From 171b0a01bd9404f8298f4ea383dbe711a788dd8c Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Sat, 28 Apr 2018 19:54:08 +0000 Subject: [PATCH] DWARF: Add .debug_addr table header for dwarf_version >= 5. GNU DebugFission didn't add table headers for the .debug_addr tables, but DWARF5 does. The table header makes it possible for a DWARF consumer to parse the address tables without having to index all .debug_info CUs first. We can keep using the .debug_addr section label as is, because the DW_AT_[GNU_]addr_base attribute points at the actual address index, which starts right after the table header. So the label is generated at the correct location whether the header is added first or not. Add DW_AT_addr_base instead of DW_AT_GNU_addr_base to the skeleton CU DIE for DWARF5. gcc/ChangeLog * dwarf2out.c (dwarf2out_finish): Add .debug_addr table header for dwarf_version >= 5. (dwarf_AT): Handle DW_AT_addr_base. (add_top_level_skeleton_die_attrs): Use dwarf_AT for DW_AT_addr_base. From-SVN: r259743 --- gcc/ChangeLog | 7 +++++++ gcc/dwarf2out.c | 25 ++++++++++++++++++++++++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1433190f209..56aec8f3352 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2018-04-28 Mark Wielaard + + * dwarf2out.c (dwarf2out_finish): Add .debug_addr table header for + dwarf_version >= 5. + (dwarf_AT): Handle DW_AT_addr_base. + (add_top_level_skeleton_die_attrs): Use dwarf_AT for DW_AT_addr_base. + 2018-04-28 Uros Bizjak PR target/84431 diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index d3d925d5279..d2d4ec009e7 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -1724,6 +1724,11 @@ dwarf_AT (enum dwarf_attribute at) return DW_AT_GNU_dwo_name; break; + case DW_AT_addr_base: + if (dwarf_version < 5) + return DW_AT_GNU_addr_base; + break; + default: break; } @@ -11106,7 +11111,7 @@ add_top_level_skeleton_die_attrs (dw_die_ref die) if (comp_dir != NULL) add_skeleton_AT_string (die, DW_AT_comp_dir, comp_dir); add_AT_pubnames (die); - add_AT_lineptr (die, DW_AT_GNU_addr_base, debug_addr_section_label); + add_AT_lineptr (die, dwarf_AT (DW_AT_addr_base), debug_addr_section_label); } /* Output skeleton debug sections that point to the dwo file. */ @@ -31293,6 +31298,24 @@ dwarf2out_finish (const char *) } switch_to_section (debug_addr_section); + /* GNU DebugFission https://gcc.gnu.org/wiki/DebugFission + which GCC uses to implement -gsplit-dwarf as DWARF GNU extension + before DWARF5, didn't have a header for .debug_addr units. + DWARF5 specifies a small header when address tables are used. */ + if (dwarf_version >= 5) + { + unsigned long addrs_length + = addr_index_table->elements () * DWARF2_ADDR_SIZE + 4; + + if (DWARF_INITIAL_LENGTH_SIZE - DWARF_OFFSET_SIZE == 4) + dw2_asm_output_data (4, 0xffffffff, + "Escape value for 64-bit DWARF extension"); + dw2_asm_output_data (DWARF_OFFSET_SIZE, addrs_length, + "Length of Address Unit"); + dw2_asm_output_data (2, 5, "DWARF addr version"); + dw2_asm_output_data (1, DWARF2_ADDR_SIZE, "Size of Address"); + dw2_asm_output_data (1, 0, "Size of Segment Descriptor"); + } ASM_OUTPUT_LABEL (asm_out_file, debug_addr_section_label); output_addr_table (); } -- 2.30.2