[PATCH 1/2] GCN, libstdc++: '#define _GLIBCXX_USE_WEAK_REF 0' [PR119369]

[Jonathan Wakely]

On Mon, 31 Mar 2025 at 10:50, Thomas Schwinge <tschwinge@baylibre.com> wrote:
>
> This fixes a few hundreds of compilation/linking FAILs (similar to PR69506),
> where the GCN/LLVM 'ld' reported:
>
>     ld: error: relocation R_AMDGPU_REL32_LO cannot be used against symbol '_ZGTtnam'; recompile with -fPIC
>     >>> defined in [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a(cow-stdexcept.o)
>     >>> referenced by cow-stdexcept.cc:259 ([...]/libstdc++-v3/src/c++11/cow-stdexcept.cc:259)
>     >>>               cow-stdexcept.o:(_txnal_cow_string_C1_for_exceptions(void*, char const*, void*)) in archive [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a
>
>     ld: error: relocation R_AMDGPU_REL32_HI cannot be used against symbol '_ZGTtnam'; recompile with -fPIC
>     >>> defined in [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a(cow-stdexcept.o)
>     >>> referenced by cow-stdexcept.cc:259 ([...]/source-gcc/libstdc++-v3/src/c++11/cow-stdexcept.cc:259)
>     >>>               cow-stdexcept.o:(_txnal_cow_string_C1_for_exceptions(void*, char const*, void*)) in archive [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a
>
>     [...]
>
> ..., which is:
>
>     $ c++filt _ZGTtnam
>     transaction clone for operator new[](unsigned long)
>
> ..., and similarly for other libitm symbols.
>
> However, the affected test cases, if applicable, then run into execution test
> FAILs, due to PR119369
> "GCN: weak undefined symbols -> execution test FAIL, 'HSA_STATUS_ERROR_VARIABLE_UNDEFINED'".
>
>         PR target/119369
>         libstdc++-v3/
>         * config/cpu/gcn/cpu_defines.h: New.
>         * configure.host [GCN] (cpu_defines_dir): Point to it.


OK for trunk, thanks.

> ---
>  libstdc++-v3/config/cpu/gcn/cpu_defines.h | 55 +++++++++++++++++++++++
>  libstdc++-v3/configure.host               |  3 ++
>  2 files changed, 58 insertions(+)
>  create mode 100644 libstdc++-v3/config/cpu/gcn/cpu_defines.h
>
> diff --git a/libstdc++-v3/config/cpu/gcn/cpu_defines.h b/libstdc++-v3/config/cpu/gcn/cpu_defines.h
> new file mode 100644
> index 000000000000..028bfb0ccff1
> --- /dev/null
> +++ b/libstdc++-v3/config/cpu/gcn/cpu_defines.h
> @@ -0,0 +1,55 @@
> +// Specific definitions for GCN platforms  -*- C++ -*-
> +
> +// Copyright (C) 2025 Free Software Foundation, Inc.
> +//
> +// This file is part of the GNU ISO C++ Library.  This library is free
> +// software; you can redistribute it and/or modify it under the
> +// terms of the GNU General Public License as published by the
> +// Free Software Foundation; either version 3, or (at your option)
> +// any later version.
> +
> +// This library is distributed in the hope that it will be useful,
> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +// GNU General Public License for more details.
> +
> +// Under Section 7 of GPL version 3, you are granted additional
> +// permissions described in the GCC Runtime Library Exception, version
> +// 3.1, as published by the Free Software Foundation.
> +
> +// You should have received a copy of the GNU General Public License and
> +// a copy of the GCC Runtime Library Exception along with this program;
> +// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +// <http://www.gnu.org/licenses/>.
> +
> +/** @file bits/cpu_defines.h
> + *  This is an internal header file, included by other library headers.
> + *  Do not attempt to use it directly. @headername{iosfwd}
> + */
> +
> +#ifndef _GLIBCXX_CPU_DEFINES
> +#define _GLIBCXX_CPU_DEFINES 1
> +
> +/* GCN appears to run into issues similar to PR69506:
> +
> +       ld: error: relocation R_AMDGPU_REL32_LO cannot be used against symbol '_ZGTtnam'; recompile with -fPIC
> +       >>> defined in [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a(cow-stdexcept.o)
> +       >>> referenced by cow-stdexcept.cc:259 ([...]/libstdc++-v3/src/c++11/cow-stdexcept.cc:259)
> +       >>>               cow-stdexcept.o:(_txnal_cow_string_C1_for_exceptions(void*, char const*, void*)) in archive [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a
> +
> +       ld: error: relocation R_AMDGPU_REL32_HI cannot be used against symbol '_ZGTtnam'; recompile with -fPIC
> +       >>> defined in [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a(cow-stdexcept.o)
> +       >>> referenced by cow-stdexcept.cc:259 ([...]/source-gcc/libstdc++-v3/src/c++11/cow-stdexcept.cc:259)
> +       >>>               cow-stdexcept.o:(_txnal_cow_string_C1_for_exceptions(void*, char const*, void*)) in archive [...]/amdgcn-amdhsa/./libstdc++-v3/src/.libs/libstdc++.a
> +
> +       [...]
> +
> +   ..., which is:
> +
> +       $ c++filt _ZGTtnam
> +       transaction clone for operator new[](unsigned long)
> +
> +   ..., and similarly for other libitm symbols.  See PR119369.  */
> +#define _GLIBCXX_USE_WEAK_REF 0
> +
> +#endif
> diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
> index cb4c28a62bf3..0bed9dfff957 100644
> --- a/libstdc++-v3/configure.host
> +++ b/libstdc++-v3/configure.host
> @@ -147,6 +147,9 @@ cpu_include_dir=cpu/${try_cpu}
>  # Set specific CPU overrides for cpu_defines_dir. Most can just use generic.
>  # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
>  case "${host_cpu}" in
> +  amdgcn)
> +    cpu_defines_dir=cpu/gcn
> +    ;;
>    arm*)
>      cpu_defines_dir=cpu/arm
>      ;;
> --
> 2.34.1
>