gdb/dwarf: skip broken .debug_macro.dwo
Running gdb.base/errno.exp with gcc <= 13 with split DWARF results in:
$ make check TESTS="gdb.base/errno.exp" RUNTESTFLAGS="CC_FOR_TARGET=gcc-13 --target_board=fission"
(gdb) break -qualified main
/home/smarchi/src/binutils-gdb/gdb/dwarf2/read.c:7549: internal-error: locate_dwo_sections: Assertion `!dw_sect->readin' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
...
FAIL: gdb.base/errno.exp: macros: gdb_breakpoint: set breakpoint at main (GDB internal error)
The assert being hit has been added in 28f15782adab ("gdb/dwarf: read
multiple .debug_info.dwo sections"), but it merely exposed an existing
problem.
gcc versions <= 13 are affected by this bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111409
Basically, it produces .dwo files with multiple .debug_macro.dwo
sections, with some unresolved links between them. I think that this
macro debug info is unusable, and all we can do is ignore it.
In locate_dwo_sections, if we detect a second .debug_macro.dwo section,
forget about the previous .debug_macro.dwo and any subsequent one. This
will effectively make it as if the macro debug info wasn't there at all.
The errno test seems happy with it:
# of expected passes 84
# of expected failures 8
Change-Id: I6489b4713954669bf69f6e91865063ddcd1ac2c8
Approved-By: Tom Tromey <tom@tromey.com>
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 550968a..891e10f 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -7516,6 +7516,7 @@ cutu_reader::locate_dwo_sections (objfile *objfile, dwo_file &dwo_file)
{
const struct dwop_section_names *names = &dwop_section_names;
dwo_sections &dwo_sections = dwo_file.sections;
+ bool complained_about_macro_already = false;
for (asection *sec : gdb_bfd_sections (dwo_file.dbfd))
{
@@ -7534,7 +7535,24 @@ cutu_reader::locate_dwo_sections (objfile *objfile, dwo_file &dwo_file)
else if (names->macinfo_dwo.matches (sec->name))
dw_sect = &dwo_sections.macinfo;
else if (names->macro_dwo.matches (sec->name))
- dw_sect = &dwo_sections.macro;
+ {
+ /* gcc versions <= 13 generate multiple .debug_macro.dwo sections with
+ some unresolved links between them. It's not usable, so do as if
+ there were not there. */
+ if (!complained_about_macro_already)
+ {
+ if (dwo_sections.macro.s.section == nullptr)
+ dw_sect = &dwo_sections.macro;
+ else
+ {
+ warning (_("Multiple .debug_macro.dwo sections found in "
+ "%s, ignoring them."), dwo_file.dbfd->filename);
+
+ dwo_sections.macro = dwarf2_section_info {};
+ complained_about_macro_already = true;
+ }
+ }
+ }
else if (names->rnglists_dwo.matches (sec->name))
dw_sect = &dwo_sections.rnglists;
else if (names->str_dwo.matches (sec->name))
