On Thu, 15 Sep 2016, Richard Biener wrote:
>
> This addresses sth I needed to address with the early LTO debug patches
> (you might now figure I'm piecemail merging stuff from that patch).
>
> When the cgraph code optimizes out a global we call the late_global_decl
> debug hook to eventually add a DW_AT_const_value to its DIE (we don't
> really expect a location as that will be invalid after optimizing out
> and will be pruned).
>
> With the early LTO debug patches I have introduced a early_dwarf_finished
> flag (mainly for consistency checking) and I figured I can use that to
> detect the call to the late hook during the early phase and provide
> the following cleaned up variant of avoiding to create locations that
> require later pruning (which doesn't work with emitting the early DIEs).
>
> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
>
> I verified it does the correct thing for a unit like
>
> static const int i = 2;
>
> (but ISTR we do have at least one testcase in the testsuite as well).
>
> Will commit if testing finishes successfully.
Ok, so it showed issues when merging that back to early-LTO-debug.
Turns out in LTO we never call early_finish and thus early_dwarf_finished
was never set. Also dwarf2out_late_global_decl itself is a better
place to constrain generating locations.
The following variant is in very late stage of testing.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
LTO bootstrap on x86_64-unknown-linux-gnu in stage3. LTO bootstrap
with early-LTO-debug in stage3, bootstraped with early-LTO-debug,
testing in progress.
Richard.
2016-09-16 Richard Biener <rguent...@suse.de>
* dwarf2out.c (early_dwarf_finished): New global.
(set_early_dwarf::set_early_dwarf): Assert early_dwarf_finished
is false.
(dwarf2out_early_finish): Set early_dwarf_finished at the end,
if called from LTO exit early.
(dwarf2out_late_global_decl): When being during the early
debug phase do not add locations but only const value attributes.
Adjust the way we generate early DIEs for LTO.
lto/
* lto.c (lto_main): Invoke early_finish debug hook.
Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c (revision 240164)
+++ gcc/dwarf2out.c (working copy)
@@ -2711,9 +2711,14 @@ die_node;
/* Set to TRUE while dwarf2out_early_global_decl is running. */
static bool early_dwarf;
+static bool early_dwarf_finished;
struct set_early_dwarf {
bool saved;
- set_early_dwarf () : saved(early_dwarf) { early_dwarf = true; }
+ set_early_dwarf () : saved(early_dwarf)
+ {
+ gcc_assert (! early_dwarf_finished);
+ early_dwarf = true;
+ }
~set_early_dwarf () { early_dwarf = saved; }
};
@@ -23878,18 +23883,31 @@ dwarf2out_early_global_decl (tree decl)
static void
dwarf2out_late_global_decl (tree decl)
{
- /* We have to generate early debug late for LTO. */
- if (in_lto_p)
- dwarf2out_early_global_decl (decl);
-
- /* Fill-in any location information we were unable to determine
- on the first pass. */
+ /* Fill-in any location information we were unable to determine
+ on the first pass. */
if (TREE_CODE (decl) == VAR_DECL
&& !POINTER_BOUNDS_P (decl))
{
dw_die_ref die = lookup_decl_die (decl);
+
+ /* We have to generate early debug late for LTO. */
+ if (! die && in_lto_p)
+ {
+ dwarf2out_decl (decl);
+ die = lookup_decl_die (decl);
+ }
+
if (die)
- add_location_or_const_value_attribute (die, decl, false);
+ {
+ /* We get called during the early debug phase via the symtab
+ code invoking late_global_decl for symbols that are optimized
+ out. When the early phase is not finished, do not add
+ locations. */
+ if (! early_dwarf_finished)
+ tree_add_const_value_attribute_for_decl (die, decl);
+ else
+ add_location_or_const_value_attribute (die, decl, false);
+ }
}
}
@@ -28137,6 +28155,14 @@ dwarf2out_early_finish (void)
{
set_early_dwarf s;
+ /* With LTO early dwarf was really finished at compile-time, so make
+ sure to adjust the phase after annotating the LTRANS CU DIE. */
+ if (in_lto_p)
+ {
+ early_dwarf_finished = true;
+ return;
+ }
+
/* Walk through the list of incomplete types again, trying once more to
emit full debugging info for them. */
retry_incomplete_types ();
@@ -28163,6 +28189,9 @@ dwarf2out_early_finish (void)
}
}
deferred_asm_name = NULL;
+
+ /* The early debug phase is now finished. */
+ early_dwarf_finished = true;
}
/* Reset all state within dwarf2out.c so that we can rerun the compiler
Index: gcc/lto/lto.c
===================================================================
--- gcc/lto/lto.c (revision 240164)
+++ gcc/lto/lto.c (working copy)
@@ -3315,6 +3315,9 @@ lto_main (void)
if (!flag_ltrans)
lto_promote_statics_nonwpa ();
+ /* Annotate the CU DIE and mark the early debug phase as finished. */
+ debug_hooks->early_finish ();
+
/* Let the middle end know that we have read and merged all of
the input files. */
symtab->compile ();
