[Bug target/45196] New: ld: warning: can't add line info to anonymous symbol

[Bug target/45196] New: ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

The cleanups to i386 prologue/epilogue generation (r162882 -r162891) cause 161
libstdc++ failures at -m32 on *86*-apple-darwin10 due to new warnings of the
form...

Executing on host: /sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/./gcc/g++
-shared-libgcc -B/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/./gcc
-nostdinc++
-L/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/x86_64-apple-darwin10.4.0/i386/libstdc++-v3/src
-L/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/x86_64-apple-darwin10.4.0/i386/libstdc++-v3/src/.libs
-B/sw/lib/gcc4.6/x86_64-apple-darwin10.4.0/bin/
-B/sw/lib/gcc4.6/x86_64-apple-darwin10.4.0/lib/ -isystem
/sw/lib/gcc4.6/x86_64-apple-darwin10.4.0/include -isystem
/sw/lib/gcc4.6/x86_64-apple-darwin10.4.0/sys-include -m32
-B/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/x86_64-apple-darwin10.4.0/i386/libstdc++-v3/src/.libs
-g -O2 -D_GLIBCXX_ASSERT -fmessage-length=0 -ffunction-sections -fdata-sections
-g -O2 -g -O2 -DLOCALEDIR="." -nostdinc++
-I/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/x86_64-apple-darwin10.4.0/i386/libstdc++-v3/include/x86_64-apple-darwin10.4.0
-I/sw/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/x86_64-apple-darwin10.4.0/i386/libstdc++-v3/include
-I/sw/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100803/libstdc++-v3/libsupc++
-I/sw/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100803/libstdc++-v3/include/backward
-I/sw/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100803/libstdc++-v3/testsuite/util
/sw/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100803/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/39882.cc
  -std=gnu++0x ./libtestc++.a   -lm   -m32 -o ./39882.exe    (timeout = 600)
ld: warning: can't add line info to anonymous symbol initializer$0 from
/var/tmp//ccuyXXr3.o^M
output is:
ld: warning: can't add line info to anonymous symbol initializer$0 from
/var/tmp//ccuyXXr3.o^M

FAIL: 19_diagnostics/error_code/cons/39882.cc (test for excess errors)
Excess errors:
ld: warning: can't add line info to anonymous symbol initializer$0 from
/var/tmp//ccuyXXr3.o

This has been filed as radar://8274440, ld: warning: can't add line info to
anonymous symbol",
with two standalone testcases generated before and after the patches.

According the darwin linker developer, the explanation and possible workaround
are as follows...

---------------------------------------------------------
ld: warning: can't add line info to anonymous symbol initializer$0 from      
39882.o
[/tmp/anonymous_symbol_post]> size -l 39882.o
      ...
        Section (__TEXT, __textcoal_nt): 176 (addr 0x6580 offset 27668)
        Section (__DATA, __mod_init_func): 4 (addr 0x6630 offset 27844)
      ...

I suspect what is happening is that the dwarf debug line info has a
pc-range that goes from the last function in the __textcoal_nt section up
to the start of the __mod_init_func section.  When ld is parsing the debug
line info, it sees a pc address that is in the __mod_init_func section and
issues the warning.   The linker should be smarter and realize the pc
address is the *end* address and therefore ok to be also the beginning       
address of another section.

You could work around this by moving  the __textcoal_nt section to be
after the __text section.  That is, put a .section __TEXT,
__textcoal_nt,blah,blah directive at the top of the file before the
.section __DWARF, blah directives.  This would mean any edge cases in the  
end of the __textcoal_nt would be into the __DWARF sections with ld
ignores.
---------------------------------------------------------

    He also mentioned that this bug doesn't appear to exist in the Xcode 4.0
linker
(so it will go away in the future) and that it is in fact a non-fatal warning
(but that
the resulting dwarf line tables might be bad).


-- 
           Summary: ld: warning: can't add line info to anonymous symbol
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: howarth at nitro dot med dot uc dot edu
 GCC build triplet: *86*-apple-darwin10
  GCC host triplet: *86*-apple-darwin10
GCC target triplet: *86*-apple-darwin10


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[iains at gcc dot gnu dot org]

------- Comment #1 from iains at gcc dot gnu dot org  2010-08-05 14:23 -------
does this solve the problem?
 (it's a hack - we should ensure that the debug sections do not appear in
between our program sections, but that's for another day).


