From: Omar Sandoval <osan...@fb.com> Macro information references file names from the line number information table, which is tricky in split DWARF for a couple of reasons.
First, the line number information for a macro unit comes from the .debug_line.dwo section in the split file, not the .debug_line section in the skeleton file. This was not specified in the GNU DebugFission design document [1] or the DWARF 5 standard, but it is how GCC and Clang behave in practice and was clarified in DWARF standard issue 200602.1 [2] for the upcoming DWARF 6 standard. dwarf_macro_getsrcfiles uses the line number information from whichever Dwarf handle it was passed. This is error-prone, since the most natural thing to do is to pass the skeleton Dwarf handle. Fix this by storing the appropriate Dwarf handle in Dwarf_Macro_Op_Table and using that one. Second, for .debug_macinfo.dwo in GNU DebugFission (generated by gcc -gdwarf-4 -gstrict-dwarf -gsplit-dwarf), the offset into .debug_line.dwo is implicitly 0. Again, this isn't in any specification, but it's how GCC behaves in practice (Clang never generates macro information for DWARF 4 split DWARF). Make get_macinfo_table default to 0 for split DWARF when it can't find DW_AT_stmt_list. 1: https://gcc.gnu.org/wiki/DebugFission 2: https://dwarfstd.org/issues/200602.1.html Signed-off-by: Omar Sandoval <osan...@fb.com> --- libdw/ChangeLog | 8 +++++--- libdw/dwarf_getmacros.c | 11 +++++++++-- libdw/dwarf_macro_getsrcfiles.c | 5 ++++- libdw/libdwP.h | 2 ++ 4 files changed, 20 insertions(+), 6 deletions(-) diff --git a/libdw/ChangeLog b/libdw/ChangeLog index d3f36cc8..be1e40bc 100644 --- a/libdw/ChangeLog +++ b/libdw/ChangeLog @@ -9,15 +9,17 @@ DW_FORM_strx, and DW_FORM_strx[1-4]. * dwarf_getmacros.c (get_macinfo_table): Replace assignment of table->is_64bit with assignments of table->address_size and - table->offset_size. + table->offset_size. Assume default DW_AT_stmt_list of 0 for split + DWARF. Set table->dbg. (get_table_for_offset): Ditto. (read_macros): Get fake CU offset_size from table->offset_size instead of table->is_64bit. * dwarf_macro_getsrcfiles.c (dwarf_macro_getsrcfiles): Get address_size for __libdw_getsrclines from table->address_size instead - of table->is_64bit. + of table->is_64bit. Get dbg for __libdw_getsrclines from table->dbg + instead of dbg parameter, which is now unused. * libdwP.h (Dwarf_Macro_Op_Table): Replace is_64bit with address_size - and offset_size. + and offset_size. Add dbg. 2023-02-22 Mark Wielaard <m...@klomp.org> diff --git a/libdw/dwarf_getmacros.c b/libdw/dwarf_getmacros.c index b7d98af4..a3a78884 100644 --- a/libdw/dwarf_getmacros.c +++ b/libdw/dwarf_getmacros.c @@ -124,13 +124,19 @@ get_macinfo_table (Dwarf *dbg, Dwarf_Word macoff, Dwarf_Die *cudie) = INTUSE(dwarf_attr) (cudie, DW_AT_stmt_list, &attr_mem); Dwarf_Off line_offset = (Dwarf_Off) -1; if (attr != NULL) - if (unlikely (INTUSE(dwarf_formudata) (attr, &line_offset) != 0)) - return NULL; + { + if (unlikely (INTUSE(dwarf_formudata) (attr, &line_offset) != 0)) + return NULL; + } + else if (cudie->cu->unit_type == DW_UT_split_compile + && dbg->sectiondata[IDX_debug_line] != NULL) + line_offset = 0; Dwarf_Macro_Op_Table *table = libdw_alloc (dbg, Dwarf_Macro_Op_Table, macinfo_data_size, 1); memcpy (table, macinfo_data, macinfo_data_size); + table->dbg = dbg; table->offset = macoff; table->sec_index = IDX_debug_macinfo; table->line_offset = line_offset; @@ -263,6 +269,7 @@ get_table_for_offset (Dwarf *dbg, Dwarf_Word macoff, macop_table_size, 1); *table = (Dwarf_Macro_Op_Table) { + .dbg = dbg, .offset = macoff, .sec_index = IDX_debug_macro, .line_offset = line_offset, diff --git a/libdw/dwarf_macro_getsrcfiles.c b/libdw/dwarf_macro_getsrcfiles.c index 4e8deeeb..11c587af 100644 --- a/libdw/dwarf_macro_getsrcfiles.c +++ b/libdw/dwarf_macro_getsrcfiles.c @@ -36,6 +36,9 @@ int dwarf_macro_getsrcfiles (Dwarf *dbg, Dwarf_Macro *macro, Dwarf_Files **files, size_t *nfiles) { + /* This was needed before Dwarf_Macro_Op_Table stored the Dwarf handle. */ + (void)dbg; + /* macro is declared NN */ Dwarf_Macro_Op_Table *const table = macro->table; if (table->files == NULL) @@ -71,7 +74,7 @@ dwarf_macro_getsrcfiles (Dwarf *dbg, Dwarf_Macro *macro, the same unit through dwarf_getsrcfiles, and the file names will be broken. */ - if (__libdw_getsrclines (dbg, line_offset, table->comp_dir, + if (__libdw_getsrclines (table->dbg, line_offset, table->comp_dir, table->address_size, NULL, &table->files) < 0) table->files = (void *) -1; } diff --git a/libdw/libdwP.h b/libdw/libdwP.h index c3fe9f93..77959b3b 100644 --- a/libdw/libdwP.h +++ b/libdw/libdwP.h @@ -508,6 +508,8 @@ typedef struct /* Prototype table. */ typedef struct { + Dwarf *dbg; + /* Offset of .debug_macro section. */ Dwarf_Off offset; -- 2.41.0
