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
> +AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
>  AM_LIBTOOLFLAGS = --tag=disable-static
>  libexecsub_LTLIBRARIES = liblto_plugin.la
>  in_gcc_libs = $(foreach lib, $(libexecsub_LTLIBRARIES), $(gcc_build_dir)/$(lib))
> diff --git a/lto-plugin/configure b/lto-plugin/configure
> index aaa91a63623..aa35bd94b3f 100755
> --- a/lto-plugin/configure
> +++ b/lto-plugin/configure
> @@ -650,6 +650,7 @@ LD
>  FGREP
>  SED
>  LIBTOOL
> +PTHREAD_CFLAGS
>  LTO_PLUGIN_USE_SYMVER_SUN_FALSE
>  LTO_PLUGIN_USE_SYMVER_SUN_TRUE
>  LTO_PLUGIN_USE_SYMVER_GNU_FALSE
> @@ -6020,6 +6021,35 @@ fi
>
>
>
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether -pthread is supported" >&5
> +$as_echo_n "checking whether -pthread is supported... " >&6; }
> +if ${lto_plugin_cv_lib_pthread+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  CFLAGS_hold=$CFLAGS
> +CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
> +cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +int i;
> +_ACEOF
> +if ac_fn_c_try_compile "$LINENO"; then :
> +  lto_plugin_cv_lib_pthread=yes
> +else
> +  lto_plugin_cv_lib_pthread=no
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> +CFLAGS=$CFLAGS_hold
> +fi
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $lto_plugin_cv_lib_pthread" >&5
> +$as_echo "$lto_plugin_cv_lib_pthread" >&6; }
> +PTHREAD_CFLAGS=
> +if test "$libgo_cv_lib_pthread" = yes; then
> +  # RISC-V apparently adds -latomic when using -pthread.
> +  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
> +fi
> +
> +
> +
>  case `pwd` in
>    *\ * | *\    *)
>      { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Libtool does not cope well with whitespace in \`pwd\`" >&5
> @@ -12091,7 +12121,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 12094 "configure"
> +#line 12124 "configure"
>  #include "confdefs.h"
>
>  #if HAVE_DLFCN_H
> @@ -12197,7 +12227,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 12200 "configure"
> +#line 12230 "configure"
>  #include "confdefs.h"
>
>  #if HAVE_DLFCN_H
> diff --git a/lto-plugin/configure.ac b/lto-plugin/configure.ac
> index c2ec512880f..ba34a5d0ca1 100644
> --- a/lto-plugin/configure.ac
> +++ b/lto-plugin/configure.ac
> @@ -91,6 +91,23 @@ AM_CONDITIONAL(LTO_PLUGIN_USE_SYMVER_SUN, [test "x$lto_plugin_use_symver" = xsun
>  AC_CHECK_HEADER(pthread.h,
>    [AC_DEFINE(HAVE_PTHREAD_H, 1, [Define to 1 if pthread.h is present.])])
>
> +dnl Test whether the compiler supports the -pthread option.
> +AC_CACHE_CHECK([whether -pthread is supported],
> +[lto_plugin_cv_lib_pthread],
> +[CFLAGS_hold=$CFLAGS
> +CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
> +AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
> +[lto_plugin_cv_lib_pthread=yes],
> +[lto_plugin_cv_lib_pthread=no])
> +CFLAGS=$CFLAGS_hold])
> +PTHREAD_CFLAGS=
> +if test "$libgo_cv_lib_pthread" = yes; then
> +  # RISC-V apparently adds -latomic when using -pthread.
> +  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
> +fi
> +AC_SUBST(PTHREAD_CFLAGS)
> +
> +
>  AM_PROG_LIBTOOL
>  ACX_LT_HOST_FLAGS
>  AC_SUBST(target_noncanonical)
> --
> 2.36.1
>
Richard Biener July 4, 2022, 12:28 p.m. UTC | #2 
On Mon, Jul 4, 2022 at 2:28 PM Richard Biener
<richard.guenther@gmail.com> wrote:
>
> On Mon, Jul 4, 2022 at 1:32 PM Martin Liška <mliska@suse.cz> wrote:
> >
> > Similarly to libgo, we need to provide -L for targets where
> > libpthread does depends on libatomic.
> >
> > Ready for master?
>
> OK

