Re: [PATCH][2/2] early LTO debug, main part

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Aug 04, 2017 at 02:21:29PM +0200, Richard Biener wrote:
> ! /* Initialize the various sections and labels for dwarf output.  */
>   
>   static void
> ! init_sections_and_labels (void)

...

These changes broke DWARF-5 support.  E.g. in gcc-7 and before this change
there was:

> !   if (!dwarf_split_debug_info)
>       {
...
> !       debug_loc_section = get_section (dwarf_version >= 5
> ! 				       ? DEBUG_LOCLISTS_SECTION
> ! 				       : DEBUG_LOC_SECTION,
> !                                        SECTION_DEBUG, NULL);

the above which would use .debug_loclists section for debug_loc_section
instead of .debug_loc for -gdwarf-5, because that is what DWARF-5 requires
and the section content is ABI incompatible.  But current trunk does
> ! 	  debug_loc_section = get_section (DEBUG_LOC_SECTION,
> ! 					   SECTION_DEBUG, NULL);
only, so the DWARF-5 content is emitted into .debug_loc section.

Or, there used to be:

> !   if (!dwarf_split_debug_info && !DWARF2_ASM_LINE_DEBUG_INFO)
> !     debug_line_str_section = get_section (DEBUG_LINE_STR_SECTION,
> ! 					  DEBUG_STR_SECTION_FLAGS, NULL);

which has no replacement at all, debug_line_str_hash is NULL and
so !DWARF2_ASM_LINE_DEBUG_INFO compiler ICEs on pretty much all
-gdwarf-5, because it can't emit the strings into that section.

Do you have rough time when you wrote changes to these functions (so that
I could diff init_sections_and_labels changes in between that date and
before your LTO debug changes and find out what needs to be double checked
besides those two)?

I presume we'll need some name for a LTO .debug_loclists variant.

Also, seeing:

#ifndef DEBUG_LINE_SECTION
#define DEBUG_LINE_SECTION      ".debug_line"
#endif
#ifndef DEBUG_DWO_LINE_SECTION
#define DEBUG_DWO_LINE_SECTION ".debug_line.dwo"
#endif
#ifndef DEBUG_LTO_LINE_SECTION
#define DEBUG_LTO_LINE_SECTION ".gnu.debuglto_.debug_line.dwo"
#endif

that looks like a pasto, , I'd expect the last one, since it doesn't have
DWO_ in the name, to be just .gnu.debuglto_.debug_line .

	Jakub