Re: [PATCH 1/2] Use POSIX nm to simplify AIX export_symbols_cmds.

[David Edelsohn]

I agree with this in principle, but I'm not convinced that the patch
itself is correct.

I also would have split the MS-compatible part of the patch as a
separate step.  It is not listed in the ChangeLog and just confuses
the patch.

I don't see that this emits TLS symbols.  Global TLS symbols are not
in the symcode list.

Global symbol pipe and exclude symbols somehow restricts the symbols
to the non "dot" symbols?

The export_symbols_cmds awk command does not have matching quotes, so
I don't know what is going on.

awk '\''{ kw = "" } /^[[VWZ]] / { kw = " weak" } { print $ 3 kw }'\''

you're starting and ending with '\" which seems odd. why aren't these
complementary?

Thanks, David

On Wed, Mar 2, 2016 at 11:19 AM, Michael Haubenwallner
<address@hidden> wrote:
> * m4/libtool.m4 (LT_PATH_NM): Detect POSIX-compatible nm for AIX.  In
> BSD mode, the AIX nm does not tell whether a symbol is weak, need to use
> POSIX mode instead.
> (_LT_CMD_GLOBAL_SYMBOLS): Support POSIX-compatible nm.  Reorder to allow
> for platform specific hooks during transformation of global_symbol_pipe
> into C source code.  For AIX, set hook to transform even weak text
> symbols as text symbols.
> (_LT_LINKER_SHLIBS): Use global_symbol_pipe to simplify forming the
> export_symbols_cmds for AIX.
> ---
>  m4/libtool.m4 | 101 
> ++++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 55 insertions(+), 46 deletions(-)
>
> diff --git a/m4/libtool.m4 b/m4/libtool.m4
> index 2c0e657..6134522 100644
> --- a/m4/libtool.m4
> +++ b/m4/libtool.m4
> @@ -3755,10 +3755,10 @@ _LT_DECL([], [want_nocaseglob], [1],
>
>  # LT_PATH_NM
>  # ----------
> -# find the pathname to a BSD- or MS-compatible name lister
> +# find the pathname to a BSD-, POSIX- or MS-compatible name lister
>  AC_DEFUN([LT_PATH_NM],
>  [AC_REQUIRE([AC_PROG_CC])dnl
> -AC_CACHE_CHECK([for BSD- or MS-compatible name lister (nm)], lt_cv_path_NM,
> +AC_CACHE_CHECK([for BSD-, POSIX- or MS-compatible name lister (nm)], 
> lt_cv_path_NM,
>  [if test -n "$NM"; then
>    # Let the user override the test.
>    lt_cv_path_NM=$NM
> @@ -3808,6 +3808,26 @@ else
>    : ${lt_cv_path_NM=no}
>  fi])
>  if test no != "$lt_cv_path_NM"; then
> +  case $host_os in
> +  aix[[4-9]]*)
> +    # With AIX nm we need the '-l' flag to get the "weak" information
> +    # for the Import File, but '-l' is ignored with the '-B' flag.  So
> +    # we use the '-P' (POSIX) flag instead.  As users often provide the
> +    # '-B' flag, which conflicts with '-P', we drop any provided flag.
> +    # AIX nm needs the '-C' flag to disable demangling.  For both GNU
> +    # and AIX nm, the '-g' flag shows public (global) symbols only,
> +    # and the '-p' flag disables sorting to improve performance.
> +    set dummy $lt_cv_path_NM
> +    case address@hidden|@2 -V 2>&1` in
> +    *GNU* | *'with BFD'*)
> +      lt_cv_path_NM="@S|@2 -Bgp"
> +      ;;
> +    *)
> +      lt_cv_path_NM="@S|@2 -PlCgp"
> +      ;;
> +    esac
> +    ;;
> +  esac
>    NM=$lt_cv_path_NM
>  else
>    # Didn't find any BSD compatible name lister, look for dumpbin.
> @@ -3832,7 +3852,7 @@ fi
>  test -z "$NM" && NM=nm
>  _LT_SET_TOOL_ABI_FLAG([NM])
>  AC_SUBST([NM])
> -_LT_DECL([], [NM], [1], [A BSD- or MS-compatible name lister])dnl
> +_LT_DECL([], [NM], [1], [A BSD-, POSIX- or MS-compatible name lister])dnl
>
>  AC_CACHE_CHECK([the name lister ($NM) interface], [lt_cv_nm_interface],
