[Bug debug/96383] [8/9/10/11 Regression] Full ABI information missing from GCC compiled C

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96383

--- Comment #25 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:c6ef9d8d3f11221df1ea6358b8d4e79e42f074fb

commit r11-2455-gc6ef9d8d3f11221df1ea6358b8d4e79e42f074fb
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jul 30 11:46:43 2020 +0200

    debug/96383 - emit debug info for used external functions

    This makes sure to emit full declaration DIEs including
    formal parameters for used external functions.  This helps
    debugging when debug information of the external entity is
    not available and also helps external tools cross-checking
    ABI compatibility which was the bug reporters use case.

    For cc1 this affects debug information size as follows:

         VM SIZE                     FILE SIZE
     ++++++++++++++ GROWING       ++++++++++++++
      [ = ]       0 .debug_info   +1.63Mi  +1.3%
      [ = ]       0 .debug_str     +263Ki  +3.4%
      [ = ]       0 .debug_abbrev  +101Ki  +4.9%
      [ = ]       0 .debug_line   +5.71Ki  +0.0%
       +44%     +16 [Unmapped]        +48  +1.2%

     -------------- SHRINKING     --------------
      [ = ]       0 .debug_loc       -213  -0.0%
      -0.0%     -48 .text             -48  -0.0%
      [ = ]       0 .debug_ranges     -16  -0.0%

      -0.0%     -32 TOTAL         +1.99Mi  +0.6%

    and DWARF compression via DWZ can only shave off minor bits
    here.

    Previously we emitted no DIEs for external functions at all
    unless they were referenced via DW_TAG_GNU_call_site which
    for some GCC revs caused a regular DIE to appear and since
    GCC 4.9 only a stub without formal parameters.  This means
    at -O0 we did not emit any DIE for external functions
    but with optimization we emitted stubs.

    2020-07-30  Richard Biener  <rguenther@suse.de>

            PR debug/96383
            * langhooks-def.h (lhd_finalize_early_debug): Declare.
            (LANG_HOOKS_FINALIZE_EARLY_DEBUG): Define.
            (LANG_HOOKS_INITIALIZER): Amend.
            * langhooks.c: Include cgraph.h and debug.h.
            (lhd_finalize_early_debug): Default implementation from
            former code in finalize_compilation_unit.
            * langhooks.h (lang_hooks::finalize_early_debug): Add.
            * cgraphunit.c (symbol_table::finalize_compilation_unit):
            Call the finalize_early_debug langhook.

    gcc/c-family/
            * c-common.h (c_common_finalize_early_debug): Declare.
            * c-common.c: Include debug.h.
            (c_common_finalize_early_debug): finalize_early_debug langhook
            implementation generating debug for extern declarations.

    gcc/c/
            * c-objc-common.h (LANG_HOOKS_FINALIZE_EARLY_DEBUG):
            Define to c_common_finalize_early_debug.

    gcc/cp/
            * cp-objcp-common.h (LANG_HOOKS_FINALIZE_EARLY_DEBUG):
            Define to c_common_finalize_early_debug.

    gcc/testsuite/
            * gcc.dg/debug/dwarf2/pr96383-1.c: New testcase.
            * gcc.dg/debug/dwarf2/pr96383-2.c: Likewise.

    libstdc++-v3/
            * testsuite/20_util/assume_aligned/3.cc: Use -g0.