Dwarf 5: Handle debug_str_offsets and indexed attributes that have base offsets.

* Process debug_str_offsets section. Handle DW_AT_str_offsets_base attribute and
keep the value in dwarf2_cu.

* Make addr_base field in dwarf2_cu optional to disambiguate 0 value
(absent or present and 0).

* During parsing, there is no guarantee that DW_AT_str_offsets_base and
DW_AT_rnglists_base fields will be processed before the attributes that need
those values for correct computation. So make two passes, on the first one mark
the attributes that depend on *_base attributes and process only the others.
On the second pass, only process the attributes that are marked on the first
pass.

* For string attributes, differentiate between addresses that directly point to
a string and those that point to an offset in debug_str_offsets section.

* There are now two attributes, DW_AT_addr_base and DW_AT_GNU_addr_base to read
address offset base. Likewise, there are two attributes, DW_AT_rnglists_base
and DW_AT_GNU_ranges_base to read ranges base. Since there is no guarantee which
ones the compiler will generate, create helper functions to handle all cases.

Tested with CC=/usr/bin/gcc (version 8.3.0) against master branch (also with
-gsplit-dwarf and -gdwarf-4 flags) and there was no increase in the set of
tests that fails. (gdb still cannot debug a 'hello world' program with DWARF 5,
so for the time being, this is all we care about).

This is part of an effort to support DWARF-5 in gdb.

1 files changed, 1 insertions, 0 deletions

diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
index 5c60610..aae2e37 100644
--- a/gdb/xcoffread.c
+++ b/gdb/xcoffread.c
@@ -166,6 +166,7 @@ static const struct dwarf2_debug_sections dwarf2_xcoff_names = {
   { NULL, NULL },
   { ".dwmac", NULL },
   { ".dwstr", NULL },
+  { NULL, NULL }, /* debug_str_offsets */
   { NULL, NULL }, /* debug_line_str */
   { ".dwrnges", NULL },
   { NULL, NULL }, /* debug_rnglists */