>    [lt_cv_nm_interface="BSD nm"
> @@ -3847,6 +3867,8 @@ AC_CACHE_CHECK([the name lister ($NM) interface], 
> [lt_cv_nm_interface],
>    cat conftest.out >&AS_MESSAGE_LOG_FD
>    if $GREP 'External.*some_variable' conftest.out > /dev/null; then
>      lt_cv_nm_interface="MS dumpbin"
> +  elif $GREP '^[[       ]]*_*some_variable' conftest.out > /dev/null; then
> +    lt_cv_nm_interface="POSIX nm"
>    fi
>    rm -f conftest*])
>  ])# LT_PATH_NM
> @@ -4012,8 +4034,33 @@ symcode='[[BCDEGRST]]'
>  # Regexp to match symbols that can be accessed directly from C.
>  sympat='\([[_A-Za-z]][[_A-Za-z0-9]]*\)'
>
> +if test "$lt_cv_nm_interface" = "MS dumpbin"; then
> +  # Gets list of data symbols to import.
> +  lt_cv_sys_global_symbol_to_import="sed -n -e 's/^I .* \(.*\)$/\1/p'"
> +  # Adjust the below global symbol transforms to fixup imported variables.
> +  lt_cdecl_hook=" -e 's/^I .* \(.*\)$/extern __declspec(dllimport) char 
> \1;/p'"
> +  lt_c_name_hook=" -e 's/^I .* \(.*\)$/  {\"\1\", (void *) 0},/p'"
> +  lt_c_name_lib_hook="\
> +  -e 's/^I .* \(lib.*\)$/  {\"\1\", (void *) 0},/p'\
> +  -e 's/^I .* \(.*\)$/  {\"lib\1\", (void *) 0},/p'"
> +else
> +  # Disable hooks by default.
> +  lt_cv_sys_global_symbol_to_import=
> +  lt_cdecl_hook=
> +  lt_c_name_hook=
> +  lt_c_name_lib_hook=
> +fi
> +
>  # Define system-specific variables.
>  case $host_os in
> +aix[[4-9]]*)
> +  case `$NM -V 2>&1` in
> +  *GNU* | *'with BFD'*) ;;
> +  *)
> +    symcode='[[BDLTVWZ]]'
> +    lt_cdecl_hook=" -e 's/^W/T/p'" # weak text symbol
> +  esac
> +  ;;
>  aix*)
>    symcode='[[BCDT]]'
>    ;;
> @@ -4054,23 +4101,6 @@ case `$NM -V 2>&1` in
>    symcode='[[ABCDGIRSTW]]' ;;
>  esac
>
> -if test "$lt_cv_nm_interface" = "MS dumpbin"; then
> -  # Gets list of data symbols to import.
> -  lt_cv_sys_global_symbol_to_import="sed -n -e 's/^I .* \(.*\)$/\1/p'"
> -  # Adjust the below global symbol transforms to fixup imported variables.
> -  lt_cdecl_hook=" -e 's/^I .* \(.*\)$/extern __declspec(dllimport) char 
> \1;/p'"
> -  lt_c_name_hook=" -e 's/^I .* \(.*\)$/  {\"\1\", (void *) 0},/p'"
> -  lt_c_name_lib_hook="\
> -  -e 's/^I .* \(lib.*\)$/  {\"\1\", (void *) 0},/p'\
> -  -e 's/^I .* \(.*\)$/  {\"lib\1\", (void *) 0},/p'"
> -else
> -  # Disable hooks by default.
> -  lt_cv_sys_global_symbol_to_import=
> -  lt_cdecl_hook=
> -  lt_c_name_hook=
> -  lt_c_name_lib_hook=
> -fi
> -
>  # Transform an extracted symbol line into a proper C declaration.
>  # Some systems (esp. on ia64) link data and code symbols differently,
>  # so use this general approach.
> @@ -4128,6 +4158,9 @@ for ac_symprfx in "" "_"; do
>  "     s[1]~/address@hidden/{print f,s[1],s[1]; next};"\
>  "     s[1]~prfx {split(s[1],t,\"@\"); print 
> f,t[1],substr(t[1],length(prfx))}"\
>  "     ' prfx=^$ac_symprfx]"
> +  elif test "$lt_cv_nm_interface" = "POSIX nm"; then
> +    symxfrm="\\2 $ac_symprfx\\1 \\1"
> +    lt_cv_sys_global_symbol_pipe="sed -n -e 's/^[[      
> ]]*$ac_symprfx$sympat[[         ]][[    ]]*\($symcode$symcode*\)[[      ]][[  
>   ]]*.*$opt_cr$/$symxfrm/p'"
>    else
>      lt_cv_sys_global_symbol_pipe="sed -n -e 's/^.*[[    
> ]]\($symcode$symcode*\)[[       ]][[    
> ]]*$ac_symprfx$sympat$opt_cr$/$symxfrm/p'"
>    fi
> @@ -5009,19 +5042,7 @@ m4_if([$1], [CXX], [
>    _LT_TAGVAR(exclude_expsyms, $1)=['_GLOBAL_OFFSET_TABLE_|_GLOBAL__F[ID]_.*']
>    case $host_os in
>    aix[[4-9]]*)
> -    # If we're using GNU nm, then we don't want the "-C" option.
