From: Sergei Trofimovich <siarh...@google.com>
r11-2447-g:1212cfad093 ("Improve var-tracking dataflow
iteration order") changed 'in_pending' initialization
from:
in_pending = sbitmap_alloc (last_basic_block_for_fn (cfun));
bitmap_ones (in_pending);
to more complex partial bit population algorithm. Due to presence
of uninitialized bits gcc started injecting extra debug entries
in seemigly arbitrary locations and started failing stage2/stage3
bootstrap comparison.
valgrind detected unilitialized bits as:
Conditional jump or move depends on uninitialised value(s)
at 0xDBED3B: vt_find_locations() (var-tracking.c:7230)
by 0xDBF2FB: variable_tracking_main_1() (var-tracking.c:10519)
...
Uninitialised value was created by a heap allocation
at 0x483779F: malloc (vg_replace_malloc.c:307)
by 0x14EE80B: xmalloc (xmalloc.c:147)
by 0x14911F9: sbitmap_alloc(unsigned int) (sbitmap.c:51)
...
The fix explicitly initializes 'in_pending' bitmap with zeros.
gcc:
2020-08-02 Sergei Trofimovich <siarh...@google.com>
PR bootstrap96404
* var-tracking.c (vt_find_locations): Fully initialize
all 'in_pending' bits.
Signed-off-by: Sergei Trofimovich <siarh...@google.com>
---
gcc/var-tracking.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 743f5dcecf6..52aea47a053 100644
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -7096,6 +7096,7 @@ vt_find_locations (void)
in_worklist = sbitmap_alloc (last_basic_block_for_fn (cfun));
in_pending = sbitmap_alloc (last_basic_block_for_fn (cfun));
bitmap_clear (in_worklist);
+ bitmap_clear (in_pending);
/* We're performing the dataflow iteration independently over the
toplevel SCCs plus leading non-cyclic entry blocks and separately
--
2.28.0
