[And this time, actually CCing the list :)].
Gentlemen!
Reading in the compiler state for pch (gt_pch_restore) obliterates the
DIE table, and consequently the DW_TAG_GNU_[BE]INCL* DIEs that may have
been in it. This causes inconsistencies when reading in _any_
pre-compiled header into a source file that uses
-feliminate-dwarf2-dups, and consequently already has some
DW_TAG_GNU_[BE]INCL* DIEs.
Normally the DIE table should be empty this early on, especially since
mainline generates dwarf at the end of the compilation unit, but the DIE
table may have DW_TAG_GNU_[BE]INCL* DIEs that were created early by
dwarf2out_start_source_file/etc or it may have the DW_TAG_compile_unit.
I suppose we could merge incoming DIEs with existing DIEs and complicate
our lives, but considering we will probably have to tackle this in the
debug-early work, I propose we disable this combination for now (and
possibly permanently, unless we really care about it).
OK for mainline pending tests?
Aldy
commit c0814b101417a5639fe70b41526b4e2d7a56ee52
Author: Aldy Hernandez <al...@redhat.com>
Date: Thu Feb 19 07:35:59 2015 -0800
PR debug/46102
* c-pch.c (c_common_read_pch): Disable -feliminate-dwarf2-dups
if reading a pre-compiled header.
diff --git a/gcc/c-family/c-pch.c b/gcc/c-family/c-pch.c
index 0ede92a..6b442e2 100644
--- a/gcc/c-family/c-pch.c
+++ b/gcc/c-family/c-pch.c
@@ -381,6 +381,23 @@ c_common_read_pch (cpp_reader *pfile, const char *name,
timevar_pop (TV_PCH_CPP_RESTORE);
gt_pch_restore (f);
+
+ /* At pre-compiled header output time, we may have outputted a few
+ DIEs corresponding to DW_TAG_GNU_[BE]INCL. Reading the compiler
+ state above will read in these DIEs, and obliterate any
+ DW_TAG_GNU_[BE]INCL so far generated.
+
+ Disable this combination for now. When early debug generation is
+ implemented, we can probably get this combo to work. */
+ if (flag_eliminate_dwarf2_dups)
+ {
+ warning_at (UNKNOWN_LOCATION, 0,
+ "Pre-compiled headers cannot be used with
-feliminate-dwarf2-dups.");
+ warning_at (UNKNOWN_LOCATION, 0,
+ "-feliminate-dwarf2-dups has been disabled.");
+ flag_eliminate_dwarf2_dups = 0;
+ }
+
cpp_set_line_map (pfile, line_table);
rebuild_location_adhoc_htab (line_table);