> -    # -C means demangle to GNU nm, but means don't demangle to AIX nm.
> -    # Without the "-l" option, or with the "-B" option, AIX nm treats
> -    # weak defined symbols like other global defined symbols, whereas
> -    # GNU nm marks them as "W".
> -    # While the 'weak' keyword is ignored in the Export File, we need
> -    # it in the Import File for the 'aix-soname' feature, so we have
> -    # to replace the "-B" option with "-P" for AIX nm.
> -    if $NM -V 2>&1 | $GREP 'GNU' > /dev/null; then
> -      _LT_TAGVAR(export_symbols_cmds, $1)='$NM -Bpg $libobjs $convenience | 
> awk '\''{ if (((\$ 2 == "T") || (\$ 2 == "D") || (\$ 2 == "B") || (\$ 2 == 
> "W")) && ([substr](\$ 3,1,1) != ".")) { if (\$ 2 == "W") { print \$ 3 " weak" 
> } else { print \$ 3 } } }'\'' | sort -u > $export_symbols'
> -    else
> -      _LT_TAGVAR(export_symbols_cmds, $1)='`func_echo_all $NM | $SED -e 
> '\''s/B\([[^B]]*\)$/P\1/'\''` -PCpgl $libobjs $convenience | awk '\''{ if 
> (((\$ 2 == "T") || (\$ 2 == "D") || (\$ 2 == "B") || (\$ 2 == "L") || (\$ 2 
> == "W") || (\$ 2 == "V") || (\$ 2 == "Z")) && ([substr](\$ 1,1,1) != ".")) { 
> if ((\$ 2 == "W") || (\$ 2 == "V") || (\$ 2 == "Z")) { print \$ 1 " weak" } 
> else { print \$ 1 } } }'\'' | sort -u > $export_symbols'
> -    fi
> +    _LT_TAGVAR(export_symbols_cmds, $1)='$NM $libobjs $convenience | 
> $global_symbol_pipe | $EGREP -v " ($exclude_expsyms)$" | awk '\''{ kw = "" } 
> /^[[VWZ]] / { kw = " weak" } { print $ 3 kw }'\'' | sort -u > $export_symbols'
>      ;;
>    pw32*)
>      _LT_TAGVAR(export_symbols_cmds, $1)=$ltdll_cmds
> @@ -5464,19 +5485,7 @@ _LT_EOF
>         exp_sym_flag='-Bexport'
>         no_entry_flag=
>        else
> -       # If we're using GNU nm, then we don't want the "-C" option.
> -       # -C means demangle to GNU nm, but means don't demangle to AIX nm.
> -       # Without the "-l" option, or with the "-B" option, AIX nm treats
> -       # weak defined symbols like other global defined symbols, whereas
> -       # GNU nm marks them as "W".
> -       # While the 'weak' keyword is ignored in the Export File, we need
> -       # it in the Import File for the 'aix-soname' feature, so we have
> -       # to replace the "-B" option with "-P" for AIX nm.
> -       if $NM -V 2>&1 | $GREP 'GNU' > /dev/null; then
> -         _LT_TAGVAR(export_symbols_cmds, $1)='$NM -Bpg $libobjs $convenience 
> | awk '\''{ if (((\$ 2 == "T") || (\$ 2 == "D") || (\$ 2 == "B") || (\$ 2 == 
> "W")) && ([substr](\$ 3,1,1) != ".")) { if (\$ 2 == "W") { print \$ 3 " weak" 
> } else { print \$ 3 } } }'\'' | sort -u > $export_symbols'
> -       else
> -         _LT_TAGVAR(export_symbols_cmds, $1)='`func_echo_all $NM | $SED -e 
> '\''s/B\([[^B]]*\)$/P\1/'\''` -PCpgl $libobjs $convenience | awk '\''{ if 
> (((\$ 2 == "T") || (\$ 2 == "D") || (\$ 2 == "B") || (\$ 2 == "L") || (\$ 2 
> == "W") || (\$ 2 == "V") || (\$ 2 == "Z")) && ([substr](\$ 1,1,1) != ".")) { 
> if ((\$ 2 == "W") || (\$ 2 == "V") || (\$ 2 == "Z")) { print \$ 1 " weak" } 
> else { print \$ 1 } } }'\'' | sort -u > $export_symbols'
> -       fi
> +       _LT_TAGVAR(export_symbols_cmds, $1)='$NM $libobjs $convenience | 
> $global_symbol_pipe | $EGREP -v " ($exclude_expsyms)$" | awk '\''{ kw = "" } 
> /^[[VWZ]] / { kw = " weak" } { print $ 3 kw }'\'' | sort -u > $export_symbols'
>         aix_use_runtimelinking=no
>
>         # Test if we are trying to use run time linking or normal
> --
> 2.4.6
>