Re: [PATCH] RISC-V: Don't report an error until the link phase if suitable multilib isn't found.

[Kito Cheng <kito.cheng@sifive.com>]

This will break some scenario which is to build anything by themself,
which does not use any header or library from the builtin one.

So that's why the spec needs to guard so many conditions, no
-nostartfiles, -nodefaultlibs, -nolibc and -nostdlib appears.

 "%{!nostartfiles:%{!nodefaultlibs:%{!nolibc:%{!nostdlib:%:riscv_multi_lib_check()}}}}
On Wed, Feb 22, 2023 at 6:26 PM Jin Ma <jinma@linux.alibaba.com> wrote:
>
> When suitable multilib isn't found, an error is not reported until the
> link period, which is inconsistent with the result of compiling option
> `-print-multi-directory`. For example, when suitable multilib isn't
> found, the return result of `-print-multi-directory` is the default
> value '.', while the actual execution result is an error during the
> link phase. This is not very reasonable.
>
> I think the error should be reported in advance, so that the compilation
> option `-print-multi-directory` will also report an error. The two
> should be consistent, either reporting errors or using default values.
>
> gcc/ChangeLog:
>
>         * common/config/riscv/riscv-common.cc
>         (riscv_compute_multilib): report an error if suitable multilib isn't found.
>         (struct riscv_multi_lib_info_t): Delet.
>         (riscv_multi_lib_check): Likewise.
>         * config/riscv/elf.h (LIB_SPEC): Likewise.
>         * config/riscv/riscv.h (riscv_multi_lib_check): Likewise.
>         (EXTRA_SPEC_FUNCTIONS): Likewise.
> ---
>  gcc/common/config/riscv/riscv-common.cc | 25 +++++--------------------
>  gcc/config/riscv/elf.h                  |  3 +--
>  gcc/config/riscv/riscv.h                |  4 +---
>  3 files changed, 7 insertions(+), 25 deletions(-)
>
> diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
> index ebc1ed7d7e4..3f27ecf4b3c 100644
> --- a/gcc/common/config/riscv/riscv-common.cc
> +++ b/gcc/common/config/riscv/riscv-common.cc
> @@ -274,9 +274,6 @@ struct riscv_multi_lib_info_t {
>                      const std::vector<std::string> &);
>  };
>
> -/* Flag for checking if there is no suitable multi-lib found.  */
> -static bool riscv_no_matched_multi_lib;
> -
>  /* Used for record value of -march and -mabi.  */
>  static std::string riscv_current_arch_str;
>  static std::string riscv_current_abi_str;
> @@ -1396,21 +1393,6 @@ riscv_expand_arch_from_cpu (int argc ATTRIBUTE_UNUSED,
>    return xasprintf ("-march=%s", arch.c_str());
>  }
>
> -/* Report error if not found suitable multilib.  */
> -const char *
> -riscv_multi_lib_check (int argc ATTRIBUTE_UNUSED,
> -                      const char **argv ATTRIBUTE_UNUSED)
> -{
> -  if (riscv_no_matched_multi_lib)
> -    fatal_error (
> -      input_location,
> -      "Cannot find suitable multilib set for %<-march=%s%>/%<-mabi=%s%>",
> -      riscv_current_arch_str.c_str (),
> -      riscv_current_abi_str.c_str ());
> -
> -  return "";
> -}
> -
>  /* We only override this in bare-metal toolchain.  */
>  #ifdef RISCV_USE_CUSTOMISED_MULTI_LIB
>
> @@ -1583,7 +1565,6 @@ riscv_compute_multilib (
>    const char *this_path;
>    size_t this_path_len;
>    bool result;
> -  riscv_no_matched_multi_lib = false;
>    riscv_subset_list *subset_list = NULL;
>
>    std::vector<riscv_multi_lib_info_t> multilib_infos;
> @@ -1709,7 +1690,11 @@ riscv_compute_multilib (
>
>    if (best_match_multi_lib == -1)
>      {
> -      riscv_no_matched_multi_lib = true;
> +      fatal_error (
> +       input_location,
> +       "Cannot find suitable multilib set for %<-march=%s%>/%<-mabi=%s%>",
> +       riscv_current_arch_str.c_str (),
> +       riscv_current_abi_str.c_str ());
>        return multilib_dir;
>      }
>    else
> diff --git a/gcc/config/riscv/elf.h b/gcc/config/riscv/elf.h
> index a725c00b637..7b8dc29d4cb 100644
> --- a/gcc/config/riscv/elf.h
> +++ b/gcc/config/riscv/elf.h
> @@ -28,8 +28,7 @@ along with GCC; see the file COPYING3.  If not see
>     Handle the circular dependence between libc and libgloss. */
>  #undef  LIB_SPEC
>  #define LIB_SPEC \
> -  "--start-group -lc %{!specs=nosys.specs:-lgloss} --end-group " \
> -  "%{!nostartfiles:%{!nodefaultlibs:%{!nolibc:%{!nostdlib:%:riscv_multi_lib_check()}}}}"
> +  "--start-group -lc %{!specs=nosys.specs:-lgloss} --end-group"
>
>  #undef  STARTFILE_SPEC
>  #define STARTFILE_SPEC "crt0%O%s crtbegin%O%s"
> diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
> index 5bc7f2f467d..b8fa5f022db 100644
> --- a/gcc/config/riscv/riscv.h
> +++ b/gcc/config/riscv/riscv.h
> @@ -46,13 +46,11 @@ along with GCC; see the file COPYING3.  If not see
>  extern const char *riscv_expand_arch (int argc, const char **argv);
>  extern const char *riscv_expand_arch_from_cpu (int argc, const char **argv);
>  extern const char *riscv_default_mtune (int argc, const char **argv);
> -extern const char *riscv_multi_lib_check (int argc, const char **argv);
>
>  # define EXTRA_SPEC_FUNCTIONS                                          \
>    { "riscv_expand_arch", riscv_expand_arch },                          \
>    { "riscv_expand_arch_from_cpu", riscv_expand_arch_from_cpu },                \
> -  { "riscv_default_mtune", riscv_default_mtune },                      \
> -  { "riscv_multi_lib_check", riscv_multi_lib_check },
> +  { "riscv_default_mtune", riscv_default_mtune },
>
>  /* Support for a compile-time default CPU, et cetera.  The rules are:
>     --with-arch is ignored if -march or -mcpu is specified.
> --
> 2.17.1
>