Index: gcc/config/darwin.c
===================================================================
--- gcc/config/darwin.c (revision 162881)
+++ gcc/config/darwin.c (working copy)
@@ -1699,6 +1699,23 @@ darwin_asm_output_dwarf_delta (FILE *file, int siz
 void
 darwin_file_start (void)
 {
+  fputs ("\t.const\n\t.static_const\n\t.cstring\n", asm_out_file) ;
+  fputs ("\t.literal4\n\t.literal8\n\t.literal16\n", asm_out_file) ;
+  fputs ("\t.data\n\t.static_data\n\t.const_data\n", asm_out_file) ;
+  if (!TARGET_64BIT) 
+    {
+      if (flag_pic == 2)
+       fputs ("\t.picsymbol_stub\n", asm_out_file) ;
+      else
+       fputs ("\t.symbol_stub\n", asm_out_file) ;
+      fputs ("\t.lazy_symbol_pointer\n\t.non_lazy_symbol_pointer\n",
asm_out_file);
+      fputs ("\t.section __TEXT,__textcoal_nt,coalesced,pure_instructions\n",
asm_out_file); 
+    }
+  else
+    {
+      fputs ("\t.section
__TEXT,__eh_frame,coalesced,no_toc+strip_static_syms+live_support\n",
asm_out_file) ;
+    }
+  in_section = NULL;
   if (write_symbols == DWARF2_DEBUG)
     {
       static const char * const debugnames[] =


-- 

iains at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |iains at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #2 from howarth at nitro dot med dot uc dot edu  2010-08-05 17:55 -------
This bug doesn't occur with the actual committed version of the cleanups to
i386 prologue/epilogue generation (as opposed to the proposed patches). Let's
leave this open for now in case it reappears.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #3 from howarth at nitro dot med dot uc dot edu  2010-08-15 17:36 -------
These still appear to be present on i386-apple-darwin10 but not
x86_64-apple-darwin10. Odd.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #4 from howarth at nitro dot med dot uc dot edu  2010-08-15 18:47 -------
Created an attachment (id=21480)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21480&action=view)
compressed preprocessed source for 20_util/auto_ptr/6.cc on
-i386-apple-darwin10


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #5 from howarth at nitro dot med dot uc dot edu  2010-08-15 18:48 -------
Created an attachment (id=21481)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21481&action=view)
compressed assembly file for 20_util/auto_ptr/6.cc on -i386-apple-darwin10


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #6 from howarth at nitro dot med dot uc dot edu  2010-08-15 18:48 -------
Created an attachment (id=21482)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21482&action=view)
compressed object file for 20_util/auto_ptr/6.cc on -i386-apple-darwin10


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196

[Bug target/45196] ld: warning: can't add line info to anonymous symbol

[howarth at nitro dot med dot uc dot edu]

------- Comment #7 from howarth at nitro dot med dot uc dot edu  2010-08-15 18:52 -------
Files created with...

/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/./gcc/g++ -shared-libgcc
-B/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/./gcc -nostdinc++
-L/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/i386-apple-darwin10.5.0/libstdc++-v3/src
-L/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/i386-apple-darwin10.5.0/libstdc++-v3/src/.libs
-B/sw_i386/lib/gcc4.6/i386-apple-darwin10.5.0/bin/
-B/sw_i386/lib/gcc4.6/i386-apple-darwin10.5.0/lib/ -isystem
/sw_i386/lib/gcc4.6/i386-apple-darwin10.5.0/include -isystem
/sw_i386/lib/gcc4.6/i386-apple-darwin10.5.0/sys-include
-B/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/i386-apple-darwin10.5.0/./libstdc++-v3/src/.libs
-g -O2 -D_GLIBCXX_ASSERT -fmessage-length=0 -ffunction-sections -fdata-sections
-g -O2 -g -O2 -DLOCALEDIR="." -nostdinc++
-I/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/i386-apple-darwin10.5.0/libstdc++-v3/include/i386-apple-darwin10.5.0
-I/sw_i386/src/fink.build/gcc46-4.6.0-1000/darwin_objdir/i386-apple-darwin10.5.0/libstdc++-v3/include
-I/sw_i386/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100814/libstdc++-v3/libsupc++
-I/sw_i386/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100814/libstdc++-v3/include/backward
-I/sw_i386/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100814/libstdc++-v3/testsuite/util
/sw_i386/src/fink.build/gcc46-4.6.0-1000/gcc-4.6-20100814/libstdc++-v3/testsuite/20_util/auto_ptr/6.cc
-include bits/stdc++.h ./libtestc++.a -L/sw_i386/lib -liconv -lm --save-temps
-m32 -o ./6.exe
ld: warning: can't add line info to anonymous symbol
cstring=A_from_A_ptr->ctor_count == 1 from 6.o


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45196