We didn't split cross-partition ranges in loclists to output a
whole-function location expression, but with nonzero locviews, we
force loclists, and then we have to split to avoid cross-partition
list entries.
From: Alexandre Oliva <aol...@redhat.com>
for gcc/ChangeLog
PR debug/86064
* dwarf2out.c (loc_list_has_views): Adjust comments.
(dw_loc_list): Split single cross-partition range with
nonzero locview.
for gcc/testsuite/ChangeLog
PR debug/86064
* gcc.dg/pr86064.c: New.
---
gcc/dwarf2out.c | 18 ++++++++++++++++--
gcc/testsuite/gcc.dg/pr86064.c | 27 +++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr86064.c
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 620e66986be6..0c5d7e0e0357 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -9982,7 +9982,15 @@ new_loc_list (dw_loc_descr_ref expr, const char *begin,
var_loc_view vbegin,
return retlist;
}
-/* Return true iff there's any nonzero view number in the loc list. */
+/* Return true iff there's any nonzero view number in the loc list.
+
+ ??? When views are not enabled, we'll often extend a single range
+ to the entire function, so that we emit a single location
+ expression rather than a location list. With views, even with a
+ single range, we'll output a list if start or end have a nonzero
+ view. If we change this, we may want to stop splitting a single
+ range in dw_loc_list just because of a nonzero view, even if it
+ straddles across hot/cold partitions. */
static bool
loc_list_has_views (dw_loc_list_ref list)
@@ -17090,7 +17098,13 @@ dw_loc_list (var_loc_list *loc_list, tree decl, int
want_address)
of first partition and second one starting at the
beginning of second partition. */
if (node == loc_list->last_before_switch
- && (node != loc_list->first || loc_list->first->next)
+ && (node != loc_list->first || loc_list->first->next
+ /* If we are to emit a view number, we will emit
+ a loclist rather than a single location
+ expression for the entire function (see
+ loc_list_has_views), so we have to split the
+ range that straddles across partitions. */
+ || !ZERO_VIEW_P (node->view))
&& current_function_decl)
{
endname = cfun->fde->dw_fde_end;
diff --git a/gcc/testsuite/gcc.dg/pr86064.c b/gcc/testsuite/gcc.dg/pr86064.c
new file mode 100644
index 000000000000..5be820c78f84
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr86064.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-g -O2 -fno-var-tracking-assignments -gsplit-dwarf" } */
+
+/* This used to fail with location views (implicitly) enabled, because
+ var-tracking (not at assignments) creates a range for d starting at
+ the load after the first call, and we did not split the range,
+ despite its crossing between hot and cold partitions, because it's
+ a single range, that we normally extend to the entire function.
+ However, because the range starts at a (presumed) nonzero view, we
+ end up outputting a loclist instead of a single location entry.
+ But then, -gsplit-dwarf selects (startx,length) loclist entries,
+ and the length ends up computing the difference between symbols in
+ different subsections. */
+
+int a;
+__attribute__((__cold__)) void b();
+
+void e(int *);
+int f();
+
+void c() {
+ int d;
+ e(&d);
+ a = d;
+ if (f())
+ b();
+}
--
2.17.1
--
Alexandre Oliva, freedom fighter https://FSFLA.org/blogs/lxo
Be the change, be Free! FSF Latin America board member
GNU Toolchain Engineer Free Software Evangelist