... but ... is libatomic properly built for the host?  libgo is a
target library.
>
> >         PR bootstrap/106156
> >
> > lto-plugin/ChangeLog:
> >
> >         * Makefile.am: Use PTHREAD_CFLAGS.
> >         * Makefile.in: Regenerate.
> >         * configure.ac: Detect if PTHREAD_CFLAGS should contain path
> >         to libatomic.
> >         * configure: Regenerate.
> > ---
> >  lto-plugin/Makefile.am  |  2 +-
> >  lto-plugin/Makefile.in  |  3 ++-
> >  lto-plugin/configure    | 34 ++++++++++++++++++++++++++++++++--
> >  lto-plugin/configure.ac | 17 +++++++++++++++++
> >  4 files changed, 52 insertions(+), 4 deletions(-)
> >
> > diff --git a/lto-plugin/Makefile.am b/lto-plugin/Makefile.am
> > index 81362eafc36..64a6bc8c943 100644
> > --- a/lto-plugin/Makefile.am
> > +++ b/lto-plugin/Makefile.am
> > @@ -10,7 +10,7 @@ libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
> >  AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
> >  AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
> >  # The plug-in depends on pthreads.
> > -AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
> > +AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
> >  AM_LIBTOOLFLAGS = --tag=disable-static
> >  override CFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(CFLAGS))
> >  override LDFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(LDFLAGS))
> > diff --git a/lto-plugin/Makefile.in b/lto-plugin/Makefile.in
> > index 2033dd9b7c2..de19c8873de 100644
> > --- a/lto-plugin/Makefile.in
> > +++ b/lto-plugin/Makefile.in
> > @@ -264,6 +264,7 @@ PACKAGE_TARNAME = @PACKAGE_TARNAME@
> >  PACKAGE_URL = @PACKAGE_URL@
> >  PACKAGE_VERSION = @PACKAGE_VERSION@
> >  PATH_SEPARATOR = @PATH_SEPARATOR@
> > +PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
> >  RANLIB = @RANLIB@
> >  SED = @SED@
> >  SET_MAKE = @SET_MAKE@
> > @@ -345,7 +346,7 @@ libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
> >  AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
> >  AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
> >  # The plug-in depends on pthreads.
> > -AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
> > +AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
> >  AM_LIBTOOLFLAGS = --tag=disable-static
> >  libexecsub_LTLIBRARIES = liblto_plugin.la
> >  in_gcc_libs = $(foreach lib, $(libexecsub_LTLIBRARIES), $(gcc_build_dir)/$(lib))
> > diff --git a/lto-plugin/configure b/lto-plugin/configure
> > index aaa91a63623..aa35bd94b3f 100755
> > --- a/lto-plugin/configure
> > +++ b/lto-plugin/configure
> > @@ -650,6 +650,7 @@ LD
> >  FGREP
> >  SED
> >  LIBTOOL
> > +PTHREAD_CFLAGS
> >  LTO_PLUGIN_USE_SYMVER_SUN_FALSE
> >  LTO_PLUGIN_USE_SYMVER_SUN_TRUE
> >  LTO_PLUGIN_USE_SYMVER_GNU_FALSE
> > @@ -6020,6 +6021,35 @@ fi
> >
> >
> >
> > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether -pthread is supported" >&5
> > +$as_echo_n "checking whether -pthread is supported... " >&6; }
> > +if ${lto_plugin_cv_lib_pthread+:} false; then :
> > +  $as_echo_n "(cached) " >&6
> > +else
> > +  CFLAGS_hold=$CFLAGS
> > +CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
> > +cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> > +/* end confdefs.h.  */
> > +int i;
> > +_ACEOF
> > +if ac_fn_c_try_compile "$LINENO"; then :
> > +  lto_plugin_cv_lib_pthread=yes
> > +else
> > +  lto_plugin_cv_lib_pthread=no
> > +fi
> > +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> > +CFLAGS=$CFLAGS_hold
> > +fi
> > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $lto_plugin_cv_lib_pthread" >&5
> > +$as_echo "$lto_plugin_cv_lib_pthread" >&6; }
> > +PTHREAD_CFLAGS=
> > +if test "$libgo_cv_lib_pthread" = yes; then
> > +  # RISC-V apparently adds -latomic when using -pthread.
> > +  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
> > +fi
> > +
> > +
> > +
> >  case `pwd` in
> >    *\ * | *\    *)
> >      { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Libtool does not cope well with whitespace in \`pwd\`" >&5
> > @@ -12091,7 +12121,7 @@ else
> >    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
> >    lt_status=$lt_dlunknown
> >    cat > conftest.$ac_ext <<_LT_EOF
> > -#line 12094 "configure"
> > +#line 12124 "configure"
> >  #include "confdefs.h"
> >
> >  #if HAVE_DLFCN_H
> > @@ -12197,7 +12227,7 @@ else
> >    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
> >    lt_status=$lt_dlunknown
> >    cat > conftest.$ac_ext <<_LT_EOF
> > -#line 12200 "configure"
> > +#line 12230 "configure"
> >  #include "confdefs.h"
> >
> >  #if HAVE_DLFCN_H
> > diff --git a/lto-plugin/configure.ac b/lto-plugin/configure.ac
> > index c2ec512880f..ba34a5d0ca1 100644
> > --- a/lto-plugin/configure.ac
> > +++ b/lto-plugin/configure.ac
> > @@ -91,6 +91,23 @@ AM_CONDITIONAL(LTO_PLUGIN_USE_SYMVER_SUN, [test "x$lto_plugin_use_symver" = xsun
> >  AC_CHECK_HEADER(pthread.h,
> >    [AC_DEFINE(HAVE_PTHREAD_H, 1, [Define to 1 if pthread.h is present.])])
> >
> > +dnl Test whether the compiler supports the -pthread option.
> > +AC_CACHE_CHECK([whether -pthread is supported],
> > +[lto_plugin_cv_lib_pthread],
> > +[CFLAGS_hold=$CFLAGS
> > +CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
> > +AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
> > +[lto_plugin_cv_lib_pthread=yes],
> > +[lto_plugin_cv_lib_pthread=no])
> > +CFLAGS=$CFLAGS_hold])
> > +PTHREAD_CFLAGS=
> > +if test "$libgo_cv_lib_pthread" = yes; then
> > +  # RISC-V apparently adds -latomic when using -pthread.
> > +  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
> > +fi
> > +AC_SUBST(PTHREAD_CFLAGS)
> > +
> > +
> >  AM_PROG_LIBTOOL
> >  ACX_LT_HOST_FLAGS
> >  AC_SUBST(target_noncanonical)
> > --
> > 2.36.1
> >
Martin Liška July 4, 2022, 1:09 p.m. UTC | #3 
On 7/4/22 14:28, Richard Biener wrote:
> ... but ... is libatomic properly built for the host?  libgo is a
> target library.

