On September 2, 2017 1:01:11 PM GMT+02:00, Eric Botcazou <ebotca...@adacore.com> wrote: >Hi, > >this is the bootstrap failure reported for the 7 branch on >SPARC64/Solaris: > >Comparing stages 2 and 3 >Bootstrap comparison failure! >gcc/go/parse.o differs >make[2]: *** [compare] Error 1 > >On Solaris, the bootstrap is usually an old-style bootstrap, meaning >that the >debug info is generated during stage2 & stage3 so the comparison also >involves >the debug info, unlike on Linux. This can be emulated on Linux by >configuring >--with-build-config=no and indeed you get the comparison failure there >too: > >Target: x86_64-suse-linux >Configured with: /home/eric/svn/gcc-7.2.0/configure >--build=x86_64-suse-linux >--prefix=/home/eric/install/gcc-7.2.0 --enable-languages=c,c++,go >--enable- >__cxa_atexit --disable-nls --with-build-config=no >Thread model: posix >gcc version 7.2.0 (GCC) > >make[3]: Leaving directory '/home/eric/build/gcc-7.2.0' >Comparing stages 2 and 3 >Bootstrap comparison failure! >gcc/go/parse.o differs >Makefile:24421: recipe for target 'compare' failed >make[2]: *** [compare] Error 1 > >The difference is: > >35 .debug_info 0016367a 0000000000000000 0000000000000000 0001faf8 > 2**0 > CONTENTS, RELOC, READONLY, DEBUGGING > >35 .debug_info 00163670 0000000000000000 0000000000000000 0001faf8 > 2**0 > CONTENTS, RELOC, READONLY, DEBUGGING > > .byte 0 ! end of children of DIE 0x161dbc > .byte 0 ! end of children of DIE 0x161d9c > .byte 0 ! end of children of DIE 0x161d5b >- .byte 0xf2,0x1 ! uleb128 0xf2; (DIE (0x161dd2) >DW_TAG_ptr_to_member_type) >- .uaword 0x10445d ! DW_AT_containing_type >- .uaword 0x14806e ! DW_AT_type >- .byte 0xa5,0x1 ! uleb128 0xa5; (DIE (0x161ddc) >DW_TAG_subprogram) >+ .byte 0xa5,0x1 ! uleb128 0xa5; (DIE (0x161dd2) >DW_TAG_subprogram) > .uaword 0x146733 ! DW_AT_abstract_origin > >It's a garbage collection issue similar to > https://gcc.gnu.org/ml/gcc-patches/2016-10/msg00541.html >but for build_offset_type instead of build_complex_type. > >It's called from the get_debug_type langhook in C++: > >tree >cp_get_debug_type (const_tree type) >{ > if (TYPE_PTRMEMFUNC_P (type) && !typedef_variant_p (type)) > return build_offset_type (TYPE_PTRMEMFUNC_OBJECT_TYPE (type), > TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (type))); > > return NULL_TREE; >} > >Since the OFFSET_TYPEs created there are not attached to any GC root, >they are >swept by every collection, meaning that the contents of the debug info >depends >on the actual collection points. > >The proposed fix is to build OFFSET_TYPEs manually instead. As >witnessed by >the change to g++.dg/debug/dwarf2/ref-3.C, this generates more DIEs in >the >debug info, but DW_TAG_ptr_to_member_type DIEs only contain 10 bytes.
A solution would be to put them into a global GCed pointer-map or vector, freeing that at free-lang-data time. Richard. >Bootstrapped on x86-64/Linux & SPARC64/Solaris, OK for mainline and 7 >branch? > > >2017-09-02 Eric Botcazou <ebotca...@adacore.com> > > PR bootstrap/81926 > * cp-objcp-common.c: Include stor-layout.h. > (cp_get_debug_type): Build OFFSET_TYPEs manually. > > >2017-09-02 Eric Botcazou <ebotca...@adacore.com> > > * g++.dg/debug/dwarf2/ref-3.C: Adjust DW_TAG_ptr_to_member_type count.
