Re: PATCH: PR lto/55466: Revision 191466 destroyed DWARF debug info

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Dec 10, 2012 at 1:09 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Fri, Dec 7, 2012 at 11:59 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> Hi,
>>
>> Since revision 191466, LTO no longer maintains its own symbol table and
>> it uses varpool for variables instead.  As the result, debug info on
>> variables is lost when GCC is configured with
>>
>> --enable-bootstrap --with-build-config=bootstrap-lto
>>
>> This patch record the global variables if WPA isn't enabled.  It
>> works when GCC is configured with
>>
>> --enable-bootstrap --with-build-config=bootstrap-lto --enable-languages=c,c++,fortran,java,lto,objc,obj-c++
>>
>> However, when go is added, I got
>>
>> lto1: internal compiler error: in add_AT_specification, at
>> dwarf2out.c:3985
>> 0x629ad9 add_AT_specification
>>         /export/gnu/import/git/gcc/gcc/dwarf2out.c:3985
>> 0x64dabb gen_variable_die
>>         /export/gnu/import/git/gcc/gcc/dwarf2out.c:18327
>> 0x65336b gen_decl_die
>>         /export/gnu/import/git/gcc/gcc/dwarf2out.c:20033
>> 0x653fcd dwarf2out_decl(tree_node*)
>>         /export/gnu/import/git/gcc/gcc/dwarf2out.c:20348
>> 0x6535f9 dwarf2out_global_decl
>>         /export/gnu/import/git/gcc/gcc/dwarf2out.c:20083
>> 0x997703 emit_debug_global_declarations(tree_node**, int)
>>         /export/gnu/import/git/gcc/gcc/toplev.c:530
>> 0x521aaa lto_write_globals
>>         /export/gnu/import/git/gcc/gcc/lto/lto-lang.c:1067
>> Please submit a full bug report,
>> with preprocessed source if appropriate.
>> Please include the complete backtrace with any bug report.
>> See <http://gcc.gnu.org/bugs.html> for instructions.
>> make[6]: *** [/tmp/cc3yYR7d.ltrans4.ltrans.o] Error 1
>> lto-wrapper: make returned 2 exit status
>> /usr/local/x86_64-unknown-linux-gnu/bin/ld: lto-wrapper failed
>> collect2: error: ld returned 1 exit status
>> make[5]: *** [go1] Error 1
>>
>> This is latent without my patch since no DWARF info on varaibles are
>>  generated.  OK to install?
>>
>> Thanks.
>>
>>
>> H.J.
>> ---
>> 2012-12-07  H.J. Lu  <hongjiu.lu@intel.com>
>>
>>         PR lto/55466
>>         * lto-symtab.c (lto_symtab_merge_decls_1): Don't record
>>         the prevailing variable.
>>         * lto.c (lto_main): Record the global variables if WPA isn't
>>         enabled.
>>
>> diff --git a/gcc/lto-symtab.c b/gcc/lto-symtab.c
>> index 0b0cdac..295fd37 100644
>> --- a/gcc/lto-symtab.c
>> +++ b/gcc/lto-symtab.c
>> @@ -443,10 +443,6 @@ lto_symtab_merge_decls_1 (symtab_node first)
>>
>>    symtab_prevail_in_asm_name_hash (prevailing);
>>
>> -  /* Record the prevailing variable.  */
>> -  if (TREE_CODE (prevailing->symbol.decl) == VAR_DECL)
>> -    vec_safe_push (lto_global_var_decls, prevailing->symbol.decl);
>> -
>
> As this is not necessary, the push in lto.c:lto_register_var_decl_in_symtab
> for statics should not be necessary either (we even call
> rest_of_decl_compilation
> there).
>
> Ok with that push removed as well.

Done.

> Please make sure to file a bugreport for the go LTO bootstrap issue.
>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55640

-- 
H.J.