You're correct.

Well, so the host library should be taken, which works for stage1 lto-plugin:

[  668s] libtool: link: gcc -shared  -fPIC -DPIC  .libs/lto-plugin.o    -pthread -static-libgcc -Wl,--version-script=../../lto-plugin/lto-plugin.map -static-libstdc++ -static-libgcc ../libiberty/pic/libiberty.a   -pthread -Wl,-soname -Wl,liblto_plugin.so -o .libs/liblto_p

while it fails in stage2:

[ 7129s] libtool: link:  /home/abuild/rpmbuild/BUILD/gcc-13.0.0+git194120/obj-riscv64-suse-linux/./prev-gcc/xgcc -B/home/abuild/rpmbuild/BUILD/gcc-13.0.0+git194120/obj-riscv64-suse-linux/./prev-gcc/ -B/usr/riscv64-suse-linux/bin/ -B/usr/riscv64-suse-linux/bin/ -B/usr/riscv64-suse-linux/lib/ -isystem /usr/riscv64-suse-linux/include -isystem /usr/riscv64-suse-linux/sys-include   -fno-checking -shared  -fPIC -DPIC  .libs/lto-plugin.o    -pthread -static-libgcc -Wl,--version-script=../../lto-plugin/lto-plugin.map -static-libstdc++ -static-libgcc ../libiberty/pic/libiberty.a   -pthread -Wl,-soname -Wl,liblto_plugin.so -o .libs/liblto_plugin.so

Where the system compiler takes the library from:
/usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so

that points to system library location:
ls -l /usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so
lrwxrwxrwx 1 root root 41 Mar 24 14:22 /usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so -> ../../../riscv64-linux-gnu/libatomic.so.1

So the question is how to fix that?

Martin
Richard Biener July 5, 2022, 7:27 a.m. UTC | #4 
On Mon, Jul 4, 2022 at 3:09 PM Martin Liška <mliska@suse.cz> wrote:
>
> On 7/4/22 14:28, Richard Biener wrote:
> > ... but ... is libatomic properly built for the host?  libgo is a
> > target library.
>
> You're correct.
>
> Well, so the host library should be taken, which works for stage1 lto-plugin:
>
> [  668s] libtool: link: gcc -shared  -fPIC -DPIC  .libs/lto-plugin.o    -pthread -static-libgcc -Wl,--version-script=../../lto-plugin/lto-plugin.map -static-libstdc++ -static-libgcc ../libiberty/pic/libiberty.a   -pthread -Wl,-soname -Wl,liblto_plugin.so -o .libs/liblto_p
>
> while it fails in stage2:
>
> [ 7129s] libtool: link:  /home/abuild/rpmbuild/BUILD/gcc-13.0.0+git194120/obj-riscv64-suse-linux/./prev-gcc/xgcc -B/home/abuild/rpmbuild/BUILD/gcc-13.0.0+git194120/obj-riscv64-suse-linux/./prev-gcc/ -B/usr/riscv64-suse-linux/bin/ -B/usr/riscv64-suse-linux/bin/ -B/usr/riscv64-suse-linux/lib/ -isystem /usr/riscv64-suse-linux/include -isystem /usr/riscv64-suse-linux/sys-include   -fno-checking -shared  -fPIC -DPIC  .libs/lto-plugin.o    -pthread -static-libgcc -Wl,--version-script=../../lto-plugin/lto-plugin.map -static-libstdc++ -static-libgcc ../libiberty/pic/libiberty.a   -pthread -Wl,-soname -Wl,liblto_plugin.so -o .libs/liblto_plugin.so
>
> Where the system compiler takes the library from:
> /usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so
>
> that points to system library location:
> ls -l /usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so
> lrwxrwxrwx 1 root root 41 Mar 24 14:22 /usr/lib/gcc/riscv64-linux-gnu/11/libatomic.so -> ../../../riscv64-linux-gnu/libatomic.so.1
>
> So the question is how to fix that?

We'd need to add libatomic as host_module in Makefile.def and also
bootstrap that (since lto-plugin is bootstrapped), plus adding
the required dependency.  At least for the targets that need this.

Or give up and use better means of serialization or use a whitelist
for now (via lto-plugin configury) and leave
all not covered targets not thread-safe (see also the mingw bugreport).

Richard.

>
> Martin
>
diff mbox series

Patch

diff --git a/lto-plugin/Makefile.am b/lto-plugin/Makefile.am
index 81362eafc36..64a6bc8c943 100644
--- a/lto-plugin/Makefile.am
+++ b/lto-plugin/Makefile.am
@@ -10,7 +10,7 @@  libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
 AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
 AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
 # The plug-in depends on pthreads.
-AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
+AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
 AM_LIBTOOLFLAGS = --tag=disable-static
 override CFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(CFLAGS))
 override LDFLAGS := $(filter-out -fsanitize=address -fsanitize=hwaddress,$(LDFLAGS))
diff --git a/lto-plugin/Makefile.in b/lto-plugin/Makefile.in
index 2033dd9b7c2..de19c8873de 100644
--- a/lto-plugin/Makefile.in
+++ b/lto-plugin/Makefile.in
@@ -264,6 +264,7 @@  PACKAGE_TARNAME = @PACKAGE_TARNAME@
 PACKAGE_URL = @PACKAGE_URL@
 PACKAGE_VERSION = @PACKAGE_VERSION@
 PATH_SEPARATOR = @PATH_SEPARATOR@
+PTHREAD_CFLAGS = @PTHREAD_CFLAGS@
 RANLIB = @RANLIB@
 SED = @SED@
 SET_MAKE = @SET_MAKE@
@@ -345,7 +346,7 @@  libexecsubdir := $(libexecdir)/gcc/$(real_target_noncanonical)/$(gcc_version)$(a
 AM_CPPFLAGS = -I$(top_srcdir)/../include $(DEFS)
 AM_CFLAGS = @ac_lto_plugin_warn_cflags@ $(CET_HOST_FLAGS)
 # The plug-in depends on pthreads.
-AM_LDFLAGS = -pthread @ac_lto_plugin_ldflags@
+AM_LDFLAGS = $(PTHREAD_CFLAGS) @ac_lto_plugin_ldflags@
 AM_LIBTOOLFLAGS = --tag=disable-static
 libexecsub_LTLIBRARIES = liblto_plugin.la
 in_gcc_libs = $(foreach lib, $(libexecsub_LTLIBRARIES), $(gcc_build_dir)/$(lib))
diff --git a/lto-plugin/configure b/lto-plugin/configure
index aaa91a63623..aa35bd94b3f 100755
--- a/lto-plugin/configure
+++ b/lto-plugin/configure
@@ -650,6 +650,7 @@  LD
 FGREP
 SED
 LIBTOOL
+PTHREAD_CFLAGS
 LTO_PLUGIN_USE_SYMVER_SUN_FALSE
 LTO_PLUGIN_USE_SYMVER_SUN_TRUE
 LTO_PLUGIN_USE_SYMVER_GNU_FALSE
@@ -6020,6 +6021,35 @@  fi
 
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether -pthread is supported" >&5
+$as_echo_n "checking whether -pthread is supported... " >&6; }
+if ${lto_plugin_cv_lib_pthread+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  CFLAGS_hold=$CFLAGS
+CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int i;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  lto_plugin_cv_lib_pthread=yes
+else
+  lto_plugin_cv_lib_pthread=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+CFLAGS=$CFLAGS_hold
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $lto_plugin_cv_lib_pthread" >&5
+$as_echo "$lto_plugin_cv_lib_pthread" >&6; }
+PTHREAD_CFLAGS=
+if test "$libgo_cv_lib_pthread" = yes; then
+  # RISC-V apparently adds -latomic when using -pthread.
+  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
+fi
+
+
+
 case `pwd` in
   *\ * | *\	*)
     { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Libtool does not cope well with whitespace in \`pwd\`" >&5
@@ -12091,7 +12121,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12094 "configure"
+#line 12124 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12197,7 +12227,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12200 "configure"
+#line 12230 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/lto-plugin/configure.ac b/lto-plugin/configure.ac
index c2ec512880f..ba34a5d0ca1 100644
--- a/lto-plugin/configure.ac
+++ b/lto-plugin/configure.ac
@@ -91,6 +91,23 @@  AM_CONDITIONAL(LTO_PLUGIN_USE_SYMVER_SUN, [test "x$lto_plugin_use_symver" = xsun
 AC_CHECK_HEADER(pthread.h,
   [AC_DEFINE(HAVE_PTHREAD_H, 1, [Define to 1 if pthread.h is present.])])
 
+dnl Test whether the compiler supports the -pthread option.
+AC_CACHE_CHECK([whether -pthread is supported],
+[lto_plugin_cv_lib_pthread],
+[CFLAGS_hold=$CFLAGS
+CFLAGS="$CFLAGS -pthread -L../$build/libatomic/.libs"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
+[lto_plugin_cv_lib_pthread=yes],
+[lto_plugin_cv_lib_pthread=no])
+CFLAGS=$CFLAGS_hold])
+PTHREAD_CFLAGS=
+if test "$libgo_cv_lib_pthread" = yes; then
+  # RISC-V apparently adds -latomic when using -pthread.
+  PTHREAD_CFLAGS="-pthread -L../$build/libatomic/.libs"
+fi
+AC_SUBST(PTHREAD_CFLAGS)
+
+
 AM_PROG_LIBTOOL
 ACX_LT_HOST_FLAGS
 AC_SUBST(target_noncanonical)